package torrent

import (
	"fmt"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/debridmediamanager/zurg/internal/config"
	"github.com/debridmediamanager/zurg/pkg/realdebrid"
	"github.com/debridmediamanager/zurg/pkg/utils"
	mapset "github.com/deckarep/golang-set/v2"
	cmap "github.com/orcaman/concurrent-map/v2"
)

func (t *TorrentManager) refreshTorrents(isInitialRun bool) []string {
	instances, _, err := t.api.GetTorrents(false)
	if err != nil {
		t.log.Warnf("Cannot get torrents: %v", err)
		return nil
	}
	t.log.Infof("Fetched %d torrents", len(instances))
	torChan := make(chan *Torrent, len(instances))
	var wg sync.WaitGroup

	for i := range instances {
		idx := i
		wg.Add(1)
		_ = t.workerPool.Submit(func() {
			defer wg.Done()
			torChan <- t.getMoreInfo(instances[idx])
		})
	}

	wg.Wait()
	close(torChan)
	t.log.Infof("Fetched info for %d torrents", len(instances))

	var updatedPaths []string
	noInfoCount := 0

	allTorrents, _ := t.DirectoryMap.Get(INT_ALL)
	freshAccessKeys := mapset.NewSet[string]()

	allHashes := mapset.NewSet[string]()
	t.getTorrentFiles().Each(func(path string) bool {
		path = filepath.Base(path)
		hash := strings.TrimSuffix(path, ".torrent_zurg")
		allHashes.Add(hash)
		return false
	})
	freshHashes := mapset.NewSet[string]()

	allIDs := mapset.NewSet[string]()
	t.getInfoFiles().Each(func(path string) bool {
		path = filepath.Base(path)
		torrentID := strings.TrimSuffix(path, ".info_zurg")
		allIDs.Add(torrentID)
		return false
	})
	freshIDs := mapset.NewSet[string]()

	for torrent := range torChan {
		if torrent == nil {
			noInfoCount++
			continue
		}

		// there's only 1 component torrent at this point, let's get it
		var tInfo *realdebrid.TorrentInfo
		for _, tInfo = range torrent.Components {
			break
		}
		accessKey := t.GetKey(torrent)
		freshAccessKeys.Add(accessKey)
		freshHashes.Add(torrent.Hash)
		freshIDs.Add(tInfo.ID)

		// update allTorrents
		isNewID := false
		mainTorrent, exists := allTorrents.Get(accessKey)
		if !exists {
			allTorrents.Set(accessKey, torrent)
			mainTorrent = torrent
			isNewID = true
		} else if _, ok := mainTorrent.Components[tInfo.ID]; !ok {
			merged := t.mergeToMain(mainTorrent, torrent)
			allTorrents.Set(accessKey, merged)
			mainTorrent = merged
			isNewID = true
		}

		if isNewID && tInfo.Progress == 100 {
			// assign to directory
			t.assignedDirectoryCb(mainTorrent, func(directory string) {
				listing, _ := t.DirectoryMap.Get(directory)
				listing.Set(accessKey, mainTorrent)

				updatedPaths = append(updatedPaths, fmt.Sprintf("%s/%s", directory, accessKey))
			})
			// write torrent to file
			if !allHashes.Contains(mainTorrent.Hash) {
				t.writeTorrentToFile(mainTorrent)
			}
		}
	}

	// removed torrents
	allAccessKeys := mapset.NewSet[string](allTorrents.Keys()...)
	allAccessKeys.Difference(freshAccessKeys).Each(func(accessKey string) bool {
		t.Delete(accessKey, false)
		return false
	})

	t.log.Infof("Compiled into %d torrents, %d were missing info", allTorrents.Count(), noInfoCount)

