/*
 * libmedia mp4 saiz box parser
 *
 * 版权所有 (C) 2024 赵高兴
 * Copyright (C) 2024 Gaoxing Zhao
 *
 * 此文件是 libmedia 的一部分
 * This file is part of libmedia.
 * 
 * libmedia 是自由软件；您可以根据 GNU Lesser General Public License（GNU LGPL）3.1
 * 或任何其更新的版本条款重新分发或修改它
 * libmedia is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.1 of the License, or (at your option) any later version.
 * 
 * libmedia 希望能够为您提供帮助，但不提供任何明示或暗示的担保，包括但不限于适销性或特定用途的保证
 * 您应自行承担使用 libmedia 的风险，并且需要遵守 GNU Lesser General Public License 中的条款和条件。
 * libmedia is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 */

import type { Atom, IsobmffContext } from '../type'
import { logger } from '@libmedia/common'
import { type IOReader } from '@libmedia/common/io'
import { type AVStream } from '@libmedia/avutil'

export default async function read(ioReader: IOReader, stream: AVStream, atom: Atom, isobmffContext: IsobmffContext) {

  const now = ioReader.getPos()

  const trackContext = isobmffContext.currentFragment.currentTrack
  const cenc = isobmffContext.cencs ? isobmffContext.cencs[trackContext.trackId] : null

  // version
  await ioReader.skip(1)

  const flags = await ioReader.readUint24()
  if (flags & 0x01) {
    const infoType = await ioReader.readUint32()
    const infoParam = await ioReader.readUint32()
    if (cenc) {
      if (infoType !== cenc.schemeType) {
        logger.warn('Ignoring saiz box with non-zero aux_info_type')
        await end()
        return
      }
      if (infoParam !== 0) {
        logger.warn('Ignoring saiz box with non-zero aux_info_type_parameter')
        await end()
        return
      }
    }
    else {
      await end()
      return
    }
  }
  else if (!cenc) {
    await end()
    return
  }

  if (!trackContext.cenc) {
    trackContext.cenc = {
      defaultSampleInfoSize: 0,
      sampleCount: 0,
      offset: 0,
      useSubsamples: false,
      sampleEncryption: [],
      sampleSizes: [],
      sampleInfoOffset: []
    }
  }

  trackContext.cenc.defaultSampleInfoSize = await ioReader.readUint8()
  trackContext.cenc.sampleCount = await ioReader.readUint32()
  if (trackContext.cenc.defaultSampleInfoSize === 0) {
    if (!trackContext.cenc.sampleCount) {
      logger.error('invalid saiz data')
      await end()
      return
    }
    for (let i = 0; i < trackContext.cenc.sampleCount; i++) {
      trackContext.cenc.sampleSizes.push(await ioReader.readUint8())
    }
  }
  await end()

  async function end() {
    const remainingLength = atom.size - Number(ioReader.getPos() - now)
    if (remainingLength > 0) {
      await ioReader.skip(remainingLength)
    }
    else if (remainingLength < 0) {
      logger.error(`read saiz error, size: ${atom.size}, read: ${atom.size - remainingLength}`)
    }
  }
}