package development

import (
	"context"
	"errors"
	"net"
	"time"

	v1 "github.com/authzed/authzed-go/proto/authzed/api/v1"
	"github.com/ccoveille/go-safecast"
	humanize "github.com/dustin/go-humanize"
	"google.golang.org/genproto/googleapis/rpc/errdetails"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/status"
	"google.golang.org/grpc/test/bufconn"

	"github.com/authzed/spicedb/internal/datastore/memdb"
	"github.com/authzed/spicedb/internal/dispatch"
	"github.com/authzed/spicedb/internal/dispatch/graph"
	maingraph "github.com/authzed/spicedb/internal/graph"
	"github.com/authzed/spicedb/internal/grpchelpers"
	log "github.com/authzed/spicedb/internal/logging"
	datastoremw "github.com/authzed/spicedb/internal/middleware/datastore"
	"github.com/authzed/spicedb/internal/namespace"
	"github.com/authzed/spicedb/internal/relationships"
	v1svc "github.com/authzed/spicedb/internal/services/v1"
	"github.com/authzed/spicedb/internal/sharederrors"
	caveattypes "github.com/authzed/spicedb/pkg/caveats/types"
	"github.com/authzed/spicedb/pkg/datastore"
	"github.com/authzed/spicedb/pkg/middleware/consistency"
	core "github.com/authzed/spicedb/pkg/proto/core/v1"
	devinterface "github.com/authzed/spicedb/pkg/proto/developer/v1"
	"github.com/authzed/spicedb/pkg/schema"
	"github.com/authzed/spicedb/pkg/schemadsl/compiler"
	"github.com/authzed/spicedb/pkg/spiceerrors"
	"github.com/authzed/spicedb/pkg/tuple"
)

const defaultConnBufferSize = humanize.MiByte

// DevContext holds the various helper types for running the developer calls.
type DevContext struct {
	Ctx            context.Context
	Datastore      datastore.Datastore
	Revision       datastore.Revision
	CompiledSchema *compiler.CompiledSchema
	Dispatcher     dispatch.Dispatcher
}

// NewDevContext creates a new DevContext from the specified request context, parsing and populating
// the datastore as needed.
func NewDevContext(ctx context.Context, requestContext *devinterface.RequestContext) (*DevContext, *devinterface.DeveloperErrors, error) {
	ds, err := memdb.NewMemdbDatastore(0, 0*time.Second, memdb.DisableGC)
	if err != nil {
		return nil, nil, err
	}
	ctx = datastoremw.ContextWithDatastore(ctx, ds)

	dctx, devErrs, nerr := newDevContextWithDatastore(ctx, requestContext, ds)
	if nerr != nil || devErrs != nil {
		// If any form of error occurred, immediately close the datastore
		derr := ds.Close()
		if derr != nil {
			return nil, nil, derr
		}

		return dctx, devErrs, nerr
	}

	return dctx, nil, nil
}

func newDevContextWithDatastore(ctx context.Context, requestContext *devinterface.RequestContext, ds datastore.Datastore) (*DevContext, *devinterface.DeveloperErrors, error) {
	// Compile the schema and load its caveats and namespaces into the datastore.
	compiled, devError, err := CompileSchema(requestContext.Schema)
	if err != nil {
		return nil, nil, err
	}

	if devError != nil {
		return nil, &devinterface.DeveloperErrors{InputErrors: []*devinterface.DeveloperError{devError}}, nil
	}

	var inputErrors []*devinterface.DeveloperError
	currentRevision, err := ds.ReadWriteTx(ctx, func(ctx context.Context, rwt datastore.ReadWriteTransaction) error {
		inputErrors, err = loadCompiled(ctx, compiled, rwt)
		if err != nil || len(inputErrors) > 0 {
			return err
		}

		// Load the test relationships into the datastore.
		relationships := make([]tuple.Relationship, 0, len(requestContext.Relationships))
		for _, rel := range requestContext.Relationships {
			if err := rel.Validate(); err != nil {
				inputErrors = append(inputErrors, &devinterface.DeveloperError{
					Message: err.Error(),
					Source:  devinterface.DeveloperError_RELATIONSHIP,
					Kind:    devinterface.DeveloperError_PARSE_ERROR,
					Context: tuple.CoreRelationToStringWithoutCaveatOrExpiration(rel),
				})
			}

			convertedRel := tuple.FromCoreRelationTuple(rel)
			if err := convertedRel.Validate(); err != nil {
				tplString, serr := tuple.String(convertedRel)
				if serr != nil {
					return serr
				}

