// Package service — NFO writer (Kodi / Jellyfin compatibility).
//
// Kodi and Jellyfin index media using sidecar XML files alongside the
// source video. We export a minimal subset that those scrapers consume
// happily:
//
//	movie.mkv    -> movie.nfo            (<movie>...</movie>)
//	tvshow/      -> tvshow.nfo           (<tvshow>...</tvshow>)  [future]
//
// Movie and episode sidecars are generated today; a library-level tvshow.nfo
// exporter can be added later when the UI exposes a series-level export action.
package service

import (
	"context"
	"encoding/xml"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"go.uber.org/zap"

	"github.com/ShukeBta/MediaStationGo/internal/model"
	"github.com/ShukeBta/MediaStationGo/internal/repository"
)

// NFOService is the entry point used by the admin "导出 NFO" action.
type NFOService struct {
	log  *zap.Logger
	repo *repository.Container
}

// NewNFOService is the constructor.
func NewNFOService(log *zap.Logger, repo *repository.Container) *NFOService {
	return &NFOService{log: log, repo: repo}
}

// movieNFO is the on-disk schema. Tag names match Kodi's expectations.
type movieNFO struct {
	XMLName  xml.Name `xml:"movie"`
	Title    string   `xml:"title"`
	Original string   `xml:"originaltitle,omitempty"`
	Year     int      `xml:"year,omitempty"`
	Plot     string   `xml:"plot,omitempty"`
	Rating   float32  `xml:"rating,omitempty"`
	Poster   string   `xml:"thumb,omitempty"`
	Fanart   string   `xml:"fanart,omitempty"`
	TMDb     int      `xml:"tmdbid,omitempty"`
	Genre    []string `xml:"genre,omitempty"`
	Country  []string `xml:"country,omitempty"`
	Language []string `xml:"language,omitempty"`
}

type episodeNFO struct {
	XMLName   xml.Name `xml:"episodedetails"`
	Title     string   `xml:"title"`
	ShowTitle string   `xml:"showtitle,omitempty"`
	Season    int      `xml:"season"`
	Episode   int      `xml:"episode"`
	Year      int      `xml:"year,omitempty"`
	Plot      string   `xml:"plot,omitempty"`
	Rating    float32  `xml:"rating,omitempty"`
	Poster    string   `xml:"thumb,omitempty"`
	Fanart    string   `xml:"fanart,omitempty"`
	TMDb      int      `xml:"tmdbid,omitempty"`
	Genre     []string `xml:"genre,omitempty"`
	Country   []string `xml:"country,omitempty"`
	Language  []string `xml:"language,omitempty"`
}

// ExportOne writes a movie.nfo file next to the media file. Existing files
// are overwritten so a re-scrape always reflects the latest metadata.
func (s *NFOService) ExportOne(ctx context.Context, mediaID string) (string, error) {
	m, err := s.repo.Media.FindByID(ctx, mediaID)
	if err != nil {
		return "", err
	}
	if m == nil {
		return "", errors.New("media not found")
	}
	if m.Path == "" {
		return "", errors.New("media has empty path")
	}

	dst, err := WriteMediaNFO(m)
	if err != nil {
		return "", err
	}
	s.log.Info("nfo exported", zap.String("media_id", m.ID), zap.String("path", dst))
	return dst, nil
}

// ExportLibrary loops through every matched movie in a library and writes
// an .nfo for each. Returns (written, error).
func (s *NFOService) ExportLibrary(ctx context.Context, libraryID string) (int, error) {
	type row struct{ ID string }
	var ids []row
	q := s.repo.DB.Table("media").Select("id").Where("scrape_status = ?", "matched")
	if libraryID != "" {
		q = q.Where("library_id = ?", libraryID)
	}
	if err := q.Scan(&ids).Error; err != nil {
		return 0, err
	}
	written := 0
	for _, r := range ids {
		if _, err := s.ExportOne(ctx, r.ID); err == nil {
			written++
		}
	}
	return written, nil
}

func nfoPath(media string) string {
	dir := filepath.Dir(media)
	base := strings.TrimSuffix(filepath.Base(media), filepath.Ext(media))
	return filepath.Join(dir, fmt.Sprintf("%s.nfo", base))
}

func WriteMediaNFO(m *model.Media) (string, error) {
	if m == nil {
		return "", errors.New("media not found")
	}
	if m.Path == "" {
		return "", errors.New("media has empty path")
	}

	var doc any
	if m.SeasonNum > 0 || m.EpisodeNum > 0 {
		title := strings.TrimSpace(m.EpisodeTitle)
		if title == "" && m.EpisodeNum > 0 {
			title = fmt.Sprintf("第 %d 集", m.EpisodeNum)
		}
		if title == "" {
			title = strings.TrimSpace(m.Title)
		}
		doc = episodeNFO{
			Title:     title,
			ShowTitle: m.Title,
			Season:    m.SeasonNum,
			Episode:   m.EpisodeNum,
			Year:      m.Year,
			Plot:      m.Overview,
			Rating:    m.Rating,
			Poster:    m.PosterURL,
			Fanart:    m.BackdropURL,
			TMDb:      m.TMDbID,
			Genre:     splitNFOList(m.Genres),
			Country:   splitNFOList(m.Countries),
			Language:  splitNFOList(m.Languages),
		}
	} else {
		doc = movieNFO{
			Title:    m.Title,
			Original: m.OriginalName,
			Year:     m.Year,
			Plot:     m.Overview,
			Rating:   m.Rating,
			Poster:   m.PosterURL,
			Fanart:   m.BackdropURL,
			TMDb:     m.TMDbID,
			Genre:    splitNFOList(m.Genres),
			Country:  splitNFOList(m.Countries),
			Language: splitNFOList(m.Languages),
		}
	}
	out, err := xml.MarshalIndent(doc, "", "  ")
	if err != nil {
		return "", err
	}
	dst := nfoPath(resolveMappedDestinationPath(m.Path))
	if err := os.WriteFile(dst, []byte(xml.Header+string(out)+"\n"), 0o644); err != nil { // #nosec G306 -- NFO sidecars must remain readable by media players.
		return "", err
	}
	return dst, nil
}

func splitNFOList(value string) []string {
	parts := strings.Split(value, ",")
	out := make([]string, 0, len(parts))
	for _, part := range parts {
		part = strings.TrimSpace(part)
		if part != "" {
			out = append(out, part)
		}
	}
	return out
}