package engine

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/torrentclaw/unarr/internal/agent"
)

// StrmDest holds the resolved location for a .strm file to be written.
type StrmDest struct {
	Dir      string // directory the .strm file lives in (created if missing)
	FileName string // filename including the .strm extension
	FullPath string // Dir + FileName, joined
}

// StrmDestForTask computes where a .strm file should land for the given
// agent task, mirroring organize()'s naming so Plex/Jellyfin sees the same
// folder structure as a real download would have produced.
//
// Returns an error if cfg lacks the relevant library directory.
func StrmDestForTask(task agent.Task, cfg OrganizeConfig) (StrmDest, error) {
	switch {
	case task.ContentType == "show":
		if cfg.TVShowsDir == "" {
			return StrmDest{}, fmt.Errorf("strm: TVShowsDir not configured")
		}
		showName := task.ContentTitle
		if showName == "" {
			showName = cleanTitle(task.Title)
		}
		dir := filepath.Join(cfg.TVShowsDir, sanitizePath(showName))
		var fileName string
		if task.Season != nil {
			dir = filepath.Join(dir, fmt.Sprintf("Season %02d", *task.Season))
			if task.Episode != nil {
				fileName = fmt.Sprintf("%s - S%02dE%02d.strm",
					sanitizePath(showName), *task.Season, *task.Episode)
			}
		}
		if fileName == "" {
			// Missing season/episode metadata — fall back to a sanitised title.
			fileName = sanitizePath(showName) + ".strm"
		}
		return StrmDest{Dir: dir, FileName: fileName, FullPath: filepath.Join(dir, fileName)}, nil

	case task.CollectionName != "" && cfg.MoviesDir != "":
		movieName := task.ContentTitle
		if movieName == "" {
			movieName = cleanTitle(task.Title)
		}
		year := strYear(task)
		base := sanitizePath(movieName)
		if year != "" {
			base = fmt.Sprintf("%s (%s)", base, year)
		}
		dir := filepath.Join(cfg.MoviesDir, sanitizePath(task.CollectionName), base)
		fileName := base + ".strm"
		return StrmDest{Dir: dir, FileName: fileName, FullPath: filepath.Join(dir, fileName)}, nil

	case task.ContentType == "movie":
		if cfg.MoviesDir == "" {
			return StrmDest{}, fmt.Errorf("strm: MoviesDir not configured")
		}
		movieName := task.ContentTitle
		if movieName == "" {
			movieName = cleanTitle(task.Title)
		}
		year := strYear(task)
		base := sanitizePath(movieName)
		if year != "" {
			base = fmt.Sprintf("%s (%s)", base, year)
		}
		dir := filepath.Join(cfg.MoviesDir, base)
		fileName := base + ".strm"
		return StrmDest{Dir: dir, FileName: fileName, FullPath: filepath.Join(dir, fileName)}, nil

	default:
		// No metadata at all — drop into MoviesDir under a sanitised title so
		// at least the file lands somewhere a library scan might find it.
		if cfg.MoviesDir == "" {
			return StrmDest{}, fmt.Errorf("strm: no library dir configured for content without metadata")
		}
		base := sanitizePath(cleanTitle(task.Title))
		if base == "" {
			base = "Unknown"
		}
		dir := filepath.Join(cfg.MoviesDir, base)
		fileName := base + ".strm"
		return StrmDest{Dir: dir, FileName: fileName, FullPath: filepath.Join(dir, fileName)}, nil
	}
}

// WriteStrm writes a .strm file containing the given URL at the destination
// computed from the task. Creates parent dirs as needed. Atomic write
// (temp + rename) so a partial file never gets indexed.
func WriteStrm(task agent.Task, cfg OrganizeConfig) (string, error) {
	if task.DirectURL == "" {
		return "", fmt.Errorf("strm: task has no directUrl")
	}

	dest, err := StrmDestForTask(task, cfg)
	if err != nil {
		return "", err
	}

	if err := os.MkdirAll(dest.Dir, 0o755); err != nil {
		return "", fmt.Errorf("strm: create dir: %w", err)
	}

	tmp := dest.FullPath + ".tmp"
	if err := os.WriteFile(tmp, []byte(strings.TrimSpace(task.DirectURL)+"\n"), 0o644); err != nil {
		return "", fmt.Errorf("strm: write temp: %w", err)
	}
	if err := os.Rename(tmp, dest.FullPath); err != nil {
		_ = os.Remove(tmp)
		return "", fmt.Errorf("strm: rename: %w", err)
	}
	return dest.FullPath, nil
}

// strYear is the agent.Task counterpart to organize.go's resolveYear.
func strYear(task agent.Task) string {
	if task.ContentYear != nil && *task.ContentYear > 0 {
		return fmt.Sprintf("%d", *task.ContentYear)
	}
	return yearRegex.FindString(task.Title)
}