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.repairPool.Submit(func() {
		t.log.Info("Checking for broken torrents")
		t.repairAll()
		t.log.Info("Finished checking for broken 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.Unrepairable {
			return
		}
		if currentGroup.Cardinality() >= maxGroupSize {
			currentGroup = mapset.NewSet[string]()
			hashGroups = append(hashGroups, currentGroup)
		}
		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)

	toRepair := mapset.NewSet[*Torrent]()
	allTorrents.IterCb(func(_ string, torrent *Torrent) {
		if torrent.AnyInProgress() || torrent.Unrepairable {
			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 !strings.HasPrefix(file.Link, "http") && file.Link != "unselect" {
				hasBrokenFiles = true
				return
			}
			if !isCached && strings.HasPrefix(file.Link, "http") {
				unrestrict := t.UnrestrictUntilOk(file.Link)
				if unrestrict == nil || file.Bytes != unrestrict.Filesize {
					hasBrokenFiles = true
					return
				}
			}
		})

		if !isCached || hasBrokenFiles || torrent.UnassignedLinks.Cardinality() > 0 {
			toRepair.Add(torrent)
		}
	})
	t.log.Debugf("Found %d broken torrents to repair in total", toRepair.Cardinality())
	toRepair.Each(func(torrent *Torrent) bool {
		t.Repair(torrent)
		return false
	})
}

func (t *TorrentManager) Repair(torrent *Torrent) {
	if torrent.Unrepairable {
		t.log.Warnf("Torrent %s is unfixable, skipping repair", t.GetKey(torrent))
		return
	}
	if t.repairs.Contains(t.GetKey(torrent)) {
		t.log.Warnf("Torrent %s is already being repaired, skipping repair", t.GetKey(torrent))
		return
	}
	t.repairs.Add(t.GetKey(torrent))
	// save the broken files to the file cache
	infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
	torrent.DownloadedIDs.Each(func(id string) bool {
		info, _ := infoCache.Get(id)
		info.SelectedFiles.IterCb(func(_ string, file *File) {
			torrent.BrokenLinks.Each(func(link string) bool {
				if file.Link == link {
					file.Link = ""
				}
				return file.Link == link
			})
		})
		t.writeTorrentToFile(id, info)
		return false
	})
	_ = t.workerPool.Submit(func() {
		t.repair(torrent)
		t.repairs.Remove(t.GetKey(torrent))
	})
}

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

	// handle torrents with incomplete links for selected files
	assignedCount := 0

	// number of rar files detected from the unrestricted links
	rarCount := 0

	newUnassignedLinks := cmap.New[*realdebrid.Download]()

	// unrestrict each unassigned link that was filled out during torrent init
	torrent.UnassignedLinks.Each(func(link string) bool {
		unrestrict := t.UnrestrictUntilOk(link)
		if unrestrict == nil {
			newUnassignedLinks.Set(link, nil)
			// return early, no point continuing
			return false
		}

		// try to assign to a selected file
		assigned := false
		torrent.SelectedFiles.IterCb(func(_ string, file *File) {
			// base it on size because why not?
			if file.Bytes == unrestrict.Filesize {
				file.Link = link
				assigned = true
				assignedCount++
			}
		})

		if !assigned {
			// if not assigned and is a rar, likely it was rar'ed by RD
			if strings.HasSuffix(unrestrict.Filename, ".rar") {
				rarCount++
			}
			newUnassignedLinks.Set(link, unrestrict)
		}
		return false
	})

	if assignedCount > 0 {
		// if there are any assigned count
		t.log.Infof("Assigned %d links to selected files for torrent %s", assignedCount, t.GetKey(torrent))
	} else if rarCount > 0 {
		// also is assignedCount=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", t.GetKey(torrent))
			t.Delete(t.GetKey(torrent), true)
		} else {
			t.log.Warnf("Torrent %s is rar'ed and we cannot repair it, skipping repair", t.GetKey(torrent))
			newUnassignedLinks.IterCb(func(_ string, unassigned *realdebrid.Download) {
				if unassigned == nil {
					return
				}
				newFile := &File{
					File: realdebrid.File{
						ID:       0,
						Path:     unassigned.Filename,
						Bytes:    unassigned.Filesize,
						Selected: 1,
					},
					Ended: torrent.Added,
					Link:  unassigned.Link,
				}
				torrent.SelectedFiles.Set(unassigned.Filename, newFile)
			})
			torrent.UnassignedLinks = mapset.NewSet[string]()
			t.markAsUnfixable(torrent)
			t.markAsUnplayable(torrent)
		}
		return
	}

	// get all broken files
	brokenFiles := getBrokenFiles(torrent)
	fileIDs := getFileIDs(brokenFiles)
	brokenFileIDs := strings.Join(fileIDs, ",")

