package scanner

import (
	"path/filepath"
	"regexp"
	"strings"
)

var (
	yearSepRe    = regexp.MustCompile(`[\.\s_-]((19|20)\d{2})[\.\s_-]`)
	yearParenRe  = regexp.MustCompile(`(?i)^(.+?)\s*\(((?:19|20)\d{2})\)\s*(?:\[.*\])?$`)
	yearEndRe    = regexp.MustCompile(`^(.+?)[\.\s_-]((?:19|20)\d{2})$`)
	resolutionRe = regexp.MustCompile(`(?i)\b(2160p|1080p|720p|480p|4K)\b`)
	sourceRe     = regexp.MustCompile(`(?i)\b(UHD\s*BluRay|BluRay|WEB-DL|WEBRip|HDTV|DVDRip)\b`)
	releaseRe    = regexp.MustCompile(`(?i)\b(REMUX|PROPER|REPACK)\b`)
	videoRe      = regexp.MustCompile(`(?i)\b(HEVC|H\.?264|H\.?265|x264|x265|AV1|XviD)\b`)
	audioRe      = regexp.MustCompile(`(?i)\b(TrueHD(\s*Atmos)?|DTS-HD|DTS|AAC|AC3|Atmos|EAC3)\b`)
	seriesRe1    = regexp.MustCompile(`(?i)(.+?)[\.\s_-]S(\d{1,2})E(\d{1,2})`)
	seriesRe2    = regexp.MustCompile(`(?i)(.+?)[\.\s_-](\d{1,2})x(\d{1,2})`)
	seasonDirRe  = regexp.MustCompile(`(?i)^(?:season|seizoen)\s*0*(\d{1,2})$|^s(\d{1,2})$`)
	episodeOnly  = regexp.MustCompile(`(?i)(?:^|[\.\s_-])(?:e|ep|episode)[\.\s_-]?0*(\d{1,3})(?:[\.\s_-]|$)`)
	junkNameRe   = regexp.MustCompile(`(?i)\b(sample|trailer|preview|featurette|extras?)\b`)
)

func parseMovie(base string) map[string]interface{} {
	title, year := extractMovieTitleYear(base)
	if title == "" {
		return nil
	}
	result := map[string]interface{}{"title": title}
	if year > 0 {
		result["year"] = year
	}
	attachTags(result, base)
	return result
}

func parseSeries(base string) map[string]interface{} {
	for _, re := range []*regexp.Regexp{seriesRe1, seriesRe2} {
		m := re.FindStringSubmatch(base)
		if len(m) >= 4 {
			title := cleanTitle(m[1])
			season := atoi(m[2])
			episode := atoi(m[3])
			if title == "" || season <= 0 || episode <= 0 {
				continue
			}
			result := map[string]interface{}{
				"title":   title,
				"season":  season,
				"episode": episode,
			}
			attachTags(result, base)
			return result
		}
	}
	return nil
}

// parseMovieFromPath prefers Plex-style "Title (Year)/file.mkv" folders.
func parseMovieFromPath(path string) map[string]interface{} {
	base := strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
	if isJunkName(base) {
		return nil
	}
	parent := filepath.Base(filepath.Dir(path))

	fromFile := parseMovie(base)
	fromFolder := parseMovieFolder(parent)

	if fromFolder == nil && fromFile == nil {
		return nil
	}
	if fromFolder == nil {
		return fromFile
	}
	if fromFile == nil {
		return fromFolder
	}

	// Folder title/year are authoritative for library layout; keep quality tags from file.
	merged := map[string]interface{}{}
	for k, v := range fromFile {
		merged[k] = v
	}
	merged["title"] = fromFolder["title"]
	if y, ok := fromFolder["year"]; ok {
		merged["year"] = y
	}
	return merged
}

// parseSeriesFromPath supports "Show/Season 01/..." and classic SxxExx filenames.
func parseSeriesFromPath(path string) map[string]interface{} {
	base := strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
	if isJunkName(base) {
		return nil
	}

	dir := filepath.Dir(path)
	parent := filepath.Base(dir)
	grandparent := filepath.Base(filepath.Dir(dir))

	seasonFromDir := parseSeasonFolder(parent)
	showFromDir := ""
	if seasonFromDir > 0 {
		showFromDir = cleanTitle(stripYearParen(grandparent))
	}

	fromFile := parseSeries(base)
	if fromFile != nil {
		if showFromDir != "" {
			fromFile["title"] = showFromDir
		}
		if seasonFromDir > 0 {
			fromFile["season"] = seasonFromDir
		}
		return fromFile
	}

	episode := parseEpisodeNumber(base)
	season := seasonFromDir
	title := showFromDir

