// Copyright 2019, Chef.  All rights reserved.
// https://github.com/q191201771/lal
//
// Use of this source code is governed by a MIT-style license
// that can be found in the License file.
//
// Author: Chef (191201771@qq.com)

package hls

// 声明，本package参考了c语言实现的开源项目nginx-rtmp-module

// TODO chef:
// - 支持HEVC
// - 检查所有的容错处理，是否会出现
// - 补充单元测试
// - 配置项
// - Server
//     - 超时时间

// https://developer.apple.com/documentation/http_live_streaming/example_playlists_for_http_live_streaming/incorporating_ads_into_a_playlist
// https://developer.apple.com/documentation/http_live_streaming/example_playlists_for_http_live_streaming/event_playlist_construction
// #EXTM3U                     // 固定串
// #EXT-X-VERSION:3            // 固定串
// #EXT-X-MEDIA-SEQUENCE       //
// #EXT-X-TARGETDURATION       // 所有TS文件，最长的时长
// #EXT-X-PLAYLIST-TYPE: EVENT
// #EXT-X-DISCONTINUITY        //
// #EXTINF:                    // 时长以及TS文件名

// 进来的数据称为Frame帧，188字节的封装称为TSPacket包，TS文件称为Fragment

// 每个TS文件都以固定的PAT，PMT开始
var FixedFragmentHeader = []byte{
	/* TS */
	0x47, 0x40, 0x00, 0x10, 0x00,
	/* PSI */
	0x00, 0xb0, 0x0d, 0x00, 0x01, 0xc1, 0x00, 0x00,
	/* PAT */
	0x00, 0x01, 0xf0, 0x01,
	/* CRC */
	0x2e, 0x70, 0x19, 0x05,

	/* stuffing 167 bytes */
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

	/* TS */
	0x47, 0x50, 0x01, 0x10, 0x00,
	/* PSI */
	0x02, 0xb0, 0x17, 0x00, 0x01, 0xc1, 0x00, 0x00,
	/* PMT */
	0xe1, 0x00,
	0xf0, 0x00,
	0x1b, 0xe1, 0x00, 0xf0, 0x00, /* avc epid 256 */
	0x0f, 0xe1, 0x01, 0xf0, 0x00, /* aac epid 257 */
	/* CRC */
	0x2f, 0x44, 0xb9, 0x9b, /* crc for aac */
	/* stuffing 157 bytes */
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
}

var audNal = []byte{
	0x00, 0x00, 0x00, 0x01, 0x09, 0xf0,
}

// AnnexB prefix
var nalStartCode = []byte{
	0x00, 0x00, 0x00, 0x01,
}

// TODO chef:
var nalStartCode3 = []byte{
	0x00, 0x00, 0x01,
}

// TS Packet Header
const (
	syncByte uint8 = 0x47

	PidPAT uint16 = 0

	// ------------------------------------------
	// <iso13818-1.pdf> <Table 2-5> <page 38/174>
	// ------------------------------------------
	AdaptationFieldControlReserved uint8 = 0 // Reserved for future use by ISO/IEC
	AdaptationFieldControlNo       uint8 = 1 // No adaptation_field, payload only
	AdaptationFieldControlOnly     uint8 = 2 // Adaptation_field only, no payload
	AdaptationFieldControlFollowed uint8 = 3 // Adaptation_field followed by payload
)

// PMT
const (
	// -----------------------------------------------------------------------------
	// <iso13818-1.pdf> <Table 2-29 Stream type assignments> <page 66/174>
	// 0x0F ISO/IEC 13818-7 Audio with ADTS transport syntax
	// 0x1B AVC video stream as defined in ITU-T Rec. H.264 | ISO/IEC 14496-10 Video
	// -----------------------------------------------------------------------------
	streamTypeAAC uint8 = 0x0F
	streamTypeAVC uint8 = 0x1B
)

// PES
const (
	// -----------------------------------------------------------------
	// <iso13818-1.pdf> <Table 2-18-Stream_id assignments> <page 52/174>
	// -----------------------------------------------------------------
	streamIDAudio uint8 = 192 // 110x xxxx 0xC0
	streamIDVideo uint8 = 224 // 1110 xxxx

	// ------------------------------
	// <iso13818-1.pdf> <page 53/174>
	// ------------------------------
	PTSDTSFlags0 uint8 = 0 // no PTS no DTS
	PTSDTSFlags1 uint8 = 1 // forbidden
	PTSDTSFlags2 uint8 = 2 // only PTS
	PTSDTSFlags3 uint8 = 3 // both PTS and DTS
)

const (
	PidVideo uint16 = 0x100
	PidAudio uint16 = 0x101
	delay    uint64 = 63000 // 700 ms PCR delay TODO chef: 具体作用？

	// TODO chef 这些在配置项中提供
	negMaxfraglen        = 1000 * 90 // 当前包时间戳回滚了，比当前fragment的首个时间戳还小，强制切割新的fragment，单位毫秒 * 90
	maxAudioDelay uint64 = 300       // 单位毫秒

	appName = "hls"
)

func SplitFragment2TSPackets(content []byte) (ret [][]byte) {
	if len(content)%188 != 0 {
		return
	}
	for {
		if len(content) == 0 {
			break
		}

		ret = append(ret, content[0:188])
		content = content[188:]
	}
	return
}