package qbittorrent

import (
	"context"
	"fmt"
	"slices"
	"time"

	"git.kmsign.ru/royalcat/tstor/pkg/qbittorrent"
	"github.com/hashicorp/golang-lru/v2/expirable"
	"github.com/royalcat/btrgo/btrsync"
)

type cacheClient struct {
	qb qbittorrent.Client

	propertiesCache *expirable.LRU[string, qbittorrent.TorrentProperties]
	torrentsCache   *expirable.LRU[string, qbittorrent.TorrentInfo]

	pieceCache btrsync.MapOf[pieceKey, int]
}

type pieceKey struct {
	hash  string
	index int
}

func wrapClient(qb qbittorrent.Client) *cacheClient {

	const (
		cacheSize = 5000
		cacheTTL  = time.Minute
	)

	return &cacheClient{
		qb:              qb,
		propertiesCache: expirable.NewLRU[string, qbittorrent.TorrentProperties](cacheSize, nil, cacheTTL),
		torrentsCache:   expirable.NewLRU[string, qbittorrent.TorrentInfo](cacheSize, nil, cacheTTL),
		pieceCache:      btrsync.MapOf[pieceKey, int]{},
	}
}

func (f *cacheClient) getInfo(ctx context.Context, hash string) (*qbittorrent.TorrentInfo, error) {
	if v, ok := f.torrentsCache.Get(hash); ok {
		return &v, nil
	}

	infos, err := f.qb.Torrent().GetTorrents(ctx, &qbittorrent.TorrentOption{
		Hashes: []string{hash},
	})
	if err != nil {
		return nil, fmt.Errorf("error to check torrent existence: %w", err)
	}

	if len(infos) == 0 {
		return nil, nil
	}

	if len(infos) > 1 {
		return nil, fmt.Errorf("multiple torrents with the same hash")
	}

	f.torrentsCache.Add(hash, *infos[0])

	return infos[0], nil
}

func (f *cacheClient) getProperties(ctx context.Context, hash string) (*qbittorrent.TorrentProperties, error) {
	if v, ok := f.propertiesCache.Get(hash); ok {
		return &v, nil
	}

	info, err := f.qb.Torrent().GetProperties(ctx, hash)
	if err != nil {
		return nil, err
	}

	f.propertiesCache.Add(hash, *info)
	return info, nil
}

func (f *cacheClient) listContent(ctx context.Context, hash string) ([]*qbittorrent.TorrentContent, error) {
	contents, err := f.qb.Torrent().GetContents(ctx, hash)
	if err != nil {
		return nil, err
	}
	return contents, nil
}

func (f *cacheClient) getContent(ctx context.Context, hash string, contentIndex int) (*qbittorrent.TorrentContent, error) {
	contents, err := f.qb.Torrent().GetContents(ctx, hash, contentIndex)
	if err != nil {
		return nil, err
	}

	contentI := slices.IndexFunc(contents, func(c *qbittorrent.TorrentContent) bool {
		return c.Index == contentIndex
	})
	if contentI == -1 {
		return nil, fmt.Errorf("content not found")
	}

	return contents[contentI], nil
}

func (f *cacheClient) isPieceComplete(ctx context.Context, hash string, pieceIndex int) (bool, error) {
	cachedPieceState, ok := f.pieceCache.Load(pieceKey{hash: hash, index: pieceIndex})
	if ok && cachedPieceState == 2 {
		return true, nil
	}

	completion, err := f.qb.Torrent().GetPiecesStates(ctx, hash)
	if err != nil {
		return false, err
	}

	for i, v := range completion {
		f.pieceCache.Store(pieceKey{hash: hash, index: i}, v)
	}

	if completion[pieceIndex] == 2 {
		return true, nil
	}

	return false, nil
}

func (f *cacheClient) waitPieceToComplete(ctx context.Context, hash string, pieceIndex int) error {
	const checkingInterval = 1 * time.Second

	ok, err := f.isPieceComplete(ctx, hash, pieceIndex)
	if err != nil {
		return err
	}
	if ok {
		return nil
	}

	if deadline, ok := ctx.Deadline(); ok && time.Until(deadline) < checkingInterval {
		return context.DeadlineExceeded
	}

	ticker := time.NewTicker(checkingInterval)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-ticker.C:
			ok, err := f.isPieceComplete(ctx, hash, pieceIndex)
			if err != nil {
				return err
			}
			if ok {
				return nil
			}

			if deadline, ok := ctx.Deadline(); ok && time.Until(deadline) < checkingInterval {
				return context.DeadlineExceeded
			}
		}
	}
}