package main

import (
	"context"
	"errors"
	"fmt"
	"net"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/anacrolix/torrent/metainfo"
	"github.com/c2h5oh/datasize"
	grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
	grpc_recovery "github.com/grpc-ecosystem/go-grpc-middleware/recovery"
	"github.com/ledgerwatch/erigon-lib/common"
	"github.com/ledgerwatch/erigon-lib/common/datadir"
	"github.com/ledgerwatch/erigon-lib/downloader"
	downloadercfg2 "github.com/ledgerwatch/erigon-lib/downloader/downloadercfg"
	proto_downloader "github.com/ledgerwatch/erigon-lib/gointerfaces/downloader"
	"github.com/ledgerwatch/erigon/cmd/downloader/downloadernat"
	"github.com/ledgerwatch/erigon/cmd/utils"
	"github.com/ledgerwatch/erigon/common/paths"
	"github.com/ledgerwatch/erigon/p2p/nat"
	"github.com/ledgerwatch/erigon/params"
	"github.com/ledgerwatch/erigon/turbo/debug"
	logging2 "github.com/ledgerwatch/erigon/turbo/logging"
	"github.com/ledgerwatch/log/v3"
	"github.com/pelletier/go-toml/v2"
	"github.com/spf13/cobra"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/health"
	"google.golang.org/grpc/health/grpc_health_v1"
	"google.golang.org/grpc/keepalive"
	"google.golang.org/grpc/reflection"
)

var (
	datadirCli                     string
	forceRebuild                   bool
	forceVerify                    bool
	downloaderApiAddr              string
	natSetting                     string
	torrentVerbosity               int
	downloadRateStr, uploadRateStr string
	torrentDownloadSlots           int
	staticPeersStr                 string
	torrentPort                    int
	torrentMaxPeers                int
	torrentConnsPerFile            int
	targetFile                     string
	disableIPV6                    bool
	disableIPV4                    bool
)

func init() {
	utils.CobraFlags(rootCmd, debug.Flags, utils.MetricFlags, logging2.Flags)

	withDataDir(rootCmd)

	rootCmd.Flags().StringVar(&natSetting, "nat", utils.NATFlag.Value, utils.NATFlag.Usage)
	rootCmd.Flags().StringVar(&downloaderApiAddr, "downloader.api.addr", "127.0.0.1:9093", "external downloader api network address, for example: 127.0.0.1:9093 serves remote downloader interface")
	rootCmd.Flags().StringVar(&downloadRateStr, "torrent.download.rate", utils.TorrentDownloadRateFlag.Value, utils.TorrentDownloadRateFlag.Usage)
	rootCmd.Flags().StringVar(&uploadRateStr, "torrent.upload.rate", utils.TorrentUploadRateFlag.Value, utils.TorrentUploadRateFlag.Usage)
	rootCmd.Flags().IntVar(&torrentVerbosity, "torrent.verbosity", utils.TorrentVerbosityFlag.Value, utils.TorrentVerbosityFlag.Usage)
	rootCmd.Flags().IntVar(&torrentPort, "torrent.port", utils.TorrentPortFlag.Value, utils.TorrentPortFlag.Usage)
	rootCmd.Flags().IntVar(&torrentMaxPeers, "torrent.maxpeers", utils.TorrentMaxPeersFlag.Value, utils.TorrentMaxPeersFlag.Usage)
	rootCmd.Flags().IntVar(&torrentConnsPerFile, "torrent.conns.perfile", utils.TorrentConnsPerFileFlag.Value, utils.TorrentConnsPerFileFlag.Usage)
	rootCmd.Flags().IntVar(&torrentDownloadSlots, "torrent.download.slots", utils.TorrentDownloadSlotsFlag.Value, utils.TorrentDownloadSlotsFlag.Usage)
	rootCmd.Flags().StringVar(&staticPeersStr, utils.TorrentStaticPeersFlag.Name, utils.TorrentStaticPeersFlag.Value, utils.TorrentStaticPeersFlag.Usage)
	rootCmd.Flags().BoolVar(&disableIPV6, "downloader.disable.ipv6", utils.DisableIPV6.Value, utils.DisableIPV6.Usage)
	rootCmd.Flags().BoolVar(&disableIPV4, "downloader.disable.ipv4", utils.DisableIPV4.Value, utils.DisableIPV6.Usage)

