refactor: move packages to internal/

13 files changed, 0 insertions, 3035 deletions

diff --git a/pkg/gitdiff/apply.go b/pkg/gitdiff/apply.go
deleted file mode 100644
index 44bbcca..0000000
--- a/pkg/gitdiff/apply.go
+++ /dev/null
@@ -1,147 +0,0 @@
-package gitdiff
-
-import (
-	"errors"
-	"fmt"
-	"io"
-	"sort"
-)
-
-// Conflict indicates an apply failed due to a conflict between the patch and
-// the source content.
-//
-// Users can test if an error was caused by a conflict by using errors.Is with
-// an empty Conflict:
-//
-//	    if errors.Is(err, &Conflict{}) {
-//		       // handle conflict
-//	    }
-type Conflict struct {
-	msg string
-}
-
-func (c *Conflict) Error() string {
-	return "conflict: " + c.msg
-}
-
-// Is implements error matching for Conflict. Passing an empty instance of
-// Conflict always returns true.
-func (c *Conflict) Is(other error) bool {
-	if other, ok := other.(*Conflict); ok {
-		return other.msg == "" || other.msg == c.msg
-	}
-	return false
-}
-
-// ApplyError wraps an error that occurs during patch application with
-// additional location information, if it is available.
-type ApplyError struct {
-	// Line is the one-indexed line number in the source data
-	Line int64
-	// Fragment is the one-indexed fragment number in the file
-	Fragment int
-	// FragmentLine is the one-indexed line number in the fragment
-	FragmentLine int
-
-	err error
-}
-
-// Unwrap returns the wrapped error.
-func (e *ApplyError) Unwrap() error {
-	return e.err
-}
-
-func (e *ApplyError) Error() string {
-	return fmt.Sprintf("%v", e.err)
-}
-
-type lineNum int
-type fragNum int
-type fragLineNum int
-
-// applyError creates a new *ApplyError wrapping err or augments the information
-// in err with args if it is already an *ApplyError. Returns nil if err is nil.
-func applyError(err error, args ...interface{}) error {
-	if err == nil {
-		return nil
-	}
-
-	e, ok := err.(*ApplyError)
-	if !ok {
-		if err == io.EOF {
-			err = io.ErrUnexpectedEOF
-		}
-		e = &ApplyError{err: err}
-	}
-	for _, arg := range args {
-		switch v := arg.(type) {
-		case lineNum:
-			e.Line = int64(v) + 1
-		case fragNum:
-			e.Fragment = int(v) + 1
-		case fragLineNum:
-			e.FragmentLine = int(v) + 1
-		}
-	}
-	return e
-}
-
-var (
-	errApplyInProgress = errors.New("gitdiff: incompatible apply in progress")
-	errApplierClosed   = errors.New("gitdiff: applier is closed")
-)
-
-// Apply applies the changes in f to src, writing the result to dst. It can
-// apply both text and binary changes.
-//
-// If an error occurs while applying, Apply returns an *ApplyError that
-// annotates the error with additional information. If the error is because of
-// a conflict with the source, the wrapped error will be a *Conflict.
-func Apply(dst io.Writer, src io.ReaderAt, f *File) error {
-	if f.IsBinary {
-		if len(f.TextFragments) > 0 {
-			return applyError(errors.New("binary file contains text fragments"))
-		}
-		if f.BinaryFragment == nil {
-			return applyError(errors.New("binary file does not contain a binary fragment"))
-		}
-	} else {
-		if f.BinaryFragment != nil {
-			return applyError(errors.New("text file contains a binary fragment"))
-		}
-	}
-
-	switch {
-	case f.BinaryFragment != nil:
-		applier := NewBinaryApplier(dst, src)
-		if err := applier.ApplyFragment(f.BinaryFragment); err != nil {
-			return err
-		}
-		return applier.Close()
-
-	case len(f.TextFragments) > 0:
-		frags := make([]*TextFragment, len(f.TextFragments))
-		copy(frags, f.TextFragments)
-
-		sort.Slice(frags, func(i, j int) bool {
-			return frags[i].OldPosition < frags[j].OldPosition
-		})
-
-		// TODO(bkeyes): consider merging overlapping fragments
-		// right now, the application fails if fragments overlap, but it should be
-		// possible to precompute the result of applying them in order
-
-		applier := NewTextApplier(dst, src)
-		for i, frag := range frags {
-			if err := applier.ApplyFragment(frag); err != nil {
-				return applyError(err, fragNum(i))
-			}
-		}
-		return applier.Close()
-
-	default:
-		// nothing to apply, just copy all the data
-		_, err := copyFrom(dst, src, 0)
-		return err
-	}
-}
diff --git a/pkg/gitdiff/apply_binary.go b/pkg/gitdiff/apply_binary.go
deleted file mode 100644
index b34772d..0000000
--- a/pkg/gitdiff/apply_binary.go
+++ /dev/null
@@ -1,206 +0,0 @@
-package gitdiff
-
-import (
-	"errors"
-	"fmt"
-	"io"
-)
-
-// BinaryApplier applies binary changes described in a fragment to source data.
-// The applier must be closed after use.
-type BinaryApplier struct {
-	dst io.Writer
-	src io.ReaderAt
-
-	closed bool
-	dirty  bool
-}
-
-// NewBinaryApplier creates an BinaryApplier that reads data from src and
-// writes modified data to dst.
-func NewBinaryApplier(dst io.Writer, src io.ReaderAt) *BinaryApplier {
-	a := BinaryApplier{
-		dst: dst,
-		src: src,
-	}
-	return &a
-}
-
-// ApplyFragment applies the changes in the fragment f and writes the result to
-// dst. ApplyFragment can be called at most once.
-//
-// If an error occurs while applying, ApplyFragment returns an *ApplyError that
-// annotates the error with additional information. If the error is because of
-// a conflict between a fragment and the source, the wrapped error will be a
-// *Conflict.
-func (a *BinaryApplier) ApplyFragment(f *BinaryFragment) error {
-	if f == nil {
-		return applyError(errors.New("nil fragment"))
-	}
-	if a.closed {
-		return applyError(errApplierClosed)
-	}
-	if a.dirty {
-		return applyError(errApplyInProgress)
-	}
-
-	// mark an apply as in progress, even if it fails before making changes
-	a.dirty = true
-
-	switch f.Method {
-	case BinaryPatchLiteral:
-		if _, err := a.dst.Write(f.Data); err != nil {
-			return applyError(err)
-		}
-	case BinaryPatchDelta:
-		if err := applyBinaryDeltaFragment(a.dst, a.src, f.Data); err != nil {
-			return applyError(err)
-		}
-	default:
-		return applyError(fmt.Errorf("unsupported binary patch method: %v", f.Method))
-	}
-	return nil
-}
-
-// Close writes any data following the last applied fragment and prevents
-// future calls to ApplyFragment.
-func (a *BinaryApplier) Close() (err error) {
-	if a.closed {
-		return nil
-	}
-
-	a.closed = true
-	if !a.dirty {
-		_, err = copyFrom(a.dst, a.src, 0)
-	} else {
-		// do nothing, applying a binary fragment copies all data
-	}
-	return err
-}
-
-func applyBinaryDeltaFragment(dst io.Writer, src io.ReaderAt, frag []byte) error {
-	srcSize, delta := readBinaryDeltaSize(frag)
-	if err := checkBinarySrcSize(src, srcSize); err != nil {
-		return err
-	}
-
-	dstSize, delta := readBinaryDeltaSize(delta)
-
-	for len(delta) > 0 {
-		op := delta[0]
-		if op == 0 {
-			return errors.New("invalid delta opcode 0")
-		}
-
-		var n int64
-		var err error
-		switch op & 0x80 {
-		case 0x80:
-			n, delta, err = applyBinaryDeltaCopy(dst, op, delta[1:], src)
-		case 0x00:
-			n, delta, err = applyBinaryDeltaAdd(dst, op, delta[1:])
-		}
-		if err != nil {
-			return err
-		}
-		dstSize -= n
-	}
-
-	if dstSize != 0 {
-		return errors.New("corrupt binary delta: insufficient or extra data")
-	}
-	return nil
-}
-
-// readBinaryDeltaSize reads a variable length size from a delta-encoded binary
-// fragment, returing the size and the unused data. Data is encoded as:
-//
-//	[[1xxxxxxx]...] [0xxxxxxx]
-//
-// in little-endian order, with 7 bits of the value per byte.
-func readBinaryDeltaSize(d []byte) (size int64, rest []byte) {
-	shift := uint(0)
-	for i, b := range d {
-		size |= int64(b&0x7F) << shift
-		shift += 7
-		if b <= 0x7F {
-			return size, d[i+1:]
-		}
-	}
-	return size, nil
-}
-
-// applyBinaryDeltaAdd applies an add opcode in a delta-encoded binary
-// fragment, returning the amount of data written and the usused part of the
-// fragment. An add operation takes the form:
-//
-//	[0xxxxxx][[data1]...]
-//
-// where the lower seven bits of the opcode is the number of data bytes
-// following the opcode. See also pack-format.txt in the Git source.
-func applyBinaryDeltaAdd(w io.Writer, op byte, delta []byte) (n int64, rest []byte, err error) {
-	size := int(op)
-	if len(delta) < size {
-		return 0, delta, errors.New("corrupt binary delta: incomplete add")
-	}
-	_, err = w.Write(delta[:size])
-	return int64(size), delta[size:], err
-}
-
-// applyBinaryDeltaCopy applies a copy opcode in a delta-encoded binary
-// fragment, returing the amount of data written and the unused part of the
-// fragment. A copy operation takes the form:
-//
-//	[1xxxxxxx][offset1][offset2][offset3][offset4][size1][size2][size3]
-//
-// where the lower seven bits of the opcode determine which non-zero offset and
-// size bytes are present in little-endian order: if bit 0 is set, offset1 is
-// present, etc. If no offset or size bytes are present, offset is 0 and size
-// is 0x10000. See also pack-format.txt in the Git source.
-func applyBinaryDeltaCopy(w io.Writer, op byte, delta []byte, src io.ReaderAt) (n int64, rest []byte, err error) {
-	const defaultSize = 0x10000
-
-	unpack := func(start, bits uint) (v int64) {
-		for i := uint(0); i < bits; i++ {
-			mask := byte(1 << (i + start))
-			if op&mask > 0 {
-				if len(delta) == 0 {
-					err = errors.New("corrupt binary delta: incomplete copy")
-					return
-				}
-				v |= int64(delta[0]) << (8 * i)
-				delta = delta[1:]
-			}
-		}
-		return
-	}
-
-	offset := unpack(0, 4)
-	size := unpack(4, 3)
-	if err != nil {
-		return 0, delta, err
-	}
-	if size == 0 {
-		size = defaultSize
-	}
-
-	// TODO(bkeyes): consider pooling these buffers
-	b := make([]byte, size)
-	if _, err := src.ReadAt(b, offset); err != nil {
-		return 0, delta, err
-	}
-
-	_, err = w.Write(b)
-	return size, delta, err
-}
-
-func checkBinarySrcSize(r io.ReaderAt, size int64) error {
-	ok, err := isLen(r, size)
-	if err != nil {
-		return err
-	}
-	if !ok {
-		return &Conflict{"fragment src size does not match actual src size"}
-	}
-	return nil
-}
diff --git a/pkg/gitdiff/apply_text.go b/pkg/gitdiff/apply_text.go
deleted file mode 100644
index 8d0accb..0000000
--- a/pkg/gitdiff/apply_text.go
+++ /dev/null
@@ -1,158 +0,0 @@
-package gitdiff
-
-import (
-	"errors"
-	"io"
-)
-
-// TextApplier applies changes described in text fragments to source data. If
-// changes are described in multiple fragments, those fragments must be applied
-// in order. The applier must be closed after use.
-//
-// By default, TextApplier operates in "strict" mode, where fragment content
-// and positions must exactly match those of the source.
