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() {
	// there is 1 repair worker, with max 1 blocking task
	_ = t.repairPool.Submit(func() {
		t.log.Info("Periodic repair invoked; searching for broken torrents")
		t.repairAll()
	})
}

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

	// collect all torrents that need to be repaired
	var toRepair mapset.Set[*Torrent]

	allTorrents.IterCb(func(_ string, torrent *Torrent) {
		if torrent.AnyInProgress() || torrent.UnrepairableReason != "" {
			return
		}

		// save the broken files to the file cache
		// broken files are also added when trying to open a file
		if torrent.BrokenLinks.Cardinality() > 0 {
			infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
			torrent.DownloadedIDs.Each(func(id string) bool {
				info, _ := infoCache.Get(id)
				hasBrokenFiles := false
				info.SelectedFiles.IterCb(func(_ string, file *File) {
					torrent.BrokenLinks.Each(func(brokenLink string) bool {
						if file.Link == brokenLink {
							hasBrokenFiles = true
							file.Link = ""
							return true
						}
						return false
					})
				})
				if hasBrokenFiles {
					info.BrokenLinks = torrent.BrokenLinks
					t.writeTorrentToFile(id, info)
				}
				return false
			})
		}

		// check 2: for broken files
		brokenFileIDs := mapset.NewSet[int]()
		torrent.SelectedFiles.IterCb(func(_ string, file *File) {
			if !strings.HasPrefix(file.Link, "http") && file.Link != "unselect" {
				brokenFileIDs.Add(file.ID)
			}
		})
		if brokenFileIDs.Cardinality() > 0 {
			t.log.Debugf("Torrent %s has broken files (ids=%v), adding to repair list", t.GetKey(torrent), brokenFileIDs.ToSlice())
			toRepair.Add(torrent)
			return
		}

		// check 3: for expired links
		if torrent.UnassignedLinks.Cardinality() > 0 {
			t.log.Debugf("Torrent %s has unassigned links, adding to repair list", t.GetKey(torrent))
			toRepair.Add(torrent)
			return
		}
	})
	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.UnrepairableReason != "" {
		t.log.Warnf("Torrent %s is unfixable (%s), skipping repair", t.GetKey(torrent), torrent.UnrepairableReason)
		return
	}
	if t.repairs.Contains(t.GetKey(torrent)) {
		t.log.Warnf("Torrent %s is already being repaired, skipping repair", t.GetKey(torrent))
		return
	}
	if torrent.AnyInProgress() {
		t.log.Infof("Torrent %s is in progress, skipping repair until download is done", t.GetKey(torrent))
		return
	}

	t.repairs.Add(t.GetKey(torrent))

	t.log.Infof("Attempting repair for torrent %s", t.GetKey(torrent))

	// blocks for approx 45 minutes if active torrents are full
	if !t.canCapacityHandle() {
		t.log.Error("Blocked for too long due to limit of active torrents, cannot continue with the repair")
		return
	}

	// assign to a worker
	_ = t.workerPool.Submit(func() {
		t.repair(torrent)
		t.repairs.Remove(t.GetKey(torrent))
	})
}

func (t *TorrentManager) repair(torrent *Torrent) {
	t.log.Infof("Started repair process for torrent %s", t.GetKey(torrent))

	// handle torrents with incomplete links for selected files
	if !t.assignUnassignedLinks(torrent) {
		return
	}

	// get all broken files
	brokenFiles := getBrokenFiles(torrent)
	t.log.Debugf("Torrent %s has %d broken out of %d files", t.GetKey(torrent), len(brokenFiles), torrent.SelectedFiles.Count())
	brokenFileIDs := getFileIDs(brokenFiles)

	// first solution: reinsert and see if the broken file is now working
	t.log.Debugf("repair_method#1: Redownloading whole torrent %s", t.GetKey(torrent))
	info, err := t.redownloadTorrent(torrent, "") // reinsert the torrent, passing ""
	if err != nil {
		t.log.Warnf("repair_method#1: Cannot repair torrent %s (error=%s)", t.GetKey(torrent), err.Error())
	} else if info != nil && info.Progress != 100 {
		t.log.Infof("repair_method#1: Torrent %s is still in progress but it should work once done (torrent is temporarily hidden until download has completed)", t.GetKey(torrent))
		return
	} else if info != nil && info.IsDone() && !t.isStillBroken(info, brokenFiles) {
		t.log.Infof("Successfully repaired torrent %s using repair_method#1", t.GetKey(torrent))
		return
	}

	if torrent.UnrepairableReason != "" {
		t.log.Debugf("Torrent %s has been marked as unfixable during repair_method#1 (%s), ending repair process early", t.GetKey(torrent), torrent.UnrepairableReason)
		return
	}

	if len(brokenFiles) == torrent.SelectedFiles.Count() {
		t.log.Warnf("Torrent %s has all broken files, marking as unplayable", t.GetKey(torrent))
		return
	}