	withDataDir(printTorrentHashes)
	printTorrentHashes.PersistentFlags().BoolVar(&forceRebuild, "rebuild", false, "Force re-create .torrent files")
	printTorrentHashes.PersistentFlags().BoolVar(&forceVerify, "verify", false, "Force verify data files if have .torrent files")
	printTorrentHashes.Flags().StringVar(&targetFile, "targetfile", "", "write output to file")
	if err := printTorrentHashes.MarkFlagFilename("targetfile"); err != nil {
		panic(err)
	}

	rootCmd.AddCommand(printTorrentHashes)
}

func withDataDir(cmd *cobra.Command) {
	cmd.Flags().StringVar(&datadirCli, utils.DataDirFlag.Name, paths.DefaultDataDir(), utils.DataDirFlag.Usage)
	if err := cmd.MarkFlagDirname(utils.DataDirFlag.Name); err != nil {
		panic(err)
	}
}

func main() {
	ctx, cancel := common.RootContext()
	defer cancel()

	if err := rootCmd.ExecuteContext(ctx); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}

var rootCmd = &cobra.Command{
	Use:     "",
	Short:   "snapshot downloader",
	Example: "go run ./cmd/snapshots --datadir <your_datadir> --downloader.api.addr 127.0.0.1:9093",
	PersistentPreRun: func(cmd *cobra.Command, args []string) {
		if err := debug.SetupCobra(cmd); err != nil {
			panic(err)
		}
	},
	PersistentPostRun: func(cmd *cobra.Command, args []string) {
		debug.Exit()
	},
	Run: func(cmd *cobra.Command, args []string) {
		_ = logging2.GetLoggerCmd("downloader", cmd)
		if err := Downloader(cmd.Context()); err != nil {
			if !errors.Is(err, context.Canceled) {
				log.Error(err.Error())
			}
			return
		}
	},
}

func Downloader(ctx context.Context) error {
	dirs := datadir.New(datadirCli)
	torrentLogLevel, _, err := downloadercfg2.Int2LogLevel(torrentVerbosity)
	if err != nil {
		return err
	}

	var downloadRate, uploadRate datasize.ByteSize
	if err := downloadRate.UnmarshalText([]byte(downloadRateStr)); err != nil {
		return err
	}
	if err := uploadRate.UnmarshalText([]byte(uploadRateStr)); err != nil {
		return err
	}

	log.Info("Run snapshot downloader", "addr", downloaderApiAddr, "datadir", dirs.DataDir, "ipv6-enabled", !disableIPV6, "ipv4-enabled", !disableIPV4, "download.rate", downloadRate.String(), "upload.rate", uploadRate.String())
	natif, err := nat.Parse(natSetting)
	if err != nil {
		return fmt.Errorf("invalid nat option %s: %w", natSetting, err)
	}
	staticPeers := strings.Split(staticPeersStr, ",")

	version := "erigon: " + params.VersionWithCommit(params.GitCommit)
	cfg, err := downloadercfg2.New(dirs.Snap, version, torrentLogLevel, downloadRate, uploadRate, torrentPort, torrentConnsPerFile, torrentDownloadSlots, staticPeers)
	if err != nil {
		return err
	}
	downloadernat.DoNat(natif, cfg)

	cfg.ClientConfig.DisableIPv6 = disableIPV6
	cfg.ClientConfig.DisableIPv4 = disableIPV4

	d, err := downloader.New(ctx, cfg)
	if err != nil {
		return err
	}
	defer d.Close()
	log.Info("[torrent] Start", "my peerID", fmt.Sprintf("%x", d.Torrent().PeerID()))
	d.MainLoopInBackground(ctx, false)

	bittorrentServer, err := downloader.NewGrpcServer(d)
	if err != nil {
		return fmt.Errorf("new server: %w", err)
	}

	grpcServer, err := StartGrpc(bittorrentServer, downloaderApiAddr, nil)
	if err != nil {
		return err
	}
	defer grpcServer.GracefulStop()

