/**
 * tng.js - png reader
 * Copyright (c) 2015, Christopher Jeffrey (MIT License).
 * https://github.com/chjj/tng
 */

const fs = require('node:fs'),
  util = require('node:util'),
  path = require('node:path'),
  zlib = require('node:zlib'),
  assert = require('node:assert'),
  cp = require('node:child_process'),
  exec = cp.execFileSync

/**
 * PNG
 */

function PNG(file, options) {
  let buf, chunks, idat, pixels

  if (!(this instanceof PNG)) {
    return new PNG(file, options)
  }

  if (!file) {
    throw new Error('no file')
  }

  this.options = options || {}
  this.colors = options.colors || require('blessed/lib/colors')
  this.optimization = this.options.optimization || 'mem'
  this.speed = this.options.speed || 1

  if (Buffer.isBuffer(file)) {
    this.file = this.options.filename || null
    buf = file
  } else {
    this.options.filename = file
    this.file = path.resolve(process.cwd(), file)
    buf = fs.readFileSync(this.file)
  }

  this.format =
    buf.readUInt32BE(0) === 0x89504e47
      ? 'png'
      : buf.slice(0, 3).toString('ascii') === 'GIF'
        ? 'gif'
        : buf.readUInt16BE(0) === 0xffd8
          ? 'jpg'
          : path.extname(this.file).slice(1).toLowerCase() || 'png'

  if (this.format !== 'png') {
    return this.toPNG(buf)
  }

  chunks = this.parseRaw(buf)
  idat = this.parseChunks(chunks)
  pixels = this.parseLines(idat)

  this.bmp = this.createBitmap(pixels)
  this.cellmap = this.createCellmap(this.bmp)
  this.frames = this.compileFrames(this.frames)
}

PNG.prototype.parseRaw = function (buf) {
  let chunks = [],
    index = 0,
    i = 0,
    len,
    type,
    name,
    data,
    crc,
    check,
    critical,
    public_,
    conforming,
    copysafe,
    pos

  this._debug(this.file)

  if (
    buf.readUInt32BE(0) !== 0x89504e47 ||
    buf.readUInt32BE(4) !== 0x0d0a1a0a
  ) {
    throw new Error('bad header')
  }

  i += 8

  while (i < buf.length) {
    try {
      len = buf.readUInt32BE(i)
      i += 4
      pos = i
      type = buf.slice(i, i + 4)
      name = type.toString('ascii')
      i += 4
      data = buf.slice(i, i + len)
      i += len
      check = this.crc32(buf.slice(pos, i))
      crc = buf.readInt32BE(i)
      i += 4
      critical = !!(~type[0] & 32)
      public_ = !!(~type[1] & 32)
      conforming = !!(~type[2] & 32)
      copysafe = !!(~type[3] & 32)
      if (crc !== check) {
        throw new Error(name + ': bad crc')
      }
    } catch (e) {
      if (this.options.debug) {
        throw e
      }
      break
    }
    chunks.push({
      index: index++,
      id: name.toLowerCase(),
      len: len,
      pos: pos,
      end: i,
      type: type,
      name: name,
      data: data,
      crc: crc,
      check: check,
      raw: buf.slice(pos, i),
      flags: {
        critical: critical,
        public_: public_,
        conforming: conforming,
        copysafe: copysafe
      }
    })
  }

  return chunks
}

PNG.prototype.parseChunks = function (chunks) {
  let i, chunk, name, data, p, idat, info

  for (i = 0; i < chunks.length; i++) {
    chunk = chunks[i]
    name = chunk.id
    data = chunk.data
    info = {}
    switch (name) {
      case 'ihdr': {
        this.width = info.width = data.readUInt32BE(0)
        this.height = info.height = data.readUInt32BE(4)
        this.bitDepth = info.bitDepth = data.readUInt8(8)
        this.colorType = info.colorType = data.readUInt8(9)
        this.compression = info.compression = data.readUInt8(10)
        this.filter = info.filter = data.readUInt8(11)
        this.interlace = info.interlace = data.readUInt8(12)
        switch (this.bitDepth) {
          case 1:
          case 2:
          case 4:
          case 8:
          case 16:
          case 24:
          case 32:
            break
          default:
            throw new Error('bad bit depth: ' + this.bitDepth)
        }
        switch (this.colorType) {
          case 0:
          case 2:
          case 3:
          case 4:
          case 6:
            break
          default:
            throw new Error('bad color: ' + this.colorType)
        }
        switch (this.compression) {
          case 0:
            break
          default:
            throw new Error('bad compression: ' + this.compression)
        }
        switch (this.filter) {
          case 0:
          case 1:
          case 2:
          case 3:
          case 4:
            break
          default:
            throw new Error('bad filter: ' + this.filter)
        }
        switch (this.interlace) {
          case 0:
          case 1:
            break
          default:
            throw new Error('bad interlace: ' + this.interlace)
        }
        break
      }
      case 'plte': {
        this.palette = info.palette = []
        for (p = 0; p < data.length; p += 3) {
          this.palette.push({
            r: data[p + 0],
            g: data[p + 1],
            b: data[p + 2],
            a: 255
          })
        }
        break
      }
      case 'idat': {
        this.size = this.size || 0
        this.size += data.length
        this.idat = this.idat || []
        this.idat.push(data)
        info.size = data.length
        break
      }
      case 'iend': {
        this.end = true
        break
      }
      case 'trns': {
        this.alpha = info.alpha = Array.prototype.slice.call(data)
        if (this.palette) {
          for (p = 0; p < data.length; p++) {
            if (!this.palette[p]) {
              break
            }
            this.palette[p].a = data[p]
          }
        }
        break
      }
      // https://wiki.mozilla.org/APNG_Specification
      case 'actl': {
        this.actl = info = {}
        this.frames = []
        this.actl.numFrames = data.readUInt32BE(0)
        this.actl.numPlays = data.readUInt32BE(4)
        break
      }
      case 'fctl': {
        // IDAT is the first frame depending on the order:
        // IDAT is a frame: acTL->fcTL->IDAT->[fcTL]->fdAT
        // IDAT is not a frame: acTL->IDAT->[fcTL]->fdAT
        if (!this.idat) {
          this.idat = []
          this.frames.push({
            idat: true,
            fctl: info,
            fdat: this.idat
          })
        } else {
          this.frames.push({
            fctl: info,
            fdat: []
          })
        }
        info.sequenceNumber = data.readUInt32BE(0)
        info.width = data.readUInt32BE(4)
        info.height = data.readUInt32BE(8)
        info.xOffset = data.readUInt32BE(12)
        info.yOffset = data.readUInt32BE(16)
        info.delayNum = data.readUInt16BE(20)
        info.delayDen = data.readUInt16BE(22)
        info.disposeOp = data.readUInt8(24)
        info.blendOp = data.readUInt8(25)
        break
      }
      case 'fdat': {
        info.sequenceNumber = data.readUInt32BE(0)
        info.data = data.slice(4)
        this.frames[this.frames.length - 1].fdat.push(info.data)
        break
      }
    }
    chunk.info = info
  }

