package generator

import (
	"encoding/xml"
	"os"
	"path/filepath"

	"mokhan.ca/xlgmokha/gitmal/internal/git"
)

type AtomFeed struct {
	XMLName xml.Name    `xml:"feed"`
	XMLNS   string      `xml:"xmlns,attr"`
	ID      string      `xml:"id"`
	Title   string      `xml:"title"`
	Updated string      `xml:"updated"`
	Link    []AtomLink  `xml:"link"`
	Entries []AtomEntry `xml:"entry"`
}

type AtomLink struct {
	Rel  string `xml:"rel,attr"`
	Type string `xml:"type,attr"`
	Href string `xml:"href,attr"`
}

type AtomEntry struct {
	ID      string     `xml:"id"`
	Title   string     `xml:"title"`
	Updated string     `xml:"updated"`
	Author  AtomAuthor `xml:"author"`
	Content string     `xml:"content"`
	Link    AtomLink   `xml:"link"`
}

type AtomAuthor struct {
	Name  string `xml:"name"`
	Email string `xml:"email,omitempty"`
}

func GenerateCommitsAtom(commits []git.Commit, params Params) error {
	outDir := filepath.Join(params.OutputDir, "commits")
	if err := os.MkdirAll(outDir, 0o755); err != nil {
		return err
	}

	var updated string
	if len(commits) > 0 {
		updated = commits[0].Date.Format("2006-01-02T15:04:05Z")
	}

	entries := make([]AtomEntry, len(commits))
	for i, c := range commits {
		content := c.Subject
		if c.Body != "" {
			content = c.Subject + "\n\n" + c.Body
		}
		entries[i] = AtomEntry{
			ID:      "urn:sha:" + c.Hash,
			Title:   c.Subject,
			Updated: c.Date.Format("2006-01-02T15:04:05Z"),
			Author:  AtomAuthor{Name: c.Author, Email: c.Email},
			Content: content,
			Link: AtomLink{
				Rel:  "alternate",
				Type: "text/html",
				Href: "commit/" + c.Hash + ".html",
			},
		}
	}

	feed := AtomFeed{
		XMLNS:   "http://www.w3.org/2005/Atom",
		ID:      "urn:gitmal:" + params.Name + ":" + params.Ref.String(),
		Title:   params.Name + " commits on " + params.Ref.String(),
		Updated: updated,
		Link: []AtomLink{
			{Rel: "self", Type: "application/atom+xml", Href: "commits/" + params.Ref.DirName() + ".atom"},
		},
		Entries: entries,
	}

	outPath := filepath.Join(outDir, params.Ref.DirName()+".atom")
	f, err := os.Create(outPath)
	if err != nil {
		return err
	}
	defer f.Close()

	if _, err := f.WriteString(xml.Header); err != nil {
		return err
	}
	encoder := xml.NewEncoder(f)
	encoder.Indent("", "  ")
	return encoder.Encode(feed)
}