package torrent

import (
	"fmt"
	"math"
	"strings"
	"time"

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

const EXPIRED_LINK_TOLERANCE_HOURS = 24

func (t *TorrentManager) RepairAll() {
	_ = t.repairWorker.Submit(func() {
		t.log.Info("Repairing all broken torrents")
		t.repairAll()
		t.log.Info("Finished repairing all torrents")
	})
}

func (t *TorrentManager) repairAll() {
	allTorrents, _ := t.DirectoryMap.Get(INT_ALL)

	var hashGroups []mapset.Set[string]
	const maxGroupSize = 399

	currentGroup := mapset.NewSet[string]()
	hashGroups = append(hashGroups, currentGroup)

	allTorrents.IterCb(func(_ string, torrent *Torrent) {
		if torrent.AnyInProgress() || torrent.Unfixable {
			return
		}
		// Check if the current group is full
		if currentGroup.Cardinality() >= maxGroupSize {
			// Create a new group and add it to the hashGroups
			currentGroup = mapset.NewSet[string]()
			hashGroups = append(hashGroups, currentGroup)
		}
		// Add the hash to the current group
		currentGroup.Add(torrent.Hash)
	})

	t.log.Debug("Checking if torrents are still cached")
	var availabilityChecks = make(map[string]bool)
	uncachedCount := 0
	for i := range hashGroups {
		if hashGroups[i].Cardinality() == 0 {
			break
		}
		resp, err := t.Api.AvailabilityCheck(hashGroups[i].ToSlice())
		if err != nil {
			t.log.Warnf("Cannot check availability: %v", err)
			continue
		}

		for hash, hosterHash := range resp {
			// Check if HosterHash is a map (Variants field is used)
			availabilityChecks[hash] = len(hosterHash.Variants) > 0
			if !availabilityChecks[hash] {
				uncachedCount++
			}
		}
	}
	t.log.Debugf("Found %d torrents that are no longer cached", uncachedCount)

	var toRepair []*Torrent
	allTorrents.IterCb(func(_ string, torrent *Torrent) {
		if torrent.AnyInProgress() || torrent.Unfixable {
			return
		}

		// check 1: for cached status
		isCached := true
		if _, ok := availabilityChecks[torrent.Hash]; !ok || !availabilityChecks[torrent.Hash] {
			isCached = false
		}
		// todo: also handle file ID checks

		// check 2: for broken files
		hasBrokenFiles := false
		torrent.SelectedFiles.IterCb(func(_ string, file *File) {
			if file.Link == "repair" || file.Link == "" {
				hasBrokenFiles = true
			}
		})

		if !isCached || hasBrokenFiles {
			toRepair = append(toRepair, torrent)
		}
	})
	t.log.Debugf("Found %d broken torrents to repair in total", len(toRepair))
	for i := range toRepair {
		torrent := toRepair[i]
		t.log.Infof("Repairing %s", torrent.AccessKey)
		t.repair(torrent)
	}
}

func (t *TorrentManager) Repair(torrent *Torrent) {
	infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
	torrent.DownloadedIDs.Each(func(id string) bool {
		infoCache.Set(id, torrent)
		t.writeTorrentToFile(id, torrent)
		return false
	})
	_ = t.repairWorker.Submit(func() {
		t.log.Infof("Repairing torrent %s", torrent.AccessKey)
		t.repair(torrent)
		t.log.Infof("Finished repairing torrent %s", torrent.AccessKey)
	})
}

func (t *TorrentManager) repair(torrent *Torrent) {
	if torrent.AnyInProgress() {
		t.log.Infof("Torrent %s is in progress, skipping repair until download is done", torrent.AccessKey)
		return
	}

	proceed := t.canCapacityHandle() // blocks for approx 45 minutes if active torrents are full
	if !proceed {
		t.log.Error("Reached the max number of active torrents, cannot continue with the repair")
		return
	}

	if torrent.OlderThanDuration(EXPIRED_LINK_TOLERANCE_HOURS * time.Hour) {
		// first solution: reinsert with same selection
		t.log.Infof("Torrent %s is older than %d hours, reinserting it", torrent.AccessKey, EXPIRED_LINK_TOLERANCE_HOURS)
		if t.reinsertTorrent(torrent, "") {
			t.log.Infof("Successfully downloaded torrent %s to repair it", torrent.AccessKey)
			return
		} else if !torrent.Unfixable {
			t.log.Warnf("Failed to repair by reinserting torrent %s, will only redownload broken files...", torrent.AccessKey)
		} else {
			t.log.Warnf("Cannot repair torrent %s", torrent.AccessKey)
			return
		}
	} else {
		t.log.Warnf("Torrent %s is not older than %d hours to be repaired by reinsertion, will only redownload broken files...", torrent.AccessKey, EXPIRED_LINK_TOLERANCE_HOURS)
	}