  this._debug(chunks)

  if (this.frames) {
    this.frames = this.frames.map(function (frame, i) {
      frame.fdat = this.decompress(frame.fdat)
      if (!frame.fdat.length) {
        throw new Error('no data')
      }
      return frame
    }, this)
  }

  idat = this.decompress(this.idat)
  if (!idat.length) {
    throw new Error('no data')
  }

  return idat
}

PNG.prototype.parseLines = function (data) {
  let pixels = [],
    x,
    p,
    prior,
    line,
    filter,
    samples,
    pendingSamples,
    ch,
    shiftStart,
    i,
    toShift,
    sample

  this.sampleDepth =
    this.colorType === 0
      ? 1
      : this.colorType === 2
        ? 3
        : this.colorType === 3
          ? 1
          : this.colorType === 4
            ? 2
            : this.colorType === 6
              ? 4
              : 1
  this.bitsPerPixel = this.bitDepth * this.sampleDepth
  this.bytesPerPixel = Math.ceil(this.bitsPerPixel / 8)
  this.wastedBits =
    (this.width * this.bitsPerPixel) / 8 -
    (((this.width * this.bitsPerPixel) / 8) | 0)
  this.byteWidth = Math.ceil(this.width * (this.bitsPerPixel / 8))

  this.shiftStart =
    (this.bitDepth + (8 / this.bitDepth - this.bitDepth) - 1) | 0
  this.shiftMult = this.bitDepth >= 8 ? 0 : this.bitDepth
  this.mask = this.bitDepth === 32 ? 0xffffffff : (1 << this.bitDepth) - 1

  if (this.interlace === 1) {
    samples = this.sampleInterlacedLines(data)
    for (i = 0; i < samples.length; i += this.sampleDepth) {
      pixels.push(samples.slice(i, i + this.sampleDepth))
    }
    return pixels
  }

  for (p = 0; p < data.length; p += this.byteWidth) {
    prior = line || []
    filter = data[p++]
    line = data.slice(p, p + this.byteWidth)
    line = this.unfilterLine(filter, line, prior)
    samples = this.sampleLine(line)
    for (i = 0; i < samples.length; i += this.sampleDepth) {
      pixels.push(samples.slice(i, i + this.sampleDepth))
    }
  }

  return pixels
}

PNG.prototype.unfilterLine = function (filter, line, prior) {
  for (let x = 0; x < line.length; x++) {
    if (filter === 0) {
      break
    } else if (filter === 1) {
      line[x] = this.filters.sub(x, line, prior, this.bytesPerPixel)
    } else if (filter === 2) {
      line[x] = this.filters.up(x, line, prior, this.bytesPerPixel)
    } else if (filter === 3) {
      line[x] = this.filters.average(x, line, prior, this.bytesPerPixel)
    } else if (filter === 4) {
      line[x] = this.filters.paeth(x, line, prior, this.bytesPerPixel)
    }
  }
  return line
}

PNG.prototype.sampleLine = function (line, width) {
  let samples = [],
    x = 0,
    pendingSamples,
    ch,
    i,
    sample,
    shiftStart,
    toShift

  while (x < line.length) {
    pendingSamples = this.sampleDepth
    while (pendingSamples--) {
      ch = line[x]
      if (this.bitDepth === 16) {
        ch = (ch << 8) | line[++x]
      } else if (this.bitDepth === 24) {
        ch = (ch << 16) | (line[++x] << 8) | line[++x]
      } else if (this.bitDepth === 32) {
        ch = (ch << 24) | (line[++x] << 16) | (line[++x] << 8) | line[++x]
      } else if (this.bitDepth > 32) {
        throw new Error('bitDepth ' + this.bitDepth + ' unsupported.')
      }
      shiftStart = this.shiftStart
      toShift = shiftStart - (x === line.length - 1 ? this.wastedBits : 0)
      for (i = 0; i <= toShift; i++) {
        sample = (ch >> (this.shiftMult * shiftStart)) & this.mask
        if (this.colorType !== 3) {
          if (this.bitDepth < 8) {
            // <= 8 would work too, doesn't matter
            // sample = sample * (0xff / this.mask) | 0; // would work too
            sample *= 0xff / this.mask
            sample |= 0
          } else if (this.bitDepth > 8) {
            sample = ((sample / this.mask) * 255) | 0
          }
        }
        samples.push(sample)
        shiftStart--
      }
      x++
    }
  }

