package page

import (
	"bytes"
	"compress/flate"
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"log/slog"
	"regexp"
	"strings"

	"git.schreifuchs.ch/schreifuchs/schreifuchs.ch/internal/components/images"
	"git.schreifuchs.ch/schreifuchs/schreifuchs.ch/internal/components/translate"
	"github.com/studio-b12/gowebdav"
)

var titleRGX = regexp.MustCompile(`(?m)^#\s+(.+)$`)

var (
	ErrMalFormedInput = errors.New("mal formed input")
	ErrNotFound       = errors.New("not found")
)

func (s *Service) getPageHeaders(ctx context.Context, uid string) (page PageHeader, err error) {
	info, err := s.fs.ReadDir(uid)
	if gowebdav.IsErrNotFound(err) { // try private
		err = ErrNotFound
	}
	if err != nil {
		return
	}

	lang := translate.Language(ctx)

	var coverImage *gowebdav.File
	var contentMD *gowebdav.File

	for _, f := range info {
		file := f.(gowebdav.File)

		if strings.HasPrefix(file.ContentType(), "image/") {
			coverImage = &file
		}

		parts := strings.Split(file.Name(), ".")

		// fallback content
		if contentMD == nil && len(parts) == 2 && parts[1] == "md" {
			contentMD = &file
		}
		// language content
		if len(parts) == 3 && parts[1] == lang && parts[2] == "md" {
			contentMD = &file
		}
	}

	slog.Debug("loaded page infos", "cover", coverImage, "content", contentMD)

	content, err := s.fs.Read(contentMD.Path())
	if err != nil {
		return
	}

	title := titleRGX.FindStringSubmatch(string(content))
	if len(title) < 2 {
		err = fmt.Errorf("%w: no matches for title", ErrMalFormedInput)
		return
	}

	page.UID = uid
	page.Title = title[1]
	page.CoverImageUID, err = images.UIDFromPath(coverImage.Path())

	return
}

func getImageUID(path string) string {
	var b bytes.Buffer
	// NewWriter with NoDict (nil) creates a raw DEFLATE compressor
	zw, _ := flate.NewWriter(&b, flate.BestCompression)

	zw.Write([]byte(path))
	zw.Close() // Essential to flush the final bits

	return base64.RawURLEncoding.EncodeToString(b.Bytes())
}