# All files parser.js

90.57% Statements 144/159
85.45% Branches 47/55
100% Functions 20/20
90.32% Lines 140/155

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     "use strict";

    let constants = require("./constants");
    let CrcCalculator = require("./crc");

    let Parser = (module.exports = function (options, dependencies) {
      this._options = options;
      options.checkCRC = options.checkCRC !== false;

      this._hasIHDR = false;
      this._hasIEND = false;
      this._emittedHeadersFinished = false;

      // input flags/metadata
      this._palette = [];
      this._colorType = 0;

      this._chunks = {};
      this._chunks[constants.TYPE_IHDR] = this._handleIHDR.bind(this);
      this._chunks[constants.TYPE_IEND] = this._handleIEND.bind(this);
      this._chunks[constants.TYPE_IDAT] = this._handleIDAT.bind(this);
      this._chunks[constants.TYPE_PLTE] = this._handlePLTE.bind(this);
      this._chunks[constants.TYPE_tRNS] = this._handleTRNS.bind(this);
      this._chunks[constants.TYPE_gAMA] = this._handleGAMA.bind(this);

      this.read = dependencies.read;
      this.error = dependencies.error;
      this.metadata = dependencies.metadata;
      this.gamma = dependencies.gamma;
      this.transColor = dependencies.transColor;
      this.palette = dependencies.palette;
      this.parsed = dependencies.parsed;
      this.inflateData = dependencies.inflateData;
      this.finished = dependencies.finished;
      this.simpleTransparency = dependencies.simpleTransparency;
      this.headersFinished = dependencies.headersFinished || function () {};
    });

    Parser.prototype.start = function () {
      this.read(constants.PNG_SIGNATURE.length, this._parseSignature.bind(this));
    };

    Parser.prototype._parseSignature = function (data) {
      let signature = constants.PNG_SIGNATURE;

      for (let i = 0; i < signature.length; i++) {
        if (data[i] !== signature[i]) {
          this.error(new Error("Invalid file signature"));
          return;
        }
      }
      this.read(8, this._parseChunkBegin.bind(this));
    };

    Parser.prototype._parseChunkBegin = function (data) {
      // chunk content length
      let length = data.readUInt32BE(0);

      // chunk type
      let type = data.readUInt32BE(4);
      let name = "";
      for (let i = 4; i < 8; i++) {
        name += String.fromCharCode(data[i]);
      }

      //console.log('chunk ', name, length);

      // chunk flags
      let ancillary = Boolean(data[4] & 0x20); // or critical
      //    priv = Boolean(data[5] & 0x20), // or public
      //    safeToCopy = Boolean(data[7] & 0x20); // or unsafe

      Iif (!this._hasIHDR && type !== constants.TYPE_IHDR) {
        this.error(new Error("Expected IHDR on beggining"));
        return;
      }

      this._crc = new CrcCalculator();
      this._crc.write(Buffer.from(name));

      if (this._chunks[type]) {
        return this._chunks[type](length);
      }

      Iif (!ancillary) {
        this.error(new Error("Unsupported critical chunk type " + name));
        return;
      }

      this.read(length + 4, this._skipChunk.bind(this));
    };

    Parser.prototype._skipChunk = function (/*data*/) {
      this.read(8, this._parseChunkBegin.bind(this));
    };

    Parser.prototype._handleChunkEnd = function () {
      this.read(4, this._parseChunkEnd.bind(this));
    };

    Parser.prototype._parseChunkEnd = function (data) {
      let fileCrc = data.readInt32BE(0);
      let calcCrc = this._crc.crc32();

      // check CRC
      if (this._options.checkCRC && calcCrc !== fileCrc) {
        this.error(new Error("Crc error - " + fileCrc + " - " + calcCrc));
        return;
      }

      if (!this._hasIEND) {
        this.read(8, this._parseChunkBegin.bind(this));
      }
    };

    Parser.prototype._handleIHDR = function (length) {
      this.read(length, this._parseIHDR.bind(this));
    };
    Parser.prototype._parseIHDR = function (data) {
      this._crc.write(data);

      let width = data.readUInt32BE(0);
      let height = data.readUInt32BE(4);
      let depth = data[8];
      let colorType = data[9]; // bits: 1 palette, 2 color, 4 alpha
      let compr = data[10];
      let filter = data[11];
      let interlace = data[12];

