var CONSTANTS = require("./constants");

function parser(arrayBuffer) {
  var data = {};
  var i = 0;
  var arr = new Int8Array(arrayBuffer);
  // Parse header
  data.type = String.fromCharCode.apply(
    null,
    arr.slice(i, CONSTANTS.HEADER.length)
  );
  if (data.type !== CONSTANTS.HEADER) {
    throw new Error("Invalid .eqf file.");
  }
  i += CONSTANTS.HEADER.length;
  // Skip "<ctrl-z>!--"
  i += 4;
  // Get the presets
  data.presets = [];
  while (i < arr.length) {
    var preset = {};
    // Get the name
    var nameStart = i;
    var nameEnd = nameStart + 257; // Str is fixed length
    // Str is null terminated
    while (arr[i] !== 0 && i <= nameEnd) {
      i++;
    }
    preset.name = String.fromCharCode.apply(null, arr.slice(nameStart, i));
    i = nameEnd; // Skip over any unused bytes

    // Get the levels
    CONSTANTS.PRESET_VALUES.forEach(function(valueName) {
      preset[valueName] = 64 - arr[i++]; // Adjust for inverse values
    });
    data.presets.push(preset);
  }
  return data;
}

module.exports = parser;