				inputErrors = append(inputErrors, &devinterface.DeveloperError{
					Message: err.Error(),
					Source:  devinterface.DeveloperError_RELATIONSHIP,
					Kind:    devinterface.DeveloperError_PARSE_ERROR,
					Context: tplString,
				})
			}

			relationships = append(relationships, convertedRel)
		}

		ie, lerr := loadsRels(ctx, relationships, rwt)
		if len(ie) > 0 {
			inputErrors = append(inputErrors, ie...)
		}

		return lerr
	})

	if err != nil || len(inputErrors) > 0 {
		return nil, &devinterface.DeveloperErrors{InputErrors: inputErrors}, err
	}

	// Sanity check: Make sure the request context for the developer is fully valid. We do this after
	// the loading to ensure that any user-created errors are reported as developer errors,
	// rather than internal errors.
	verr := requestContext.Validate()
	if verr != nil {
		return nil, nil, verr
	}

	return &DevContext{
		Ctx:            ctx,
		Datastore:      ds,
		CompiledSchema: compiled,
		Revision:       currentRevision,
		Dispatcher:     graph.NewLocalOnlyDispatcher(caveattypes.Default.TypeSet, 10, 100),
	}, nil, nil
}

// RunV1InMemoryService runs a V1 server in-memory on a buffconn over the given
// development context and returns a client connection and a function to shutdown
// the server. It is the responsibility of the caller to call the function to close
// the server.
func (dc *DevContext) RunV1InMemoryService() (*grpc.ClientConn, func(), error) {
	listener := bufconn.Listen(defaultConnBufferSize)

	s := grpc.NewServer(
		grpc.ChainUnaryInterceptor(
			datastoremw.UnaryServerInterceptor(dc.Datastore),
			consistency.UnaryServerInterceptor("development"),
		),
		grpc.ChainStreamInterceptor(
			datastoremw.StreamServerInterceptor(dc.Datastore),
			consistency.StreamServerInterceptor("development"),
		),
	)
	ps := v1svc.NewPermissionsServer(dc.Dispatcher, v1svc.PermissionsServerConfig{
		MaxUpdatesPerWrite:           50,
		MaxPreconditionsCount:        50,
		MaximumAPIDepth:              50,
		MaxCaveatContextSize:         0,
		ExpiringRelationshipsEnabled: true,
		CaveatTypeSet:                caveattypes.Default.TypeSet,
	})
	ss := v1svc.NewSchemaServer(caveattypes.Default.TypeSet, false, true)

	v1.RegisterPermissionsServiceServer(s, ps)
	v1.RegisterSchemaServiceServer(s, ss)

	go func() {
		if err := s.Serve(listener); err != nil {
			log.Err(err).Msg("error when serving in-memory server")
		}
	}()

	conn, err := grpchelpers.DialAndWait(
		context.Background(),
		"",
		grpc.WithContextDialer(func(context.Context, string) (net.Conn, error) {
			return listener.Dial()
		}),
		grpc.WithTransportCredentials(insecure.NewCredentials()),
	)
	return conn, func() {
		conn.Close()
		listener.Close()
		s.Stop()
	}, err
}

// Dispose disposes of the DevContext and its underlying datastore.
func (dc *DevContext) Dispose() {
	if dc.Dispatcher == nil {
		return
	}
	if err := dc.Dispatcher.Close(); err != nil {
		log.Ctx(dc.Ctx).Err(err).Msg("error when disposing of dispatcher in devcontext")
	}

	if dc.Datastore == nil {
		return
	}

	if err := dc.Datastore.Close(); err != nil {
		log.Ctx(dc.Ctx).Err(err).Msg("error when disposing of datastore in devcontext")
	}
}

func loadsRels(ctx context.Context, rels []tuple.Relationship, rwt datastore.ReadWriteTransaction) ([]*devinterface.DeveloperError, error) {
	devErrors := make([]*devinterface.DeveloperError, 0, len(rels))
	updates := make([]tuple.RelationshipUpdate, 0, len(rels))
	for _, rel := range rels {
		if err := relationships.ValidateRelationshipsForCreateOrTouch(ctx, rwt, caveattypes.Default.TypeSet, rel); err != nil {
			relString, serr := tuple.String(rel)
			if serr != nil {
				return nil, serr
			}

