/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 hello

import (
	"encoding/binary"
	"errors"
)

import (
	"gitee.com/git4chen/dubbo-getty"
)

type PackageHandler struct{}

func (h *PackageHandler) Read(ss getty.Session, data []byte) (interface{}, int, error) {
	dataLen := len(data)
	if dataLen < 4 {
		return nil, 0, nil
	}

	start := 0
	pos := start + 4
	pkgLen := int(binary.LittleEndian.Uint32(data[start:pos]))
	if dataLen < pos+pkgLen {
		return nil, pos + pkgLen, nil
	}
	start = pos

	pos = start + pkgLen
	s := string(data[start:pos])

	return s, pos, nil
}

func (h *PackageHandler) Write(ss getty.Session, p interface{}) ([]byte, error) {
	pkg, ok := p.(string)
	if !ok {
		log.Infof("illegal pkg:%+v", p)
		return nil, errors.New("invalid package")
	}

	pkgLen := int32(len(pkg))
	pkgStreams := make([]byte, 0, 4+len(pkg))

	// pkg len
	start := 0
	pos := start + 4
	binary.LittleEndian.PutUint32(pkgStreams[start:pos], uint32(pkgLen))
	start = pos

	// pkg
	pos = start + int(pkgLen)
	copy(pkgStreams[start:pos], pkg[:])

	return pkgStreams[:pos], nil
}