package torrent

import (
	"encoding/gob"
	"fmt"
	"log"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/debridmediamanager.com/zurg/internal/config"
	"github.com/debridmediamanager.com/zurg/pkg/realdebrid"
)

type TorrentManager struct {
	token      string
	torrents   []Torrent
	workerPool chan bool
	config     config.ConfigInterface
	checksum   string
}

func (t *TorrentManager) refreshTorrents() {
	log.Println("Starting periodic refresh")
	for {
		<-time.After(time.Duration(t.config.GetRefreshEverySeconds()) * time.Second)
		checksum := t.getChecksum()
		if checksum == t.checksum {
			continue
		}
		t.checksum = checksum
		t.torrents = t.getAll()
		for _, torrent := range t.torrents {
			go func(id string) {
				t.workerPool <- true
				t.getInfo(id)
				<-t.workerPool
				time.Sleep(1 * time.Second) // sleep for 1 second to avoid rate limiting
			}(torrent.ID)
		}
	}
}

// NewTorrentManager creates a new torrent manager
// it will fetch all torrents and their info in the background
// and store them in-memory
func NewTorrentManager(config config.ConfigInterface) *TorrentManager {
	handler := &TorrentManager{
		token:      config.GetToken(),
		workerPool: make(chan bool, config.GetNumOfWorkers()),
		config:     config,
	}

	// Initialize torrents for the first time
	handler.torrents = handler.getAll()

	for _, torrent := range handler.torrents {
		go func(id string) {
			handler.workerPool <- true
			handler.getInfo(id)
			<-handler.workerPool
			time.Sleep(1 * time.Second) // sleep for 1 second to avoid rate limiting
		}(torrent.ID)
	}

	// Start the periodic refresh
	go handler.refreshTorrents()

	return handler
}

func (t *TorrentManager) getChecksum() string {
	torrents, totalCount, err := realdebrid.GetTorrents(t.token, 1)
	if err != nil {
		log.Printf("Cannot get torrents: %v\n", err)
		return t.checksum
	}
	if len(torrents) == 0 {
		log.Println("Huh, no torrents returned")
		return t.checksum
	}
	return fmt.Sprintf("%d-%s", totalCount, torrents[0].ID)
}

func (t *TorrentManager) getAll() []Torrent {
	log.Println("Getting all torrents")

	torrents, totalCount, err := realdebrid.GetTorrents(t.token, 0)
	if err != nil {
		log.Printf("Cannot get torrents: %v\n", err)
		return nil
	}
	t.checksum = fmt.Sprintf("%d-%s", totalCount, torrents[0].ID)

	var torrentsV2 []Torrent
	for _, torrent := range torrents {
		torrent.Name = strings.TrimSuffix(torrent.Name, "/")
		torrentV2 := Torrent{
			Torrent:       torrent,
			SelectedFiles: nil,
		}
		torrentsV2 = append(torrentsV2, torrentV2)
	}
	log.Printf("Fetched %d torrents", len(torrentsV2))

	version := t.config.GetVersion()
	if version == "v1" {
		configV1 := t.config.(*config.ZurgConfigV1)
		groupMap := configV1.GetGroupMap()
		for group, directories := range groupMap {
			log.Printf("Processing directory group: %s, %v\n", group, directories)
			for i := range torrents {
				for _, directory := range directories {
					if configV1.MeetsConditions(directory, torrentsV2[i].ID, torrentsV2[i].Name) {
						torrentsV2[i].Directories = append(torrentsV2[i].Directories, directory)
						break
					}
				}
			}
		}
	}
	log.Println("Finished mapping to groups")

	return torrentsV2
}

func (t *TorrentManager) GetByDirectory(directory string) []Torrent {
	var torrents []Torrent
	for i := range t.torrents {
		for _, dir := range t.torrents[i].Directories {
			if dir == directory {
				torrents = append(torrents, t.torrents[i])
			}
		}
	}
	return torrents
}

func (t *TorrentManager) RefreshInfo(torrentID string) {
	filePath := fmt.Sprintf("data/%s.bin", torrentID)
	// Check the last modified time of the .bin file
	fileInfo, err := os.Stat(filePath)
	if err == nil {
		modTime := fileInfo.ModTime()
		// If the file was modified less than an hour ago, don't refresh
		if time.Since(modTime) < time.Duration(t.config.GetCacheTimeHours())*time.Hour {
			return
		}
		err = os.Remove(filePath)
		if err != nil && !os.IsNotExist(err) { // File doesn't exist or other error
			log.Printf("Cannot remove file: %v\n", err)
		}
	} else if !os.IsNotExist(err) { // Error other than file not existing
		log.Printf("Error checking file info: %v\n", err)
		return
	}
	info := t.getInfo(torrentID)
	log.Println("Refreshed info for", info.Name)
}