-type TextApplier struct {
-	dst      io.Writer
-	src      io.ReaderAt
-	lineSrc  LineReaderAt
-	nextLine int64
-
-	closed bool
-	dirty  bool
-}
-
-// NewTextApplier creates a TextApplier that reads data from src and writes
-// modified data to dst. If src implements LineReaderAt, it is used directly.
-func NewTextApplier(dst io.Writer, src io.ReaderAt) *TextApplier {
-	a := TextApplier{
-		dst: dst,
-		src: src,
-	}
-
-	if lineSrc, ok := src.(LineReaderAt); ok {
-		a.lineSrc = lineSrc
-	} else {
-		a.lineSrc = &lineReaderAt{r: src}
-	}
-
-	return &a
-}
-
-// ApplyFragment applies the changes in the fragment f, writing unwritten data
-// before the start of the fragment and any changes from the fragment. If
-// multiple text fragments apply to the same content, ApplyFragment must be
-// called in order of increasing start position. As a result, each fragment can
-// be applied at most once.
-//
-// If an error occurs while applying, ApplyFragment returns an *ApplyError that
-// annotates the error with additional information. If the error is because of
-// a conflict between the fragment and the source, the wrapped error will be a
-// *Conflict.
-func (a *TextApplier) ApplyFragment(f *TextFragment) error {
-	if a.closed {
-		return applyError(errApplierClosed)
-	}
-
-	// mark an apply as in progress, even if it fails before making changes
-	a.dirty = true
-
-	// application code assumes fragment fields are consistent
-	if err := f.Validate(); err != nil {
-		return applyError(err)
-	}
-
-	// lines are 0-indexed, positions are 1-indexed (but new files have position = 0)
-	fragStart := f.OldPosition - 1
-	if fragStart < 0 {
-		fragStart = 0
-	}
-	fragEnd := fragStart + f.OldLines
-
-	start := a.nextLine
-	if fragStart < start {
-		return applyError(&Conflict{"fragment overlaps with an applied fragment"})
-	}
-
-	if f.OldPosition == 0 {
-		ok, err := isLen(a.src, 0)
-		if err != nil {
-			return applyError(err)
-		}
-		if !ok {
-			return applyError(&Conflict{"cannot create new file from non-empty src"})
-		}
-	}
-
-	preimage := make([][]byte, fragEnd-start)
-	n, err := a.lineSrc.ReadLinesAt(preimage, start)
-	if err != nil {
-		// an EOF indicates that source file is shorter than the patch expects,
-		// which should be reported as a conflict rather than a generic error
-		if errors.Is(err, io.EOF) {
-			err = &Conflict{"src has fewer lines than required by fragment"}
-		}
-		return applyError(err, lineNum(start+int64(n)))
-	}
-
-	// copy leading data before the fragment starts
-	for i, line := range preimage[:fragStart-start] {
-		if _, err := a.dst.Write(line); err != nil {
-			a.nextLine = start + int64(i)
-			return applyError(err, lineNum(a.nextLine))
-		}
-	}
-	preimage = preimage[fragStart-start:]
-
-	// apply the changes in the fragment
-	used := int64(0)
-	for i, line := range f.Lines {
-		if err := applyTextLine(a.dst, line, preimage, used); err != nil {
-			a.nextLine = fragStart + used
-			return applyError(err, lineNum(a.nextLine), fragLineNum(i))
-		}
-		if line.Old() {
-			used++
-		}
-	}
-	a.nextLine = fragStart + used
-
-	// new position of +0,0 mean a full delete, so check for leftovers
-	if f.NewPosition == 0 && f.NewLines == 0 {
-		var b [1][]byte
-		n, err := a.lineSrc.ReadLinesAt(b[:], a.nextLine)
-		if err != nil && err != io.EOF {
-			return applyError(err, lineNum(a.nextLine))
-		}
-		if n > 0 {
-			return applyError(&Conflict{"src still has content after full delete"}, lineNum(a.nextLine))
-		}
-	}
-
-	return nil
-}
-
-func applyTextLine(dst io.Writer, line Line, preimage [][]byte, i int64) (err error) {
-	if line.Old() && string(preimage[i]) != line.Line {
-		return &Conflict{"fragment line does not match src line"}
-	}
-	if line.New() {
-		_, err = io.WriteString(dst, line.Line)
-	}
-	return err
-}
-
-// Close writes any data following the last applied fragment and prevents
-// future calls to ApplyFragment.
-func (a *TextApplier) Close() (err error) {
-	if a.closed {
-		return nil
-	}
-
-	a.closed = true
-	if !a.dirty {
-		_, err = copyFrom(a.dst, a.src, 0)
-	} else {
-		_, err = copyLinesFrom(a.dst, a.lineSrc, a.nextLine)
-	}
-	return err
-}
diff --git a/pkg/gitdiff/base85.go b/pkg/gitdiff/base85.go
deleted file mode 100644
index 86db117..0000000
--- a/pkg/gitdiff/base85.go
+++ /dev/null
@@ -1,91 +0,0 @@
-package gitdiff
-
-import (
-	"fmt"
-)
-
-var (
-	b85Table map[byte]byte
-	b85Alpha = []byte(
-		"0123456789" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "!#$%&()*+-;<=>?@^_`{|}~",
-	)
-)
-
-func init() {
-	b85Table = make(map[byte]byte)
-	for i, c := range b85Alpha {
-		b85Table[c] = byte(i)
-	}
-}
-
-// base85Decode decodes Base85-encoded data from src into dst. It uses the
-// alphabet defined by base85.c in the Git source tree. src must contain at
-// least len(dst) bytes of encoded data.
-func base85Decode(dst, src []byte) error {
-	var v uint32
-	var n, ndst int
-	for i, b := range src {
-		if b, ok := b85Table[b]; ok {
-			v = 85*v + uint32(b)
-			n++
-		} else {
-			return fmt.Errorf("invalid base85 byte at index %d: 0x%X", i, src[i])
-		}
-		if n == 5 {
-			rem := len(dst) - ndst
-			for j := 0; j < 4 && j < rem; j++ {
-				dst[ndst] = byte(v >> 24)
-				ndst++
-				v <<= 8
-			}
-			v = 0
-			n = 0
-		}
-	}
-	if n > 0 {
-		return fmt.Errorf("base85 data terminated by underpadded sequence")
-	}
-	if ndst < len(dst) {
-		return fmt.Errorf("base85 data underrun: %d < %d", ndst, len(dst))
-	}
-	return nil
-}
-
-// base85Encode encodes src in Base85, writing the result to dst. It uses the
-// alphabet defined by base85.c in the Git source tree.
-func base85Encode(dst, src []byte) {
-	var di, si int
-
-	encode := func(v uint32) {
-		dst[di+0] = b85Alpha[(v/(85*85*85*85))%85]
-		dst[di+1] = b85Alpha[(v/(85*85*85))%85]
-		dst[di+2] = b85Alpha[(v/(85*85))%85]
-		dst[di+3] = b85Alpha[(v/85)%85]
-		dst[di+4] = b85Alpha[v%85]
-	}
-
-	n := (len(src) / 4) * 4
-	for si < n {
-		encode(uint32(src[si+0])<<24 | uint32(src[si+1])<<16 | uint32(src[si+2])<<8 | uint32(src[si+3]))
-		si += 4
-		di += 5
-	}
-
-	var v uint32
-	switch len(src) - si {
-	case 3:
-		v |= uint32(src[si+2]) << 8
-		fallthrough
-	case 2:
-		v |= uint32(src[si+1]) << 16
-		fallthrough
-	case 1:
-		v |= uint32(src[si+0]) << 24
-		encode(v)
-	}
-}
-
-// base85Len returns the length of n bytes of Base85 encoded data.
-func base85Len(n int) int {
-	return (n + 3) / 4 * 5
-}
diff --git a/pkg/gitdiff/binary.go b/pkg/gitdiff/binary.go
deleted file mode 100644
index 282e323..0000000
--- a/pkg/gitdiff/binary.go
+++ /dev/null
@@ -1,186 +0,0 @@
-package gitdiff
-
-import (
-	"bytes"
-	"compress/zlib"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"strconv"
-	"strings"
-)
-
-func (p *parser) ParseBinaryFragments(f *File) (n int, err error) {
-	isBinary, hasData, err := p.ParseBinaryMarker()
-	if err != nil || !isBinary {
-		return 0, err
-	}
-
-	f.IsBinary = true
-	if !hasData {
-		return 0, nil
-	}
-
-	forward, err := p.ParseBinaryFragmentHeader()
-	if err != nil {
-		return 0, err
-	}
-	if forward == nil {
-		return 0, p.Errorf(0, "missing data for binary patch")
-	}
-	if err := p.ParseBinaryChunk(forward); err != nil {
-		return 0, err
-	}
-	f.BinaryFragment = forward
-
-	// valid for reverse to not exist, but it must be valid if present
-	reverse, err := p.ParseBinaryFragmentHeader()
-	if err != nil {
-		return 1, err
-	}
-	if reverse == nil {
-		return 1, nil
-	}
-	if err := p.ParseBinaryChunk(reverse); err != nil {
-		return 1, err
-	}
-	f.ReverseBinaryFragment = reverse
-
-	return 1, nil
-}
-
-func (p *parser) ParseBinaryMarker() (isBinary bool, hasData bool, err error) {
-	line := p.Line(0)
-	switch {
-	case line == "GIT binary patch\n":
-		hasData = true
-	case isBinaryNoDataMarker(line):
-	default:
-		return false, false, nil
-	}
-
-	if err = p.Next(); err != nil && err != io.EOF {
-		return false, false, err
-	}
-	return true, hasData, nil
-}
-
-func isBinaryNoDataMarker(line string) bool {
-	if strings.HasSuffix(line, " differ\n") {
-		return strings.HasPrefix(line, "Binary files ") || strings.HasPrefix(line, "Files ")
-	}
-	return false
-}
-
-func (p *parser) ParseBinaryFragmentHeader() (*BinaryFragment, error) {
-	parts := strings.SplitN(strings.TrimSuffix(p.Line(0), "\n"), " ", 2)
-	if len(parts) < 2 {
-		return nil, nil
-	}
-
-	frag := &BinaryFragment{}
-	switch parts[0] {
-	case "delta":
-		frag.Method = BinaryPatchDelta
-	case "literal":
-		frag.Method = BinaryPatchLiteral
-	default:
-		return nil, nil
-	}
-
-	var err error
-	if frag.Size, err = strconv.ParseInt(parts[1], 10, 64); err != nil {
-		nerr := err.(*strconv.NumError)
-		return nil, p.Errorf(0, "binary patch: invalid size: %v", nerr.Err)
-	}
-
-	if err := p.Next(); err != nil && err != io.EOF {
-		return nil, err
-	}
-	return frag, nil
-}
-
-func (p *parser) ParseBinaryChunk(frag *BinaryFragment) error {
-	// Binary fragments are encoded as a series of base85 encoded lines. Each
-	// line starts with a character in [A-Za-z] giving the number of bytes on
-	// the line, where A = 1 and z = 52, and ends with a newline character.
-	//
-	// The base85 encoding means each line is a multiple of 5 characters + 2
-	// additional characters for the length byte and the newline. The fragment
-	// ends with a blank line.