  // Needed for deinterlacing?
  if (width != null) {
    samples = samples.slice(0, width * this.sampleDepth)
  }

  return samples
}

// http://www.w3.org/TR/PNG-Filters.html
PNG.prototype.filters = {
  sub: function Sub(x, line, prior, bpp) {
    if (x < bpp) {
      return line[x]
    }
    return (line[x] + line[x - bpp]) % 256
  },
  up: function Up(x, line, prior, bpp) {
    return (line[x] + (prior[x] || 0)) % 256
  },
  average: function Average(x, line, prior, bpp) {
    if (x < bpp) {
      return Math.floor((prior[x] || 0) / 2)
    }
    // if (x < bpp) return (prior[x] || 0) >> 1;
    return (
      (line[x] + Math.floor((line[x - bpp] + prior[x]) / 2)) %
      // + ((line[x - bpp] + prior[x]) >> 1)
      256
    )
  },
  paeth: function Paeth(x, line, prior, bpp) {
    if (x < bpp) {
      return prior[x] || 0
    }
    return (
      (line[x] +
        this._predictor(line[x - bpp], prior[x] || 0, prior[x - bpp] || 0)) %
      256
    )
  },
  _predictor: function PaethPredictor(a, b, c) {
    // a = left, b = above, c = upper left
    const p = a + b - c,
      pa = Math.abs(p - a),
      pb = Math.abs(p - b),
      pc = Math.abs(p - c)
    if (pa <= pb && pa <= pc) {
      return a
    }
    if (pb <= pc) {
      return b
    }
    return c
  }
}

/**
 * Adam7 deinterlacing ported to javascript from PyPNG:
 * pypng - Pure Python library for PNG image encoding/decoding
 * Copyright (c) 2009-2015, David Jones (MIT License).
 * https://github.com/drj11/pypng
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

PNG.prototype.sampleInterlacedLines = function (raw) {
  let psize,
    vpr,
    samples,
    source_offset,
    i,
    pass,
    xstart,
    ystart,
    xstep,
    ystep,
    recon,
    ppr,
    row_size,
    y,
    filter_type,
    scanline,
    flat,
    offset,
    end_offset,
    skip,
    j,
    k,
    f

  const adam7 = [
    [0, 0, 8, 8],
    [4, 0, 8, 8],
    [0, 4, 4, 8],
    [2, 0, 4, 4],
    [0, 2, 2, 4],
    [1, 0, 2, 2],
    [0, 1, 1, 2]
  ]

  // Fractional bytes per pixel
  psize = (this.bitDepth / 8) * this.sampleDepth

  // Values per row (of the target image)
  vpr = this.width * this.sampleDepth

  // Make a result array, and make it big enough. Interleaving
  // writes to the output array randomly (well, not quite), so the
  // entire output array must be in memory.
  samples = new Buffer(vpr * this.height)
  samples.fill(0)

  source_offset = 0

  for (i = 0; i < adam7.length; i++) {
    pass = adam7[i]
    xstart = pass[0]
    ystart = pass[1]
    xstep = pass[2]
    ystep = pass[3]
    if (xstart >= this.width) {
      continue
    }
    // The previous (reconstructed) scanline. Empty array at the
    // beginning of a pass to indicate that there is no previous
    // line.
    recon = []
    // Pixels per row (reduced pass image)
    ppr = Math.ceil((this.width - xstart) / xstep)
    // Row size in bytes for this pass.
    row_size = Math.ceil(psize * ppr)
    for (y = ystart; y < this.height; y += ystep) {
      filter_type = raw[source_offset]
      source_offset += 1
      scanline = raw.slice(source_offset, source_offset + row_size)
      source_offset += row_size
      recon = this.unfilterLine(filter_type, scanline, recon)
      // Convert so that there is one element per pixel value
      flat = this.sampleLine(recon, ppr)
      if (xstep === 1) {
        assert.equal(xstart, 0)
        offset = y * vpr
        for (k = offset, f = 0; k < offset + vpr; k++, f++) {
          samples[k] = flat[f]
        }
      } else {
        offset = y * vpr + xstart * this.sampleDepth
        end_offset = (y + 1) * vpr
        skip = this.sampleDepth * xstep
        for (j = 0; j < this.sampleDepth; j++) {
          for (
            k = offset + j, f = j;
            k < end_offset;
            k += skip, f += this.sampleDepth
          ) {
            samples[k] = flat[f]
          }
        }
      }
    }
  }

  return samples
}

PNG.prototype.createBitmap = function (pixels) {
  let bmp = [],
    i

  if (this.colorType === 0) {
    pixels = pixels.map(function (sample) {
      return { r: sample[0], g: sample[0], b: sample[0], a: 255 }
    })
  } else if (this.colorType === 2) {
    pixels = pixels.map(function (sample) {
      return { r: sample[0], g: sample[1], b: sample[2], a: 255 }
    })
  } else if (this.colorType === 3) {
    pixels = pixels.map(function (sample) {
      if (!this.palette[sample[0]]) {
        throw new Error('bad palette index')
      }
      return this.palette[sample[0]]
    }, this)
  } else if (this.colorType === 4) {
    pixels = pixels.map(function (sample) {
      return { r: sample[0], g: sample[0], b: sample[0], a: sample[1] }
    })
  } else if (this.colorType === 6) {
    pixels = pixels.map(function (sample) {
      return { r: sample[0], g: sample[1], b: sample[2], a: sample[3] }
    })
  }

  for (i = 0; i < pixels.length; i += this.width) {
    bmp.push(pixels.slice(i, i + this.width))
  }

  return bmp
}

PNG.prototype.createCellmap = function (bmp, options) {
  bmp = bmp || this.bmp
  options = options || this.options
  let cellmap = [],
    scale = options.scale || 0.2,
    height = bmp.length,
    width = bmp[0].length,
    cmwidth = options.width,
    cmheight = options.height,
    line,
    x,
    y,
    xx,
    yy,
    xs,
    ys

  if (cmwidth) {
    scale = cmwidth / width
  } else if (cmheight) {
    scale = cmheight / height
  }