func (t *TorrentManager) getInfo(torrentID string) *Torrent {
	torrentFromFile := t.readFromFile(torrentID)
	if torrentFromFile != nil {
		torrent := t.getByID(torrentID)
		if torrent != nil {
			torrent.SelectedFiles = torrentFromFile.SelectedFiles
		}
		return torrent
	}
	log.Println("Getting info for", torrentID)
	info, err := realdebrid.GetTorrentInfo(t.token, torrentID)
	if err != nil {
		log.Printf("Cannot get info: %v\n", err)
		return nil
	}
	var selectedFiles []File
	for _, file := range info.Files {
		if file.Selected == 0 {
			continue
		}
		selectedFiles = append(selectedFiles, File{
			File: file,
			Link: "",
		})
	}
	if len(selectedFiles) != len(info.Links) {
		// TODO: This means some files have expired
		// we need to 'fix' this torrent then, at least the missing selected files
		log.Println("Some links has expired for", info.Name)
		type Result struct {
			Response *realdebrid.UnrestrictResponse
		}

		resultsChan := make(chan Result, len(info.Links))
		var wg sync.WaitGroup

		// Limit concurrency
		sem := make(chan struct{}, t.config.GetNumOfWorkers())

		for _, link := range info.Links {
			wg.Add(1)
			sem <- struct{}{} // Acquire semaphore
			go func(lnk string) {
				defer wg.Done()
				defer func() { <-sem }() // Release semaphore

				unrestrictFn := func() (*realdebrid.UnrestrictResponse, error) {
					return realdebrid.UnrestrictCheck(t.token, lnk)
				}
				resp := realdebrid.RetryUntilOk(unrestrictFn)
				if resp != nil {
					resultsChan <- Result{Response: resp}
				}
			}(link)
		}

		go func() {
			wg.Wait()
			close(sem)
			close(resultsChan)
		}()

		for result := range resultsChan {
			found := false
			for i := range selectedFiles {
				if strings.HasSuffix(selectedFiles[i].Path, result.Response.Filename) {
					selectedFiles[i].Link = result.Response.Link
					found = true
				}
			}
			if !found {
				selectedFiles = append(selectedFiles, File{
					File: realdebrid.File{
						Path:     result.Response.Filename,
						Bytes:    result.Response.Filesize,
						Selected: 1,
					},
					Link: result.Response.Link,
				})
			}
		}
	} else {
		for i, link := range info.Links {
			selectedFiles[i].Link = link
		}
	}
	torrent := t.getByID(torrentID)
	if torrent != nil {
		torrent.SelectedFiles = selectedFiles
	}
	if len(torrent.SelectedFiles) > 0 {
		t.writeToFile(torrentID, torrent)
	}
	return torrent
}

func (t *TorrentManager) MarkFileAsDeleted(torrent *Torrent, file *File) {
	log.Println("Marking file as deleted", file.Path)
	file.Link = ""
	t.writeToFile(torrent.ID, torrent)
}

func (t *TorrentManager) GetInfo(torrentID string) *Torrent {
	for i := range t.torrents {
		if t.torrents[i].ID == torrentID {
			return &t.torrents[i]
		}
	}
	return t.getInfo(torrentID)
}

func (t *TorrentManager) getByID(torrentID string) *Torrent {
	for i := range t.torrents {
		if t.torrents[i].ID == torrentID {
			return &t.torrents[i]
		}
	}
	return nil
}

func (t *TorrentManager) writeToFile(torrentID string, torrent *Torrent) {
	filePath := fmt.Sprintf("data/%s.bin", torrentID)
	file, err := os.Create(filePath)
	if err != nil {
		log.Fatalf("Failed creating file: %s", err)
		return
	}
	defer file.Close()

	dataEncoder := gob.NewEncoder(file)
	dataEncoder.Encode(torrent)
}

func (t *TorrentManager) readFromFile(torrentID string) *Torrent {
	filePath := fmt.Sprintf("data/%s.bin", torrentID)
	file, err := os.Open(filePath)
	if err != nil {
		return nil
	}
	defer file.Close()

	var torrent Torrent
	dataDecoder := gob.NewDecoder(file)
	err = dataDecoder.Decode(&torrent)
	if err != nil {
		log.Fatalf("Failed decoding file: %s", err)
		return nil
	}

	return &torrent
}