-	const (
-		shortestValidLine = "A00000\n"
-		maxBytesPerLine   = 52
-	)
-
-	var data bytes.Buffer
-	buf := make([]byte, maxBytesPerLine)
-	for {
-		line := p.Line(0)
-		if line == "\n" {
-			break
-		}
-		if len(line) < len(shortestValidLine) || (len(line)-2)%5 != 0 {
-			return p.Errorf(0, "binary patch: corrupt data line")
-		}
-
-		byteCount, seq := int(line[0]), line[1:len(line)-1]
-		switch {
-		case 'A' <= byteCount && byteCount <= 'Z':
-			byteCount = byteCount - 'A' + 1
-		case 'a' <= byteCount && byteCount <= 'z':
-			byteCount = byteCount - 'a' + 27
-		default:
-			return p.Errorf(0, "binary patch: invalid length byte")
-		}
-
-		// base85 encodes every 4 bytes into 5 characters, with up to 3 bytes of end padding
-		maxByteCount := len(seq) / 5 * 4
-		if byteCount > maxByteCount || byteCount < maxByteCount-3 {
-			return p.Errorf(0, "binary patch: incorrect byte count")
-		}
-
-		if err := base85Decode(buf[:byteCount], []byte(seq)); err != nil {
-			return p.Errorf(0, "binary patch: %v", err)
-		}
-		data.Write(buf[:byteCount])
-
-		if err := p.Next(); err != nil {
-			if err == io.EOF {
-				return p.Errorf(0, "binary patch: unexpected EOF")
-			}
-			return err
-		}
-	}
-
-	if err := inflateBinaryChunk(frag, &data); err != nil {
-		return p.Errorf(0, "binary patch: %v", err)
-	}
-
-	// consume the empty line that ended the fragment
-	if err := p.Next(); err != nil && err != io.EOF {
-		return err
-	}
-	return nil
-}
-
-func inflateBinaryChunk(frag *BinaryFragment, r io.Reader) error {
-	zr, err := zlib.NewReader(r)
-	if err != nil {
-		return err
-	}
-
-	data, err := ioutil.ReadAll(zr)
-	if err != nil {
-		return err
-	}
-	if err := zr.Close(); err != nil {
-		return err
-	}
-
-	if int64(len(data)) != frag.Size {
-		return fmt.Errorf("%d byte fragment inflated to %d", frag.Size, len(data))
-	}
-	frag.Data = data
-	return nil
-}
diff --git a/pkg/gitdiff/file_header.go b/pkg/gitdiff/file_header.go
deleted file mode 100644
index 7ae4bc9..0000000
--- a/pkg/gitdiff/file_header.go
+++ /dev/null
@@ -1,546 +0,0 @@
-package gitdiff
-
-import (
-	"fmt"
-	"io"
-	"os"
-	"strconv"
-	"strings"
-	"time"
-)
-
-const (
-	devNull = "/dev/null"
-)
-
-// ParseNextFileHeader finds and parses the next file header in the stream. If
-// a header is found, it returns a file and all input before the header. It
-// returns nil if no headers are found before the end of the input.
-func (p *parser) ParseNextFileHeader() (*File, string, error) {
-	var preamble strings.Builder
-	var file *File
-	for {
-		// check for disconnected fragment headers (corrupt patch)
-		frag, err := p.ParseTextFragmentHeader()
-		if err != nil {
-			// not a valid header, nothing to worry about
-			goto NextLine
-		}
-		if frag != nil {
-			return nil, "", p.Errorf(-1, "patch fragment without file header: %s", frag.Header())
-		}
-
-		// check for a git-generated patch
-		file, err = p.ParseGitFileHeader()
-		if err != nil {
-			return nil, "", err
-		}
-		if file != nil {
-			return file, preamble.String(), nil
-		}
-
-		// check for a "traditional" patch
-		file, err = p.ParseTraditionalFileHeader()
-		if err != nil {
-			return nil, "", err
-		}
-		if file != nil {
-			return file, preamble.String(), nil
-		}
-
-	NextLine:
-		preamble.WriteString(p.Line(0))
-		if err := p.Next(); err != nil {
-			if err == io.EOF {
-				break
-			}
-			return nil, "", err
-		}
-	}
-	return nil, preamble.String(), nil
-}
-
-func (p *parser) ParseGitFileHeader() (*File, error) {
-	const prefix = "diff --git "
-
-	if !strings.HasPrefix(p.Line(0), prefix) {
-		return nil, nil
-	}
-	header := p.Line(0)[len(prefix):]
-
-	defaultName, err := parseGitHeaderName(header)
-	if err != nil {
-		return nil, p.Errorf(0, "git file header: %v", err)
-	}
-
-	f := &File{}
-	for {
-		end, err := parseGitHeaderData(f, p.Line(1), defaultName)
-		if err != nil {
-			return nil, p.Errorf(1, "git file header: %v", err)
-		}
-
-		if err := p.Next(); err != nil {
-			if err == io.EOF {
-				break
-			}
-			return nil, err
-		}
-
-		if end {
-			break
-		}
-	}
-
-	if f.OldName == "" && f.NewName == "" {
-		if defaultName == "" {
-			return nil, p.Errorf(0, "git file header: missing filename information")
-		}
-		f.OldName = defaultName
-		f.NewName = defaultName
-	}
-
-	if (f.NewName == "" && !f.IsDelete) || (f.OldName == "" && !f.IsNew) {
-		return nil, p.Errorf(0, "git file header: missing filename information")
-	}
-
-	return f, nil
-}
-
-func (p *parser) ParseTraditionalFileHeader() (*File, error) {
-	const shortestValidFragHeader = "@@ -1 +1 @@\n"
-	const (
-		oldPrefix = "--- "
-		newPrefix = "+++ "
-	)
-
-	oldLine, newLine := p.Line(0), p.Line(1)
-
-	if !strings.HasPrefix(oldLine, oldPrefix) || !strings.HasPrefix(newLine, newPrefix) {
-		return nil, nil
-	}
-	// heuristic: only a file header if followed by a (probable) fragment header
-	if len(p.Line(2)) < len(shortestValidFragHeader) || !strings.HasPrefix(p.Line(2), "@@ -") {
-		return nil, nil
-	}
-
-	// advance past the first two lines so parser is after the header
-	// no EOF check needed because we know there are >=3 valid lines
-	if err := p.Next(); err != nil {
-		return nil, err
-	}
-	if err := p.Next(); err != nil {
-		return nil, err
-	}
-
-	oldName, _, err := parseName(oldLine[len(oldPrefix):], '\t', 0)
-	if err != nil {
-		return nil, p.Errorf(0, "file header: %v", err)
-	}
-
-	newName, _, err := parseName(newLine[len(newPrefix):], '\t', 0)
-	if err != nil {
-		return nil, p.Errorf(1, "file header: %v", err)
-	}
-
-	f := &File{}
-	switch {
-	case oldName == devNull || hasEpochTimestamp(oldLine):
-		f.IsNew = true
-		f.NewName = newName
-	case newName == devNull || hasEpochTimestamp(newLine):
-		f.IsDelete = true
-		f.OldName = oldName
-	default:
-		// if old name is a prefix of new name, use that instead
-		// this avoids picking variants like "file.bak" or "file~"
-		if strings.HasPrefix(newName, oldName) {
-			f.OldName = oldName
-			f.NewName = oldName
-		} else {
-			f.OldName = newName
-			f.NewName = newName
-		}
-	}
-
-	return f, nil
-}
-
-// parseGitHeaderName extracts a default file name from the Git file header
-// line. This is required for mode-only changes and creation/deletion of empty
-// files. Other types of patch include the file name(s) in the header data.
-// If the names in the header do not match because the patch is a rename,
-// return an empty default name.
-func parseGitHeaderName(header string) (string, error) {
-	header = strings.TrimSuffix(header, "\n")
-	if len(header) == 0 {
-		return "", nil
-	}
-
-	var err error
-	var first, second string
-
-	// there are 4 cases to account for:
-	//
-	//   1) unquoted unquoted
-	//   2) unquoted "quoted"
-	//   3) "quoted" unquoted
-	//   4) "quoted" "quoted"
-	//
-	quote := strings.IndexByte(header, '"')
-	switch {
-	case quote < 0:
-		// case 1
-		first = header
-
-	case quote > 0:
-		// case 2
-		first = header[:quote-1]
-		if !isSpace(header[quote-1]) {
-			return "", fmt.Errorf("missing separator")
-		}
-
-		second, _, err = parseQuotedName(header[quote:])
-		if err != nil {
-			return "", err
-		}
-
-	case quote == 0:
-		// case 3 or case 4
-		var n int
-		first, n, err = parseQuotedName(header)
-		if err != nil {
-			return "", err
-		}
-
-		// git accepts multiple spaces after a quoted name, but not after an
-		// unquoted name, since the name might end with one or more spaces
-		for n < len(header) && isSpace(header[n]) {
-			n++
-		}
-		if n == len(header) {
-			return "", nil
-		}
-
-		if header[n] == '"' {
-			second, _, err = parseQuotedName(header[n:])
-			if err != nil {
-				return "", err
-			}
-		} else {
-			second = header[n:]
-		}
-	}
-
-	first = trimTreePrefix(first, 1)
-	if second != "" {
-		if first == trimTreePrefix(second, 1) {
-			return first, nil
-		}
-		return "", nil
-	}
-
-	// at this point, both names are unquoted (case 1)
-	// since names may contain spaces, we can't use a known separator
-	// instead, look for a split that produces two equal names
-
-	for i := 0; i < len(first)-1; i++ {
-		if !isSpace(first[i]) {
-			continue
-		}
-		second = trimTreePrefix(first[i+1:], 1)
-		if name := first[:i]; name == second {
-			return name, nil
-		}
-	}
-	return "", nil
-}
-
-// parseGitHeaderData parses a single line of metadata from a Git file header.
-// It returns true when header parsing is complete; in that case, line was the
-// first line of non-header content.
-func parseGitHeaderData(f *File, line, defaultName string) (end bool, err error) {
-	if len(line) > 0 && line[len(line)-1] == '\n' {
-		line = line[:len(line)-1]
-	}
-
-	for _, hdr := range []struct {
-		prefix string
-		end    bool
-		parse  func(*File, string, string) error
-	}{
-		{"@@ -", true, nil},
-		{"--- ", false, parseGitHeaderOldName},
-		{"+++ ", false, parseGitHeaderNewName},
-		{"old mode ", false, parseGitHeaderOldMode},
-		{"new mode ", false, parseGitHeaderNewMode},
-		{"deleted file mode ", false, parseGitHeaderDeletedMode},
-		{"new file mode ", false, parseGitHeaderCreatedMode},
-		{"copy from ", false, parseGitHeaderCopyFrom},
-		{"copy to ", false, parseGitHeaderCopyTo},
-		{"rename old ", false, parseGitHeaderRenameFrom},
-		{"rename new ", false, parseGitHeaderRenameTo},
-		{"rename from ", false, parseGitHeaderRenameFrom},
-		{"rename to ", false, parseGitHeaderRenameTo},
-		{"similarity index ", false, parseGitHeaderScore},
-		{"dissimilarity index ", false, parseGitHeaderScore},
-		{"index ", false, parseGitHeaderIndex},
-	} {
-		if strings.HasPrefix(line, hdr.prefix) {
-			if hdr.parse != nil {
-				err = hdr.parse(f, line[len(hdr.prefix):], defaultName)
-			}
-			return hdr.end, err
-		}
-	}
-
-	// unknown line indicates the end of the header
-	// this usually happens if the diff is empty
-	return true, nil
-}
-
-func parseGitHeaderOldName(f *File, line, defaultName string) error {
-	name, _, err := parseName(line, '\t', 1)
-	if err != nil {
-		return err
-	}
-	if f.OldName == "" && !f.IsNew {
-		f.OldName = name
-		return nil
-	}
-	return verifyGitHeaderName(name, f.OldName, f.IsNew, "old")
-}
-
-func parseGitHeaderNewName(f *File, line, defaultName string) error {
-	name, _, err := parseName(line, '\t', 1)
-	if err != nil {
-		return err
-	}
-	if f.NewName == "" && !f.IsDelete {
-		f.NewName = name
-		return nil
-	}
-	return verifyGitHeaderName(name, f.NewName, f.IsDelete, "new")
-}
-
-func parseGitHeaderOldMode(f *File, line, defaultName string) (err error) {
-	f.OldMode, err = parseMode(strings.TrimSpace(line))
-	return
-}
-
-func parseGitHeaderNewMode(f *File, line, defaultName string) (err error) {
-	f.NewMode, err = parseMode(strings.TrimSpace(line))
-	return
-}
-
-func parseGitHeaderDeletedMode(f *File, line, defaultName string) error {
-	f.IsDelete = true
-	f.OldName = defaultName
-	return parseGitHeaderOldMode(f, line, defaultName)
-}
-
-func parseGitHeaderCreatedMode(f *File, line, defaultName string) error {
-	f.IsNew = true
-	f.NewName = defaultName
-	return parseGitHeaderNewMode(f, line, defaultName)
-}
-
-func parseGitHeaderCopyFrom(f *File, line, defaultName string) (err error) {
-	f.IsCopy = true
-	f.OldName, _, err = parseName(line, 0, 0)
-	return
-}
-
-func parseGitHeaderCopyTo(f *File, line, defaultName string) (err error) {
-	f.IsCopy = true
-	f.NewName, _, err = parseName(line, 0, 0)
-	return
-}
-
-func parseGitHeaderRenameFrom(f *File, line, defaultName string) (err error) {
-	f.IsRename = true
-	f.OldName, _, err = parseName(line, 0, 0)
-	return
-}
-
-func parseGitHeaderRenameTo(f *File, line, defaultName string) (err error) {
-	f.IsRename = true
-	f.NewName, _, err = parseName(line, 0, 0)
-	return
-}
-
-func parseGitHeaderScore(f *File, line, defaultName string) error {
-	score, err := strconv.ParseInt(strings.TrimSuffix(line, "%"), 10, 32)
-	if err != nil {
-		nerr := err.(*strconv.NumError)
-		return fmt.Errorf("invalid score line: %v", nerr.Err)
-	}
-	if score <= 100 {
-		f.Score = int(score)
-	}
-	return nil
-}
-
-func parseGitHeaderIndex(f *File, line, defaultName string) error {
-	const sep = ".."