			devErr, wireErr := distinguishGraphError(ctx, err, devinterface.DeveloperError_RELATIONSHIP, 0, 0, relString)
			if wireErr != nil {
				return devErrors, wireErr
			}

			if devErr != nil {
				devErrors = append(devErrors, devErr)
			}
		}

		updates = append(updates, tuple.Touch(rel))
	}

	err := rwt.WriteRelationships(ctx, updates)
	return devErrors, err
}

func loadCompiled(
	ctx context.Context,
	compiled *compiler.CompiledSchema,
	rwt datastore.ReadWriteTransaction,
) ([]*devinterface.DeveloperError, error) {
	errors := make([]*devinterface.DeveloperError, 0, len(compiled.OrderedDefinitions))
	ts := schema.NewTypeSystem(schema.ResolverForCompiledSchema(*compiled))

	for _, caveatDef := range compiled.CaveatDefinitions {
		cverr := namespace.ValidateCaveatDefinition(caveattypes.Default.TypeSet, caveatDef)
		if cverr == nil {
			if err := rwt.WriteCaveats(ctx, []*core.CaveatDefinition{caveatDef}); err != nil {
				return errors, err
			}
			continue
		}

		errWithSource, ok := spiceerrors.AsWithSourceError(cverr)
		if ok {
			// NOTE: zeroes are fine here to mean "unknown"
			lineNumber, err := safecast.ToUint32(errWithSource.LineNumber)
			if err != nil {
				log.Err(err).Msg("could not cast lineNumber to uint32")
			}
			columnPosition, err := safecast.ToUint32(errWithSource.ColumnPosition)
			if err != nil {
				log.Err(err).Msg("could not cast columnPosition to uint32")
			}
			errors = append(errors, &devinterface.DeveloperError{
				Message: cverr.Error(),
				Kind:    devinterface.DeveloperError_SCHEMA_ISSUE,
				Source:  devinterface.DeveloperError_SCHEMA,
				Context: errWithSource.SourceCodeString,
				Line:    lineNumber,
				Column:  columnPosition,
			})
		} else {
			errors = append(errors, &devinterface.DeveloperError{
				Message: cverr.Error(),
				Kind:    devinterface.DeveloperError_SCHEMA_ISSUE,
				Source:  devinterface.DeveloperError_SCHEMA,
				Context: caveatDef.Name,
			})
		}
	}

	for _, nsDef := range compiled.ObjectDefinitions {
		def, terr := schema.NewDefinition(ts, nsDef)
		if terr != nil {
			errWithSource, ok := spiceerrors.AsWithSourceError(terr)
			// NOTE: zeroes are fine here to mean "unknown"
			lineNumber, err := safecast.ToUint32(errWithSource.LineNumber)
			if err != nil {
				log.Err(err).Msg("could not cast lineNumber to uint32")
			}
			columnPosition, err := safecast.ToUint32(errWithSource.ColumnPosition)
			if err != nil {
				log.Err(err).Msg("could not cast columnPosition to uint32")
			}
			if ok {
				errors = append(errors, &devinterface.DeveloperError{
					Message: terr.Error(),
					Kind:    devinterface.DeveloperError_SCHEMA_ISSUE,
					Source:  devinterface.DeveloperError_SCHEMA,
					Context: errWithSource.SourceCodeString,
					Line:    lineNumber,
					Column:  columnPosition,
				})
				continue
			}

			errors = append(errors, &devinterface.DeveloperError{
				Message: terr.Error(),
				Kind:    devinterface.DeveloperError_SCHEMA_ISSUE,
				Source:  devinterface.DeveloperError_SCHEMA,
				Context: nsDef.Name,
			})
			continue
		}

		_, tverr := def.Validate(ctx)
		if tverr == nil {
			if err := rwt.WriteNamespaces(ctx, nsDef); err != nil {
				return errors, err
			}
			continue
		}

		errWithSource, ok := spiceerrors.AsWithSourceError(tverr)
		if ok {
			// NOTE: zeroes are fine here to mean "unknown"
			lineNumber, err := safecast.ToUint32(errWithSource.LineNumber)
			if err != nil {
				log.Err(err).Msg("could not cast lineNumber to uint32")
			}
			columnPosition, err := safecast.ToUint32(errWithSource.ColumnPosition)
			if err != nil {
				log.Err(err).Msg("could not cast columnPosition to uint32")
			}
			errors = append(errors, &devinterface.DeveloperError{
				Message: tverr.Error(),
				Kind:    devinterface.DeveloperError_SCHEMA_ISSUE,
				Source:  devinterface.DeveloperError_SCHEMA,
				Context: errWithSource.SourceCodeString,
				Line:    lineNumber,
				Column:  columnPosition,
			})
		} else {
			errors = append(errors, &devinterface.DeveloperError{
				Message: tverr.Error(),
				Kind:    devinterface.DeveloperError_SCHEMA_ISSUE,
				Source:  devinterface.DeveloperError_SCHEMA,
				Context: nsDef.Name,
			})
		}
	}

