'use strict';

/**
 * @return {number}
 */
exports.d16 = exports.data16 = function data(buf, offset) {
  if (buf.length < offset + 2) {
    return buf.length - offset;
  }
  return 2 + buf.readUInt16LE(offset);
};

exports.d = exports.data = exports.d16;

/**
 * @return {number}
 */
exports.d32 = exports.data32 = function data32(buf, offset) {
  if (buf.length < offset + 4) {
    return buf.length - offset;
  }
  return 4 + buf.readUInt32LE(offset);
};

exports.ycc = function ycc(buf, offset) {
  if (buf.length - offset < 3) {
    return buf.length;
  }
  var k = buf[offset + 2] - buf[offset + 1] + 1;
  var num = 3;
  for (var i = 0; i < k; i++) {
    num += buf[offset + num] * buf[offset] + 1;
  }
  return num;
};

exports.escd = function escd(buf, offset) {
  var start = offset;
  while (offset < buf.length) {
    if (buf[offset++] === 0) break;
  }
  return offset - start;
};

exports.xy = function xy(buf, offset) {
  if (buf.length - offset < 2) {
    return buf.length;
  }
  return 2 + buf[offset] * buf[offset + 1] * 8;
};

/**
 *  GS V
 * @param buf
 * @param offset
 * @returns {*}
 */
exports.gsV = function gsvu(buf, offset) {
  if (buf.length - offset < 2) {
    return buf.length;
  }
  var m = buf[offset];
  if (m === 0 || m === 1 || m === 48 || m === 49) {
    return 1;
  }
  return 2;
};

exports.gsk = function gsk(buf, offset) {
  if (buf.length - offset < 3) {
    return buf.length;
  }
  if (buf[offset] >= 0 && buf[offset] <= 6) {
    var start = offset;
    while (offset < buf.length) {
      if (buf[offset++] === 0) break;
    }
    return offset - start;
  } else {
    return 2 + buf[offset + 1];
  }
};

exports.fsq = function fsq(buf, offset) {
  if (buf.length - offset < 2) {
    return buf.length;
  }
  return 1 + (buf.readUInt16LE(offset + 1) * buf.readUInt16LE(offset + 3) * 8 + 4) * buf[offset];
};

/**
 * GS v 0
 * @param buf
 * @param offset
 * @returns {*}
 */
exports.gsv0 = function gsv0(buf, offset) {
  if (buf.length - offset < 4) {
    return buf.length;
  }
  return 4 + buf.readUInt16LE(offset) * buf.readUInt16LE(offset + 2);
};

exports.bitimage = function bitimage (buf, offset) {
  var m = buf.readUInt8(offset);
  var n = m > 1 ? 3 : 1;
  return 3 + buf.readUInt16LE(offset + 1) * n;
};