-
-	// note that git stops parsing if the OIDs are too long to be valid
-	// checking this requires knowing if the repository uses SHA1 or SHA256
-	// hashes, which we don't know, so we just skip that check
-
-	parts := strings.SplitN(line, " ", 2)
-	oids := strings.SplitN(parts[0], sep, 2)
-
-	if len(oids) < 2 {
-		return fmt.Errorf("invalid index line: missing %q", sep)
-	}
-	f.OldOIDPrefix, f.NewOIDPrefix = oids[0], oids[1]
-
-	if len(parts) > 1 {
-		return parseGitHeaderOldMode(f, parts[1], defaultName)
-	}
-	return nil
-}
-
-func parseMode(s string) (os.FileMode, error) {
-	mode, err := strconv.ParseInt(s, 8, 32)
-	if err != nil {
-		nerr := err.(*strconv.NumError)
-		return os.FileMode(0), fmt.Errorf("invalid mode line: %v", nerr.Err)
-	}
-	return os.FileMode(mode), nil
-}
-
-// parseName extracts a file name from the start of a string and returns the
-// name and the index of the first character after the name. If the name is
-// unquoted and term is non-zero, parsing stops at the first occurrence of
-// term.
-//
-// If the name is exactly "/dev/null", no further processing occurs. Otherwise,
-// if dropPrefix is greater than zero, that number of prefix components
-// separated by forward slashes are dropped from the name and any duplicate
-// slashes are collapsed.
-func parseName(s string, term byte, dropPrefix int) (name string, n int, err error) {
-	if len(s) > 0 && s[0] == '"' {
-		name, n, err = parseQuotedName(s)
-	} else {
-		name, n, err = parseUnquotedName(s, term)
-	}
-	if err != nil {
-		return "", 0, err
-	}
-	if name == devNull {
-		return name, n, nil
-	}
-	return cleanName(name, dropPrefix), n, nil
-}
-
-func parseQuotedName(s string) (name string, n int, err error) {
-	for n = 1; n < len(s); n++ {
-		if s[n] == '"' && s[n-1] != '\\' {
-			n++
-			break
-		}
-	}
-	if n == 2 {
-		return "", 0, fmt.Errorf("missing name")
-	}
-	if name, err = strconv.Unquote(s[:n]); err != nil {
-		return "", 0, err
-	}
-	return name, n, err
-}
-
-func parseUnquotedName(s string, term byte) (name string, n int, err error) {
-	for n = 0; n < len(s); n++ {
-		if s[n] == '\n' {
-			break
-		}
-		if term > 0 && s[n] == term {
-			break
-		}
-	}
-	if n == 0 {
-		return "", 0, fmt.Errorf("missing name")
-	}
-	return s[:n], n, nil
-}
-
-// verifyGitHeaderName checks a parsed name against state set by previous lines
-func verifyGitHeaderName(parsed, existing string, isNull bool, side string) error {
-	if existing != "" {
-		if isNull {
-			return fmt.Errorf("expected %s, but filename is set to %s", devNull, existing)
-		}
-		if existing != parsed {
-			return fmt.Errorf("inconsistent %s filename", side)
-		}
-	}
-	if isNull && parsed != devNull {
-		return fmt.Errorf("expected %s", devNull)
-	}
-	return nil
-}
-
-// cleanName removes double slashes and drops prefix segments.
-func cleanName(name string, drop int) string {
-	var b strings.Builder
-	for i := 0; i < len(name); i++ {
-		if name[i] == '/' {
-			if i < len(name)-1 && name[i+1] == '/' {
-				continue
-			}
-			if drop > 0 {
-				drop--
-				b.Reset()
-				continue
-			}
-		}
-		b.WriteByte(name[i])
-	}
-	return b.String()
-}
-
-// trimTreePrefix removes up to n leading directory components from name.
-func trimTreePrefix(name string, n int) string {
-	i := 0
-	for ; i < len(name) && n > 0; i++ {
-		if name[i] == '/' {
-			n--
-		}
-	}
-	return name[i:]
-}
-
-// hasEpochTimestamp returns true if the string ends with a POSIX-formatted
-// timestamp for the UNIX epoch after a tab character. According to git, this
-// is used by GNU diff to mark creations and deletions.
-func hasEpochTimestamp(s string) bool {
-	const posixTimeLayout = "2006-01-02 15:04:05.9 -0700"
-
-	start := strings.IndexRune(s, '\t')
-	if start < 0 {
-		return false
-	}
-
-	ts := strings.TrimSuffix(s[start+1:], "\n")
-
-	// a valid timestamp can have optional ':' in zone specifier
-	// remove that if it exists so we have a single format
-	if len(ts) >= 3 && ts[len(ts)-3] == ':' {
-		ts = ts[:len(ts)-3] + ts[len(ts)-2:]
-	}
-
-	t, err := time.Parse(posixTimeLayout, ts)
-	if err != nil {
-		return false
-	}
-	if !t.Equal(time.Unix(0, 0)) {
-		return false
-	}
-	return true
-}
-
-func isSpace(c byte) bool {
-	return c == ' ' || c == '\t' || c == '\n'
-}
diff --git a/pkg/gitdiff/format.go b/pkg/gitdiff/format.go
deleted file mode 100644
index d97aba9..0000000
--- a/pkg/gitdiff/format.go
+++ /dev/null
@@ -1,281 +0,0 @@
-package gitdiff
-
-import (
-	"bytes"
-	"compress/zlib"
-	"fmt"
-	"io"
-	"strconv"
-)
-
-type formatter struct {
-	w   io.Writer
-	err error
-}
-
-func newFormatter(w io.Writer) *formatter {
-	return &formatter{w: w}
-}
-
-func (fm *formatter) Write(p []byte) (int, error) {
-	if fm.err != nil {
-		return len(p), nil
-	}
-	if _, err := fm.w.Write(p); err != nil {
-		fm.err = err
-	}
-	return len(p), nil
-}
-
-func (fm *formatter) WriteString(s string) (int, error) {
-	fm.Write([]byte(s))
-	return len(s), nil
-}
-
-func (fm *formatter) WriteByte(c byte) error {
-	fm.Write([]byte{c})
-	return nil
-}
-
-func (fm *formatter) WriteQuotedName(s string) {
-	qpos := 0
-	for i := 0; i < len(s); i++ {
-		ch := s[i]
-		if q, quoted := quoteByte(ch); quoted {
-			if qpos == 0 {
-				fm.WriteByte('"')
-			}
-			fm.WriteString(s[qpos:i])
-			fm.Write(q)
-			qpos = i + 1
-		}
-	}
-	fm.WriteString(s[qpos:])
-	if qpos > 0 {
-		fm.WriteByte('"')
-	}
-}
-
-var quoteEscapeTable = map[byte]byte{
-	'\a': 'a',
-	'\b': 'b',
-	'\t': 't',
-	'\n': 'n',
-	'\v': 'v',
-	'\f': 'f',
-	'\r': 'r',
-	'"':  '"',
-	'\\': '\\',
-}
-
-func quoteByte(b byte) ([]byte, bool) {
-	if q, ok := quoteEscapeTable[b]; ok {
-		return []byte{'\\', q}, true
-	}
-	if b < 0x20 || b >= 0x7F {
-		return []byte{
-			'\\',
-			'0' + (b>>6)&0o3,
-			'0' + (b>>3)&0o7,
-			'0' + (b>>0)&0o7,
-		}, true
-	}
-	return nil, false
-}
-
-func (fm *formatter) FormatFile(f *File) {
-	fm.WriteString("diff --git ")
-
-	var aName, bName string
-	switch {
-	case f.OldName == "":
-		aName = f.NewName
-		bName = f.NewName
-
-	case f.NewName == "":
-		aName = f.OldName
-		bName = f.OldName
-
-	default:
-		aName = f.OldName
-		bName = f.NewName
-	}
-
-	fm.WriteQuotedName("a/" + aName)
-	fm.WriteByte(' ')
-	fm.WriteQuotedName("b/" + bName)
-	fm.WriteByte('\n')
-
-	if f.OldMode != 0 {
-		if f.IsDelete {
-			fmt.Fprintf(fm, "deleted file mode %o\n", f.OldMode)
-		} else if f.NewMode != 0 {
-			fmt.Fprintf(fm, "old mode %o\n", f.OldMode)
-		}
-	}
-
-	if f.NewMode != 0 {
-		if f.IsNew {
-			fmt.Fprintf(fm, "new file mode %o\n", f.NewMode)
-		} else if f.OldMode != 0 {
-			fmt.Fprintf(fm, "new mode %o\n", f.NewMode)
-		}
-	}
-
-	if f.Score > 0 {
-		if f.IsCopy || f.IsRename {
-			fmt.Fprintf(fm, "similarity index %d%%\n", f.Score)
-		} else {
-			fmt.Fprintf(fm, "dissimilarity index %d%%\n", f.Score)
-		}
-	}
-
-	if f.IsCopy {
-		if f.OldName != "" {
-			fm.WriteString("copy from ")
-			fm.WriteQuotedName(f.OldName)
-			fm.WriteByte('\n')
-		}
-		if f.NewName != "" {
-			fm.WriteString("copy to ")
-			fm.WriteQuotedName(f.NewName)
-			fm.WriteByte('\n')
-		}
-	}
-
-	if f.IsRename {
-		if f.OldName != "" {
-			fm.WriteString("rename from ")
-			fm.WriteQuotedName(f.OldName)
-			fm.WriteByte('\n')
-		}
-		if f.NewName != "" {
-			fm.WriteString("rename to ")
-			fm.WriteQuotedName(f.NewName)
-			fm.WriteByte('\n')
-		}
-	}
-
-	if f.OldOIDPrefix != "" && f.NewOIDPrefix != "" {
-		fmt.Fprintf(fm, "index %s..%s", f.OldOIDPrefix, f.NewOIDPrefix)
-
-		// Mode is only included on the index line when it is not changing
-		if f.OldMode != 0 && ((f.NewMode == 0 && !f.IsDelete) || f.OldMode == f.NewMode) {
-			fmt.Fprintf(fm, " %o", f.OldMode)
-		}
-
-		fm.WriteByte('\n')
-	}
-
-	if f.IsBinary {
-		if f.BinaryFragment == nil {
-			fm.WriteString("Binary files ")
-			fm.WriteQuotedName("a/" + aName)
-			fm.WriteString(" and ")
-			fm.WriteQuotedName("b/" + bName)
-			fm.WriteString(" differ\n")
-		} else {
-			fm.WriteString("GIT binary patch\n")
-			fm.FormatBinaryFragment(f.BinaryFragment)
-			if f.ReverseBinaryFragment != nil {
-				fm.FormatBinaryFragment(f.ReverseBinaryFragment)
-			}
-		}
-	}
-
-	// The "---" and "+++" lines only appear for text patches with fragments
-	if len(f.TextFragments) > 0 {
-		fm.WriteString("--- ")
-		if f.OldName == "" {
-			fm.WriteString("/dev/null")
-		} else {
-			fm.WriteQuotedName("a/" + f.OldName)
-		}
-		fm.WriteByte('\n')
-
-		fm.WriteString("+++ ")
-		if f.NewName == "" {
-			fm.WriteString("/dev/null")
-		} else {
-			fm.WriteQuotedName("b/" + f.NewName)
-		}
-		fm.WriteByte('\n')
-
-		for _, frag := range f.TextFragments {
-			fm.FormatTextFragment(frag)
-		}
-	}
-}
-
-func (fm *formatter) FormatTextFragment(f *TextFragment) {
-	fm.FormatTextFragmentHeader(f)
-	fm.WriteByte('\n')
-
-	for _, line := range f.Lines {
-		fm.WriteString(line.Op.String())
-		fm.WriteString(line.Line)
-		if line.NoEOL() {
-			fm.WriteString("\n\\ No newline at end of file\n")
-		}
-	}
-}
-
-func (fm *formatter) FormatTextFragmentHeader(f *TextFragment) {
-	fmt.Fprintf(fm, "@@ -%d,%d +%d,%d @@", f.OldPosition, f.OldLines, f.NewPosition, f.NewLines)
-	if f.Comment != "" {
-		fm.WriteByte(' ')
-		fm.WriteString(f.Comment)
-	}
-}
-
-func (fm *formatter) FormatBinaryFragment(f *BinaryFragment) {
-	const (
-		maxBytesPerLine = 52
-	)
-
-	switch f.Method {
-	case BinaryPatchDelta:
-		fm.WriteString("delta ")
-	case BinaryPatchLiteral:
