package wal

import (
	"encoding/binary"
	"io"
	"net"
	"time"

	"git.crumpington.com/public/jldb/lib/errs"
)

func (wal *WAL) Recv(conn net.Conn, timeout time.Duration) error {
	defer conn.Close()

	var (
		rec     Record
		msgType = make([]byte, 1)
	)

	// Send sequence number.
	seqNum := wal.Info().LastSeqNum + 1
	conn.SetWriteDeadline(time.Now().Add(timeout))
	if err := binary.Write(conn, binary.LittleEndian, seqNum); err != nil {
		return errs.IO.WithErr(err)
	}
	conn.SetWriteDeadline(time.Time{})

	for {
		conn.SetReadDeadline(time.Now().Add(timeout))

		if _, err := io.ReadFull(conn, msgType); err != nil {
			return errs.IO.WithErr(err)
		}

		switch msgType[0] {

		case msgTypeHeartbeat:
			// Nothing to do.

		case msgTypeError:
			e := &errs.Error{}
			if err := e.Read(conn); err != nil {
				return err
			}

			return e

		case msgTypeRec:
			if err := rec.readFrom(conn); err != nil {
				return err
			}

			if _, _, err := wal.appendRecord(rec); err != nil {
				return err
			}

		default:
			return errs.Unexpected.WithMsg("Unknown message type: %d", msgType[0])
		}
	}
}