/*
   Copyright 2021 Erigon contributors

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package downloader

import (
	"context"
	"fmt"
	"time"

	"github.com/anacrolix/torrent/metainfo"
	"github.com/ledgerwatch/erigon-lib/gointerfaces"
	proto_downloader "github.com/ledgerwatch/erigon-lib/gointerfaces/downloader"
	prototypes "github.com/ledgerwatch/erigon-lib/gointerfaces/types"
	"github.com/ledgerwatch/log/v3"
	"google.golang.org/protobuf/types/known/emptypb"
)

var (
	_ proto_downloader.DownloaderServer = &GrpcServer{}
)

func NewGrpcServer(d *Downloader) (*GrpcServer, error) {
	return &GrpcServer{d: d}, nil
}

type GrpcServer struct {
	proto_downloader.UnimplementedDownloaderServer
	d *Downloader
}

// Download - create new .torrent ONLY if initialSync, everything else Erigon can generate by itself
func (s *GrpcServer) Download(ctx context.Context, request *proto_downloader.DownloadRequest) (*emptypb.Empty, error) {
	logEvery := time.NewTicker(20 * time.Second)
	defer logEvery.Stop()

	for i, it := range request.Items {
		if it.Path == "" {
			return nil, fmt.Errorf("field 'path' is required")
		}

		select {
		case <-logEvery.C:
			log.Info("[snapshots] initializing", "files", fmt.Sprintf("%d/%d", i, len(request.Items)))
		default:
		}

		if it.TorrentHash == nil {
			// if we don't have the torrent hash then we seed a new snapshot
			if err := s.d.AddNewSeedableFile(ctx, it.Path); err != nil {
				return nil, err
			}
			continue
		}

		if err := s.d.AddInfoHashAsMagnetLink(ctx, Proto2InfoHash(it.TorrentHash), it.Path); err != nil {
			return nil, err
		}
	}
	s.d.ReCalcStats(10 * time.Second) // immediately call ReCalc to set stat.Complete flag
	return &emptypb.Empty{}, nil
}

func (s *GrpcServer) Verify(ctx context.Context, request *proto_downloader.VerifyRequest) (*emptypb.Empty, error) {
	err := s.d.VerifyData(ctx)
	if err != nil {
		return nil, err
	}
	return &emptypb.Empty{}, nil
}

func (s *GrpcServer) Stats(ctx context.Context, request *proto_downloader.StatsRequest) (*proto_downloader.StatsReply, error) {
	stats := s.d.Stats()
	return &proto_downloader.StatsReply{
		MetadataReady: stats.MetadataReady,
		FilesTotal:    stats.FilesTotal,

		Completed: stats.Completed,
		Progress:  stats.Progress,

		PeersUnique:      stats.PeersUnique,
		ConnectionsTotal: stats.ConnectionsTotal,

		BytesCompleted: stats.BytesCompleted,
		BytesTotal:     stats.BytesTotal,
		UploadRate:     stats.UploadRate,
		DownloadRate:   stats.DownloadRate,
	}, nil
}

func Proto2InfoHash(in *prototypes.H160) metainfo.Hash {
	return gointerfaces.ConvertH160toAddress(in)
}