-		fm.WriteString("literal ")
-	}
-	fm.Write(strconv.AppendInt(nil, f.Size, 10))
-	fm.WriteByte('\n')
-
-	data := deflateBinaryChunk(f.Data)
-	n := (len(data) / maxBytesPerLine) * maxBytesPerLine
-
-	buf := make([]byte, base85Len(maxBytesPerLine))
-	for i := 0; i < n; i += maxBytesPerLine {
-		base85Encode(buf, data[i:i+maxBytesPerLine])
-		fm.WriteByte('z')
-		fm.Write(buf)
-		fm.WriteByte('\n')
-	}
-	if remainder := len(data) - n; remainder > 0 {
-		buf = buf[0:base85Len(remainder)]
-
-		sizeChar := byte(remainder)
-		if remainder <= 26 {
-			sizeChar = 'A' + sizeChar - 1
-		} else {
-			sizeChar = 'a' + sizeChar - 27
-		}
-
-		base85Encode(buf, data[n:])
-		fm.WriteByte(sizeChar)
-		fm.Write(buf)
-		fm.WriteByte('\n')
-	}
-	fm.WriteByte('\n')
-}
-
-func deflateBinaryChunk(data []byte) []byte {
-	var b bytes.Buffer
-
-	zw := zlib.NewWriter(&b)
-	_, _ = zw.Write(data)
-	_ = zw.Close()
-
-	return b.Bytes()
-}
diff --git a/pkg/gitdiff/gitdiff.go b/pkg/gitdiff/gitdiff.go
deleted file mode 100644
index 5365645..0000000
--- a/pkg/gitdiff/gitdiff.go
+++ /dev/null
@@ -1,230 +0,0 @@
-package gitdiff
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"strings"
-)
-
-// File describes changes to a single file. It can be either a text file or a
-// binary file.
-type File struct {
-	OldName string
-	NewName string
-
-	IsNew    bool
-	IsDelete bool
-	IsCopy   bool
-	IsRename bool
-
-	OldMode os.FileMode
-	NewMode os.FileMode
-
-	OldOIDPrefix string
-	NewOIDPrefix string
-	Score        int
-
-	// TextFragments contains the fragments describing changes to a text file. It
-	// may be empty if the file is empty or if only the mode changes.
-	TextFragments []*TextFragment
-
-	// IsBinary is true if the file is a binary file. If the patch includes
-	// binary data, BinaryFragment will be non-nil and describe the changes to
-	// the data. If the patch is reversible, ReverseBinaryFragment will also be
-	// non-nil and describe the changes needed to restore the original file
-	// after applying the changes in BinaryFragment.
-	IsBinary              bool
-	BinaryFragment        *BinaryFragment
-	ReverseBinaryFragment *BinaryFragment
-}
-
-// String returns a git diff representation of this file. The value can be
-// parsed by this library to obtain the same File, but may not be the same as
-// the original input.
-func (f *File) String() string {
-	var diff strings.Builder
-	newFormatter(&diff).FormatFile(f)
-	return diff.String()
-}
-
-// TextFragment describes changed lines starting at a specific line in a text file.
-type TextFragment struct {
-	Comment string
-
-	OldPosition int64
-	OldLines    int64
-
-	NewPosition int64
-	NewLines    int64
-
-	LinesAdded   int64
-	LinesDeleted int64
-
-	LeadingContext  int64
-	TrailingContext int64
-
-	Lines []Line
-}
-
-// String returns a git diff format of this fragment. See [File.String] for
-// more details on this format.
-func (f *TextFragment) String() string {
-	var diff strings.Builder
-	newFormatter(&diff).FormatTextFragment(f)
-	return diff.String()
-}
-
-// Header returns a git diff header of this fragment. See [File.String] for
-// more details on this format.
-func (f *TextFragment) Header() string {
-	var hdr strings.Builder
-	newFormatter(&hdr).FormatTextFragmentHeader(f)
-	return hdr.String()
-}
-
-// Validate checks that the fragment is self-consistent and appliable. Validate
-// returns an error if and only if the fragment is invalid.
-func (f *TextFragment) Validate() error {
-	if f == nil {
-		return errors.New("nil fragment")
-	}
-
-	var (
-		oldLines, newLines                     int64
-		leadingContext, trailingContext        int64
-		contextLines, addedLines, deletedLines int64
-	)
-
-	// count the types of lines in the fragment content
-	for i, line := range f.Lines {
-		switch line.Op {
-		case OpContext:
-			oldLines++
-			newLines++
-			contextLines++
-			if addedLines == 0 && deletedLines == 0 {
-				leadingContext++
-			} else {
-				trailingContext++
-			}
-		case OpAdd:
-			newLines++
-			addedLines++
-			trailingContext = 0
-		case OpDelete:
-			oldLines++
-			deletedLines++
-			trailingContext = 0
-		default:
-			return fmt.Errorf("unknown operator %q on line %d", line.Op, i+1)
-		}
-	}
-
-	// check the actual counts against the reported counts
-	if oldLines != f.OldLines {
-		return lineCountErr("old", oldLines, f.OldLines)
-	}
-	if newLines != f.NewLines {
-		return lineCountErr("new", newLines, f.NewLines)
-	}
-	if leadingContext != f.LeadingContext {
-		return lineCountErr("leading context", leadingContext, f.LeadingContext)
-	}
-	if trailingContext != f.TrailingContext {
-		return lineCountErr("trailing context", trailingContext, f.TrailingContext)
-	}
-	if addedLines != f.LinesAdded {
-		return lineCountErr("added", addedLines, f.LinesAdded)
-	}
-	if deletedLines != f.LinesDeleted {
-		return lineCountErr("deleted", deletedLines, f.LinesDeleted)
-	}
-
-	// if a file is being created, it can only contain additions
-	if f.OldPosition == 0 && f.OldLines != 0 {
-		return errors.New("file creation fragment contains context or deletion lines")
-	}
-
-	return nil
-}
-
-func lineCountErr(kind string, actual, reported int64) error {
-	return fmt.Errorf("fragment contains %d %s lines but reports %d", actual, kind, reported)
-}
-
-// Line is a line in a text fragment.
-type Line struct {
-	Op   LineOp
-	Line string
-}
-
-func (fl Line) String() string {
-	return fl.Op.String() + fl.Line
-}
-
-// Old returns true if the line appears in the old content of the fragment.
-func (fl Line) Old() bool {
-	return fl.Op == OpContext || fl.Op == OpDelete
-}
-
-// New returns true if the line appears in the new content of the fragment.
-func (fl Line) New() bool {
-	return fl.Op == OpContext || fl.Op == OpAdd
-}
-
-// NoEOL returns true if the line is missing a trailing newline character.
-func (fl Line) NoEOL() bool {
-	return len(fl.Line) == 0 || fl.Line[len(fl.Line)-1] != '\n'
-}
-
-// LineOp describes the type of a text fragment line: context, added, or removed.
-type LineOp int
-
-const (
-	// OpContext indicates a context line
-	OpContext LineOp = iota
-	// OpDelete indicates a deleted line
-	OpDelete
-	// OpAdd indicates an added line
-	OpAdd
-)
-
-func (op LineOp) String() string {
-	switch op {
-	case OpContext:
-		return " "
-	case OpDelete:
-		return "-"
-	case OpAdd:
-		return "+"
-	}
-	return "?"
-}
-
-// BinaryFragment describes changes to a binary file.
-type BinaryFragment struct {
-	Method BinaryPatchMethod
-	Size   int64
-	Data   []byte
-}
-
-// BinaryPatchMethod is the method used to create and apply the binary patch.
-type BinaryPatchMethod int
-
-const (
-	// BinaryPatchDelta indicates the data uses Git's packfile encoding
-	BinaryPatchDelta BinaryPatchMethod = iota
-	// BinaryPatchLiteral indicates the data is the exact file content
-	BinaryPatchLiteral
-)
-
-// String returns a git diff format of this fragment. Due to differences in
-// zlib implementation between Go and Git, encoded binary data in the result
-// will likely differ from what Git produces for the same input. See
-// [File.String] for more details on this format.
-func (f *BinaryFragment) String() string {
-	var diff strings.Builder
-	newFormatter(&diff).FormatBinaryFragment(f)
-	return diff.String()
-}
diff --git a/pkg/gitdiff/io.go b/pkg/gitdiff/io.go
deleted file mode 100644
index 8143238..0000000
--- a/pkg/gitdiff/io.go
+++ /dev/null
@@ -1,220 +0,0 @@
-package gitdiff
-
-import (
-	"errors"
-	"io"
-)
-
-const (
-	byteBufferSize  = 32 * 1024 // from io.Copy
-	lineBufferSize  = 32
-	indexBufferSize = 1024
-)
-
-// LineReaderAt is the interface that wraps the ReadLinesAt method.
-//
-// ReadLinesAt reads len(lines) into lines starting at line offset. It returns
-// the number of lines read (0 <= n <= len(lines)) and any error encountered.
-// Line numbers are zero-indexed.
-//
-// If n < len(lines), ReadLinesAt returns a non-nil error explaining why more
-// lines were not returned.
-//
-// Lines read by ReadLinesAt include the newline character. The last line does
-// not have a final newline character if the input ends without one.
-type LineReaderAt interface {
-	ReadLinesAt(lines [][]byte, offset int64) (n int, err error)
-}
-
-type lineReaderAt struct {
-	r     io.ReaderAt
-	index []int64
-	eof   bool
-}
-
-func (r *lineReaderAt) ReadLinesAt(lines [][]byte, offset int64) (n int, err error) {
-	if offset < 0 {
-		return 0, errors.New("ReadLinesAt: negative offset")
-	}
-	if len(lines) == 0 {
-		return 0, nil
-	}
-
-	count := len(lines)
-	startLine := offset
-	endLine := startLine + int64(count)
-
-	if endLine > int64(len(r.index)) && !r.eof {
-		if err := r.indexTo(endLine); err != nil {
-			return 0, err
-		}
-	}
-	if startLine >= int64(len(r.index)) {
-		return 0, io.EOF
-	}
-
-	buf, byteOffset, err := r.readBytes(startLine, int64(count))
-	if err != nil {
-		return 0, err
-	}
-
-	for n = 0; n < count && startLine+int64(n) < int64(len(r.index)); n++ {
-		lineno := startLine + int64(n)
-		start, end := int64(0), r.index[lineno]-byteOffset
-		if lineno > 0 {
-			start = r.index[lineno-1] - byteOffset
-		}
-		lines[n] = buf[start:end]
-	}
-
-	if n < count {
-		return n, io.EOF
-	}
-	return n, nil
-}
-
-// indexTo reads data and computes the line index until there is information
-// for line or a read returns io.EOF. It returns an error if and only if there
-// is an error reading data.
