package torrent

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"runtime"
	"strings"
	"sync"
	"time"

	"github.com/debridmediamanager/zurg/internal/config"
	"github.com/debridmediamanager/zurg/internal/fs"
	"github.com/debridmediamanager/zurg/pkg/logutil"
	"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"
	"github.com/panjf2000/ants/v2"
	"gopkg.in/vansante/go-ffprobe.v2"
)

const (
	INT_ALL = "int__all__"
)

type TorrentManager struct {
	requiredVersion string

	Config     config.ConfigInterface
	rd         *realdebrid.RealDebrid
	workerPool *ants.Pool
	log        *logutil.Logger
	repairLog  *logutil.Logger

	DirectoryMap cmap.ConcurrentMap[string, cmap.ConcurrentMap[string, *Torrent]] // directory -> accessKey -> Torrent
	DownloadMap  cmap.ConcurrentMap[string, *realdebrid.Download]

	RootNode *fs.FileNode

	RefreshWorkerKillSwitch chan struct{}
	RepairWorkerKillSwitch  chan struct{}
	RemountTrigger          chan struct{}
	RepairAllTrigger        chan struct{}
	DumpTrigger             chan struct{}
	AnalyzeTrigger          chan struct{}

	latestState *LibraryState

	RepairQueue     mapset.Set[*Torrent]
	repairRunning   bool
	repairRunningMu sync.Mutex

	OnceDoneBin mapset.Set[string]
	hasFFprobe  bool
}

// NewTorrentManager creates a new torrent manager
// it will fetch all torrents and their info in the background
// and store them in-memory and cached in files
func NewTorrentManager(cfg config.ConfigInterface, api *realdebrid.RealDebrid, workerPool *ants.Pool, hasFFprobe bool, log, repairLog *logutil.Logger) *TorrentManager {
	t := &TorrentManager{
		requiredVersion: "0.10.0",

		Config:     cfg,
		rd:         api,
		workerPool: workerPool,
		log:        log,
		repairLog:  repairLog,

		DirectoryMap: cmap.New[cmap.ConcurrentMap[string, *Torrent]](),
		DownloadMap:  cmap.New[*realdebrid.Download](),

		RootNode: fs.NewFileNode("root", true),

		RefreshWorkerKillSwitch: make(chan struct{}, 1),
		RepairWorkerKillSwitch:  make(chan struct{}, 1),
		RemountTrigger:          make(chan struct{}, 1),
		// RepairAllTrigger:        make(chan struct{}, 1), // initialized in repair.go
		DumpTrigger:    make(chan struct{}, 1),
		AnalyzeTrigger: make(chan struct{}, 1),

		latestState: &LibraryState{log: log},

		OnceDoneBin: mapset.NewSet[string](),
		hasFFprobe:  hasFFprobe,
	}

	t.initializeBins()
	t.initializeDirectoryMaps()

	var wg sync.WaitGroup
	wg.Add(3)

	t.workerPool.Submit(func() {
		defer wg.Done()
		t.loadDumpedTorrents()
	})
	t.workerPool.Submit(func() {
		defer wg.Done()

		// initial load of existing *.zurgtorrent files
		torrents, _ := t.DirectoryMap.Get(INT_ALL)
		t.getTorrentFiles("data").Each(func(filePath string) bool {
			torrent := t.readTorrentFromFile(filePath)
			if torrent != nil {
				accessKey := t.GetKey(torrent)
				torrents.Set(accessKey, torrent)
				t.assignDirectory(torrent, false, false)
			}
			return false
		})

		t.refreshTorrents(true)
	})
	t.workerPool.Submit(func() {
		defer wg.Done()
		t.mountNewDownloads()
	})

	t.workerPool.Submit(func() {
		wg.Wait()
		t.StartRefreshJob()
		t.StartDownloadsJob()
		t.StartRepairJob()
		t.StartDumpJob()
		t.StartMediaAnalysisJob()

		t.setNewLatestState(t.getCurrentState())

		t.EnqueueForRepair(nil)
	})

	return t
}

// proxy function
func (t *TorrentManager) UnrestrictFile(file *File) (*realdebrid.Download, error) {
	if file.State.Is("deleted_file") {
		return nil, fmt.Errorf("file %s has been deleted", file.Path)
	} else if file.State.Is("broken_file") {
		return nil, fmt.Errorf("file %s is broken", file.Path)
	}
	return t.rd.UnrestrictAndVerify(file.Link)
}

func (t *TorrentManager) GetKey(torrent *Torrent) string {
	if !t.Config.ShouldIgnoreRenames() && torrent.Rename != "" {
		return torrent.Rename
	}
	if t.Config.EnableRetainRDTorrentName() {
		return torrent.Name
	}
	// drop the extension from the name
	if t.Config.EnableRetainFolderNameExtension() && strings.Contains(torrent.Name, torrent.OriginalName) {
		return torrent.Name
	} else {
		ret := strings.TrimSuffix(torrent.OriginalName, ".mp4")
		ret = strings.TrimSuffix(ret, ".mkv")
		return ret
	}
}

func (t *TorrentManager) GetPath(file *File) string {
	if !t.Config.ShouldIgnoreRenames() && file.Rename != "" {
		return file.Rename
	}
	filename := filepath.Base(file.Path)
	return filename
}