  if (!cmheight) {
    cmheight = Math.round(height * scale)
  }

  if (!cmwidth) {
    cmwidth = Math.round(width * scale)
  }

  ys = height / cmheight
  xs = width / cmwidth

  for (y = 0; y < bmp.length; y += ys) {
    line = []
    yy = Math.round(y)
    if (!bmp[yy]) {
      break
    }
    for (x = 0; x < bmp[yy].length; x += xs) {
      xx = Math.round(x)
      if (!bmp[yy][xx]) {
        break
      }
      line.push(bmp[yy][xx])
    }
    cellmap.push(line)
  }

  return cellmap
}

PNG.prototype.renderANSI = function (bmp) {
  let self = this,
    out = ''

  bmp.forEach(function (line, y) {
    line.forEach(function (pixel, x) {
      const outch = self.getOutch(x, y, line, pixel)
      out += self.pixelToSGR(pixel, outch)
    })
    out += '\n'
  })

  return out
}

PNG.prototype.renderContent = function (bmp, el) {
  let self = this,
    out = ''

  bmp.forEach(function (line, y) {
    line.forEach(function (pixel, x) {
      const outch = self.getOutch(x, y, line, pixel)
      out += self.pixelToTags(pixel, outch)
    })
    out += '\n'
  })

  el.setContent(out)

  return out
}

PNG.prototype.renderScreen = function (bmp, screen, xi, xl, yi, yl) {
  let self = this,
    lines = screen.lines,
    cellLines,
    y,
    yy,
    x,
    xx,
    alpha,
    attr,
    ch

  cellLines = bmp.reduce(function (cellLines, line, y) {
    const cellLine = []
    line.forEach(function (pixel, x) {
      const outch = self.getOutch(x, y, line, pixel),
        cell = self.pixelToCell(pixel, outch)
      cellLine.push(cell)
    })
    cellLines.push(cellLine)
    return cellLines
  }, [])

  for (y = yi; y < yl; y++) {
    yy = y - yi
    for (x = xi; x < xl; x++) {
      xx = x - xi
      if (lines[y] && lines[y][x] && cellLines[yy] && cellLines[yy][xx]) {
        alpha = cellLines[yy][xx].pop()
        // completely transparent
        if (alpha === 0.0) {
          continue
        }
        // translucency / blending
        if (alpha < 1.0) {
          attr = cellLines[yy][xx][0]
          ch = cellLines[yy][xx][1]
          lines[y][x][0] = this.colors.blend(lines[y][x][0], attr, alpha)
          if (ch !== ' ') {
            lines[y][x][1] = ch
          }
          lines[y].dirty = true
          continue
        }
        // completely opaque
        lines[y][x] = cellLines[yy][xx]
        lines[y].dirty = true
      }
    }
  }
}

PNG.prototype.renderElement = function (bmp, el) {
  const xi = el.aleft + el.ileft,
    xl = el.aleft + el.width - el.iright,
    yi = el.atop + el.itop,
    yl = el.atop + el.height - el.ibottom

  return this.renderScreen(bmp, el.screen, xi, xl, yi, yl)
}

PNG.prototype.pixelToSGR = function (pixel, ch) {
  let bga = 1.0,
    fga = 0.5,
    a = pixel.a / 255,
    bg,
    fg

  bg = this.colors.match(
    (pixel.r * a * bga) | 0,
    (pixel.g * a * bga) | 0,
    (pixel.b * a * bga) | 0
  )

  if (ch && this.options.ascii) {
    fg = this.colors.match(
      (pixel.r * a * fga) | 0,
      (pixel.g * a * fga) | 0,
      (pixel.b * a * fga) | 0
    )
    if (a === 0) {
      return '\x1b[38;5;' + fg + 'm' + ch + '\x1b[m'
    }
    return '\x1b[38;5;' + fg + 'm\x1b[48;5;' + bg + 'm' + ch + '\x1b[m'
  }

  if (a === 0) {
    return ' '
  }

  return '\x1b[48;5;' + bg + 'm \x1b[m'
}

PNG.prototype.pixelToTags = function (pixel, ch) {
  let bga = 1.0,
    fga = 0.5,
    a = pixel.a / 255,
    bg,
    fg

  bg = this.colors.RGBtoHex(
    (pixel.r * a * bga) | 0,
    (pixel.g * a * bga) | 0,
    (pixel.b * a * bga) | 0
  )

  if (ch && this.options.ascii) {
    fg = this.colors.RGBtoHex(
      (pixel.r * a * fga) | 0,
      (pixel.g * a * fga) | 0,
      (pixel.b * a * fga) | 0
    )
    if (a === 0) {
      return '{' + fg + '-fg}' + ch + '{/}'
    }
    return '{' + fg + '-fg}{' + bg + '-bg}' + ch + '{/}'
  }

  if (a === 0) {
    return ' '
  }

  return '{' + bg + '-bg} {/' + bg + '-bg}'
}

PNG.prototype.pixelToCell = function (pixel, ch) {
  let bga = 1.0,
    fga = 0.5,
    a = pixel.a / 255,
    bg,
    fg

  bg = this.colors.match(
    (pixel.r * bga) | 0,
    (pixel.g * bga) | 0,
    (pixel.b * bga) | 0
  )

  if (ch && this.options.ascii) {
    fg = this.colors.match(
      (pixel.r * fga) | 0,
      (pixel.g * fga) | 0,
      (pixel.b * fga) | 0
    )
  } else {
    fg = 0x1ff
    ch = null
  }

  // if (a === 0) bg = 0x1ff;

  return [(0 << 18) | (fg << 9) | (bg << 0), ch || ' ', a]
}

// Taken from libcaca:
PNG.prototype.getOutch = (function () {
  const dchars = "????8@8@#8@8##8#MKXWwz$&%x><\\/xo;+=|^-:i'.`,  `.        "

  const luminance = function (pixel) {
    const a = pixel.a / 255,
      r = pixel.r * a,
      g = pixel.g * a,
      b = pixel.b * a,
      l = 0.2126 * r + 0.7152 * g + 0.0722 * b

    return l / 255
  }

  return function (x, y, line, pixel) {
    const lumi = luminance(pixel),
      outch = dchars[(lumi * (dchars.length - 1)) | 0]

    return outch
  }
})()