	// Flat: Show Name/S01E02.mkv (no season folder)
	if title == "" {
		title = cleanTitle(stripYearParen(parent))
	}
	if season <= 0 && fromFile == nil {
		// Try SxxExx-less season in parent already handled; leave 0
	}

	if title == "" || season <= 0 || episode <= 0 {
		return nil
	}
	result := map[string]interface{}{
		"title":   title,
		"season":  season,
		"episode": episode,
	}
	attachTags(result, base)
	return result
}

func parseMovieFolder(name string) map[string]interface{} {
	name = strings.TrimSpace(name)
	if name == "" || name == "." || name == string(filepath.Separator) {
		return nil
	}
	// Skip generic root-ish folder names
	lower := strings.ToLower(name)
	if lower == "movies" || lower == "films" || lower == "movie" || lower == "film" ||
		lower == "media" || lower == "video" || lower == "videos" {
		return nil
	}
	return parseMovie(name)
}

func extractMovieTitleYear(base string) (string, int) {
	if m := yearParenRe.FindStringSubmatch(base); len(m) >= 3 {
		return cleanTitle(m[1]), atoi(m[2])
	}
	if yearMatch := yearSepRe.FindStringSubmatchIndex(base); len(yearMatch) >= 4 {
		return cleanTitle(base[:yearMatch[0]]), atoi(base[yearMatch[2]:yearMatch[3]])
	}
	if m := yearEndRe.FindStringSubmatch(base); len(m) >= 3 {
		return cleanTitle(m[1]), atoi(m[2])
	}
	title := cleanTitle(base)
	return title, 0
}

func parseSeasonFolder(name string) int {
	m := seasonDirRe.FindStringSubmatch(strings.TrimSpace(name))
	if len(m) == 0 {
		return 0
	}
	if m[1] != "" {
		return atoi(m[1])
	}
	return atoi(m[2])
}

func parseEpisodeNumber(base string) int {
	if m := episodeOnly.FindStringSubmatch(base); len(m) >= 2 {
		return atoi(m[1])
	}
	// Bare leading number: "01 - Pilot" / "1. Pilot"
	re := regexp.MustCompile(`^0*(\d{1,3})(?:[\.\s_-]|$)`)
	if m := re.FindStringSubmatch(base); len(m) >= 2 {
		n := atoi(m[1])
		if n > 0 && n < 1000 {
			return n
		}
	}
	return 0
}

func stripYearParen(s string) string {
	if m := yearParenRe.FindStringSubmatch(s); len(m) >= 2 {
		return m[1]
	}
	return s
}

func attachTags(result map[string]interface{}, base string) {
	if m := resolutionRe.FindStringSubmatch(base); len(m) > 1 {
		result["resolution"] = m[1]
	}
	if m := sourceRe.FindStringSubmatch(base); len(m) > 1 {
		result["source"] = m[1]
	}
	if m := releaseRe.FindStringSubmatch(base); len(m) > 1 {
		result["releaseType"] = m[1]
	}
	if m := videoRe.FindStringSubmatch(base); len(m) > 1 {
		result["videoCodec"] = m[1]
	}
	if m := audioRe.FindStringSubmatch(base); len(m) > 0 {
		result["audio"] = m[0]
	}
}

func isJunkName(s string) bool {
	return junkNameRe.MatchString(s)
}

func cleanTitle(s string) string {
	s = strings.ReplaceAll(s, ".", " ")
	s = strings.ReplaceAll(s, "_", " ")
	s = strings.ReplaceAll(s, "-", " ")
	tagRe := regexp.MustCompile(`(?i)\b(2160p|1080p|720p|480p|4K|UHD|BluRay|WEB-?DL|WEBRip|HDTV|DVDRip|REMUX|PROPER|REPACK|HEVC|H\.?264|H\.?265|x264|x265|AV1|XviD|TrueHD(\s*Atmos)?|DTS-?HD|DTS|AAC|AC-?3|EAC3|Atmos|HDR10?\+?|Dolby\s*Vision|DV)\b`)
	s = tagRe.ReplaceAllString(s, " ")
	return strings.Join(strings.Fields(s), " ")
}

func atoi(s string) int {
	n := 0
	for _, c := range s {
		if c < '0' || c > '9' {
			return 0
		}
		n = n*10 + int(c-'0')
	}
	return n
}