/// torrent functions

func (t *TorrentManager) getTorrentFiles(parentDir string) mapset.Set[string] {
	files, err := filepath.Glob(parentDir + "/*.zurgtorrent")
	if err != nil {
		t.log.Warnf("Cannot get files in %s directory: %v", parentDir, err)
		return nil
	}
	return mapset.NewSet[string](files...)
}

func (t *TorrentManager) writeTorrentToFile(torrent *Torrent) {
	filePath := "data/" + t.getTorrentFilename(torrent) + ".zurgtorrent"
	file, err := os.Create(filePath)
	if err != nil {
		t.log.Warnf("Cannot create file %s: %v", filePath, err)
		return
	}
	defer file.Close()

	torrent.Version = t.requiredVersion

	jsonData, err := json.Marshal(torrent)
	if err != nil {
		t.log.Warnf("Cannot marshal torrent: %v", err)
		return
	}

	if _, err := file.Write(jsonData); err != nil {
		t.log.Warnf("Cannot write to file %s: %v", filePath, err)
		return
	}

	// t.log.Debugf("Saved torrent %s to file", t.GetKey(torrent))
}

func (t *TorrentManager) sendTorrentToAPI(torrent *Torrent) {
	torrent.Version = t.requiredVersion
	jsonData, err := json.Marshal(torrent)
	if err != nil {
		return
	}
	req, err := http.NewRequest(
		"POST",
		"https://zurgtorrent.debridmediamanager.com/api/torrents",
		bytes.NewBuffer(jsonData),
	)
	if err != nil {
		return
	}
	req.Header.Set("Content-Type", "application/json")
	client := &http.Client{}
	client.Do(req)
}

func (t *TorrentManager) applyMediaInfoDetails(torrent *Torrent) error {
	changesApplied := false
	bwLimitReached := false
	torrent.SelectedFiles.IterCb(func(_ string, file *File) {
		if bwLimitReached {
			return
		}
		isPlayable := utils.IsVideo(file.Path) || t.IsPlayable(file.Path)
		if file.MediaInfo != nil || !file.State.Is("ok_file") || !isPlayable {
			return
		}
		unrestrict, err := t.UnrestrictFile(file)
		if utils.AreAllTokensExpired(err) {
			bwLimitReached = true
			return
		}
		if unrestrict == nil {
			file.State.Event(context.Background(), "break_file")
			t.EnqueueForRepair(torrent)
			changesApplied = true
			return
		}
		ctx, cancelFn := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancelFn()
		data, err := ffprobe.ProbeURL(ctx, unrestrict.Download)
		if err != nil {
			t.log.Warnf("Cannot probe file %s: %v", file.Path, err)
			return
		}
		file.MediaInfo = data
		changesApplied = true
	})
	if changesApplied {
		t.writeTorrentToFile(torrent)
	}
	t.sendTorrentToAPI(torrent)
	if bwLimitReached {
		t.log.Warnf("Your account has reached the bandwidth limit, cannot apply media info details to the rest of the files")
		return fmt.Errorf("bandwidth limit reached")
	}
	return nil
}

func (t *TorrentManager) readTorrentFromFile(filePath string) *Torrent {
	file, err := os.Open(filePath)
	if err != nil {
		return nil
	}
	defer file.Close()
	jsonData, err := io.ReadAll(file)
	if err != nil {
		return nil
	}
	var torrent *Torrent
	if err := json.Unmarshal(jsonData, &torrent); err != nil {
		return nil
	}
	if torrent.Version != t.requiredVersion {
		return nil
	}

	torrent.SelectedFiles.IterCb(func(_ string, file *File) {
		if strings.HasPrefix(file.Link, "https://real-debrid.com/d/") {
			// set link to max 39 chars (26 + 13)
			file.Link = file.Link[0:39]
		}
	})

	unassignedLinks := mapset.NewSet[string]()
	torrent.UnassignedLinks.Each(func(link string) bool {
		if strings.HasPrefix(link, "https://real-debrid.com/d/") {
			// set link to max 39 chars (26 + 13)
			unassignedLinks.Add(link[0:39])
		} else {
			unassignedLinks.Add(link)
		}
		return false
	})
	torrent.UnassignedLinks = unassignedLinks