PNG.prototype.compileFrames = function (frames) {
  return this.optimization === 'mem'
    ? this.compileFrames_lomem(frames)
    : this.compileFrames_locpu(frames)
}

PNG.prototype.compileFrames_lomem = function (frames) {
  if (!this.actl) {
    return
  }
  return frames.map(function (frame, i) {
    this.width = frame.fctl.width
    this.height = frame.fctl.height

    const pixels = frame._pixels || this.parseLines(frame.fdat),
      bmp = frame._bmp || this.createBitmap(pixels),
      fc = frame.fctl

    return {
      actl: this.actl,
      fctl: frame.fctl,
      delay: ((fc.delayNum / (fc.delayDen || 100)) * 1000) | 0,
      bmp: bmp
    }
  }, this)
}

PNG.prototype.compileFrames_locpu = function (frames) {
  if (!this.actl) {
    return
  }

  this._curBmp = null
  this._lastBmp = null

  return frames.map(function (frame, i) {
    this.width = frame.fctl.width
    this.height = frame.fctl.height

    const pixels = frame._pixels || this.parseLines(frame.fdat),
      bmp = frame._bmp || this.createBitmap(pixels),
      renderBmp = this.renderFrame(bmp, frame, i),
      cellmap = this.createCellmap(renderBmp),
      fc = frame.fctl

    return {
      actl: this.actl,
      fctl: frame.fctl,
      delay: ((fc.delayNum / (fc.delayDen || 100)) * 1000) | 0,
      bmp: renderBmp,
      cellmap: cellmap
    }
  }, this)
}

PNG.prototype.renderFrame = function (bmp, frame, i) {
  let first = this.frames[0],
    last = this.frames[i - 1],
    fc = frame.fctl,
    xo = fc.xOffset,
    yo = fc.yOffset,
    lxo,
    lyo,
    x,
    y,
    line,
    p

  if (!this._curBmp) {
    this._curBmp = []
    for (y = 0; y < first.fctl.height; y++) {
      line = []
      for (x = 0; x < first.fctl.width; x++) {
        p = bmp[y][x]
        line.push({ r: p.r, g: p.g, b: p.b, a: p.a })
      }
      this._curBmp.push(line)
    }
  }

  if (last && last.fctl.disposeOp !== 0) {
    lxo = last.fctl.xOffset
    lyo = last.fctl.yOffset
    for (y = 0; y < last.fctl.height; y++) {
      for (x = 0; x < last.fctl.width; x++) {
        if (last.fctl.disposeOp === 0) {
          // none / keep
        } else if (last.fctl.disposeOp === 1) {
          // background / clear
          this._curBmp[lyo + y][lxo + x] = { r: 0, g: 0, b: 0, a: 0 }
        } else if (last.fctl.disposeOp === 2) {
          // previous / restore
          p = this._lastBmp[y][x]
          this._curBmp[lyo + y][lxo + x] = { r: p.r, g: p.g, b: p.b, a: p.a }
        }
      }
    }
  }

  if (frame.fctl.disposeOp === 2) {
    this._lastBmp = []
    for (y = 0; y < frame.fctl.height; y++) {
      line = []
      for (x = 0; x < frame.fctl.width; x++) {
        p = this._curBmp[yo + y][xo + x]
        line.push({ r: p.r, g: p.g, b: p.b, a: p.a })
      }
      this._lastBmp.push(line)
    }
  } else {
    this._lastBmp = null
  }

  for (y = 0; y < frame.fctl.height; y++) {
    for (x = 0; x < frame.fctl.width; x++) {
      p = bmp[y][x]
      if (fc.blendOp === 0) {
        // source
        this._curBmp[yo + y][xo + x] = { r: p.r, g: p.g, b: p.b, a: p.a }
      } else if (fc.blendOp === 1) {
        // over
        if (p.a !== 0) {
          this._curBmp[yo + y][xo + x] = { r: p.r, g: p.g, b: p.b, a: p.a }
        }
      }
    }
  }

  return this._curBmp
}

PNG.prototype._animate = function (callback) {
  if (!this.frames) {
    return callback(this.bmp, this.cellmap)
  }

  let self = this,
    numPlays = this.actl.numPlays || Infinity,
    running = 0,
    i = -1

  this._curBmp = null
  this._lastBmp = null

  const next_lomem = function () {
    if (!running) {
      return
    }

    const frame = self.frames[++i]
    if (!frame) {
      if (!--numPlays) {
        return callback()
      }
      i = -1
      // XXX may be able to optimize by only setting the self._curBmp once???
      self._curBmp = null
      self._lastBmp = null
      return setImmediate(next)
    }

    const bmp = frame.bmp,
      renderBmp = self.renderFrame(bmp, frame, i),
      cellmap = self.createCellmap(renderBmp)

    callback(renderBmp, cellmap)
    return setTimeout(next, (frame.delay / self.speed) | 0)
  }

  const next_locpu = function () {
    if (!running) {
      return
    }
    const frame = self.frames[++i]
    if (!frame) {
      if (!--numPlays) {
        return callback()
      }
      i = -1
      return setImmediate(next)
    }
    callback(frame.bmp, frame.cellmap)
    return setTimeout(next, (frame.delay / self.speed) | 0)
  }

  const next = this.optimization === 'mem' ? next_lomem : next_locpu

  this._control = function (state) {
    if (state === -1) {
      i = -1
      self._curBmp = null
      self._lastBmp = null
      running = 0
      callback(
        self.frames[0].bmp,
        self.frames[0].cellmap || self.createCellmap(self.frames[0].bmp)
      )
      return
    }
    if (state === running) {
      return
    }
    running = state
    return next()
  }

  this._control(1)
}

PNG.prototype.play = function (callback) {
  if (!this._control || callback) {
    this.stop()
    return this._animate(callback)
  }
  this._control(1)
}