-func (r *lineReaderAt) indexTo(line int64) error {
-	var buf [indexBufferSize]byte
-
-	offset := r.lastOffset()
-	for int64(len(r.index)) < line {
-		n, err := r.r.ReadAt(buf[:], offset)
-		if err != nil && err != io.EOF {
-			return err
-		}
-		for _, b := range buf[:n] {
-			offset++
-			if b == '\n' {
-				r.index = append(r.index, offset)
-			}
-		}
-		if err == io.EOF {
-			if offset > r.lastOffset() {
-				r.index = append(r.index, offset)
-			}
-			r.eof = true
-			break
-		}
-	}
-	return nil
-}
-
-func (r *lineReaderAt) lastOffset() int64 {
-	if n := len(r.index); n > 0 {
-		return r.index[n-1]
-	}
-	return 0
-}
-
-// readBytes reads the bytes of the n lines starting at line and returns the
-// bytes and the offset of the first byte in the underlying source.
-func (r *lineReaderAt) readBytes(line, n int64) (b []byte, offset int64, err error) {
-	indexLen := int64(len(r.index))
-
-	var size int64
-	if line > indexLen {
-		offset = r.index[indexLen-1]
-	} else if line > 0 {
-		offset = r.index[line-1]
-	}
-	if n > 0 {
-		if line+n > indexLen {
-			size = r.index[indexLen-1] - offset
-		} else {
-			size = r.index[line+n-1] - offset
-		}
-	}
-
-	b = make([]byte, size)
-	if _, err := r.r.ReadAt(b, offset); err != nil {
-		if err == io.EOF {
-			err = errors.New("ReadLinesAt: corrupt line index or changed source data")
-		}
-		return nil, 0, err
-	}
-	return b, offset, nil
-}
-
-func isLen(r io.ReaderAt, n int64) (bool, error) {
-	off := n - 1
-	if off < 0 {
-		off = 0
-	}
-
-	var b [2]byte
-	nr, err := r.ReadAt(b[:], off)
-	if err == io.EOF {
-		return (n == 0 && nr == 0) || (n > 0 && nr == 1), nil
-	}
-	return false, err
-}
-
-// copyFrom writes bytes starting from offset off in src to dst stopping at the
-// end of src or at the first error. copyFrom returns the number of bytes
-// written and any error.
-func copyFrom(dst io.Writer, src io.ReaderAt, off int64) (written int64, err error) {
-	buf := make([]byte, byteBufferSize)
-	for {
-		nr, rerr := src.ReadAt(buf, off)
-		if nr > 0 {
-			nw, werr := dst.Write(buf[0:nr])
-			if nw > 0 {
-				written += int64(nw)
-			}
-			if werr != nil {
-				err = werr
-				break
-			}
-			if nr != nw {
-				err = io.ErrShortWrite
-				break
-			}
-			off += int64(nr)
-		}
-		if rerr != nil {
-			if rerr != io.EOF {
-				err = rerr
-			}
-			break
-		}
-	}
-	return written, err
-}
-
-// copyLinesFrom writes lines starting from line off in src to dst stopping at
-// the end of src or at the first error. copyLinesFrom returns the number of
-// lines written and any error.
-func copyLinesFrom(dst io.Writer, src LineReaderAt, off int64) (written int64, err error) {
-	buf := make([][]byte, lineBufferSize)
-ReadLoop:
-	for {
-		nr, rerr := src.ReadLinesAt(buf, off)
-		if nr > 0 {
-			for _, line := range buf[0:nr] {
-				nw, werr := dst.Write(line)
-				if nw > 0 {
-					written++
-				}
-				if werr != nil {
-					err = werr
-					break ReadLoop
-				}
-				if len(line) != nw {
-					err = io.ErrShortWrite
-					break ReadLoop
-				}
-			}
-			off += int64(nr)
-		}
-		if rerr != nil {
-			if rerr != io.EOF {
-				err = rerr
-			}
-			break
-		}
-	}
-	return written, err
-}
diff --git a/pkg/gitdiff/parser.go b/pkg/gitdiff/parser.go
deleted file mode 100644
index e8f8430..0000000
--- a/pkg/gitdiff/parser.go
+++ /dev/null
@@ -1,142 +0,0 @@
-// Package gitdiff parses and applies patches generated by Git. It supports
-// line-oriented text patches, binary patches, and can also parse standard
-// unified diffs generated by other tools.
-package gitdiff
-
-import (
-	"bufio"
-	"fmt"
-	"io"
-)
-
-// Parse parses a patch with changes to one or more files. Any content before
-// the first file is returned as the second value. If an error occurs while
-// parsing, it returns all files parsed before the error.
-//
-// Parse expects to receive a single patch. If the input may contain multiple
-// patches (for example, if it is an mbox file), callers should split it into
-// individual patches and call Parse on each one.
-func Parse(r io.Reader) ([]*File, string, error) {
-	p := newParser(r)
-
-	if err := p.Next(); err != nil {
-		if err == io.EOF {
-			return nil, "", nil
-		}
-		return nil, "", err
-	}
-
-	var preamble string
-	var files []*File
-	for {
-		file, pre, err := p.ParseNextFileHeader()
-		if err != nil {
-			return files, preamble, err
-		}
-		if len(files) == 0 {
-			preamble = pre
-		}
-		if file == nil {
-			break
-		}
-
-		for _, fn := range []func(*File) (int, error){
-			p.ParseTextFragments,
-			p.ParseBinaryFragments,
-		} {
-			n, err := fn(file)
-			if err != nil {
-				return files, preamble, err
-			}
-			if n > 0 {
-				break
-			}
-		}
-
-		files = append(files, file)
-	}
-
-	return files, preamble, nil
-}
-
-// TODO(bkeyes): consider exporting the parser type with configuration
-// this would enable OID validation, p-value guessing, and prefix stripping
-// by allowing users to set or override defaults
-
-// parser invariants:
-// - methods that parse objects:
-//     - start with the parser on the first line of the first object
-//     - if returning nil, do not advance
-//     - if returning an error, do not advance past the object
-//     - if returning an object, advance to the first line after the object
-// - any exported parsing methods must initialize the parser by calling Next()
-
-type stringReader interface {
-	ReadString(delim byte) (string, error)
-}
-
-type parser struct {
-	r stringReader
-
-	eof    bool
-	lineno int64
-	lines  [3]string
-}
-
-func newParser(r io.Reader) *parser {
-	if r, ok := r.(stringReader); ok {
-		return &parser{r: r}
-	}
-	return &parser{r: bufio.NewReader(r)}
-}
-
-// Next advances the parser by one line. It returns any error encountered while
-// reading the line, including io.EOF when the end of stream is reached.
-func (p *parser) Next() error {
-	if p.eof {
-		return io.EOF
-	}
-
-	if p.lineno == 0 {
-		// on first call to next, need to shift in all lines
-		for i := 0; i < len(p.lines)-1; i++ {
-			if err := p.shiftLines(); err != nil && err != io.EOF {
-				return err
-			}
-		}
-	}
-
-	err := p.shiftLines()
-	if err != nil && err != io.EOF {
-		return err
-	}
-
-	p.lineno++
-	if p.lines[0] == "" {
-		p.eof = true
-		return io.EOF
-	}
-	return nil
-}
-
-func (p *parser) shiftLines() (err error) {
-	for i := 0; i < len(p.lines)-1; i++ {
-		p.lines[i] = p.lines[i+1]
-	}
-	p.lines[len(p.lines)-1], err = p.r.ReadString('\n')
-	return
-}
-
-// Line returns a line from the parser without advancing it. A delta of 0
-// returns the current line, while higher deltas return read-ahead lines. It
-// returns an empty string if the delta is higher than the available lines,
-// either because of the buffer size or because the parser reached the end of
-// the input. Valid lines always contain at least a newline character.
-func (p *parser) Line(delta uint) string {
-	return p.lines[delta]
-}
-
-// Errorf generates an error and appends the current line information.
-func (p *parser) Errorf(delta int64, msg string, args ...interface{}) error {
-	return fmt.Errorf("gitdiff: line %d: %s", p.lineno+delta, fmt.Sprintf(msg, args...))
-}
diff --git a/pkg/gitdiff/patch_header.go b/pkg/gitdiff/patch_header.go
deleted file mode 100644
index f047059..0000000
--- a/pkg/gitdiff/patch_header.go
+++ /dev/null
@@ -1,470 +0,0 @@
-package gitdiff
-
-import (
-	"bufio"
-	"errors"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"mime/quotedprintable"
-	"net/mail"
-	"strconv"
-	"strings"
-	"time"
-	"unicode"
-)
-
-const (
-	mailHeaderPrefix        = "From "
-	prettyHeaderPrefix      = "commit "
-	mailMinimumHeaderPrefix = "From:"
-)
-
-// PatchHeader is a parsed version of the preamble content that appears before
-// the first diff in a patch. It includes metadata about the patch, such as the
-// author and a subject.
-type PatchHeader struct {
-	// The SHA of the commit the patch was generated from. Empty if the SHA is
-	// not included in the header.
-	SHA string
-
-	// The author details of the patch. If these details are not included in
-	// the header, Author is nil and AuthorDate is the zero time.
-	Author     *PatchIdentity
-	AuthorDate time.Time
-
-	// The committer details of the patch. If these details are not included in
-	// the header, Committer is nil and CommitterDate is the zero time.
-	Committer     *PatchIdentity
-	CommitterDate time.Time
-
-	// The title and body of the commit message describing the changes in the
-	// patch. Empty if no message is included in the header.
-	Title string
-	Body  string
-
-	// If the preamble looks like an email, ParsePatchHeader will
-	// remove prefixes such as `Re: ` and `[PATCH v3 5/17]` from the
-	// Title and place them here.
-	SubjectPrefix string
-
-	// If the preamble looks like an email, and it contains a `---`
-	// line, that line will be removed and everything after it will be
-	// placed in BodyAppendix.
-	BodyAppendix string
-}
-
-// Message returns the commit message for the header. The message consists of
-// the title and the body separated by an empty line.
-func (h *PatchHeader) Message() string {
-	var msg strings.Builder
-	if h != nil {
-		msg.WriteString(h.Title)
-		if h.Body != "" {
-			msg.WriteString("\n\n")
-			msg.WriteString(h.Body)
-		}
-	}
-	return msg.String()
-}
-
-// ParsePatchDate parses a patch date string. It returns the parsed time or an
-// error if s has an unknown format. ParsePatchDate supports the iso, rfc,
-// short, raw, unix, and default formats (with local variants) used by the
-// --date flag in Git.
