// Copyright 2015 CoreOS, Inc.
//
// 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 rafthttp

import (
	"encoding/binary"
	"io"

	"github.com/coreos/etcd/pkg/metrics"
	"github.com/coreos/etcd/pkg/types"
	"github.com/coreos/etcd/raft/raftpb"
)

type entryWriter struct {
	w         io.Writer
	id        types.ID
	ents      *metrics.Counter
	bytes     *metrics.Counter
	lastIndex *metrics.Gauge
}

func newEntryWriter(w io.Writer, id types.ID) *entryWriter {
	ew := &entryWriter{
		w:         w,
		id:        id,
		ents:      metrics.GetMap("rafthttp.stream.entries_sent").NewCounter(id.String()),
		bytes:     metrics.GetMap("rafthttp.stream.bytes_sent").NewCounter(id.String()),
		lastIndex: metrics.GetMap("rafthttp.stream.last_index_sent").NewGauge(id.String()),
	}
	return ew
}

func (ew *entryWriter) writeEntries(ents []raftpb.Entry) error {
	l := len(ents)
	if l == 0 {
		return nil
	}
	if err := binary.Write(ew.w, binary.BigEndian, uint64(l)); err != nil {
		return err
	}
	ew.bytes.AddBy(8)
	for i := 0; i < l; i++ {
		if err := ew.writeEntry(&ents[i]); err != nil {
			return err
		}
		ew.ents.Add()
	}
	ew.lastIndex.Set(int64(ents[l-1].Index))
	return nil
}

func (ew *entryWriter) writeEntry(ent *raftpb.Entry) error {
	size := ent.Size()
	if err := binary.Write(ew.w, binary.BigEndian, uint64(size)); err != nil {
		return err
	}
	b, err := ent.Marshal()
	if err != nil {
		return err
	}
	_, err = ew.w.Write(b)
	ew.bytes.AddBy(8 + int64(size))
	return err
}

func (ew *entryWriter) stop() {
	metrics.GetMap("rafthttp.stream.entries_sent").Delete(ew.id.String())
	metrics.GetMap("rafthttp.stream.bytes_sent").Delete(ew.id.String())
	metrics.GetMap("rafthttp.stream.last_index_sent").Delete(ew.id.String())
}