package importmedia

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

var videoExt = map[string]bool{
	".mkv": true, ".mp4": true, ".m4v": true,
	".avi": true, ".ts": true, ".m2ts": true,
}

var sampleRe = regexp.MustCompile(`(?i)(?:^|[.\-_])(sample|trailer|preview)(?:[.\-_]|$)`)

type SubtitleFile struct {
	Language string
	Ext      string
	Content  []byte
}

type Result struct {
	ImportedPath  string
	SubtitlePath  string
}

type Options struct {
	SourcePath  string
	DestDir     string
	Title       string
	Year        *int
	ReleaseTags string
	QualityHint string
	Subtitle    *SubtitleFile
}

// ImportMovie moves the largest video into destDir as:
//
//	Title (Year) - <release tags>.ext
//
// and optionally writes a sidecar subtitle next to it.
func ImportMovie(opts Options) (*Result, error) {
	sourcePath := filepath.Clean(strings.TrimSpace(opts.SourcePath))
	destDir := filepath.Clean(strings.TrimSpace(opts.DestDir))
	if sourcePath == "" || destDir == "" {
		return nil, fmt.Errorf("source/dest pad ontbreekt")
	}

	video, err := findLargestVideo(sourcePath)
	if err != nil {
		return nil, err
	}

	if err := os.MkdirAll(destDir, 0o755); err != nil {
		return nil, fmt.Errorf("doelmap aanmaken: %w", err)
	}

	ext := strings.ToLower(filepath.Ext(video))
	base := sanitizeName(opts.Title)
	if opts.Year != nil && *opts.Year > 1900 {
		base = fmt.Sprintf("%s (%d)", base, *opts.Year)
	}

	tags := strings.TrimSpace(opts.ReleaseTags)
	if tags == "" {
		tags = ExtractReleaseTags(filepath.Base(video), opts.Title, opts.Year)
	}
	if tags == "" {
		tags = strings.TrimSpace(opts.QualityHint)
	}
	if tags == "" {
		tags = "2160p"
	}
	tags = sanitizeName(tags)

	destName := fmt.Sprintf("%s - %s%s", base, tags, ext)
	destPath := filepath.Join(destDir, destName)

	if err := moveFile(video, destPath); err != nil {
		return nil, err
	}

	result := &Result{ImportedPath: destPath}

	if opts.Subtitle != nil && len(opts.Subtitle.Content) > 0 {
		lang := strings.ToLower(strings.TrimSpace(opts.Subtitle.Language))
		if lang == "" {
			lang = "nl"
		}
		subExt := strings.ToLower(strings.TrimSpace(opts.Subtitle.Ext))
		if subExt == "" {
			subExt = ".srt"
		}
		if !strings.HasPrefix(subExt, ".") {
			subExt = "." + subExt
		}
		stem := strings.TrimSuffix(destName, ext)
		subPath := filepath.Join(destDir, fmt.Sprintf("%s.%s%s", stem, lang, subExt))
		if err := os.WriteFile(subPath, opts.Subtitle.Content, 0o644); err != nil {
			return nil, fmt.Errorf("ondertitel schrijven: %w", err)
		}
		result.SubtitlePath = subPath
	}

	cleanupSource(sourcePath, video)
	return result, nil
}

// ExtractReleaseTags keeps quality/group tokens from a release name.
func ExtractReleaseTags(release, title string, year *int) string {
	s := release
	s = regexp.MustCompile(`(?i)\.(mkv|mp4|m4v|avi|ts|m2ts|srt|ass|sub)$`).ReplaceAllString(s, "")
	s = strings.ReplaceAll(s, ".", " ")
	s = strings.ReplaceAll(s, "_", " ")
	for _, w := range strings.Fields(title) {
		if len(w) < 2 {
			continue
		}
		re := regexp.MustCompile(`(?i)\b` + regexp.QuoteMeta(w) + `\b`)
		s = re.ReplaceAllString(s, " ")
	}
	if year != nil && *year > 1900 {
		re := regexp.MustCompile(`\b` + fmt.Sprintf("%d", *year) + `\b`)
		s = re.ReplaceAllString(s, " ")
	}
	return strings.Join(strings.Fields(s), " ")
}

func findLargestVideo(sourcePath string) (string, error) {
	info, err := os.Stat(sourcePath)
	if err != nil {
		return "", fmt.Errorf("bron niet gevonden: %w", err)
	}

	var best string
	var bestSize int64

	consider := func(path string, size int64) {
		if !videoExt[strings.ToLower(filepath.Ext(path))] {
			return
		}
		name := filepath.Base(path)
		if sampleRe.MatchString(name) {
			return
		}
		if size > bestSize {
			bestSize = size
			best = path
		}
	}

	if !info.IsDir() {
		consider(sourcePath, info.Size())
		if best == "" {
			return "", fmt.Errorf("geen videobestand: %s", sourcePath)
		}
		return best, nil
	}

	err = filepath.Walk(sourcePath, func(path string, fi os.FileInfo, walkErr error) error {
		if walkErr != nil || fi == nil || fi.IsDir() {
			return nil
		}
		consider(path, fi.Size())
		return nil
	})
	if err != nil {
		return "", err
	}
	if best == "" {
		return "", fmt.Errorf("geen videobestand in %s", sourcePath)
	}
	return best, nil
}

func moveFile(src, dst string) error {
	if err := os.Rename(src, dst); err == nil {
		return nil
	}
	in, err := os.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()

	out, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o644)
	if err != nil {
		return err
	}
	if _, err := io.Copy(out, in); err != nil {
		out.Close()
		_ = os.Remove(dst)
		return err
	}
	if err := out.Close(); err != nil {
		return err
	}
	return os.Remove(src)
}

func cleanupSource(sourcePath, movedVideo string) {
	info, err := os.Stat(sourcePath)
	if err != nil {
		parent := filepath.Dir(sourcePath)
		_ = removeEmptyDirs(parent)
		return
	}
	if !info.IsDir() {
		_ = os.Remove(sourcePath)
		_ = removeEmptyDirs(filepath.Dir(sourcePath))
		return
	}

	_ = filepath.Walk(sourcePath, func(path string, fi os.FileInfo, walkErr error) error {
		if walkErr != nil || fi == nil {
			return nil
		}
		if path == movedVideo {
			return nil
		}
		if !fi.IsDir() {
			_ = os.Remove(path)
		}
		return nil
	})
	_ = removeEmptyDirs(sourcePath)
}

func removeEmptyDirs(root string) error {
	var dirs []string
	_ = filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
		if err == nil && fi != nil && fi.IsDir() {
			dirs = append(dirs, path)
		}
		return nil
	})
	for i := len(dirs) - 1; i >= 0; i-- {
		_ = os.Remove(dirs[i])
	}
	return nil
}

func sanitizeName(s string) string {
	s = strings.TrimSpace(s)
	replacer := strings.NewReplacer(
		"<", "", ">", "", ":", "", `"`, "", "/", "", "\\", "",
		"|", "", "?", "", "*", "",
	)
	s = replacer.Replace(s)
	return strings.Join(strings.Fields(s), " ")
}