// Package service — filesystem scanner.
//
// ScannerService walks the configured library roots looking for video
// files, then upserts a model.Media row per file. Each upsert also runs
// ffprobe (when available) and queues a metadata lookup for newly added
// rows.
//
// When a filename exposes season + episode numbers we store them on the
// Media row for every library type, so variety shows and other episodic
// collections get the same grouping experience as TV/anime.
package service

import (
	"context"
	"errors"
	"strings"
	"sync"
	"time"

	"go.uber.org/zap"

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

// videoExtensions lists the file extensions treated as media. Matches the
// legacy Python defaults.
var videoExtensions = map[string]struct{}{
	".mkv":  {},
	".mp4":  {},
	".m4v":  {},
	".avi":  {},
	".mov":  {},
	".webm": {},
	".ts":   {},
	".rmvb": {},
	".rm":   {},
	".3gp":  {},
	".mpg":  {},
	".mpeg": {},
	".strm": {},
}

// ScannerService walks libraries on disk and upserts model.Media rows.
type ScannerService struct {
	cfg       *config.Config
	log       *zap.Logger
	repo      *repository.Container
	hub       *Hub
	probe     *FFprobeService
	scraper   *ScraperService
	organizer *OrganizerService
	storage   *StorageConfigService
	cache     *RuntimeCacheService
	notify    *NotifyChannelService

	imageProxy *ImageProxy

	cloudScanMu             sync.Mutex
	cloudScans              map[string]*cloudScanEntry
	cloudSlots              chan struct{}
	cloudImagePrefetchOnce  sync.Once
	cloudImagePrefetchQueue chan cloudImagePrefetchTask
	cloudImagePrefetchMu    sync.Mutex
	cloudImagePrefetching   map[string]struct{}
	cloudMediaProbeOnce     sync.Once
	cloudMediaProbeQueue    chan cloudMediaProbeTask
	cloudMediaProbeMu       sync.Mutex
	cloudMediaProbing       map[string]struct{}
	cloudMediaProbeBackoff  map[string]time.Time
	cloudMediaProbeWarnMu   sync.Mutex
	cloudMediaProbeLastWarn time.Time
	localMediaProbeOnce     sync.Once
	localMediaProbeQueue    chan localMediaProbeTask
	localMediaProbeMu       sync.Mutex
	localMediaProbing       map[string]struct{}
	localScanMu             sync.Mutex
	localScans              map[string]struct{}
}

// NewScannerService is the constructor.
func NewScannerService(
	cfg *config.Config,
	log *zap.Logger,
	repo *repository.Container,
	hub *Hub,
	probe *FFprobeService,
	scraper *ScraperService,
) *ScannerService {
	return &ScannerService{
		cfg: cfg, log: log, repo: repo, hub: hub,
		probe:                   probe,
		scraper:                 scraper,
		cloudScans:              make(map[string]*cloudScanEntry),
		cloudSlots:              make(chan struct{}, 1),
		cloudImagePrefetchQueue: make(chan cloudImagePrefetchTask, 256),
		cloudImagePrefetching:   make(map[string]struct{}),
		cloudMediaProbeQueue:    make(chan cloudMediaProbeTask, 1024),
		cloudMediaProbing:       make(map[string]struct{}),
		cloudMediaProbeBackoff:  make(map[string]time.Time),
		localMediaProbeQueue:    make(chan localMediaProbeTask, 1024),
		localMediaProbing:       make(map[string]struct{}),
		localScans:              make(map[string]struct{}),
	}
}

// SetStorageConfig wires cloud-disk storage access into the scanner. It is set
// after service construction because StorageConfigService depends on Crypto,
// while the scanner is needed earlier by watcher/download services.
func (s *ScannerService) SetStorageConfig(storage *StorageConfigService) {
	s.storage = storage
	if storage != nil && s.probe != nil {
		s.cloudMediaProbeOnce.Do(func() {
			workers := s.ffprobeWorkerCount()
			for i := 0; i < workers; i++ {
				go s.cloudMediaProbeWorker()
			}
		})
	}
}

func (s *ScannerService) SetOrganizer(organizer *OrganizerService) {
	if s != nil {
		s.organizer = organizer
	}
}

func (s *ScannerService) SetRuntimeCache(cache *RuntimeCacheService) {
	if s != nil {
		s.cache = cache
	}
}

func (s *ScannerService) SetNotifyChannels(notify *NotifyChannelService) {
	if s != nil {
		s.notify = notify
	}
}

