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Filename : binding.js
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'use strict'
/* eslint camelcase: "off" */

var assert = require('assert')

var Zstream = require('pako/lib/zlib/zstream')
var zlib_deflate = require('pako/lib/zlib/deflate.js')
var zlib_inflate = require('pako/lib/zlib/inflate.js')
var constants = require('pako/lib/zlib/constants')

for (var key in constants) {
  exports[key] = constants[key]
}

// zlib modes
exports.NONE = 0
exports.DEFLATE = 1
exports.INFLATE = 2
exports.GZIP = 3
exports.GUNZIP = 4
exports.DEFLATERAW = 5
exports.INFLATERAW = 6
exports.UNZIP = 7

var GZIP_HEADER_ID1 = 0x1f
var GZIP_HEADER_ID2 = 0x8b

/**
 * Emulate Node's zlib C++ layer for use by the JS layer in index.js
 */
function Zlib (mode) {
  if (typeof mode !== 'number' || mode < exports.DEFLATE || mode > exports.UNZIP) {
    throw new TypeError('Bad argument')
  }

  this.dictionary = null
  this.err = 0
  this.flush = 0
  this.init_done = false
  this.level = 0
  this.memLevel = 0
  this.mode = mode
  this.strategy = 0
  this.windowBits = 0
  this.write_in_progress = false
  this.pending_close = false
  this.gzip_id_bytes_read = 0
}

Zlib.prototype.close = function () {
  if (this.write_in_progress) {
    this.pending_close = true
    return
  }

  this.pending_close = false

  assert(this.init_done, 'close before init')
  assert(this.mode <= exports.UNZIP)

  if (this.mode === exports.DEFLATE || this.mode === exports.GZIP || this.mode === exports.DEFLATERAW) {
    zlib_deflate.deflateEnd(this.strm)
  } else if (this.mode === exports.INFLATE || this.mode === exports.GUNZIP ||
      this.mode === exports.INFLATERAW || this.mode === exports.UNZIP) {
    zlib_inflate.inflateEnd(this.strm)
  }

  this.mode = exports.NONE

  this.dictionary = null
}

Zlib.prototype.write = function (flush, input, in_off, in_len, out, out_off, out_len) {
  return this._write(true, flush, input, in_off, in_len, out, out_off, out_len)
}

Zlib.prototype.writeSync = function (flush, input, in_off, in_len, out, out_off, out_len) {
  return this._write(false, flush, input, in_off, in_len, out, out_off, out_len)
}

Zlib.prototype._write = function (async, flush, input, in_off, in_len, out, out_off, out_len) {
  assert.equal(arguments.length, 8)

  assert(this.init_done, 'write before init')
  assert(this.mode !== exports.NONE, 'already finalized')
  assert.equal(false, this.write_in_progress, 'write already in progress')
  assert.equal(false, this.pending_close, 'close is pending')

  this.write_in_progress = true

  assert.equal(false, flush === undefined, 'must provide flush value')

  this.write_in_progress = true

  if (flush !== exports.Z_NO_FLUSH &&
    flush !== exports.Z_PARTIAL_FLUSH &&
    flush !== exports.Z_SYNC_FLUSH &&
    flush !== exports.Z_FULL_FLUSH &&
    flush !== exports.Z_FINISH &&
    flush !== exports.Z_BLOCK) {
    throw new Error('Invalid flush value')
  }

  if (input == null) {
    input = Buffer.alloc(0)
    in_len = 0
    in_off = 0
  }

  this.strm.avail_in = in_len
  this.strm.input = input
  this.strm.next_in = in_off
  this.strm.avail_out = out_len
  this.strm.output = out
  this.strm.next_out = out_off
  this.flush = flush

  if (!async) {
    // sync version
    this._process()

    if (this._checkError()) {
      return this._afterSync()
    }
    return
  }

  // async version
  var self = this
  process.nextTick(function () {
    self._process()
    self._after()
  })

