package torrent

import (
	"fmt"
	"io"
	"net/http"
	"path"
	"strings"
	"time"

	"github.com/rs/zerolog/log"

	pb "homelab.lan/music-agregator/gen/music_agregator/torrent/v1"
)

type TorrentService struct {
	client TorrentClient
	token  string
}

func NewTorrentService(client TorrentClient) *TorrentService {
	return &TorrentService{
		client: client,
	}
}

func (service *TorrentService) List(req *pb.ListRequest) (*pb.ListResponse, error) {
	torrents, err := service.client.List()
	if err != nil {
		return nil, err
	}

	return &pb.ListResponse{Items: toProtoItems(torrents)}, nil
}

func (service *TorrentService) Add(req *pb.AddRequest) (*pb.AddResponse, error) {
	var file TorrentFile

	if len(req.GetTorrentData()) > 0 {
		file = TorrentFile{
			Filename: req.GetFilename(),
			Data:     req.GetTorrentData(),
		}
	} else if req.GetDownloadUrl() != "" {
		downloaded, err := downloadTorrentFile(req.GetDownloadUrl())
		if err != nil {
			return nil, err
		}
		file = *downloaded
	} else {
		return nil, fmt.Errorf("either torrent_data or download_url must be provided")
	}

	if err := service.client.AddTorrent(file, ""); err != nil {
		return nil, err
	}

	time.Sleep(500 * time.Millisecond)

	searchName := strings.TrimSuffix(file.Filename, ".torrent")
	torrents, err := service.client.Find(FindOptions{Name: searchName})
	if err != nil {
		log.Warn().Err(err).Msg("torrent added but failed to find it afterwards")
		return &pb.AddResponse{}, nil
	}

	if len(torrents) == 0 {
		log.Warn().Str("filename", file.Filename).Msg("torrent added but not found in client")
		return &pb.AddResponse{}, nil
	}

	return &pb.AddResponse{Item: toProtoItem(torrents[0])}, nil
}

func toProtoItems(torrents []TorrentInfo) []*pb.ListItem {
	items := make([]*pb.ListItem, len(torrents))
	for i, t := range torrents {
		items[i] = toProtoItem(t)
	}
	return items
}

func toProtoItem(t TorrentInfo) *pb.ListItem {
	return &pb.ListItem{
		Hash:         t.Hash,
		Name:         t.Name,
		Size:         t.Size,
		Progress:     t.Progress,
		Dlspeed:      t.DlSpeed,
		Upspeed:      t.UpSpeed,
		NumSeeds:     t.NumSeeds,
		NumLeechs:    t.NumLeechs,
		State:        t.State,
		Eta:          t.ETA,
		Ratio:        t.Ratio,
		Category:     t.Category,
		Tags:         t.Tags,
		AddedOn:      t.AddedOn,
		CompletionOn: t.CompletionOn,
		SavePath:     t.SavePath,
		ContentPath:  t.ContentPath,
		Downloaded:   t.Downloaded,
		Uploaded:     t.Uploaded,
		Tracker:      t.Tracker,
		SeedingTime:  t.SeedingTime,
		AmountLeft:   t.AmountLeft,
		Availability: t.Availability,

		SizeFormatted:         formatBytes(t.Size),
		ProgressFormatted:     fmt.Sprintf("%.1f%%", t.Progress*100),
		DlspeedFormatted:      formatSpeed(t.DlSpeed),
		UpspeedFormatted:      formatSpeed(t.UpSpeed),
		AddedOnFormatted:      formatTimestamp(t.AddedOn),
		CompletionOnFormatted: formatTimestamp(t.CompletionOn),
		DownloadedFormatted:   formatBytes(t.Downloaded),
		UploadedFormatted:     formatBytes(t.Uploaded),
		AmountLeftFormatted:   formatBytes(t.AmountLeft),
		AvailabilityFormatted: fmt.Sprintf("%.2f", t.Availability),
		EtaFormatted:          formatETA(t.ETA),
	}
}

func formatBytes(b int64) string {
	switch {
	case b >= 1<<30:
		return fmt.Sprintf("%.2f GB", float64(b)/float64(1<<30))
	case b >= 1<<20:
		return fmt.Sprintf("%.1f MB", float64(b)/float64(1<<20))
	case b >= 1<<10:
		return fmt.Sprintf("%.0f KB", float64(b)/float64(1<<10))
	default:
		return fmt.Sprintf("%d B", b)
	}
}

func formatSpeed(bytesPerSec int64) string {
	if bytesPerSec == 0 {
		return "0 B/s"
	}
	return formatBytes(bytesPerSec) + "/s"
}

func formatTimestamp(ts int64) string {
	if ts <= 0 {
		return ""
	}
	return time.Unix(ts, 0).Format("2006-01-02 15:04:05")
}

func formatETA(seconds int64) string {
	if seconds <= 0 || seconds >= 8640000 {
		return "∞"
	}
	d := time.Duration(seconds) * time.Second
	h := int(d.Hours())
	m := int(d.Minutes()) % 60
	s := int(d.Seconds()) % 60
	if h > 0 {
		return fmt.Sprintf("%dh %dm %ds", h, m, s)
	}
	if m > 0 {
		return fmt.Sprintf("%dm %ds", m, s)
	}
	return fmt.Sprintf("%ds", s)
}

func downloadTorrentFile(url string) (*TorrentFile, error) {
	log.Trace().Str("url", url).Msg("downloading torrent file")

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Get(url)
	if err != nil {
		log.Error().Err(err).Str("url", url).Msg("downloading torrent file failed")
		return nil, fmt.Errorf("downloading torrent file: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		log.Error().Int("status", resp.StatusCode).Str("url", url).Msg("torrent download returned non-OK status")
		return nil, fmt.Errorf("torrent download returned status %d", resp.StatusCode)
	}

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("reading torrent file: %w", err)
	}

	filename := path.Base(resp.Request.URL.Path)
	if !strings.HasSuffix(strings.ToLower(filename), ".torrent") {
		filename += ".torrent"
	}

	log.Debug().Str("filename", filename).Int("size", len(data)).Msg("torrent file downloaded")

	return &TorrentFile{
		Filename: filename,
		Data:     data,
	}, nil
}