package media

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

const maxComponentRunes = 80
const maxComponentBytes = 60

// RelativeVideoPath は worker と web が共有する保存先の相対パスを返す。
func RelativeVideoPath(seriesTitle, episodeTitle, episodeID string) string {
	series := sanitizeComponent(seriesTitle)
	episode := sanitizeComponent(episodeTitle)
	id := sanitizeComponent(episodeID)
	return filepath.Join(series, series+" "+episode+" ["+id+"].mp4")
}

func sanitizeComponent(value string) string {
	var result []rune
	lastReplacement := false
	for _, r := range value {
		invalid := unicode.IsControl(r) || strings.ContainsRune(`<>:"/\|?*`, r)
		if invalid {
			if !lastReplacement {
				result = append(result, '_')
				lastReplacement = true
			}
			continue
		}
		if unicode.IsSpace(r) {
			r = ' '
		}
		result = append(result, r)
		lastReplacement = false
	}
	clean := strings.Trim(string(result), " .")
	if clean == "" || clean == "." || clean == ".." {
		return "名称未設定"
	}
	runes := []rune(clean)
	if len(runes) > maxComponentRunes {
		runes = runes[:maxComponentRunes]
	}
	var limited []rune
	bytes := 0
	for _, r := range runes {
		size := len(string(r))
		if bytes+size > maxComponentBytes {
			break
		}
		limited = append(limited, r)
		bytes += size
	}
	clean = strings.Trim(string(limited), " .")
	if clean == "" || clean == "." || clean == ".." {
		return "名称未設定"
	}
	return clean
}