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() []string {
	instances, _, err := t.Api.GetTorrents(0, false)
	if err != nil {
		t.log.Warnf("Cannot get torrents: %v", err)
		return nil
	}
	infoChan := make(chan *Torrent, len(instances))
	var wg sync.WaitGroup

	allTorrents, _ := t.DirectoryMap.Get(INT_ALL)
	for i := range instances {
		idx := i
		wg.Add(1)
		_ = t.workerPool.Submit(func() {
			defer wg.Done()
			infoChan <- t.getMoreInfo(instances[idx])
		})
	}

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

	newlyFetchedKeys := mapset.NewSet[string]()
	noInfoCount := 0
	for info := range infoChan {
		if info == nil {
			noInfoCount++
			continue
		}
		accessKey := t.GetKey(info)
		if !info.AllInProgress() {
			newlyFetchedKeys.Add(accessKey)
		}

		if torrent, exists := allTorrents.Get(accessKey); !exists {
			allTorrents.Set(accessKey, info)
		} else if !info.DownloadedIDs.Difference(torrent.DownloadedIDs).IsEmpty() {
			mainTorrent := t.mergeToMain(torrent, info)
			allTorrents.Set(accessKey, &mainTorrent)
		}
	}
	t.log.Infof("Compiled into %d torrents, %d were missing info", allTorrents.Count(), noInfoCount)

	var updatedPaths []string
	// torrents yet to be assigned in a directory
	newlyFetchedKeys.Difference(t.allAccessKeys).Each(func(accessKey string) bool {
		// assign to directories
		tor, ok := allTorrents.Get(accessKey)
		if !ok {
			return false
		}
		var directories []string
		t.assignedDirectoryCb(tor, func(directory string) {
			torrents, _ := t.DirectoryMap.Get(directory)
			torrents.Set(accessKey, tor)
			updatedPaths = append(updatedPaths, fmt.Sprintf("%s/%s", directory, accessKey))
			// this is just for the logs
			if directory != config.ALL_TORRENTS {
				directories = append(directories, directory)
			}
		})
		// t.log.Debugf("Added %s to %v", accessKey, directories)
		t.allAccessKeys.Add(accessKey)
		return false
	})
	// removed torrents
	t.allAccessKeys.Difference(newlyFetchedKeys).Each(func(accessKey string) bool {
		t.Delete(accessKey, false)
		return false
	})

	if t.Config.EnableRepair() {
		t.workerPool.Submit(func() {
			t.handleFixers()
		})
	}

	return updatedPaths
}

// StartRefreshJob periodically refreshes the torrents
func (t *TorrentManager) StartRefreshJob() {
	_ = t.workerPool.Submit(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()
				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 {
	infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
	if torrentFromCache, exists := infoCache.Get(rdTorrent.ID); exists &&
		!torrentFromCache.AnyInProgress() &&
		torrentFromCache.SelectedFiles.Count() == len(rdTorrent.Links) {
		return torrentFromCache
	} else if !exists {
		torrentFromFile := t.readTorrentFromFile(rdTorrent.ID)
		if torrentFromFile != nil &&
			!torrentFromFile.AnyInProgress() &&
			torrentFromFile.SelectedFiles.Count() == len(rdTorrent.Links) {

			hasBrokenFiles := false
			torrentFromFile.SelectedFiles.IterCb(func(filepath string, file *File) {
				if file.IsBroken && !file.IsDeleted {
					hasBrokenFiles = true
				}
			})

			if !hasBrokenFiles {
				infoCache.Set(rdTorrent.ID, torrentFromFile)
				t.ResetSelectedFiles(torrentFromFile)
				return torrentFromFile
			} else {
				t.log.Warnf("Torrent %s has broken files, will not save on info cache", rdTorrent.ID)
			}
		}
	}

	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
	}

	torrent := Torrent{
		Name:         info.Name,
		OriginalName: info.OriginalName,
		Added:        info.Added,
		Hash:         info.Hash,
	}
	// 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
	// if some Links are empty, we need to repair it
	for _, file := range info.Files {
		if file.Selected == 0 {
			continue
		}
		selectedFiles = append(selectedFiles, &File{
			File:     file,
			Ended:    info.Ended,
			Link:     "", // no link yet
			IsBroken: true,
		})
	}
	if len(selectedFiles) == len(info.Links) {
		// all links are still intact! good!
		for i, file := range selectedFiles {
			file.Link = info.Links[i]
			file.IsBroken = false
		}
		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.DownloadedIDs = mapset.NewSet[string]()
	torrent.InProgressIDs = mapset.NewSet[string]()
	if info.IsDone() {
		torrent.DownloadedIDs.Add(info.ID)
	} else {
		torrent.InProgressIDs.Add(info.ID)
	}

	infoCache.Set(rdTorrent.ID, &torrent)
	t.saveTorrentChangesToDisk(&torrent, nil)

	return &torrent
}

// ResetSelectedFiles will rename the file based on config
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
	}

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

		DownloadedIDs:      newer.DownloadedIDs.Union(older.DownloadedIDs),
		InProgressIDs:      newer.InProgressIDs.Union(older.InProgressIDs),
		UnassignedLinks:    newer.UnassignedLinks.Union(older.UnassignedLinks),
		SelectedFiles:      newer.SelectedFiles,
		UnrepairableReason: newer.UnrepairableReason,
	}

	// 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
	}

	// update in progress ids
	mainTorrent.DownloadedIDs.Each(func(id string) bool {
		mainTorrent.InProgressIDs.Remove(id)
		return false
	})

	// the link can have the following values
	// 1. https://*** - the file is available
	// 3. empty - the file is not available
	mainTorrent.SelectedFiles.IterCb(func(key string, file *File) {
		if file.IsBroken {
			file, ok := older.SelectedFiles.Get(key)
			if ok {
				mainTorrent.SelectedFiles.Set(key, file)
			}
		}
	})
	older.SelectedFiles.IterCb(func(key string, file *File) {
		if !mainTorrent.SelectedFiles.Has(key) {
			mainTorrent.SelectedFiles.Set(key, file)
		} else if file.IsDeleted {
			mainTorrent.SelectedFiles.Set(key, file)
		}
	})

	return mainTorrent
}

func (t *TorrentManager) assignedDirectoryCb(tor *Torrent, cb func(string)) {
	torrentIDs := tor.DownloadedIDs.Union(tor.InProgressIDs).ToSlice()
	// 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 unplayable && utils.IsStreamable(file.Path) {
			unplayable = false
		}
	})
	// 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 unplayable {
					cb(config.UNPLAYABLE_TORRENTS)
					break
				}
				if t.Config.MeetsConditions(directory, t.GetKey(tor), tor.ComputeTotalSize(), torrentIDs, filenames, fileSizes) {
					cb(directory)
					break
				}
			}
		}
	}
}