	// sleep for 30 seconds to let the torrent accumulate more broken files if scanning
	time.Sleep(30 * time.Second)

	// handle rar'ed torrents
	assignedCount := 0
	rarCount := 0
	unassignedDownloads := make([]*realdebrid.Download, 0)
	torrent.UnassignedLinks.Each(func(link string) bool {
		unrestrict := t.UnrestrictUntilOk(link)
		if unrestrict != nil {
			// assign to a selected file
			assigned := false
			torrent.SelectedFiles.IterCb(func(_ string, file *File) {
				// if strings.HasSuffix(file.Path, unrestrict.Filename) {
				if file.Bytes == unrestrict.Filesize {
					file.Link = unrestrict.Link
					assigned = true
					assignedCount++
				}
			})
			if !assigned {
				if strings.HasSuffix(unrestrict.Filename, ".rar") {
					rarCount++
				}
				unassignedDownloads = append(unassignedDownloads, unrestrict)
			}
		}
		return false
	})

	if assignedCount > 0 {
		t.log.Infof("Assigned %d links to selected files for torrent %s", assignedCount, torrent.AccessKey)
	} else if rarCount > 0 {
		// this is a rar'ed torrent, nothing we can do
		if t.Config.ShouldDeleteRarFiles() {
			t.log.Warnf("Torrent %s is rar'ed and we cannot repair it, deleting it as configured", torrent.AccessKey)
			t.Delete(torrent.AccessKey, true)
		} else {
			for _, unassigned := range unassignedDownloads {
				newFile := &File{
					File: realdebrid.File{
						ID:       0,
						Path:     unassigned.Filename,
						Bytes:    unassigned.Filesize,
						Selected: 1,
					},
					Ended: torrent.LatestAdded,
					Link:  unassigned.Link,
				}
				torrent.SelectedFiles.Set(unassigned.Filename, newFile)
			}
			t.markAsUnfixable(torrent)
			t.markAsUnplayable(torrent)
		}
		return
	}

	// second solution: add only the broken files
	var brokenFiles []File
	torrent.SelectedFiles.IterCb(func(_ string, file *File) {
		if file.Link == "repair" || file.Link == "" {
			brokenFiles = append(brokenFiles, *file)
			file.Link = "repairing"
		}
	})
	t.log.Debugf("During repair, zurg found %d broken files for torrent %s", len(brokenFiles), torrent.AccessKey)

	// todo: to verify removed logic when there's only 1 selected file selected and it's broken

	if len(brokenFiles) == 1 && torrent.SelectedFiles.Count() > 1 {
		// if we download a single file, it will be named differently
		// so we need to download 1 extra file to preserve the name
		// this is only relevant if we enable retain_rd_torrent_name
		// add the first file link encountered with a prefix of http
		t.log.Debugf("Torrent %s has only 1 broken file, adding 1 extra file to preserve the name", torrent.AccessKey)
		for _, file := range torrent.SelectedFiles.Items() {
			if strings.HasPrefix(file.Link, "http") {
				brokenFiles = append(brokenFiles, *file)
				break
			}
		}
	}

	if len(brokenFiles) > 0 {
		t.log.Infof("Redownloading the %d broken files for torrent %s", len(brokenFiles), torrent.AccessKey)
		brokenFileIDs := strings.Join(getFileIDs(brokenFiles), ",")
		if t.reinsertTorrent(torrent, brokenFileIDs) {
			t.log.Infof("Successfully downloaded torrent %s to repair it", torrent.AccessKey)
		} else {
			t.log.Warnf("Cannot repair torrent %s", torrent.AccessKey)
		}
	} else {
		t.log.Warnf("Torrent %s has no broken files to repair", torrent.AccessKey)
	}
}

func (t *TorrentManager) reinsertTorrent(torrent *Torrent, brokenFiles string) bool {
	oldTorrentIDs := make([]string, 0)
	// broken files means broken links
	// if brokenFiles is not provided
	if brokenFiles == "" {
		// only replace the torrent if we are reinserting all files
		oldTorrentIDs = torrent.DownloadedIDs.ToSlice()
		tmpSelection := ""
		torrent.SelectedFiles.IterCb(func(_ string, file *File) {
			tmpSelection += fmt.Sprintf("%d,", file.ID) // select all files
		})
		if tmpSelection == "" {
			return true // nothing to repair
		} else {
			brokenFiles = tmpSelection[:len(tmpSelection)-1]
		}
	}