  return this
}

Zlib.prototype._afterSync = function () {
  var avail_out = this.strm.avail_out
  var avail_in = this.strm.avail_in

  this.write_in_progress = false

  return [avail_in, avail_out]
}

Zlib.prototype._process = function () {
  var next_expected_header_byte = null

  // If the avail_out is left at 0, then it means that it ran out
  // of room.  If there was avail_out left over, then it means
  // that all of the input was consumed.
  switch (this.mode) {
    case exports.DEFLATE:
    case exports.GZIP:
    case exports.DEFLATERAW:
      this.err = zlib_deflate.deflate(this.strm, this.flush)
      break
    case exports.UNZIP:
      if (this.strm.avail_in > 0) {
        next_expected_header_byte = this.strm.next_in
      }

      switch (this.gzip_id_bytes_read) {
        case 0:
          if (next_expected_header_byte === null) {
            break
          }

          if (this.strm.input[next_expected_header_byte] === GZIP_HEADER_ID1) {
            this.gzip_id_bytes_read = 1
            next_expected_header_byte++

            if (this.strm.avail_in === 1) {
              // The only available byte was already read.
              break
            }
          } else {
            this.mode = exports.INFLATE
            break
          }

          // fallthrough
        case 1:
          if (next_expected_header_byte === null) {
            break
          }

          if (this.strm.input[next_expected_header_byte] === GZIP_HEADER_ID2) {
            this.gzip_id_bytes_read = 2
            this.mode = exports.GUNZIP
          } else {
            // There is no actual difference between INFLATE and INFLATERAW
            // (after initialization).
            this.mode = exports.INFLATE
          }

          break
        default:
          throw new Error('invalid number of gzip magic number bytes read')
      }

      // fallthrough
    case exports.INFLATE:
    case exports.GUNZIP:
    case exports.INFLATERAW:
      this.err = zlib_inflate.inflate(this.strm, this.flush)

      // If data was encoded with dictionary
      if (this.err === exports.Z_NEED_DICT && this.dictionary) {
        // Load it
        this.err = zlib_inflate.inflateSetDictionary(this.strm, this.dictionary)
        if (this.err === exports.Z_OK) {
          // And try to decode again
          this.err = zlib_inflate.inflate(this.strm, this.flush)
        } else if (this.err === exports.Z_DATA_ERROR) {
          // Both inflateSetDictionary() and inflate() return Z_DATA_ERROR.
          // Make it possible for After() to tell a bad dictionary from bad
          // input.
          this.err = exports.Z_NEED_DICT
        }
      }
      while (this.strm.avail_in > 0 &&
             this.mode === exports.GUNZIP &&
             this.err === exports.Z_STREAM_END &&
             this.strm.next_in[0] !== 0x00) {
        // Bytes remain in input buffer. Perhaps this is another compressed
        // member in the same archive, or just trailing garbage.
        // Trailing zero bytes are okay, though, since they are frequently
        // used for padding.

        this.reset()
        this.err = zlib_inflate.inflate(this.strm, this.flush)
      }
      break
    default:
      throw new Error('Unknown mode ' + this.mode)
  }
}

Zlib.prototype._checkError = function () {
  // Acceptable error states depend on the type of zlib stream.
  switch (this.err) {
    case exports.Z_OK:
    case exports.Z_BUF_ERROR:
      if (this.strm.avail_out !== 0 && this.flush === exports.Z_FINISH) {
        this._error('unexpected end of file')
        return false
      }
      break
    case exports.Z_STREAM_END:
      // normal statuses, not fatal
      break
    case exports.Z_NEED_DICT:
      if (this.dictionary == null) {
        this._error('Missing dictionary')
      } else {
        this._error('Bad dictionary')
      }
      return false
    default:
      // something else.
      this._error('Zlib error')
      return false
  }

  return true
}

Zlib.prototype._after = function () {
  if (!this._checkError()) {
    return
  }

  var avail_out = this.strm.avail_out
  var avail_in = this.strm.avail_in

  this.write_in_progress = false

  // call the write() cb
  this.callback(avail_in, avail_out)

  if (this.pending_close) {
    this.close()
  }
}

Zlib.prototype._error = function (message) {
  if (this.strm.msg) {
    message = this.strm.msg
  }
  this.onerror(message, this.err)