PNG.prototype.pause = function () {
  if (!this._control) {
    return
  }
  this._control(0)
}

PNG.prototype.stop = function () {
  if (!this._control) {
    return
  }
  this._control(-1)
}

PNG.prototype.toPNG = function (input) {
  let options = this.options,
    file = this.file,
    format = this.format,
    buf,
    img,
    gif,
    i,
    control,
    disposeOp

  if (format !== 'gif') {
    buf = exec('convert', [format + ':-', 'png:-'], {
      stdio: ['pipe', 'pipe', 'ignore'],
      input: input
    })
    img = PNG(buf, options)
    img.file = file
    return img
  }

  gif = GIF(input, options)

  this.width = gif.width
  this.height = gif.height
  this.frames = []

  for (i = 0; i < gif.images.length; i++) {
    img = gif.images[i]
    // Convert from gif disposal to png disposal. See:
    // http://www.w3.org/Graphics/GIF/spec-gif89a.txt
    control = img.control || gif
    disposeOp = Math.max(0, (control.disposeMethod || 0) - 1)
    if (disposeOp > 2) {
      disposeOp = 0
    }
    this.frames.push({
      fctl: {
        sequenceNumber: i,
        width: img.width,
        height: img.height,
        xOffset: img.left,
        yOffset: img.top,
        delayNum: control.delay,
        delayDen: 100,
        disposeOp: disposeOp,
        blendOp: 1
      },
      fdat: [],
      _pixels: [],
      _bmp: img.bmp
    })
  }

  this.bmp = this.frames[0]._bmp
  this.cellmap = this.createCellmap(this.bmp)

  if (this.frames.length > 1) {
    this.actl = { numFrames: gif.images.length, numPlays: gif.numPlays || 0 }
    this.frames = this.compileFrames(this.frames)
  } else {
    this.frames = undefined
  }

  return this
}

// Convert a gif to an apng using imagemagick. Unfortunately imagemagick
// doesn't support apngs, so we coalesce the gif frames into one image and then
// slice them into frames.
PNG.prototype.gifMagick = function (input) {
  let options = this.options,
    file = this.file,
    format = this.format,
    buf,
    fmt,
    img,
    frames,
    frame,
    width,
    height,
    iwidth,
    twidth,
    i,
    lines,
    line,
    x,
    y

  buf = exec('convert', [format + ':-', '-coalesce', '+append', 'png:-'], {
    stdio: ['pipe', 'pipe', 'ignore'],
    input: input
  })

  fmt = '{"W":%W,"H":%H,"w":%w,"h":%h,"d":%T,"x":"%X","y":"%Y"},'
  frames = exec('identify', ['-format', fmt, format + ':-'], {
    encoding: 'utf8',
    stdio: ['pipe', 'pipe', 'ignore'],
    input: input
  })
  frames = JSON.parse('[' + frames.trim().slice(0, -1) + ']')

  img = PNG(buf, options)
  img.file = file
  Object.keys(img).forEach(function (key) {
    this[key] = img[key]
  }, this)

  width = frames[0].W
  height = frames[0].H
  iwidth = 0
  twidth = 0

  this.width = width
  this.height = height

  this.frames = []

  for (i = 0; i < frames.length; i++) {
    frame = frames[i]
    frame.x = +frame.x
    frame.y = +frame.y

    iwidth = twidth
    twidth += width

    lines = []
    for (y = frame.y; y < height; y++) {
      line = []
      for (x = iwidth + frame.x; x < twidth; x++) {
        line.push(img.bmp[y][x])
      }
      lines.push(line)
    }

    this.frames.push({
      fctl: {
        sequenceNumber: i,
        width: frame.w,
        height: frame.h,
        xOffset: frame.x,
        yOffset: frame.y,
        delayNum: frame.d,
        delayDen: 100,
        disposeOp: 0,
        blendOp: 0
      },
      fdat: [],
      _pixels: [],
      _bmp: lines
    })
  }

  this.bmp = this.frames[0]._bmp
  this.cellmap = this.createCellmap(this.bmp)

  if (this.frames.length > 1) {
    this.actl = { numFrames: frames.length, numPlays: 0 }
    this.frames = this.compileFrames(this.frames)
  } else {
    this.frames = undefined
  }

  return this
}

PNG.prototype.decompress = function (buffers) {
  return zlib.inflateSync(
    new Buffer(
      buffers.reduce(function (out, data) {
        return out.concat(Array.prototype.slice.call(data))
      }, [])
    )
  )
}

/**
 * node-crc
 * https://github.com/alexgorbatchev/node-crc
 * https://github.com/alexgorbatchev/node-crc/blob/master/LICENSE
 *
 * The MIT License (MIT)
 *
 * Copyright 2014 Alex Gorbatchev
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

PNG.prototype.crc32 = (function () {
  const crcTable = [
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
    0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
    0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
    0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
    0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
    0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
    0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
    0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
    0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
    0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
    0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
    0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
    0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
    0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
    0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
    0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
    0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
    0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
    0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
    0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
    0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
    0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
  ]

  return function crc32(buf) {
    //var crc = previous === 0 ? 0 : ~~previous ^ -1;
    let crc = -1
    for (let i = 0, len = buf.length; i < len; i++) {
      crc = crcTable[(crc ^ buf[i]) & 0xff] ^ (crc >>> 8)
    }
    return crc ^ -1
  }
})()

PNG.prototype._debug = function () {
  if (!this.options.log) {
    return
  }
  return this.options.log.apply(null, arguments)
}