      // console.log('    width', width, 'height', height,
      //     'depth', depth, 'colorType', colorType,
      //     'compr', compr, 'filter', filter, 'interlace', interlace
      // );

      if (
        depth !== 8 &&
        depth !== 4 &&
        depth !== 2 &&
        depth !== 1 &&
        depth !== 16
      ) {
        this.error(new Error("Unsupported bit depth " + depth));
        return;
      }
      if (!(colorType in constants.COLORTYPE_TO_BPP_MAP)) {
        this.error(new Error("Unsupported color type"));
        return;
      }
      Iif (compr !== 0) {
        this.error(new Error("Unsupported compression method"));
        return;
      }
      Iif (filter !== 0) {
        this.error(new Error("Unsupported filter method"));
        return;
      }
      Iif (interlace !== 0 && interlace !== 1) {
        this.error(new Error("Unsupported interlace method"));
        return;
      }

      this._colorType = colorType;

      let bpp = constants.COLORTYPE_TO_BPP_MAP[this._colorType];

      this._hasIHDR = true;

      this.metadata({
        width: width,
        height: height,
        depth: depth,
        interlace: Boolean(interlace),
        palette: Boolean(colorType & constants.COLORTYPE_PALETTE),
        color: Boolean(colorType & constants.COLORTYPE_COLOR),
        alpha: Boolean(colorType & constants.COLORTYPE_ALPHA),
        bpp: bpp,
        colorType: colorType,
      });

      this._handleChunkEnd();
    };

    Parser.prototype._handlePLTE = function (length) {
      this.read(length, this._parsePLTE.bind(this));
    };
    Parser.prototype._parsePLTE = function (data) {
      this._crc.write(data);

      let entries = Math.floor(data.length / 3);
      // console.log('Palette:', entries);

      for (let i = 0; i < entries; i++) {
        this._palette.push([data[i * 3], data[i * 3 + 1], data[i * 3 + 2], 0xff]);
      }

      this.palette(this._palette);

      this._handleChunkEnd();
    };

    Parser.prototype._handleTRNS = function (length) {
      this.simpleTransparency();
      this.read(length, this._parseTRNS.bind(this));
    };
    Parser.prototype._parseTRNS = function (data) {
      this._crc.write(data);

      // palette
      if (this._colorType === constants.COLORTYPE_PALETTE_COLOR) {
        Iif (this._palette.length === 0) {
          this.error(new Error("Transparency chunk must be after palette"));
          return;
        }
        Iif (data.length > this._palette.length) {
          this.error(new Error("More transparent colors than palette size"));
          return;
        }
        for (let i = 0; i < data.length; i++) {
          this._palette[i][3] = data[i];
        }
        this.palette(this._palette);
      }

      // for colorType 0 (grayscale) and 2 (rgb)
      // there might be one gray/color defined as transparent
      if (this._colorType === constants.COLORTYPE_GRAYSCALE) {
        // grey, 2 bytes
        this.transColor([data.readUInt16BE(0)]);
      }
      if (this._colorType === constants.COLORTYPE_COLOR) {
        this.transColor([
          data.readUInt16BE(0),
          data.readUInt16BE(2),
          data.readUInt16BE(4),
        ]);
      }

      this._handleChunkEnd();
    };

    Parser.prototype._handleGAMA = function (length) {
      this.read(length, this._parseGAMA.bind(this));
    };
    Parser.prototype._parseGAMA = function (data) {
      this._crc.write(data);
      this.gamma(data.readUInt32BE(0) / constants.GAMMA_DIVISION);

      this._handleChunkEnd();
    };

    Parser.prototype._handleIDAT = function (length) {
      if (!this._emittedHeadersFinished) {
        this._emittedHeadersFinished = true;
        this.headersFinished();
      }
      this.read(-length, this._parseIDAT.bind(this, length));
    };
    Parser.prototype._parseIDAT = function (length, data) {
      this._crc.write(data);

      Iif (
        this._colorType === constants.COLORTYPE_PALETTE_COLOR &&
        this._palette.length === 0
      ) {
        throw new Error("Expected palette not found");
      }

      this.inflateData(data);
      let leftOverLength = length - data.length;

      if (leftOverLength > 0) {
        this._handleIDAT(leftOverLength);
      } else {
        this._handleChunkEnd();
      }
    };

    Parser.prototype._handleIEND = function (length) {
      this.read(length, this._parseIEND.bind(this));
    };
    Parser.prototype._parseIEND = function (data) {
      this._crc.write(data);

      this._hasIEND = true;
      this._handleChunkEnd();

      if (this.finished) {
        this.finished();
      }
    };