package p2pv2

import (
	"bufio"
	"bytes"
	"context"
	"encoding/binary"
	"fmt"
	"io"
	"time"

	"github.com/harmony-one/harmony/log"
	libp2p "github.com/libp2p/go-libp2p"
	host "github.com/libp2p/go-libp2p-host"
	net "github.com/libp2p/go-libp2p-net"
	peer "github.com/libp2p/go-libp2p-peer"
	peerstore "github.com/libp2p/go-libp2p-peerstore"
	multiaddr "github.com/multiformats/go-multiaddr"
)

var (
	myHost host.Host // TODO(ricl): this should be a field in node.
)

const (
	// BatchSizeInByte The batch size in byte (64MB) in which we return data
	BatchSizeInByte = 1 << 16
	// ProtocolID The ID of protocol used in stream handling.
	ProtocolID = "/harmony/0.0.1"
)

// InitHost Initialize a host for p2p communication
func InitHost(ip, port string) {
	addr := fmt.Sprintf("/ip4/%s/tcp/%s", ip, port)
	sourceAddr, err := multiaddr.NewMultiaddr(addr)
	catchError(err)
	priv := addrToPrivKey(addr)
	myHost, err = libp2p.New(context.Background(),
		libp2p.ListenAddrs(sourceAddr),
		libp2p.Identity(priv),
		libp2p.NoSecurity, // The security (signature generation and verification) is, for now, taken care by ourselves.
		// TODO(ricl): Other features to probe
		// libp2p.EnableRelay; libp2p.Routing;
	)
	catchError(err)
	log.Debug("Host is up!", "port", port, "id", myHost.ID().Pretty(), "addrs", sourceAddr)
}

// BindHandler bind a streamHandler to the harmony protocol.
func BindHandler(handler net.StreamHandler) {
	myHost.SetStreamHandler(ProtocolID, handler)
}

// Send a p2p message sending function with signature compatible to p2pv1.
func Send(ip, port string, message []byte) error {
	addr := fmt.Sprintf("/ip4/%s/tcp/%s", ip, port)
	targetAddr, err := multiaddr.NewMultiaddr(addr)

	priv := addrToPrivKey(addr)
	peerID, _ := peer.IDFromPrivateKey(priv)
	myHost.Peerstore().AddAddrs(peerID, []multiaddr.Multiaddr{targetAddr}, peerstore.PermanentAddrTTL)
	s, err := myHost.NewStream(context.Background(), peerID, ProtocolID)
	catchError(err)

	// Create a buffered stream so that read and writes are non blocking.
	w := bufio.NewWriter(bufio.NewWriter(s))

	// Create a thread to read and write data.
	go writeData(w, message)
	return nil
}

// ReadData Call this function in streamHandler to get the binary data.
func ReadData(s net.Stream) ([]byte, error) {
	timeoutDuration := 1 * time.Second
	s.SetReadDeadline(time.Now().Add(timeoutDuration))

	// Create a buffered stream so that read and writes are non blocking.
	rw := bufio.NewReadWriter(bufio.NewReader(s), bufio.NewWriter(s))

	contentBuf := bytes.NewBuffer([]byte{})
	// Read 1 byte for message type
	_, err := rw.ReadByte()
	switch err {
	case nil:
		//log.Printf("Received p2p message type: %x\n", msgType)
	case io.EOF:
		fallthrough
	default:
		log.Error("Error reading the p2p message type field", "err", err)
		return contentBuf.Bytes(), err
	}
	// TODO: check on msgType and take actions accordingly

	// Read 4 bytes for message size
	fourBytes := make([]byte, 4)
	n, err := rw.Read(fourBytes)
	if err != nil {
		log.Error("Error reading the p2p message size field", "err", err)
		return contentBuf.Bytes(), err
	} else if n < len(fourBytes) {
		log.Error("Invalid byte size", "bytes", n)
		return contentBuf.Bytes(), err
	}

	//log.Print(fourBytes)
	// Number of bytes for the message content
	bytesToRead := binary.BigEndian.Uint32(fourBytes)
	//log.Printf("The content size is %d bytes.", bytesToRead)

	// Read the content in chunk of size `BatchSizeInByte`
	tmpBuf := make([]byte, BatchSizeInByte)
ILOOP:
	for {
		// TODO(ricl): is this necessary? If yes, figure out how to make it work
		// timeoutDuration := 10 * time.Second
		// s.SetReadDeadline(time.Now().Add(timeoutDuration))
		if bytesToRead < BatchSizeInByte {
			// Read the last number of bytes less than `BatchSizeInByte`
			tmpBuf = make([]byte, bytesToRead)
		}
		n, err := rw.Read(tmpBuf)
		contentBuf.Write(tmpBuf[:n])

		switch err {
		case io.EOF:
			// TODO: should we return error here, or just ignore it?
			log.Error("EOF reached while reading p2p message")
			break ILOOP
		case nil:
			bytesToRead -= uint32(n) // TODO: think about avoid the casting in every loop
			if bytesToRead <= 0 {
				break ILOOP
			}
		default:
			log.Error("Error reading p2p message")
			return []byte{}, err
		}
	}
	return contentBuf.Bytes(), nil
}

// GetHost Get the p2p host
func GetHost() host.Host {
	return myHost
}