package wal

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

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

const (
	msgTypeRec       = 8
	msgTypeHeartbeat = 16
	msgTypeError     = 32
)

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

	var (
		seqNum           int64
		heartbeatTimeout = timeout / 8
	)

	conn.SetReadDeadline(time.Now().Add(timeout))
	if err := binary.Read(conn, binary.LittleEndian, &seqNum); err != nil {
		return errs.IO.WithErr(err)
	}
	conn.SetReadDeadline(time.Time{})

	it, err := wal.Iterator(seqNum)
	if err != nil {
		return err
	}
	defer it.Close()

	for {
		if it.Next(heartbeatTimeout) {
			rec := it.Record()

			conn.SetWriteDeadline(time.Now().Add(timeout))

			if _, err := conn.Write([]byte{msgTypeRec}); err != nil {
				return errs.IO.WithErr(err)
			}

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

			continue
		}

		if it.Error() != nil {
			conn.SetWriteDeadline(time.Now().Add(timeout))
			if _, err := conn.Write([]byte{msgTypeError}); err != nil {
				return errs.IO.WithErr(err)
			}

			err, ok := it.Error().(*errs.Error)
			if !ok {
				err = errs.Unexpected.WithErr(err)
			}
			err.Write(conn)
			//			w.Flush()
			return err
		}

		conn.SetWriteDeadline(time.Now().Add(timeout))
		if _, err := conn.Write([]byte{msgTypeHeartbeat}); err != nil {
			return errs.IO.WithErr(err)
		}
	}
}