// SetImageProxy lets cloud scans warm sidecar poster/backdrop files into the
// local image cache. This keeps library opening fast without forcing the UI or
// Emby clients to resolve/download every cloud poster on demand.
func (s *ScannerService) SetImageProxy(imageProxy *ImageProxy) {
	s.imageProxy = imageProxy
	if imageProxy != nil {
		s.cloudImagePrefetchOnce.Do(func() {
			go s.cloudImagePrefetchWorker()
		})
	}
}

// ScanResult summarises a scan run.
type ScanResult struct {
	LibraryID     string   `json:"library_id"`
	Visited       int      `json:"visited"`
	Added         int      `json:"added"`
	Updated       int      `json:"updated"`
	Skipped       int      `json:"skipped"`
	Probed        int      `json:"probed"`
	LocalMetadata int      `json:"local_metadata"`
	Removed       int64    `json:"removed"`
	ErrorCount    int      `json:"error_count,omitempty"`
	Errors        []string `json:"errors,omitempty"`
}

var ErrCloudScanAlreadyRunning = errors.New("cloud scan already running")
var ErrLocalScanAlreadyRunning = errors.New("local scan already running")

const maxScanErrorDetails = 20

func addScanError(res *ScanResult, path string, err error) {
	if res == nil || err == nil {
		return
	}
	res.ErrorCount++
	if len(res.Errors) >= maxScanErrorDetails {
		return
	}
	path = strings.TrimSpace(path)
	msg := strings.TrimSpace(err.Error())
	if path != "" {
		msg = path + ": " + msg
	}
	res.Errors = append(res.Errors, msg)
}

const maxCloudMediaProbeQueuePerScan = 256

const cloudMediaProbeFailureBackoff = 6 * time.Hour

// cloudMediaProbeQueueFullBackoff 是探测队列饱和时给单个文件挂的短退避，
// 防止后续扫描轮次对同一批文件反复尝试入队。
const cloudMediaProbeQueueFullBackoff = 30 * time.Minute

// CloudScanStatus is the operator-facing state for long-running cloud scans.
type CloudScanStatus struct {
	LibraryID      string    `json:"library_id"`
	Provider       string    `json:"provider"`
	Stage          string    `json:"stage"`
	State          string    `json:"state"`
	StartedAt      time.Time `json:"started_at,omitempty"`
	UpdatedAt      time.Time `json:"updated_at,omitempty"`
	FinishedAt     time.Time `json:"finished_at,omitempty"`
	Dirs           int       `json:"dirs"`
	Discovered     int       `json:"discovered"`
	Visited        int       `json:"visited"`
	Added          int       `json:"added"`
	Updated        int       `json:"updated"`
	Skipped        int       `json:"skipped"`
	Removed        int64     `json:"removed"`
	ErrorCount     int       `json:"error_count,omitempty"`
	Errors         []string  `json:"errors,omitempty"`
	Error          string    `json:"error,omitempty"`
	ResumeHint     string    `json:"resume_hint,omitempty"`
	Estimate       string    `json:"estimate_message,omitempty"`
	FilesPerSecond float64   `json:"files_per_second,omitempty"`
}

type cloudScanEntry struct {
	status CloudScanStatus
	cancel context.CancelFunc
}

type cloudMediaProbeTask struct {
	typ  string
	ref  string
	path string
}

type localMediaProbeTask struct {
	path string
}

type existingCloudMedia struct {
	LibraryID    string
	Title        string
	OriginalName string
	EpisodeTitle string
	SizeBytes    int64
	DurationSec  int
	Width        int
	Height       int
	VideoCodec   string
	AudioCodec   string
	Container    string
	PosterURL    string
	BackdropURL  string
	STRMURL      string
	Overview     string
	Year         int
	Rating       float32
	TMDbID       int
	BangumiID    int
	DoubanID     string
	TheTVDBID    string
	SeasonNum    int
	EpisodeNum   int
	Genres       string
	Countries    string
	Languages    string
	NSFW         bool
	ScrapeStatus string
}

type existingLocalMedia struct {
	Title        string
	OriginalName string
	EpisodeTitle string
	SizeBytes    int64
	DurationSec  int
	Width        int
	Height       int
	VideoCodec   string
	AudioCodec   string
	Container    string
	STRMURL      string
	FileID       string
	PosterURL    string
	BackdropURL  string
	Overview     string
	Year         int
	Rating       float32
	TMDbID       int
	BangumiID    int
	DoubanID     string
	TheTVDBID    string
	SeasonNum    int
	EpisodeNum   int
	Genres       string
	Countries    string
	Languages    string
	NSFW         bool
	ScrapeStatus string
}