-func ParsePatchDate(s string) (time.Time, error) {
-	const (
-		isoFormat          = "2006-01-02 15:04:05 -0700"
-		isoStrictFormat    = "2006-01-02T15:04:05-07:00"
-		rfc2822Format      = "Mon, 2 Jan 2006 15:04:05 -0700"
-		shortFormat        = "2006-01-02"
-		defaultFormat      = "Mon Jan 2 15:04:05 2006 -0700"
-		defaultLocalFormat = "Mon Jan 2 15:04:05 2006"
-	)
-
-	if s == "" {
-		return time.Time{}, nil
-	}
-
-	for _, fmt := range []string{
-		isoFormat,
-		isoStrictFormat,
-		rfc2822Format,
-		shortFormat,
-		defaultFormat,
-		defaultLocalFormat,
-	} {
-		if t, err := time.ParseInLocation(fmt, s, time.Local); err == nil {
-			return t, nil
-		}
-	}
-
-	// unix format
-	if unix, err := strconv.ParseInt(s, 10, 64); err == nil {
-		return time.Unix(unix, 0), nil
-	}
-
-	// raw format
-	if space := strings.IndexByte(s, ' '); space > 0 {
-		unix, uerr := strconv.ParseInt(s[:space], 10, 64)
-		zone, zerr := time.Parse("-0700", s[space+1:])
-		if uerr == nil && zerr == nil {
-			return time.Unix(unix, 0).In(zone.Location()), nil
-		}
-	}
-
-	return time.Time{}, fmt.Errorf("unknown date format: %s", s)
-}
-
-// A PatchHeaderOption modifies the behavior of ParsePatchHeader.
-type PatchHeaderOption func(*patchHeaderOptions)
-
-// SubjectCleanMode controls how ParsePatchHeader cleans subject lines when
-// parsing mail-formatted patches.
-type SubjectCleanMode int
-
-const (
-	// SubjectCleanWhitespace removes leading and trailing whitespace.
-	SubjectCleanWhitespace SubjectCleanMode = iota
-
-	// SubjectCleanAll removes leading and trailing whitespace, leading "Re:",
-	// "re:", and ":" strings, and leading strings enclosed by '[' and ']'.
-	// This is the default behavior of git (see `git mailinfo`) and this
-	// package.
-	SubjectCleanAll
-
-	// SubjectCleanPatchOnly is the same as SubjectCleanAll, but only removes
-	// leading strings enclosed by '[' and ']' if they start with "PATCH".
-	SubjectCleanPatchOnly
-)
-
-// WithSubjectCleanMode sets the SubjectCleanMode for header parsing. By
-// default, uses SubjectCleanAll.
-func WithSubjectCleanMode(m SubjectCleanMode) PatchHeaderOption {
-	return func(opts *patchHeaderOptions) {
-		opts.subjectCleanMode = m
-	}
-}
-
-type patchHeaderOptions struct {
-	subjectCleanMode SubjectCleanMode
-}
-
-// ParsePatchHeader parses the preamble string returned by [Parse] into a
-// PatchHeader. Due to the variety of header formats, some fields of the parsed
-// PatchHeader may be unset after parsing.
-//
-// Supported formats are the short, medium, full, fuller, and email pretty
-// formats used by `git diff`, `git log`, and `git show` and the UNIX mailbox
-// format used by `git format-patch`.
-//
-// When parsing mail-formatted headers, ParsePatchHeader tries to remove
-// email-specific content from the title and body:
-//
-//   - Based on the SubjectCleanMode, remove prefixes like reply markers and
-//     "[PATCH]" strings from the subject, saving any removed content in the
-//     SubjectPrefix field. Parsing always discards leading and trailing
-//     whitespace from the subject line. The default mode is SubjectCleanAll.
-//
-//   - If the body contains a "---" line (3 hyphens), remove that line and any
-//     content after it from the body and save it in the BodyAppendix field.
-//
-// ParsePatchHeader tries to process content it does not understand wthout
-// returning errors, but will return errors if well-identified content like
-// dates or identies uses unknown or invalid formats.
-func ParsePatchHeader(header string, options ...PatchHeaderOption) (*PatchHeader, error) {
-	opts := patchHeaderOptions{
-		subjectCleanMode: SubjectCleanAll, // match git defaults
-	}
-	for _, optFn := range options {
-		optFn(&opts)
-	}
-
-	header = strings.TrimSpace(header)
-	if header == "" {
-		return &PatchHeader{}, nil
-	}
-
-	var firstLine, rest string
-	if idx := strings.IndexByte(header, '\n'); idx >= 0 {
-		firstLine = header[:idx]
-		rest = header[idx+1:]
-	} else {
-		firstLine = header
-		rest = ""
-	}
-
-	switch {
-	case strings.HasPrefix(firstLine, mailHeaderPrefix):
-		return parseHeaderMail(firstLine, strings.NewReader(rest), opts)
-
-	case strings.HasPrefix(firstLine, mailMinimumHeaderPrefix):
-		// With a minimum header, the first line is part of the actual mail
-		// content and needs to be parsed as part of the "rest"
-		return parseHeaderMail("", strings.NewReader(header), opts)
-
-	case strings.HasPrefix(firstLine, prettyHeaderPrefix):
-		return parseHeaderPretty(firstLine, strings.NewReader(rest))
-	}
-
-	return nil, errors.New("unrecognized patch header format")
-}
-
-func parseHeaderPretty(prettyLine string, r io.Reader) (*PatchHeader, error) {
-	const (
-		authorPrefix     = "Author:"
-		commitPrefix     = "Commit:"
-		datePrefix       = "Date:"
-		authorDatePrefix = "AuthorDate:"
-		commitDatePrefix = "CommitDate:"
-	)
-
-	h := &PatchHeader{}
-
-	prettyLine = strings.TrimPrefix(prettyLine, prettyHeaderPrefix)
-	if i := strings.IndexByte(prettyLine, ' '); i > 0 {
-		h.SHA = prettyLine[:i]
-	} else {
-		h.SHA = prettyLine
-	}
-
-	s := bufio.NewScanner(r)
-	for s.Scan() {
-		line := s.Text()
-
-		// empty line marks end of fields, remaining lines are title/message
-		if strings.TrimSpace(line) == "" {
-			break
-		}
-
-		switch {
-		case strings.HasPrefix(line, authorPrefix):
-			u, err := ParsePatchIdentity(line[len(authorPrefix):])
-			if err != nil {
-				return nil, err
-			}
-			h.Author = &u
-
-		case strings.HasPrefix(line, commitPrefix):
-			u, err := ParsePatchIdentity(line[len(commitPrefix):])
-			if err != nil {
-				return nil, err
-			}
-			h.Committer = &u
-
-		case strings.HasPrefix(line, datePrefix):
-			d, err := ParsePatchDate(strings.TrimSpace(line[len(datePrefix):]))
-			if err != nil {
-				return nil, err
-			}
-			h.AuthorDate = d
-
-		case strings.HasPrefix(line, authorDatePrefix):
-			d, err := ParsePatchDate(strings.TrimSpace(line[len(authorDatePrefix):]))
-			if err != nil {
-				return nil, err
-			}
-			h.AuthorDate = d
-
-		case strings.HasPrefix(line, commitDatePrefix):
-			d, err := ParsePatchDate(strings.TrimSpace(line[len(commitDatePrefix):]))
-			if err != nil {
-				return nil, err
-			}
-			h.CommitterDate = d
-		}
-	}
-	if s.Err() != nil {
-		return nil, s.Err()
-	}
-
-	title, indent := scanMessageTitle(s)
-	if s.Err() != nil {
-		return nil, s.Err()
-	}
-	h.Title = title
-
-	if title != "" {
-		// Don't check for an appendix, pretty headers do not contain them
-		body, _ := scanMessageBody(s, indent, false)
-		if s.Err() != nil {
-			return nil, s.Err()
-		}
-		h.Body = body
-	}
-
-	return h, nil
-}
-
-func scanMessageTitle(s *bufio.Scanner) (title string, indent string) {
-	var b strings.Builder
-	for i := 0; s.Scan(); i++ {
-		line := s.Text()
-		trimLine := strings.TrimSpace(line)
-		if trimLine == "" {
-			break
-		}
-
-		if i == 0 {
-			if start := strings.IndexFunc(line, func(c rune) bool { return !unicode.IsSpace(c) }); start > 0 {
-				indent = line[:start]
-			}
-		}
-		if b.Len() > 0 {
-			b.WriteByte(' ')
-		}
-		b.WriteString(trimLine)
-	}
-	return b.String(), indent
-}
-
-func scanMessageBody(s *bufio.Scanner, indent string, separateAppendix bool) (string, string) {
-	// Body and appendix
-	var body, appendix strings.Builder
-	c := &body
-	var empty int
-	for i := 0; s.Scan(); i++ {
-		line := s.Text()
-
-		line = strings.TrimRightFunc(line, unicode.IsSpace)
-		line = strings.TrimPrefix(line, indent)
-
-		if line == "" {
-			empty++
-			continue
-		}
-
-		// If requested, parse out "appendix" information (often added
-		// by `git format-patch` and removed by `git am`).
-		if separateAppendix && c == &body && line == "---" {
-			c = &appendix
-			continue
-		}
-
-		if c.Len() > 0 {
-			c.WriteByte('\n')
-			if empty > 0 {
-				c.WriteByte('\n')
-			}
-		}
-		empty = 0
-
-		c.WriteString(line)
-	}
-	return body.String(), appendix.String()
-}
-
-func parseHeaderMail(mailLine string, r io.Reader, opts patchHeaderOptions) (*PatchHeader, error) {
-	msg, err := mail.ReadMessage(r)
-	if err != nil {
-		return nil, err
-	}
-
-	h := &PatchHeader{}
-
-	if strings.HasPrefix(mailLine, mailHeaderPrefix) {
-		mailLine = strings.TrimPrefix(mailLine, mailHeaderPrefix)
-		if i := strings.IndexByte(mailLine, ' '); i > 0 {
-			h.SHA = mailLine[:i]
-		}
-	}
-
-	from := msg.Header.Get("From")
-	if from != "" {
-		u, err := ParsePatchIdentity(from)
-		if err != nil {
-			return nil, err
-		}
-		h.Author = &u
-	}
-
-	date := msg.Header.Get("Date")
-	if date != "" {
-		d, err := ParsePatchDate(date)
-		if err != nil {
-			return nil, err
-		}
-		h.AuthorDate = d
-	}
-
-	subject := msg.Header.Get("Subject")
-	h.SubjectPrefix, h.Title = cleanSubject(subject, opts.subjectCleanMode)
-
-	s := bufio.NewScanner(msg.Body)
-	h.Body, h.BodyAppendix = scanMessageBody(s, "", true)
-	if s.Err() != nil {
-		return nil, s.Err()
-	}
-
-	return h, nil
-}
-
-func cleanSubject(s string, mode SubjectCleanMode) (prefix string, subject string) {
-	switch mode {
-	case SubjectCleanAll, SubjectCleanPatchOnly:
-	case SubjectCleanWhitespace:
-		return "", strings.TrimSpace(decodeSubject(s))
-	default:
-		panic(fmt.Sprintf("unknown clean mode: %d", mode))
-	}
-
-	// Based on the algorithm from Git in mailinfo.c:cleanup_subject()
-	// If compatibility with `git am` drifts, go there to see if there are any updates.
-
-	at := 0
-	for at < len(s) {
-		switch s[at] {
-		case 'r', 'R':
-			// Detect re:, Re:, rE: and RE:
-			if at+2 < len(s) && (s[at+1] == 'e' || s[at+1] == 'E') && s[at+2] == ':' {
-				at += 3
-				continue
-			}
-
-		case ' ', '\t', ':':
-			// Delete whitespace and duplicate ':' characters
-			at++
-			continue
-
-		case '[':
-			if i := strings.IndexByte(s[at:], ']'); i > 0 {
-				if mode == SubjectCleanAll || strings.Contains(s[at:at+i+1], "PATCH") {
-					at += i + 1
-					continue
-				}
-			}
-		}
-
-		// Nothing was removed, end processing
-		break
-	}
-
-	prefix = strings.TrimLeftFunc(s[:at], unicode.IsSpace)
-	subject = strings.TrimRightFunc(decodeSubject(s[at:]), unicode.IsSpace)
-	return
-}
-
-// Decodes a subject line. Currently only supports quoted-printable UTF-8. This format is the result
-// of a `git format-patch` when the commit title has a non-ASCII character (i.e. an emoji).