	// data directory cleanup
	allHashes.Difference(freshHashes).Each(func(hash string) bool {
		t.log.Infof("Deleting stale torrent file %s", hash)
		t.deleteTorrentFile(hash)
		return false
	})
	allIDs.Difference(freshIDs).Each(func(id string) bool {
		t.log.Infof("Deleting stale info file %s", id)
		t.deleteInfoFile(id)
		return false
	})

	if t.Config.EnableRepair() {
		if isInitialRun {
			t.removeExpiredFixers(instances)
			t.processFixers(instances)
		} else {
			t.workerPool.Submit(func() {
				t.processFixers(instances)
			})
		}
	}

	return updatedPaths
}

// StartRefreshJob periodically refreshes the torrents
func (t *TorrentManager) StartRefreshJob() {
	go func() {
		t.log.Info("Starting periodic refresh job")
		refreshTicker := time.NewTicker(time.Duration(t.Config.GetRefreshEverySecs()) * time.Second)
		defer refreshTicker.Stop()

		for {
			select {
			case <-refreshTicker.C:
				checksum := t.getCurrentState()
				if t.latestState.Eq(checksum) {
					continue
				}
				t.log.Infof("Detected changes! Refreshing %d torrents", checksum.TotalCount)
				t.setNewLatestState(checksum)

				updatedPaths := t.refreshTorrents(false)
				t.log.Info("Finished refreshing torrents")

				t.TriggerHookOnLibraryUpdate(updatedPaths)
			case <-t.RefreshKillSwitch:
				t.log.Info("Stopping periodic refresh job")
				return
			}
		}
	}()
}

// getMoreInfo gets original name, size and files for a torrent
func (t *TorrentManager) getMoreInfo(rdTorrent realdebrid.Torrent) *Torrent {
	diskTor := t.readTorrentFromFile(rdTorrent.Hash)
	if diskTor != nil {
		if diskInfo, ok := diskTor.Components[rdTorrent.ID]; ok && diskInfo.Progress == 100 {
			diskTor.Components = map[string]*realdebrid.TorrentInfo{rdTorrent.ID: diskInfo}
			return diskTor
		}
	}

	info := t.readInfoFromFile(rdTorrent.ID)
	if info == nil {
		var err error
		info, err = t.api.GetTorrentInfo(rdTorrent.ID)
		if err != nil {
			t.log.Warnf("Cannot get info for id=%s: %v", rdTorrent.ID, err)
			return nil
		}
		if info.Progress == 100 {
			t.writeInfoToFile(info)
		}
	}

	torrent := Torrent{
		Name:         info.Name,
		OriginalName: info.OriginalName,
		Added:        info.Added,
		Hash:         info.Hash,
		State:        NewTorrentState("ok"),
	}

	// SelectedFiles is a subset of Files with only the selected ones
	// it also has a Link field, which can be empty
	// if it is empty, it means the file is no longer available
	// Files+Links together are the same as SelectedFiles
	var selectedFiles []*File
	for _, file := range info.Files {
		if file.Selected == 0 {
			continue
		}
		selectedFiles = append(selectedFiles, &File{
			File:  file,
			Ended: info.Ended,
			Link:  "", // no link yet, consider it broken
			State: NewFileState("broken"),
		})
	}
	if len(selectedFiles) == len(info.Links) {
		// all links are still intact! good!
		for i, file := range selectedFiles {
			file.Link = info.Links[i]
			file.State.SetState("ok")
		}
		torrent.UnassignedLinks = mapset.NewSet[string]()
	} else {
		torrent.UnassignedLinks = mapset.NewSet[string](info.Links...)
	}
	torrent.SelectedFiles = cmap.New[*File]()
	for _, file := range selectedFiles {
		filename := t.GetPath(file)
		// todo better handling of duplicate filenames
		if torrent.SelectedFiles.Has(filename) {
			oldName := filename
			ext := filepath.Ext(oldName)
			noExtension := strings.TrimSuffix(oldName, ext)
			newName := fmt.Sprintf("%s (%d)%s", noExtension, file.ID, ext)
			torrent.SelectedFiles.Set(newName, file)
		} else {
			torrent.SelectedFiles.Set(filename, file)
		}
	}
	torrent.Components = map[string]*realdebrid.TorrentInfo{rdTorrent.ID: info}