	// second solution: add only the broken files
	if len(brokenFiles) > 0 {
		t.log.Infof("repair_method#2: Redownloading %dof%d files only for torrent %s", len(brokenFiles), torrent.SelectedFiles.Count(), t.GetKey(torrent))
		_, err := t.redownloadTorrent(torrent, brokenFileIDs)
		if err != nil {
			t.log.Warnf("repair_method#2: Cannot repair torrent %s (error=%s)", t.GetKey(torrent), err.Error())
		}
		return
	}

	t.log.Infof("Torrent %s has no broken files to repair", t.GetKey(torrent))
}

func (t *TorrentManager) assignUnassignedLinks(torrent *Torrent) bool {
	// handle torrents with incomplete links for selected files
	assignedCount := 0
	rarCount := 0
	newUnassignedLinks := cmap.New[*realdebrid.Download]()
	torrent.UnassignedLinks.Each(func(link string) bool {
		// unrestrict each unassigned link that was filled out during torrent init
		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(strings.ToLower(unrestrict.Filename), ".rar") {
				rarCount++
			}
			newUnassignedLinks.Set(link, unrestrict)
		}
		return false
	})
	if assignedCount == 0 && rarCount > 0 && newUnassignedLinks.Count() > 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", 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, "rar'ed by RD")
			t.markAsUnplayable(torrent, "rar'ed by RD")
		}
		t.log.Debugf("Ending repair process early for torrent %s", t.GetKey(torrent))
		return false
	}
	// empty the unassigned links as we have assigned them
	if torrent.UnassignedLinks.Cardinality() > 0 {
		infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
		torrent.DownloadedIDs.Each(func(id string) bool {
			info, _ := infoCache.Get(id)
			info.UnassignedLinks = mapset.NewSet[string]()
			t.writeTorrentToFile(id, info)
			return false
		})
	}

	return true
}

func (t *TorrentManager) redownloadTorrent(torrent *Torrent, selection string) (*realdebrid.TorrentInfo, error) {
	// broken files means broken links
	// if brokenFiles is not provided, we will redownload all files
	oldTorrentIDs := make([]string, 0)
	if selection == "" {
		// only delete the old 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 {
			selection = tmpSelection[:len(tmpSelection)-1]
		}
	}

	// redownload torrent
	resp, err := t.Api.AddMagnetHash(torrent.Hash)
	if err != nil {
		if strings.Contains(err.Error(), "infringing") {
			t.markAsUnfixable(torrent, "infringing torrent")
		} else if strings.Contains(err.Error(), "unsupported") {
			t.markAsUnfixable(torrent, "unsupported torrent")
		} else if strings.Contains(err.Error(), "unavailable") {
			t.markAsUnfixable(torrent, "unavailable torrent")
		} else if strings.Contains(err.Error(), "invalid") {
			t.markAsUnfixable(torrent, "invalid torrent")
		} else if strings.Contains(err.Error(), "big") {
			t.markAsUnfixable(torrent, "torrent too big")
		} else if strings.Contains(err.Error(), "allowed") {
			t.markAsUnfixable(torrent, "torrent not allowed")
		}
		return nil, fmt.Errorf("cannot redownload torrent: %v", err)
	}

	// sleep for 1 second to let RD process the magnet
	time.Sleep(1 * time.Second)

	// select files
	newTorrentID := resp.ID
	err = t.Api.SelectTorrentFiles(newTorrentID, selection)
	if err != nil {
		t.Api.DeleteTorrent(newTorrentID)
		t.deleteOnceDone.Add(newTorrentID)
		return nil, fmt.Errorf("cannot start redownloading: %v", err)
	}

	// sleep for 1 second to let RD process the magnet
	time.Sleep(1 * time.Second)