	return torrent
}

/// end torrent functions

/// info functions

func (t *TorrentManager) getInfoFiles() mapset.Set[string] {
	files, err := filepath.Glob("data/info/*.zurginfo")
	if err != nil {
		t.log.Warnf("Cannot get files in data directory: %v", err)
		return nil
	}
	return mapset.NewSet[string](files...)
}

func (t *TorrentManager) writeInfoToFile(info *realdebrid.TorrentInfo) {
	filePath := "data/info/" + info.ID + ".zurginfo"
	file, err := os.Create(filePath)
	if err != nil {
		t.log.Warnf("Cannot create info file %s: %v", filePath, err)
		return
	}
	defer file.Close()

	jsonData, err := json.Marshal(info)
	if err != nil {
		t.log.Warnf("Cannot marshal torrent info: %v", err)
		return
	}

	if _, err := file.Write(jsonData); err != nil {
		t.log.Warnf("Cannot write to info file %s: %v", filePath, err)
		return
	}

	// t.log.Debugf("Saved torrent %s to info file", info.ID)
}

func (t *TorrentManager) readInfoFromFile(torrentID string) *realdebrid.TorrentInfo {
	filePath := "data/info/" + torrentID + ".zurginfo"
	file, err := os.Open(filePath)
	if err != nil {
		return nil
	}
	defer file.Close()
	jsonData, err := io.ReadAll(file)
	if err != nil {
		return nil
	}
	var info *realdebrid.TorrentInfo
	if err := json.Unmarshal(jsonData, &info); err != nil {
		return nil
	}
	if info.Progress != 100 {
		return nil
	}
	return info
}

func (t *TorrentManager) deleteInfoFile(torrentID string) {
	filePath := "data/info/" + torrentID + ".zurginfo"
	_ = os.Remove(filePath)
}

/// end info functions

func (t *TorrentManager) mountNewDownloads() {
	token := t.Config.GetToken()
	tokenMap, _ := t.rd.UnrestrictMap.Get(token)

	// clear maps
	tokenMap.Clear()
	t.DownloadMap.Clear()

	downloads := t.rd.GetDownloads()
	mountedCount := 0
	for i := range downloads {
		downloads[i].Token = token

		if strings.HasPrefix(downloads[i].Link, "https://real-debrid.com/d/") {
			downloads[i].Link = downloads[i].Link[0:39]
			tokenMap.Set(downloads[i].Link, &downloads[i])
			continue
		}

		filename := filepath.Base(downloads[i].Filename)

		// account for resolution in the type
		if strings.Contains(downloads[i].Type, "x") {
			// extract extension from the filename
			ext := filepath.Ext(filename)
			trimmed := strings.TrimSuffix(filename, ext)
			// it's a resolution so extract 2nd part and add it to the filename
			parts := strings.Split(downloads[i].Type, "x")
			if len(parts) > 1 {
				filename = fmt.Sprintf("%s (%sp)%s", trimmed, parts[1], ext)
			}
		}
		// t.log.Debugf("Download dump: %+v", downloads[i])

		t.DownloadMap.Set(filename, &downloads[i])
		mountedCount++
	}
	if mountedCount > 0 {
		t.log.Infof("Mounted %d new downloads", mountedCount)
	} else {
		t.log.Debugf("No new downloads to mount")
	}
}

// StartDownloadsJob: permanent job for remounting downloads
func (t *TorrentManager) StartDownloadsJob() {
	t.workerPool.Submit(func() {
		remountTicker := time.NewTicker(time.Duration(t.Config.GetDownloadsEveryMins()) * time.Minute)
		defer remountTicker.Stop()

		for {
			select {
			case <-remountTicker.C:
				t.mountNewDownloads()
			case <-t.RemountTrigger:
				t.mountNewDownloads()
			}
		}
	})
}

func (t *TorrentManager) dumpTorrents() {
	files := t.getTorrentFiles("data")
	for file := range files.Iter() {
		destPath := "dump/" + filepath.Base(file)
		if err := copyFile(file, destPath); err != nil {
			t.log.Warnf("Cannot copy file %s to %s: %v", file, destPath, err)
		}
	}
}

func copyFile(sourcePath, destPath string) error {
	source, err := os.Open(sourcePath)
	if err != nil {
		return err
	}
	defer source.Close()

	destination, err := os.Create(destPath)
	if err != nil {
		return err
	}
	defer destination.Close()