  // no hope of rescue.
  this.write_in_progress = false
  if (this.pending_close) {
    this.close()
  }
}

Zlib.prototype.init = function (windowBits, level, memLevel, strategy, dictionary) {
  assert(arguments.length === 4 || arguments.length === 5, 'init(windowBits, level, memLevel, strategy, [dictionary])')

  assert(windowBits >= 8 && windowBits <= 15, 'invalid windowBits')
  assert(level >= -1 && level <= 9, 'invalid compression level')

  assert(memLevel >= 1 && memLevel <= 9, 'invalid memlevel')

  assert(strategy === exports.Z_FILTERED ||
         strategy === exports.Z_HUFFMAN_ONLY ||
         strategy === exports.Z_RLE ||
         strategy === exports.Z_FIXED ||
         strategy === exports.Z_DEFAULT_STRATEGY, 'invalid strategy')

  this._init(level, windowBits, memLevel, strategy, dictionary)
  this._setDictionary()
}

Zlib.prototype.params = function () {
  throw new Error('deflateParams Not supported')
}

Zlib.prototype.reset = function () {
  this._reset()
  this._setDictionary()
}

Zlib.prototype._init = function (level, windowBits, memLevel, strategy, dictionary) {
  this.level = level
  this.windowBits = windowBits
  this.memLevel = memLevel
  this.strategy = strategy

  this.flush = exports.Z_NO_FLUSH

  this.err = exports.Z_OK

  if (this.mode === exports.GZIP || this.mode === exports.GUNZIP) {
    this.windowBits += 16
  }

  if (this.mode === exports.UNZIP) {
    this.windowBits += 32
  }

  if (this.mode === exports.DEFLATERAW || this.mode === exports.INFLATERAW) {
    this.windowBits = -1 * this.windowBits
  }

  this.strm = new Zstream()

  switch (this.mode) {
    case exports.DEFLATE:
    case exports.GZIP:
    case exports.DEFLATERAW:
      this.err = zlib_deflate.deflateInit2(
        this.strm,
        this.level,
        exports.Z_DEFLATED,
        this.windowBits,
        this.memLevel,
        this.strategy
      )
      break
    case exports.INFLATE:
    case exports.GUNZIP:
    case exports.INFLATERAW:
    case exports.UNZIP:
      this.err = zlib_inflate.inflateInit2(
        this.strm,
        this.windowBits
      )
      break
    default:
      throw new Error('Unknown mode ' + this.mode)
  }

  if (this.err !== exports.Z_OK) {
    this._error('Init error')
  }

  this.dictionary = dictionary

  this.write_in_progress = false
  this.init_done = true
}

Zlib.prototype._setDictionary = function () {
  if (this.dictionary == null) {
    return
  }

  this.err = exports.Z_OK

  switch (this.mode) {
    case exports.DEFLATE:
    case exports.DEFLATERAW:
      this.err = zlib_deflate.deflateSetDictionary(this.strm, this.dictionary)
      break
    default:
      break
  }

  if (this.err !== exports.Z_OK) {
    this._error('Failed to set dictionary')
  }
}

Zlib.prototype._reset = function () {
  this.err = exports.Z_OK

  switch (this.mode) {
    case exports.DEFLATE:
    case exports.DEFLATERAW:
    case exports.GZIP:
      this.err = zlib_deflate.deflateReset(this.strm)
      break
    case exports.INFLATE:
    case exports.INFLATERAW:
    case exports.GUNZIP:
      this.err = zlib_inflate.inflateReset(this.strm)
      break
    default:
      break
  }

  if (this.err !== exports.Z_OK) {
    this._error('Failed to reset stream')
  }
}

exports.Zlib = Zlib