import { translate } from '../i18n'

export interface ZipArchiveFile {
  name: string
  data: Uint8Array
}

const crcTable = Array.from({ length: 256 }, (_, value) => {
  let crc = value
  for (let bit = 0; bit < 8; bit++) crc = (crc & 1) ? 0xedb88320 ^ (crc >>> 1) : crc >>> 1
  return crc >>> 0
})

function crc32(data: Uint8Array) {
  let crc = 0xffffffff
  for (const byte of data) crc = crcTable[(crc ^ byte) & 0xff] ^ (crc >>> 8)
  return (crc ^ 0xffffffff) >>> 0
}

function safeArchivePath(value: string) {
  const parts = String(value || '').replace(/\\/g, '/').split('/').filter((part) => part && part !== '.')
  if (!parts.length || parts.some((part) => part === '..')) throw new Error(translate('errors.invalidZipPath'))
  return parts.join('/')
}

function dateTime(date = new Date()) {
  const year = Math.max(1980, date.getFullYear())
  return {
    time: (date.getHours() << 11) | (date.getMinutes() << 5) | Math.floor(date.getSeconds() / 2),
    date: ((year - 1980) << 9) | ((date.getMonth() + 1) << 5) | date.getDate(),
  }
}

function header(size: number) {
  const bytes = new Uint8Array(size)
  return { bytes, view: new DataView(bytes.buffer) }
}

function combine(chunks: Uint8Array[]) {
  const output = new Uint8Array(chunks.reduce((total, chunk) => total + chunk.length, 0))
  let offset = 0
  for (const chunk of chunks) { output.set(chunk, offset); offset += chunk.length }
  return output
}

/** 创建 Store 模式 ZIP；图片本身已经压缩，避免引入额外打包依赖。 */
export function createZipArchive(files: ZipArchiveFile[]) {
  const encoder = new TextEncoder()
  const localChunks: Uint8Array[] = []
  const centralChunks: Uint8Array[] = []
  const timestamp = dateTime()
  let offset = 0

  for (const file of files) {
    const name = encoder.encode(safeArchivePath(file.name))
    const crc = crc32(file.data)
    const local = header(30)
    local.view.setUint32(0, 0x04034b50, true)
    local.view.setUint16(4, 20, true)
    local.view.setUint16(6, 0x0800, true)
    local.view.setUint16(10, timestamp.time, true)
    local.view.setUint16(12, timestamp.date, true)
    local.view.setUint32(14, crc, true)
    local.view.setUint32(18, file.data.length, true)
    local.view.setUint32(22, file.data.length, true)
    local.view.setUint16(26, name.length, true)
    localChunks.push(local.bytes, name, file.data)

    const central = header(46)
    central.view.setUint32(0, 0x02014b50, true)
    central.view.setUint16(4, 20, true)
    central.view.setUint16(6, 20, true)
    central.view.setUint16(8, 0x0800, true)
    central.view.setUint16(12, timestamp.time, true)
    central.view.setUint16(14, timestamp.date, true)
    central.view.setUint32(16, crc, true)
    central.view.setUint32(20, file.data.length, true)
    central.view.setUint32(24, file.data.length, true)
    central.view.setUint16(28, name.length, true)
    central.view.setUint32(42, offset, true)
    centralChunks.push(central.bytes, name)
    offset += local.bytes.length + name.length + file.data.length
  }

  const centralDirectory = combine(centralChunks)
  const end = header(22)
  end.view.setUint32(0, 0x06054b50, true)
  end.view.setUint16(8, files.length, true)
  end.view.setUint16(10, files.length, true)
  end.view.setUint32(12, centralDirectory.length, true)
  end.view.setUint32(16, offset, true)
  return new Blob([combine([...localChunks, centralDirectory, end.bytes])], { type: 'application/zip' })
}