-// See for reference: https://stackoverflow.com/questions/27695749/gmail-api-not-respecting-utf-encoding-in-subject
-func decodeSubject(encoded string) string {
-	if !strings.HasPrefix(encoded, "=?UTF-8?q?") {
-		// not UTF-8 encoded
-		return encoded
-	}
-
-	// If the subject is too long, `git format-patch` may produce a subject line across
-	// multiple lines. When parsed, this can look like the following:
-	// <UTF8-prefix><first-line> <UTF8-prefix><second-line>
-	payload := " " + encoded
-	payload = strings.ReplaceAll(payload, " =?UTF-8?q?", "")
-	payload = strings.ReplaceAll(payload, "?=", "")
-
-	decoded, err := ioutil.ReadAll(quotedprintable.NewReader(strings.NewReader(payload)))
-	if err != nil {
-		// if err, abort decoding and return original subject
-		return encoded
-	}
-
-	return string(decoded)
-}
diff --git a/pkg/gitdiff/patch_identity.go b/pkg/gitdiff/patch_identity.go
deleted file mode 100644
index 018f80c..0000000
--- a/pkg/gitdiff/patch_identity.go
+++ /dev/null
@@ -1,166 +0,0 @@
-package gitdiff
-
-import (
-	"fmt"
-	"strings"
-)
-
-// PatchIdentity identifies a person who authored or committed a patch.
-type PatchIdentity struct {
-	Name  string
-	Email string
-}
-
-func (i PatchIdentity) String() string {
-	name := i.Name
-	if name == "" {
-		name = `""`
-	}
-	return fmt.Sprintf("%s <%s>", name, i.Email)
-}
-
-// ParsePatchIdentity parses a patch identity string. A patch identity contains
-// an email address and an optional name in [RFC 5322] format. This is either a
-// plain email adddress or a name followed by an address in angle brackets:
-//
-//	author@example.com
-//	Author Name <author@example.com>
-//
-// If the input is not one of these formats, ParsePatchIdentity applies a
-// heuristic to separate the name and email portions. If both the name and
-// email are missing or empty, ParsePatchIdentity returns an error. It
-// otherwise does not validate the result.
-//
-// [RFC 5322]: https://datatracker.ietf.org/doc/html/rfc5322
-func ParsePatchIdentity(s string) (PatchIdentity, error) {
-	s = normalizeSpace(s)
-	s = unquotePairs(s)
-
-	var name, email string
-	if at := strings.IndexByte(s, '@'); at >= 0 {
-		start, end := at, at
-		for start >= 0 && !isRFC5332Space(s[start]) && s[start] != '<' {
-			start--
-		}
-		for end < len(s) && !isRFC5332Space(s[end]) && s[end] != '>' {
-			end++
-		}
-		email = s[start+1 : end]
-
-		// Adjust the boundaries so that we drop angle brackets, but keep
-		// spaces when removing the email to form the name.
-		if start < 0 || s[start] != '<' {
-			start++
-		}
-		if end >= len(s) || s[end] != '>' {
-			end--
-		}
-		name = s[:start] + s[end+1:]
-	} else {
-		start, end := 0, 0
-		for i := 0; i < len(s); i++ {
-			if s[i] == '<' && start == 0 {
-				start = i + 1
-			}
-			if s[i] == '>' && start > 0 {
-				end = i
-				break
-			}
-		}
-		if start > 0 && end >= start {
-			email = strings.TrimSpace(s[start:end])
-			name = s[:start-1]
-		}
-	}
-
-	// After extracting the email, the name might contain extra whitespace
-	// again and may be surrounded by comment characters. The git source gives
-	// these examples of when this can happen:
-	//
-	//   "Name <email@domain>"
-	//   "email@domain (Name)"
-	//   "Name <email@domain> (Comment)"
-	//
-	name = normalizeSpace(name)
-	if strings.HasPrefix(name, "(") && strings.HasSuffix(name, ")") {
-		name = name[1 : len(name)-1]
-	}
-	name = strings.TrimSpace(name)
-
-	// If the name is empty or contains email-like characters, use the email
-	// instead (assuming one exists)
-	if name == "" || strings.ContainsAny(name, "@<>") {
-		name = email
-	}
-
-	if name == "" && email == "" {
-		return PatchIdentity{}, fmt.Errorf("invalid identity string %q", s)
-	}
-	return PatchIdentity{Name: name, Email: email}, nil
-}
-
-// unquotePairs process the RFC5322 tokens "quoted-string" and "comment" to
-// remove any "quoted-pairs" (backslash-espaced characters). It also removes
-// the quotes from any quoted strings, but leaves the comment delimiters.
-func unquotePairs(s string) string {
-	quote := false
-	comments := 0
-	escaped := false
-
-	var out strings.Builder
-	for i := 0; i < len(s); i++ {
-		if escaped {
-			escaped = false
-		} else {
-			switch s[i] {
-			case '\\':
-				// quoted-pair is only allowed in quoted-string/comment
-				if quote || comments > 0 {
-					escaped = true
-					continue // drop '\' character
-				}
-
-			case '"':
-				if comments == 0 {
-					quote = !quote
-					continue // drop '"' character
-				}
-
-			case '(':
-				if !quote {
-					comments++
-				}
-			case ')':
-				if comments > 0 {
-					comments--
-				}
-			}
-		}
-		out.WriteByte(s[i])
-	}
-	return out.String()
-}
-
-// normalizeSpace trims leading and trailing whitespace from s and converts
-// inner sequences of one or more whitespace characters to single spaces.
-func normalizeSpace(s string) string {
-	var sb strings.Builder
-	for i := 0; i < len(s); i++ {
-		c := s[i]
-		if !isRFC5332Space(c) {
-			if sb.Len() > 0 && isRFC5332Space(s[i-1]) {
-				sb.WriteByte(' ')
-			}
-			sb.WriteByte(c)
-		}
-	}
-	return sb.String()
-}
-
-func isRFC5332Space(c byte) bool {
-	switch c {
-	case '\t', '\n', '\r', ' ':
-		return true
-	}
-	return false
-}
diff --git a/pkg/gitdiff/text.go b/pkg/gitdiff/text.go
deleted file mode 100644
index ee30792..0000000
--- a/pkg/gitdiff/text.go
+++ /dev/null
@@ -1,192 +0,0 @@
-package gitdiff
-
-import (
-	"fmt"
-	"io"
-	"strconv"
-	"strings"
-)
-
-// ParseTextFragments parses text fragments until the next file header or the
-// end of the stream and attaches them to the given file. It returns the number
-// of fragments that were added.
-func (p *parser) ParseTextFragments(f *File) (n int, err error) {
-	for {
-		frag, err := p.ParseTextFragmentHeader()
-		if err != nil {
-			return n, err
-		}
-		if frag == nil {
-			return n, nil
-		}
-
-		if f.IsNew && frag.OldLines > 0 {
-			return n, p.Errorf(-1, "new file depends on old contents")
-		}
-		if f.IsDelete && frag.NewLines > 0 {
-			return n, p.Errorf(-1, "deleted file still has contents")
-		}
-
-		if err := p.ParseTextChunk(frag); err != nil {
-			return n, err
-		}
-
-		f.TextFragments = append(f.TextFragments, frag)
-		n++
-	}
-}
-
-func (p *parser) ParseTextFragmentHeader() (*TextFragment, error) {
-	const (
-		startMark = "@@ -"
-		endMark   = " @@"
-	)
-
-	if !strings.HasPrefix(p.Line(0), startMark) {
-		return nil, nil
-	}
-
-	parts := strings.SplitAfterN(p.Line(0), endMark, 2)
-	if len(parts) < 2 {
-		return nil, p.Errorf(0, "invalid fragment header")
-	}
-
-	f := &TextFragment{}
-	f.Comment = strings.TrimSpace(parts[1])
-
-	header := parts[0][len(startMark) : len(parts[0])-len(endMark)]
-	ranges := strings.Split(header, " +")
-	if len(ranges) != 2 {
-		return nil, p.Errorf(0, "invalid fragment header")
-	}
-
-	var err error
-	if f.OldPosition, f.OldLines, err = parseRange(ranges[0]); err != nil {
-		return nil, p.Errorf(0, "invalid fragment header: %v", err)
-	}
-	if f.NewPosition, f.NewLines, err = parseRange(ranges[1]); err != nil {
-		return nil, p.Errorf(0, "invalid fragment header: %v", err)
-	}
-
-	if err := p.Next(); err != nil && err != io.EOF {
-		return nil, err
-	}
-	return f, nil
-}
-
-func (p *parser) ParseTextChunk(frag *TextFragment) error {
-	if p.Line(0) == "" {
-		return p.Errorf(0, "no content following fragment header")
-	}
-
-	oldLines, newLines := frag.OldLines, frag.NewLines
-	for oldLines > 0 || newLines > 0 {
-		line := p.Line(0)
-		op, data := line[0], line[1:]
-
-		switch op {
-		case '\n':
-			data = "\n"
-			fallthrough // newer GNU diff versions create empty context lines
-		case ' ':
-			oldLines--
-			newLines--
-			if frag.LinesAdded == 0 && frag.LinesDeleted == 0 {
-				frag.LeadingContext++
-			} else {
-				frag.TrailingContext++
-			}
-			frag.Lines = append(frag.Lines, Line{OpContext, data})
-		case '-':
-			oldLines--
-			frag.LinesDeleted++
-			frag.TrailingContext = 0
-			frag.Lines = append(frag.Lines, Line{OpDelete, data})
-		case '+':
-			newLines--
-			frag.LinesAdded++
-			frag.TrailingContext = 0
-			frag.Lines = append(frag.Lines, Line{OpAdd, data})
-		case '\\':
-			// this may appear in middle of fragment if it's for a deleted line
-			if isNoNewlineMarker(line) {
-				removeLastNewline(frag)
-				break
-			}
-			fallthrough
-		default:
-			// TODO(bkeyes): if this is because we hit the next header, it
-			// would be helpful to return the miscounts line error. We could
-			// either test for the common headers ("@@ -", "diff --git") or
-			// assume any invalid op ends the fragment; git returns the same
-			// generic error in all cases so either is compatible
-			return p.Errorf(0, "invalid line operation: %q", op)
-		}
-
-		if err := p.Next(); err != nil {
-			if err == io.EOF {
-				break
-			}
-			return err
-		}
-	}
-
-	if oldLines != 0 || newLines != 0 {
-		hdr := max(frag.OldLines-oldLines, frag.NewLines-newLines) + 1
-		return p.Errorf(-hdr, "fragment header miscounts lines: %+d old, %+d new", -oldLines, -newLines)
-	}
-	if frag.LinesAdded == 0 && frag.LinesDeleted == 0 {
-		return p.Errorf(0, "fragment contains no changes")
-	}
-
-	// check for a final "no newline" marker since it is not included in the
-	// counters used to stop the loop above
-	if isNoNewlineMarker(p.Line(0)) {
-		removeLastNewline(frag)
-		if err := p.Next(); err != nil && err != io.EOF {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func isNoNewlineMarker(s string) bool {
-	// test for "\ No newline at end of file" by prefix because the text
-	// changes by locale (git claims all versions are at least 12 chars)
-	return len(s) >= 12 && s[:2] == "\\ "
-}
-
-func removeLastNewline(frag *TextFragment) {
-	if len(frag.Lines) > 0 {
-		last := &frag.Lines[len(frag.Lines)-1]
-		last.Line = strings.TrimSuffix(last.Line, "\n")
-	}
-}
-
-func parseRange(s string) (start int64, end int64, err error) {
-	parts := strings.SplitN(s, ",", 2)
-
-	if start, err = strconv.ParseInt(parts[0], 10, 64); err != nil {
-		nerr := err.(*strconv.NumError)
-		return 0, 0, fmt.Errorf("bad start of range: %s: %v", parts[0], nerr.Err)
-	}
-
-	if len(parts) > 1 {
-		if end, err = strconv.ParseInt(parts[1], 10, 64); err != nil {
-			nerr := err.(*strconv.NumError)
-			return 0, 0, fmt.Errorf("bad end of range: %s: %v", parts[1], nerr.Err)
-		}
-	} else {
-		end = 1
-	}
-
-	return
-}
-
-func max(a, b int64) int64 {
-	if a > b {
-		return a
-	}
-	return b
-}