	// first solution: reinsert and see if the broken file is now working
	t.log.Debugf("repair_method#1: Trying to redownload torrent %s to repair files (%s)", t.GetKey(torrent), brokenFileIDs)
	info, err := t.redownloadTorrent(torrent, "")
	if err != nil {
		t.log.Warnf("Cannot repair torrent %s using repair_method#1", t.GetKey(torrent))
	}
	if info != nil && info.Progress != 100 {
		t.log.Infof("Redownloading torrent %s after repair_method#1, it should work once done", t.GetKey(torrent))
		return
	}
	if info != nil && info.IsDone() && !t.isStillBroken(info, brokenFiles) {
		t.log.Infof("Successfully repaired torrent %s using repair_method#1", t.GetKey(torrent))
		return
	}

	// second solution: add only the broken files
	if len(brokenFiles) > 0 {
		t.log.Infof("repair_method#2: Redownloading %dof%d broken files for torrent %s", len(brokenFiles), torrent.SelectedFiles.Count(), t.GetKey(torrent))
		_, err := t.redownloadTorrent(torrent, brokenFileIDs)
		if err != nil {
			t.log.Warnf("Cannot repair torrent %s using repair_method#2", t.GetKey(torrent))
		} else {
			t.log.Infof("Successfully repaired torrent %s using repair_method#2", t.GetKey(torrent))
		}
	} else {
		t.log.Warnf("Torrent %s has no broken files to repair", t.GetKey(torrent))
	}
}

func (t *TorrentManager) redownloadTorrent(torrent *Torrent, brokenFiles string) (*realdebrid.TorrentInfo, error) {
	t.log.Debugf("Redownloading torrent %s, broken files=%s (all if empty)", t.GetKey(torrent), brokenFiles)
	oldTorrentIDs := make([]string, 0)
	// broken files means broken links
	// if brokenFiles is not provided
	if brokenFiles == "" {
		// only replace the torrent if we are redownloading 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 nil, nil // nothing to repair
		} else {
			brokenFiles = tmpSelection[:len(tmpSelection)-1]
		}
	}

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

	// select files
	newTorrentID := resp.ID
	err = t.Api.SelectTorrentFiles(newTorrentID, brokenFiles)
	if err != nil {
		t.Api.DeleteTorrent(newTorrentID)
		return nil, fmt.Errorf("cannot start redownloading: %v", err)
	}
	time.Sleep(1 * time.Second)

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

	// documented status: magnet_error, magnet_conversion, waiting_files_selection, queued, downloading, downloaded, error, virus, compressing, uploading, dead
	okStatuses := []string{"magnet_conversion", "waiting_files_selection", "queued", "downloading", "downloaded", "uploading"}
	// not compressing because we need playable files
	isOkStatus := false
	for _, status := range okStatuses {
		if info.Status == status {
			isOkStatus = true
			break
		}
	}
	if !isOkStatus {
		t.Api.DeleteTorrent(newTorrentID)
		return nil, fmt.Errorf("the redownloaded torrent %s (id=%s) is in error state: %s", t.GetKey(torrent), newTorrentID, info.Status)
	}

	if info.Progress != 100 {
		t.log.Infof("Torrent %s (id=%s) is not cached anymore so we have to wait until completion (this should fix the issue already)", t.GetKey(torrent), info.ID)
		if len(oldTorrentIDs) > 0 {
			// only triggered when brokenFiles == ""
			for _, id := range oldTorrentIDs {
				t.Api.DeleteTorrent(id)
			}
		} else {
			t.fixers.Set(newTorrentID, torrent)
		}
		return info, nil
	}

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

	if len(oldTorrentIDs) > 0 {
		// only triggered when brokenFiles == ""
		for _, id := range oldTorrentIDs {
			t.Api.DeleteTorrent(id)
		}
	} else {
		t.fixers.Set(newTorrentID, torrent)
	}
	return info, nil
}

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-1 {
			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", t.GetKey(torrent))
	t.DirectoryMap.IterCb(func(directory string, torrents cmap.ConcurrentMap[string, *Torrent]) {
		torrents.Remove(t.GetKey(torrent))
	})
	torrents, _ := t.DirectoryMap.Get(config.UNPLAYABLE_TORRENTS)
	torrents.Set(t.GetKey(torrent), torrent)
}

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

func getBrokenFiles(torrent *Torrent) []*File {
	var brokenFiles []*File
	torrent.SelectedFiles.IterCb(func(_ string, file *File) {
		if !strings.HasPrefix(file.Link, "http") && file.Link != "unselect" {
			brokenFiles = append(brokenFiles, file)
		}
	})
	return brokenFiles
}

func (t *TorrentManager) isStillBroken(info *realdebrid.TorrentInfo, brokenFiles []*File) bool {
	for _, oldFile := range brokenFiles {
		for idx, newFile := range info.Files {
			if oldFile.Path == newFile.Path {
				unrestrict := t.UnrestrictUntilOk(info.Links[idx])
				if unrestrict == nil || oldFile.Bytes != unrestrict.Filesize {
					return true
				}
			}
		}
	}
	return false
}