// Copyright (C) 2018 Storj Labs, Inc.
// See LICENSE for copying information.

package psclient

import (
	"bufio"
	"crypto"
	"crypto/ecdsa"
	"flag"
	"fmt"
	"io"
	"log"
	"time"

	"github.com/gtank/cryptopasta"
	"github.com/zeebo/errs"
	"go.uber.org/zap"
	"golang.org/x/net/context"

	"storj.io/storj/internal/memory"
	"storj.io/storj/pkg/pb"
	"storj.io/storj/pkg/ranger"
	"storj.io/storj/pkg/storj"
	"storj.io/storj/pkg/transport"
)

// ClientError is any error returned by the client
var ClientError = errs.Class("piecestore client error")

var (
	defaultBandwidthMsgSize memory.Size = 32 * memory.KB
	maxBandwidthMsgSize     memory.Size = 64 * memory.KB
)

func init() {
	flag.Var(&defaultBandwidthMsgSize,
		"piecestore.rpc.client.default-bandwidth-msg-size",
		"default bandwidth message size in bytes")
	flag.Var(&maxBandwidthMsgSize,
		"piecestore.rpc.client.max-bandwidth-msg-size",
		"max bandwidth message size in bytes")
}

// Client is an interface describing the functions for interacting with piecestore nodes
type Client interface {
	Meta(ctx context.Context, id PieceID) (*pb.PieceSummary, error)
	Put(ctx context.Context, id PieceID, data io.Reader, ttl time.Time, ba *pb.PayerBandwidthAllocation, authorization *pb.SignedMessage) error
	Get(ctx context.Context, id PieceID, size int64, ba *pb.PayerBandwidthAllocation, authorization *pb.SignedMessage) (ranger.Ranger, error)
	Delete(ctx context.Context, pieceID PieceID, authorization *pb.SignedMessage) error
	Stats(ctx context.Context) (*pb.StatSummary, error)
	io.Closer
}

// PieceStore -- Struct Info needed for protobuf api calls
type PieceStore struct {
	closeFunc        func() error              // function that closes the transport connection
	client           pb.PieceStoreRoutesClient // PieceStore for interacting with Storage Node
	prikey           crypto.PrivateKey         // Uplink private key
	bandwidthMsgSize int                       // max bandwidth message size in bytes
	nodeID           storj.NodeID              // Storage node being connected to
}

// NewPSClient initilizes a piecestore client
func NewPSClient(ctx context.Context, tc transport.Client, n *pb.Node, bandwidthMsgSize int) (Client, error) {
	n.Type.DPanicOnInvalid("new ps client")
	conn, err := tc.DialNode(ctx, n)
	if err != nil {
		return nil, err
	}

	if bandwidthMsgSize < 0 || bandwidthMsgSize > maxBandwidthMsgSize.Int() {
		return nil, ClientError.New("invalid Bandwidth Message Size: %v", bandwidthMsgSize)
	}

	if bandwidthMsgSize == 0 {
		bandwidthMsgSize = defaultBandwidthMsgSize.Int()
	}

	return &PieceStore{
		closeFunc:        conn.Close,
		client:           pb.NewPieceStoreRoutesClient(conn),
		bandwidthMsgSize: bandwidthMsgSize,
		prikey:           tc.Identity().Key,
		nodeID:           n.Id,
	}, nil
}

// NewCustomRoute creates new PieceStore with custom client interface
func NewCustomRoute(client pb.PieceStoreRoutesClient, target *pb.Node, bandwidthMsgSize int, prikey crypto.PrivateKey) (*PieceStore, error) {
	target.Type.DPanicOnInvalid("new custom route")
	if bandwidthMsgSize < 0 || bandwidthMsgSize > maxBandwidthMsgSize.Int() {
		return nil, ClientError.New("invalid Bandwidth Message Size: %v", bandwidthMsgSize)
	}

	if bandwidthMsgSize == 0 {
		bandwidthMsgSize = defaultBandwidthMsgSize.Int()
	}

	return &PieceStore{
		client:           client,
		bandwidthMsgSize: bandwidthMsgSize,
		prikey:           prikey,
		nodeID:           target.Id,
	}, nil
}

// Close closes the connection with piecestore
func (ps *PieceStore) Close() error {
	if ps.closeFunc == nil {
		return nil
	}

	return ps.closeFunc()
}

// Meta requests info about a piece by Id
func (ps *PieceStore) Meta(ctx context.Context, id PieceID) (*pb.PieceSummary, error) {
	return ps.client.Piece(ctx, &pb.PieceId{Id: id.String()})
}

// Put uploads a Piece to a piece store Server
func (ps *PieceStore) Put(ctx context.Context, id PieceID, data io.Reader, ttl time.Time, ba *pb.PayerBandwidthAllocation, authorization *pb.SignedMessage) error {
	stream, err := ps.client.Store(ctx)
	if err != nil {
		return err
	}

	msg := &pb.PieceStore{
		PieceData:     &pb.PieceStore_PieceData{Id: id.String(), ExpirationUnixSec: ttl.Unix()},
		Authorization: authorization,
	}
	if err = stream.Send(msg); err != nil {
		if _, closeErr := stream.CloseAndRecv(); closeErr != nil {
			zap.S().Errorf("error closing stream %s :: %v.Send() = %v", closeErr, stream, closeErr)
		}

		return fmt.Errorf("%v.Send() = %v", stream, err)
	}

	writer := &StreamWriter{signer: ps, stream: stream, pba: ba}

	defer func() {
		if err := writer.Close(); err != nil && err != io.EOF {
			log.Printf("failed to close writer: %s\n", err)
		}
	}()

	bufw := bufio.NewWriterSize(writer, 32*1024)

	_, err = io.Copy(bufw, data)
	if err == io.ErrUnexpectedEOF {
		_ = writer.Close()
		zap.S().Infof("Node cut from upload due to slow connection. Deleting piece %s...", id)
		deleteErr := ps.Delete(ctx, id, authorization)
		if deleteErr != nil {
			return deleteErr
		}
	}
	if err != nil {
		return err
	}

	return bufw.Flush()
}

// Get begins downloading a Piece from a piece store Server
func (ps *PieceStore) Get(ctx context.Context, id PieceID, size int64, ba *pb.PayerBandwidthAllocation, authorization *pb.SignedMessage) (ranger.Ranger, error) {
	stream, err := ps.client.Retrieve(ctx)
	if err != nil {
		return nil, err
	}

	return PieceRangerSize(ps, stream, id, size, ba, authorization), nil
}

// Delete a Piece from a piece store Server
func (ps *PieceStore) Delete(ctx context.Context, id PieceID, authorization *pb.SignedMessage) error {
	reply, err := ps.client.Delete(ctx, &pb.PieceDelete{Id: id.String(), Authorization: authorization})
	if err != nil {
		return err
	}
	zap.S().Infof("Delete request route summary: %v", reply)
	return nil
}

// Stats will retrieve stats about a piece storage node
func (ps *PieceStore) Stats(ctx context.Context) (*pb.StatSummary, error) {
	return ps.client.Stats(ctx, &pb.StatsReq{})
}

// sign a message using the clients private key
func (ps *PieceStore) sign(msg []byte) (signature []byte, err error) {
	if ps.prikey == nil {
		return nil, ClientError.New("failed to sign msg: Private Key not Set")
	}

	// use c.pkey to sign msg
	return cryptopasta.Sign(msg, ps.prikey.(*ecdsa.PrivateKey))
}