	<-ctx.Done()
	return nil
}

var printTorrentHashes = &cobra.Command{
	Use:     "torrent_hashes",
	Example: "go run ./cmd/downloader torrent_hashes --datadir <your_datadir>",
	RunE: func(cmd *cobra.Command, args []string) error {
		dirs := datadir.New(datadirCli)
		ctx := cmd.Context()

		if forceVerify { // remove and create .torrent files (will re-read all snapshots)
			return downloader.VerifyDtaFiles(ctx, dirs.Snap)
		}

		if forceRebuild { // remove and create .torrent files (will re-read all snapshots)
			//removePieceCompletionStorage(snapDir)
			files, err := downloader.AllTorrentPaths(dirs.Snap)
			if err != nil {
				return err
			}
			for _, filePath := range files {
				if err := os.Remove(filePath); err != nil {
					return err
				}
			}
			if _, err := downloader.BuildTorrentFilesIfNeed(ctx, dirs.Snap); err != nil {
				return err
			}
		}

		res := map[string]string{}
		files, err := downloader.AllTorrentPaths(dirs.Snap)
		if err != nil {
			return err
		}
		for _, torrentFilePath := range files {
			mi, err := metainfo.LoadFromFile(torrentFilePath)
			if err != nil {
				return err
			}
			info, err := mi.UnmarshalInfo()
			if err != nil {
				return err
			}
			res[info.Name] = mi.HashInfoBytes().String()
		}
		serialized, err := toml.Marshal(res)
		if err != nil {
			return err
		}

		if targetFile == "" {
			fmt.Printf("%s\n", serialized)
			return nil
		}

		oldContent, err := os.ReadFile(targetFile)
		if err != nil {
			return err
		}
		oldLines := map[string]string{}
		if err := toml.Unmarshal(oldContent, &oldLines); err != nil {
			return fmt.Errorf("unmarshal: %w", err)
		}
		if len(oldLines) >= len(res) {
			log.Info("amount of lines in target file is equal or greater than amount of lines in snapshot dir", "old", len(oldLines), "new", len(res))
			return nil
		}
		if err := os.WriteFile(targetFile, serialized, 0644); err != nil { // nolint
			return err
		}
		return nil
	},
}

// nolint
func removePieceCompletionStorage(snapDir string) {
	_ = os.RemoveAll(filepath.Join(snapDir, "db"))
	_ = os.RemoveAll(filepath.Join(snapDir, ".torrent.db"))
	_ = os.RemoveAll(filepath.Join(snapDir, ".torrent.bolt.db"))
	_ = os.RemoveAll(filepath.Join(snapDir, ".torrent.db-shm"))
	_ = os.RemoveAll(filepath.Join(snapDir, ".torrent.db-wal"))
}

func StartGrpc(snServer *downloader.GrpcServer, addr string, creds *credentials.TransportCredentials) (*grpc.Server, error) {
	lis, err := net.Listen("tcp", addr)
	if err != nil {
		return nil, fmt.Errorf("could not create listener: %w, addr=%s", err, addr)
	}

	var (
		streamInterceptors []grpc.StreamServerInterceptor
		unaryInterceptors  []grpc.UnaryServerInterceptor
	)
	streamInterceptors = append(streamInterceptors, grpc_recovery.StreamServerInterceptor())
	unaryInterceptors = append(unaryInterceptors, grpc_recovery.UnaryServerInterceptor())

	//if metrics.Enabled {
	//	streamInterceptors = append(streamInterceptors, grpc_prometheus.StreamServerInterceptor)
	//	unaryInterceptors = append(unaryInterceptors, grpc_prometheus.UnaryServerInterceptor)
	//}

	opts := []grpc.ServerOption{
		// https://github.com/grpc/grpc-go/issues/3171#issuecomment-552796779
		grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
			MinTime:             10 * time.Second,
			PermitWithoutStream: true,
		}),
		grpc.StreamInterceptor(grpc_middleware.ChainStreamServer(streamInterceptors...)),
		grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(unaryInterceptors...)),
	}
	if creds == nil {
		// no specific opts
	} else {
		opts = append(opts, grpc.Creds(*creds))
	}
	grpcServer := grpc.NewServer(opts...)
	reflection.Register(grpcServer) // Register reflection service on gRPC server.
	if snServer != nil {
		proto_downloader.RegisterDownloaderServer(grpcServer, snServer)
	}

	//if metrics.Enabled {
	//	grpc_prometheus.Register(grpcServer)
	//}

	healthServer := health.NewServer()
	grpc_health_v1.RegisterHealthServer(grpcServer, healthServer)

	go func() {
		defer healthServer.Shutdown()
		if err := grpcServer.Serve(lis); err != nil {
			log.Error("gRPC server stop", "err", err)
		}
	}()
	log.Info("Started gRPC server", "on", addr)
	return grpcServer, nil
}