/**
 * GIF
 */

function GIF(file, options) {
  const self = this

  if (!(this instanceof GIF)) {
    return new GIF(file, options)
  }

  let info = {},
    p = 0,
    buf,
    i,
    total,
    sig,
    desc,
    img,
    ext,
    label,
    size

  if (!file) {
    throw new Error('no file')
  }

  options = options || {}

  this.options = options

  // XXX If the gif is not optimized enough
  // it may OOM the process with too many frames.
  // TODO: Implement in PNG reader.
  this.pixelLimit = this.options.pixelLimit || 7622550
  this.totalPixels = 0

  if (Buffer.isBuffer(file)) {
    buf = file
    file = null
  } else {
    file = path.resolve(process.cwd(), file)
    buf = fs.readFileSync(file)
  }

  sig = buf.slice(0, 6).toString('ascii')
  if (sig !== 'GIF87a' && sig !== 'GIF89a') {
    throw new Error('bad header: ' + sig)
  }

  this.width = buf.readUInt16LE(6)
  this.height = buf.readUInt16LE(8)

  this.flags = buf.readUInt8(10)
  this.gct = !!(this.flags & 0x80)
  this.gctsize = (this.flags & 0x07) + 1

  this.bgIndex = buf.readUInt8(11)
  this.aspect = buf.readUInt8(12)
  p += 13

  if (this.gct) {
    this.colors = []
    total = 1 << this.gctsize
    for (i = 0; i < total; i++, p += 3) {
      this.colors.push([buf[p], buf[p + 1], buf[p + 2], 255])
    }
  }

  this.images = []
  this.extensions = []

  try {
    while (p < buf.length) {
      desc = buf.readUInt8(p)
      p += 1
      if (desc === 0x2c) {
        img = {}

        img.left = buf.readUInt16LE(p)
        p += 2
        img.top = buf.readUInt16LE(p)
        p += 2

        img.width = buf.readUInt16LE(p)
        p += 2
        img.height = buf.readUInt16LE(p)
        p += 2

        img.flags = buf.readUInt8(p)
        p += 1

        img.lct = !!(img.flags & 0x80)
        img.ilace = !!(img.flags & 0x40)
        img.lctsize = (img.flags & 0x07) + 1

        if (img.lct) {
          img.lcolors = []
          total = 1 << img.lctsize
          for (i = 0; i < total; i++, p += 3) {
            img.lcolors.push([buf[p], buf[p + 1], buf[p + 2], 255])
          }
        }

        img.codeSize = buf.readUInt8(p)
        p += 1

        img.size = buf.readUInt8(p)
        p += 1

        img.lzw = [buf.slice(p, p + img.size)]
        p += img.size

        while (buf[p] !== 0x00) {
          // Some gifs screw up their size.
          // XXX Same for all subblocks?
          if (buf[p] === 0x3b && p === buf.length - 1) {
            p--
            break
          }
          size = buf.readUInt8(p)
          p += 1
          img.lzw.push(buf.slice(p, p + size))
          p += size
        }

        assert.equal(buf.readUInt8(p), 0x00)
        p += 1

        if (ext && ext.label === 0xf9) {
          img.control = ext
        }

        this.totalPixels += img.width * img.height

        this.images.push(img)

        if (this.totalPixels >= this.pixelLimit) {
          break
        }
      } else if (desc === 0x21) {
        // Extensions:
        // http://www.w3.org/Graphics/GIF/spec-gif89a.txt
        ext = {}
        label = buf.readUInt8(p)
        p += 1
        ext.label = label
        if (label === 0xf9) {
          size = buf.readUInt8(p)
          assert.equal(size, 0x04)
          p += 1
          ext.fields = buf.readUInt8(p)
          ext.disposeMethod = (ext.fields >> 2) & 0x07
          ext.useTransparent = !!(ext.fields & 0x01)
          p += 1
          ext.delay = buf.readUInt16LE(p)
          p += 2
          ext.transparentColor = buf.readUInt8(p)
          p += 1
          while (buf[p] !== 0x00) {
            size = buf.readUInt8(p)
            p += 1
            p += size
          }
          assert.equal(buf.readUInt8(p), 0x00)
          p += 1
          this.delay = ext.delay
          this.transparentColor = ext.transparentColor
          this.disposeMethod = ext.disposeMethod
          this.useTransparent = ext.useTransparent
        } else if (label === 0xff) {
          // https://wiki.whatwg.org/wiki/GIF#Specifications
          size = buf.readUInt8(p)
          p += 1
          ext.id = buf.slice(p, p + 8).toString('ascii')
          p += 8
          ext.auth = buf.slice(p, p + 3).toString('ascii')
          p += 3
          ext.data = []
          while (buf[p] !== 0x00) {
            size = buf.readUInt8(p)
            p += 1
            ext.data.push(buf.slice(p, p + size))
            p += size
          }
          ext.data = new Buffer(
            ext.data.reduce(function (out, data) {
              return out.concat(Array.prototype.slice.call(data))
            }, [])
          )
          // AnimExts looping extension (identical to netscape)
          if (ext.id === 'ANIMEXTS' && ext.auth === '1.0') {
            ext.id = 'NETSCAPE'
            ext.auth = '2.0'
            ext.animexts = true
          }
          // Netscape extensions
          if (ext.id === 'NETSCAPE' && ext.auth === '2.0') {
            if (ext.data.readUInt8(0) === 0x01) {
              // Netscape looping extension
              // http://graphcomp.com/info/specs/ani_gif.html
              ext.numPlays = ext.data.readUInt16LE(1)
              this.numPlays = ext.numPlays
            } else if (ext.data.readUInt8(0) === 0x02) {
              // Netscape buffering extension
              this.minBuffer = ext.data
            }
          }
          // Adobe XMP extension
          if (ext.id === 'XMP Data' && ext.auth === 'XMP') {
            ext.xmp = ext.data.toString('utf8')
            this.xmp = ext.xmp
          }
          // ICC extension
          if (ext.id === 'ICCRGBG1' && ext.auth === '012') {
            // NOTE: Says size is 4 bytes, not 1? Maybe just buffer size?
            this.icc = ext.data
          }
          // fractint extension
          if (ext.id === 'fractint' && /^00[1-7]$/.test(ext.auth)) {
            // NOTE: Says size is 4 bytes, not 1? Maybe just buffer size?
            // Size: '!\377\013' == [0x00, 0x15, 0xff, 0x0b]
            this.fractint = ext.data
          }
          assert.equal(buf.readUInt8(p), 0x00)
          p += 1
        } else {
          ext.data = []
          while (buf[p] !== 0x00) {
            size = buf.readUInt8(p)
            p += 1
            ext.data.push(buf.slice(p, p + size))
            p += size
          }
          assert.equal(buf.readUInt8(p), 0x00)
          p += 1
        }
        this.extensions.push(ext)
      } else if (desc === 0x3b) {
        break
      } else if (p === buf.length - 1) {
        // } else if (desc === 0x00 && p === buf.length - 1) {
        break
      } else {
        throw new Error('unknown block')
      }
    }
  } catch (e) {
    if (options.debug) {
      throw e
    }
  }