	// redownload torrent
	resp, err := t.Api.AddMagnetHash(torrent.Hash)
	if err != nil {
		t.log.Warnf("Cannot redownload torrent: %v", err)
		if strings.Contains(err.Error(), "infringing_file") {
			t.markAsUnfixable(torrent)
		}
		return false
	}
	time.Sleep(1 * time.Second)

	// select files
	newTorrentID := resp.ID
	err = t.Api.SelectTorrentFiles(newTorrentID, brokenFiles)
	if err != nil {
		t.log.Warnf("Cannot start redownloading: %v", err)
		t.Api.DeleteTorrent(newTorrentID)
		return false
	}
	time.Sleep(10 * time.Second)

	// see if the torrent is ready
	info, err := t.Api.GetTorrentInfo(newTorrentID)
	if err != nil {
		t.log.Warnf("Cannot get info on redownloaded torrent id=%s : %v", newTorrentID, err)
		t.Api.DeleteTorrent(newTorrentID)
		return false
	}

	if info.Status == "magnet_error" || info.Status == "error" || info.Status == "virus" || info.Status == "dead" {
		t.log.Warnf("The redownloaded torrent id=%s is in error state: %s", newTorrentID, info.Status)
		t.Api.DeleteTorrent(newTorrentID)
		return false
	}

	if info.Progress != 100 {
		t.log.Infof("Torrent id=%s is not cached anymore so we have to wait until completion (this should fix the issue already)", info.ID)
		for _, id := range oldTorrentIDs {
			t.Api.DeleteTorrent(id)
		}
		return true
	}

	brokenCount := len(strings.Split(brokenFiles, ","))
	if len(info.Links) != brokenCount {
		t.log.Infof("It did not fix the issue for id=%s, only got %d files but we need %d, undoing", info.ID, len(info.Links), brokenCount)
		t.Api.DeleteTorrent(newTorrentID)
		return false
	}

	t.log.Infof("Repair successful id=%s", newTorrentID)
	for _, id := range oldTorrentIDs {
		t.Api.DeleteTorrent(id)
	}
	return true
}

func (t *TorrentManager) canCapacityHandle() bool {
	// max waiting time is 45 minutes
	const maxRetries = 50
	const baseDelay = 1 * time.Second
	const maxDelay = 60 * time.Second
	retryCount := 0
	for {
		count, err := t.Api.GetActiveTorrentCount()
		if err != nil {
			t.log.Warnf("Cannot get active downloads count: %v", err)
			if retryCount >= maxRetries {
				t.log.Error("Max retries reached. Exiting.")
				return false
			}
			delay := time.Duration(math.Pow(2, float64(retryCount))) * baseDelay
			if delay > maxDelay {
				delay = maxDelay
			}
			time.Sleep(delay)
			retryCount++
			continue
		}

		if count.DownloadingCount < count.MaxNumberOfTorrents {
			return true
		}

		delay := time.Duration(math.Pow(2, float64(retryCount))) * baseDelay
		if delay > maxDelay {
			delay = maxDelay
		}
		t.log.Infof("We have reached the max number of active torrents, waiting for %s seconds before retrying", delay)

		if retryCount >= maxRetries {
			t.log.Error("Max retries reached. Exiting.")
			return false
		}

		time.Sleep(delay)
		retryCount++
	}
}

func (t *TorrentManager) markAsUnplayable(torrent *Torrent) {
	t.log.Warnf("Marking torrent %s as unplayable", torrent.AccessKey)
	t.DirectoryMap.IterCb(func(directory string, torrents cmap.ConcurrentMap[string, *Torrent]) {
		torrents.Remove(torrent.AccessKey)
	})
	torrents, _ := t.DirectoryMap.Get(config.UNPLAYABLE_TORRENTS)
	torrents.Set(torrent.AccessKey, torrent)
}

func (t *TorrentManager) markAsUnfixable(torrent *Torrent) {
	t.log.Warnf("Marking torrent %s as unfixable", torrent.AccessKey)
	torrent.Unfixable = true
	infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
	torrent.DownloadedIDs.Each(func(id string) bool {
		info, _ := infoCache.Get(id)
		info.Unfixable = true
		t.writeTorrentToFile(id, torrent)
		return false
	})
}