	return &torrent
}

// ResetSelectedFiles resets the selected files for a torrent
func (t *TorrentManager) ResetSelectedFiles(torrent *Torrent) {
	// reset selected files
	newSelectedFiles := cmap.New[*File]()
	torrent.SelectedFiles.IterCb(func(_ string, file *File) {
		filename := t.GetPath(file)
		if newSelectedFiles.Has(filename) {
			oldName := filename
			ext := filepath.Ext(oldName)
			noExtension := strings.TrimSuffix(oldName, ext)
			newName := fmt.Sprintf("%s (%d)%s", noExtension, file.ID, ext)
			newSelectedFiles.Set(newName, file)
		} else {
			newSelectedFiles.Set(filename, file)
		}
	})
	torrent.SelectedFiles = newSelectedFiles
}

func (t *TorrentManager) mergeToMain(existing, toMerge *Torrent) *Torrent {
	var newer, older *Torrent
	if existing.Added < toMerge.Added {
		newer = toMerge
		older = existing
	} else {
		newer = existing
		older = toMerge
	}

	mergedComponents := map[string]*realdebrid.TorrentInfo{}
	for k, v := range older.Components {
		mergedComponents[k] = v
	}
	for k, v := range newer.Components {
		mergedComponents[k] = v
	}

	// build the main torrent
	mainTorrent := Torrent{
		Name:         newer.Name,
		OriginalName: newer.OriginalName,
		Rename:       newer.Rename,
		Hash:         newer.Hash,
		Added:        newer.Added,

		Components:         mergedComponents,
		UnassignedLinks:    newer.UnassignedLinks.Union(older.UnassignedLinks),
		UnrepairableReason: newer.UnrepairableReason,

		State: older.State,
	}

	// unrepairable reason
	if mainTorrent.UnrepairableReason != "" && older.UnrepairableReason != "" && mainTorrent.UnrepairableReason != older.UnrepairableReason {
		mainTorrent.UnrepairableReason = fmt.Sprintf("%s, %s", mainTorrent.UnrepairableReason, older.UnrepairableReason)
	} else if older.UnrepairableReason != "" {
		mainTorrent.UnrepairableReason = older.UnrepairableReason
	}

	// the link can have the following values
	// 1. https://*** - the file is available
	// 3. empty - the file is not available
	mainTorrent.SelectedFiles = cmap.New[*File]()
	newer.SelectedFiles.IterCb(func(key string, newerFile *File) {
		mainTorrent.SelectedFiles.Set(key, newerFile)
	})
	older.SelectedFiles.IterCb(func(key string, olderFile *File) {
		if !mainTorrent.SelectedFiles.Has(key) {
			mainTorrent.SelectedFiles.Set(key, olderFile)
		} else if olderFile.State.Is("deleted") {
			newerFile, _ := mainTorrent.SelectedFiles.Get(key)
			newerFile.State.SetState("deleted")
		}
	})
	t.CheckDeletedStatus(&mainTorrent)

	return &mainTorrent
}

func (t *TorrentManager) assignedDirectoryCb(tor *Torrent, cb func(string)) {
	torrentIDs := []string{}
	for id := range tor.Components {
		torrentIDs = append(torrentIDs, id)
	}
	// get filenames needed for directory conditions
	var filenames []string
	var fileSizes []int64
	unplayable := true
	tor.SelectedFiles.IterCb(func(key string, file *File) {
		filenames = append(filenames, filepath.Base(file.Path))
		fileSizes = append(fileSizes, file.Bytes)
		if utils.IsPlayable(file.Path) || t.IsPlayable(file.Path) {
			unplayable = false
		}
	})

	if unplayable {
		t.markAsUnplayable(tor, "no playable files")
		return
	}

	// Map torrents to directories
	switch t.Config.GetVersion() {
	case "v1":
		configV1 := t.Config.(*config.ZurgConfigV1)
		for _, directories := range configV1.GetGroupMap() {
			for _, directory := range directories {
				if t.Config.MeetsConditions(directory, t.GetKey(tor), tor.ComputeTotalSize(), torrentIDs, filenames, fileSizes) {
					cb(directory)
					break
				}
			}
		}
	}
}

func (t *TorrentManager) IsPlayable(filePath string) bool {
	filePath = strings.ToLower(filePath)
	playableExts := t.Config.GetPlayableExtensions()
	for _, ext := range playableExts {
		if strings.HasSuffix(filePath, fmt.Sprintf(".%s", ext)) {
			return true
		}
	}
	return false
}