	return errors, nil
}

// DistinguishGraphError turns an error from a dispatch call into either a user-facing
// DeveloperError or an internal error, based on the error raised by the dispatcher.
func DistinguishGraphError(devContext *DevContext, dispatchError error, source devinterface.DeveloperError_Source, line uint32, column uint32, context string) (*devinterface.DeveloperError, error) {
	return distinguishGraphError(devContext.Ctx, dispatchError, source, line, column, context)
}

func distinguishGraphError(ctx context.Context, dispatchError error, source devinterface.DeveloperError_Source, line uint32, column uint32, context string) (*devinterface.DeveloperError, error) {
	var nsNotFoundError sharederrors.UnknownNamespaceError
	var relNotFoundError sharederrors.UnknownRelationError
	var invalidRelError relationships.InvalidSubjectTypeError
	var maxDepthErr dispatch.MaxDepthExceededError

	if errors.As(dispatchError, &maxDepthErr) {
		return &devinterface.DeveloperError{
			Message: dispatchError.Error(),
			Source:  source,
			Kind:    devinterface.DeveloperError_MAXIMUM_RECURSION,
			Line:    line,
			Column:  column,
			Context: context,
		}, nil
	}

	details, ok := spiceerrors.GetDetails[*errdetails.ErrorInfo](dispatchError)
	if ok && details.Reason == "ERROR_REASON_MAXIMUM_DEPTH_EXCEEDED" {
		status, _ := status.FromError(dispatchError)
		return &devinterface.DeveloperError{
			Message: status.Message(),
			Source:  source,
			Kind:    devinterface.DeveloperError_MAXIMUM_RECURSION,
			Line:    line,
			Column:  column,
			Context: context,
		}, nil
	}

	if errors.As(dispatchError, &invalidRelError) {
		return &devinterface.DeveloperError{
			Message: dispatchError.Error(),
			Source:  source,
			Kind:    devinterface.DeveloperError_INVALID_SUBJECT_TYPE,
			Line:    line,
			Column:  column,
			Context: context,
		}, nil
	}

	if errors.As(dispatchError, &nsNotFoundError) {
		return &devinterface.DeveloperError{
			Message: dispatchError.Error(),
			Source:  source,
			Kind:    devinterface.DeveloperError_UNKNOWN_OBJECT_TYPE,
			Line:    line,
			Column:  column,
			Context: context,
		}, nil
	}

	if errors.As(dispatchError, &relNotFoundError) {
		return &devinterface.DeveloperError{
			Message: dispatchError.Error(),
			Source:  source,
			Kind:    devinterface.DeveloperError_UNKNOWN_RELATION,
			Line:    line,
			Column:  column,
			Context: context,
		}, nil
	}

	return nil, rewriteACLError(ctx, dispatchError)
}

func rewriteACLError(ctx context.Context, err error) error {
	var nsNotFoundError sharederrors.UnknownNamespaceError
	var relNotFoundError sharederrors.UnknownRelationError

	switch {
	case errors.As(err, &nsNotFoundError):
		fallthrough
	case errors.As(err, &relNotFoundError):
		fallthrough

	case errors.As(err, &datastore.InvalidRevisionError{}):
		return status.Errorf(codes.OutOfRange, "invalid zookie: %s", err)

	case errors.As(err, &maingraph.RelationMissingTypeInfoError{}):
		return status.Errorf(codes.FailedPrecondition, "failed precondition: %s", err)

	case errors.As(err, &maingraph.AlwaysFailError{}):
		log.Ctx(ctx).Err(err).Msg("internal graph error in devcontext")
		return status.Errorf(codes.Internal, "internal error: %s", err)

	case errors.Is(err, context.DeadlineExceeded):
		return status.Errorf(codes.DeadlineExceeded, "%s", err)

	case errors.Is(err, context.Canceled):
		return status.Errorf(codes.Canceled, "%s", err)

	default:
		log.Ctx(ctx).Err(err).Msg("unexpected graph error in devcontext")
		return err
	}
}