	buf := make([]byte, 4096)
	for {
		n, err := source.Read(buf)
		if err != nil && err != io.EOF {
			return err
		}
		if n == 0 {
			break
		}

		if _, err := destination.Write(buf[:n]); err != nil {
			return err
		}
	}

	return nil
}

// StartDumpJob: permanent job for dumping torrents
func (t *TorrentManager) StartDumpJob() {
	t.workerPool.Submit(func() {
		dumpTicker := time.NewTicker(time.Duration(t.Config.GetDumpTorrentsEveryMins()) * time.Minute)
		defer dumpTicker.Stop()

		for {
			select {
			case <-dumpTicker.C:
				t.dumpTorrents()
				t.loadDumpedTorrents()
			case <-t.DumpTrigger:
				t.dumpTorrents()
				t.loadDumpedTorrents()
			}
		}
	})
}

func (t *TorrentManager) analyzeAllTorrents() {
	torrents, _ := t.DirectoryMap.Get(INT_ALL)
	totalCount := torrents.Count()
	t.log.Infof("Applying media info details to all %d torrents", totalCount)
	idx := 0
	skipTheRest := false
	torrents.IterCb(func(_ string, torrent *Torrent) {
		if skipTheRest {
			return
		}
		err := t.applyMediaInfoDetails(torrent)
		if err != nil && err.Error() == "bandwidth limit reached" {
			skipTheRest = true
			return
		}
		idx++
		t.log.Debugf("Applied media info details to torrent %s (%d/%d)", t.GetKey(torrent), idx, totalCount)
	})
	if skipTheRest {
		t.log.Warnf("Bandwidth limit reached, skipped the rest of the torrents")
	}
}

// StartMediaAnalysisJob: permanent job for analyzing media info (triggered by the user)
func (t *TorrentManager) StartMediaAnalysisJob() {
	t.workerPool.Submit(func() {
		for range t.AnalyzeTrigger {
			t.analyzeAllTorrents()
		}
	})
}

func (t *TorrentManager) initializeDirectoryMaps() {
	// create internal directories
	t.DirectoryMap.Set(INT_ALL, cmap.New[*Torrent]()) // key is GetAccessKey()
	// create directory maps
	for _, directory := range t.Config.GetDirectories() {
		t.DirectoryMap.Set(directory, cmap.New[*Torrent]())
	}
	// create special directories
	t.DirectoryMap.Set(config.ALL_TORRENTS, cmap.New[*Torrent]())
	t.DirectoryMap.Set(config.DOWNLOADS, cmap.New[*Torrent]())
	t.DirectoryMap.Set(config.DUMPED_TORRENTS, cmap.New[*Torrent]())
	t.DirectoryMap.Set(config.UNPLAYABLE_TORRENTS, cmap.New[*Torrent]())
}

func (t *TorrentManager) getTorrentFilename(torrent *Torrent) string {
	if t.Config.EnableRetainRDTorrentName() {
		return sanitizeFileName(torrent.Name)
	}
	// drop the extension from the name
	if t.Config.EnableRetainFolderNameExtension() && strings.Contains(torrent.Name, torrent.OriginalName) {
		return sanitizeFileName(torrent.Name)
	}

	ret := strings.TrimSuffix(torrent.OriginalName, ".mp4")
	ret = strings.TrimSuffix(ret, ".mkv")
	return sanitizeFileName(ret)
}

func (t *TorrentManager) getTorrentInfoFilename(torrent *realdebrid.TorrentInfo) string {
	if t.Config.EnableRetainRDTorrentName() {
		return sanitizeFileName(torrent.Name)
	}
	// drop the extension from the name
	if t.Config.EnableRetainFolderNameExtension() && strings.Contains(torrent.Name, torrent.OriginalName) {
		return sanitizeFileName(torrent.Name)
	}

	ret := strings.TrimSuffix(torrent.OriginalName, ".mp4")
	ret = strings.TrimSuffix(ret, ".mkv")
	return sanitizeFileName(ret)
}

// sanitizeFileName takes a string and converts it to a valid Windows filename
func sanitizeFileName(input string) string {
	if !isWindows() {
		return input
	}
	// Define a regex pattern to match invalid filename characters
	invalidChars := regexp.MustCompile(`[<>:"/\\|?*]+`)

	// Replace invalid characters with an underscore
	sanitized := invalidChars.ReplaceAllString(input, "_")

	// Trim leading and trailing whitespace and dots
	sanitized = strings.TrimSpace(sanitized)
	sanitized = strings.Trim(sanitized, ".")

	// Ensure the filename is not empty
	if sanitized == "" {
		sanitized = "default_filename"
	}

	return sanitized
}

func isWindows() bool {
	return runtime.GOOS == "windows"
}