	// see if the torrent is ready
	info, err := t.Api.GetTorrentInfo(newTorrentID)
	if err != nil {
		t.Api.DeleteTorrent(newTorrentID)
		t.deleteOnceDone.Add(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)
		t.deleteOnceDone.Add(newTorrentID)
		return nil, fmt.Errorf("the redownloaded torrent %s (id=%s) is in error state: %s", t.GetKey(torrent), newTorrentID, info.Status)
	}

	// check if incorrect number of links
	selectionCount := len(strings.Split(selection, ","))
	if info.Progress == 100 && len(info.Links) != selectionCount {
		t.Api.DeleteTorrent(newTorrentID)
		t.deleteOnceDone.Add(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), selectionCount)
	}

	// looks like it's fixed

	if len(oldTorrentIDs) > 0 {
		// replace the old torrent
		for _, id := range oldTorrentIDs {
			t.Api.DeleteTorrent(id)
			t.deleteOnceDone.Add(id)
		}
	} else {
		// it's a fixer
		t.fixers.Set(newTorrentID, torrent)
		t.deleteOnceDone.Add(newTorrentID)
	}
	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, reason string) {
	t.log.Warnf("Marking torrent %s as unplayable - %s", t.GetKey(torrent), reason)
	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, reason string) {
	t.log.Warnf("Marking torrent %s as unfixable - %s", t.GetKey(torrent), reason)
	torrent.UnrepairableReason = reason
	infoCache, _ := t.DirectoryMap.Get(INT_INFO_CACHE)
	torrent.DownloadedIDs.Each(func(id string) bool {
		info, _ := infoCache.Get(id)
		info.UnrepairableReason = reason
		t.writeTorrentToFile(id, info)
		return false
	})
}

// getBrokenFiles returns the files that are not http links and not unselect
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
}

// isStillBroken checks if the torrent is still broken
// if it's not broken anymore, it will assign the links to the files
func (t *TorrentManager) isStillBroken(info *realdebrid.TorrentInfo, brokenFiles []*File) bool {
	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
		})
	}
	if len(selectedFiles) == len(info.Links) {
		// all links are still intact! good!
		for i, file := range selectedFiles {
			file.Link = info.Links[i]
		}
	} else {
		// if we can't assign links, it's still broken
		return true
	}

	if len(brokenFiles) == 0 {
		// just check for the last file
		brokenFiles = append(brokenFiles, selectedFiles[len(selectedFiles)-1])
	}

	// check if the broken files can now be unrestricted
	for _, oldFile := range brokenFiles {
		for idx, newFile := range selectedFiles {
			if oldFile.Path == newFile.Path || oldFile.Bytes == newFile.Bytes {
				unrestrict := t.UnrestrictUntilOk(selectedFiles[idx].Link)
				if unrestrict == nil || oldFile.Bytes != unrestrict.Filesize {
					return true
				}
			}
		}
	}
	return false
}

func (t *TorrentManager) handleFixers(fixer realdebrid.Torrent) *Torrent {
	// since fixer is done, we can pop it from the fixers set
	torrent, _ := t.fixers.Pop(fixer.ID)
	if torrent == nil {
		t.log.Warnf("repair_method#2: Fixer for %s (id=%s) is done but torrent has been deleted, deleting fixer...", fixer.Name, fixer.ID)
		t.Api.DeleteTorrent(fixer.ID)
		t.deleteOnceDone.Add(fixer.ID)
		return nil
	}

	brokenFiles := getBrokenFiles(torrent)
	info, err := t.redownloadTorrent(torrent, "") // reinsert
	if err != nil {
		t.log.Warnf("repair_method#2: Cannot repair torrent %s (error=%s)", t.GetKey(torrent), err.Error())
		return nil
	}

	if info.IsDone() {
		if t.isStillBroken(info, brokenFiles) {
			t.log.Warnf("repair_method#2: Fixer is done but torrent %s is still broken; let's keep the fixer", t.GetKey(torrent))
			t.Api.DeleteTorrent(info.ID)
			t.deleteOnceDone.Add(fixer.ID)
			return t.getMoreInfo(fixer)
		} else {
			t.log.Infof("Successfully repaired torrent %s using repair_method#2", t.GetKey(torrent))
		}
	} else {
		t.log.Infof("repair_method#2: Torrent %s is still in progress but it should work once done (torrent is temporarily hidden until download has completed)", t.GetKey(torrent))
	}

	t.Api.DeleteTorrent(fixer.ID) // delete the fixer
	t.deleteOnceDone.Add(fixer.ID)
	return nil
}