  this.images = this.images
    .map(function (img, imageIndex) {
      const control = img.control || this

      img.lzw = new Buffer(
        img.lzw.reduce(function (out, data) {
          return out.concat(Array.prototype.slice.call(data))
        }, [])
      )

      try {
        img.data = this.decompress(img.lzw, img.codeSize)
      } catch (e) {
        if (options.debug) {
          throw e
        }
        return
      }

      const interlacing = [
        [0, 8],
        [4, 8],
        [2, 4],
        [1, 2],
        [0, 0]
      ]

      let table = img.lcolors || this.colors,
        row = 0,
        col = 0,
        ilp = 0,
        p = 0,
        b,
        idx,
        i,
        y,
        x,
        line,
        pixel

      img.samples = []
      // Rewritten version of:
      // https://github.com/lbv/ka-cs-programs/blob/master/lib/gif-reader.js
      for (;;) {
        b = img.data[p++]
        if (b == null) {
          break
        }
        idx = (row * img.width + col) * 4
        if (!table[b]) {
          if (options.debug) {
            throw new Error('bad samples')
          }
          table[b] = [0, 0, 0, 0]
        }
        img.samples[idx] = table[b][0]
        img.samples[idx + 1] = table[b][1]
        img.samples[idx + 2] = table[b][2]
        img.samples[idx + 3] = table[b][3]
        if (control.useTransparent && b === control.transparentColor) {
          img.samples[idx + 3] = 0
        }
        if (++col >= img.width) {
          col = 0
          if (img.ilace) {
            row += interlacing[ilp][1]
            if (row >= img.height) {
              row = interlacing[++ilp][0]
            }
          } else {
            row++
          }
        }
      }

      img.pixels = []
      for (i = 0; i < img.samples.length; i += 4) {
        img.pixels.push(img.samples.slice(i, i + 4))
      }

      img.bmp = []
      for (y = 0, p = 0; y < img.height; y++) {
        line = []
        for (x = 0; x < img.width; x++) {
          pixel = img.pixels[p++]
          if (!pixel) {
            if (options.debug) {
              throw new Error('no pixel')
            }
            line.push({ r: 0, g: 0, b: 0, a: 0 })
            continue
          }
          line.push({ r: pixel[0], g: pixel[1], b: pixel[2], a: pixel[3] })
        }
        img.bmp.push(line)
      }

      return img
    }, this)
    .filter(Boolean)

  if (!this.images.length) {
    throw new Error('no image data or bad decompress')
  }
}

// Rewritten version of:
// https://github.com/lbv/ka-cs-programs/blob/master/lib/gif-reader.js
GIF.prototype.decompress = function (input, codeSize) {
  let bitDepth = codeSize + 1,
    CC = 1 << codeSize,
    EOI = CC + 1,
    stack = [],
    table = [],
    ntable = 0,
    oldCode = null,
    buffer = 0,
    nbuffer = 0,
    p = 0,
    buf = [],
    bits,
    read,
    ans,
    n,
    code,
    i,
    K,
    b,
    maxElem

  for (;;) {
    if (stack.length === 0) {
      bits = bitDepth
      read = 0
      ans = 0
      while (read < bits) {
        if (nbuffer === 0) {
          if (p >= input.length) {
            return buf
          }
          buffer = input[p++]
          nbuffer = 8
        }
        n = Math.min(bits - read, nbuffer)
        ans |= (buffer & ((1 << n) - 1)) << read
        read += n
        nbuffer -= n
        buffer >>= n
      }
      code = ans

      if (code === EOI) {
        break
      }

      if (code === CC) {
        table = []
        for (i = 0; i < CC; ++i) {
          table[i] = [i, -1, i]
        }
        bitDepth = codeSize + 1
        maxElem = 1 << bitDepth
        ntable = CC + 2
        oldCode = null
        continue
      }

      if (oldCode === null) {
        oldCode = code
        buf.push(table[code][0])
        continue
      }

      if (code < ntable) {
        for (i = code; i >= 0; i = table[i][1]) {
          stack.push(table[i][0])
        }
        table[ntable++] = [table[code][2], oldCode, table[oldCode][2]]
      } else {
        K = table[oldCode][2]
        table[ntable++] = [K, oldCode, K]
        for (i = code; i >= 0; i = table[i][1]) {
          stack.push(table[i][0])
        }
      }

      oldCode = code
      if (ntable === maxElem) {
        maxElem = 1 << ++bitDepth
        if (bitDepth > 12) {
          bitDepth = 12
        }
      }
    }
    b = stack.pop()
    if (b == null) {
      break
    }
    buf.push(b)
  }

  return buf
}

/**
 * Expose
 */

exports = PNG
exports.png = PNG
exports.gif = GIF

module.exports = exports
