pocketrocket / floatify

var floatify = function floatify(str, preferDecimalSeparator) {

  // by default we prefer thousands separators

  var preferThousandsSeparators = preferDecimalSeparator !== true;

  var toFloatFormat = function toFloatFormat(str, ts, ds) {

    var string = str;

    var decimalSeparator = ds || '';

    string = string.split(ts || '').join('');

    if (decimalSeparator !== '') {

      string = string.split(decimalSeparator).join('.');

    }

    return parseFloat(string);

  };

  var parseParts = function parseParts(str, ele, count, preferThousandsSeparators) {

    var string = str;

    var element = ele;

    var parts = string.split(element);

    function parseMidPart() {

      if (current.length !== 3) {

        return Number.NaN;

      }

      if (left.length > 3) {

        return Number.NaN;

      }

      // no decision, continue

      return null;

    }

    function parseEndPart() {

      if ((leftVal === 0 || isNaN(leftVal) || left.length > 3)) {

        return toFloatFormat(string, '', element);

      }

      if (current.length === 3) {

        if (preferThousandsSeparators) {

          return toFloatFormat(string, element, '');

        }

        return toFloatFormat(string, '', element);

      }

      if (count === 1) {

        return toFloatFormat(string, '', element);

      }

      return Number.NaN;

    }

    for (var i = 1; i < parts.length; i++) {

      var current = parts[i];

      var left = parts[i - 1];

      var leftVal = parseInt(left, 10);

      var isLast = parts.length - 1 === i;

      var parseResult;

      if (!isLast) {

        parseResult = parseMidPart();

      } else {

        parseResult = parseEndPart();

      }

      if (parseResult !== null) {

        break;

      }

    }

    return parseResult || Number.NaN;

  };

  var parse = function parse(str, preferThousandsSeparators) {

    var string = str;

    var spacePos;

    var spaceSplit;

    var spaceCount;

    var dotPos;

    var commaPos;

    var lDotPos;

    var lCommaPos;

    var dotCount;

    var commaCount;

    function parseMixedSeparators() {

      // format is using dot and comma

      // last dot position

      lDotPos = string.lastIndexOf('.');

      // last comma position

      lCommaPos = string.lastIndexOf(',');

      // order of 1st dot -> comma must be same as last dot -> comma

      // 123.123.123,123 -> ok 123.123,123.123 -> not ok

      if (Math.sign(dotPos - commaPos) !== Math.sign(lDotPos - lCommaPos)) {

        return Number.NaN;

      }

      // check positions to guess the thousands separator

      if (dotPos > commaPos) {

        if (dotCount > 1) {

          return Number.NaN;

        }

        // best guess: . is thousands separator and , is decimal point

        return toFloatFormat(string, ',', '.');

      }

      if (commaCount > 1) {

        return Number.NaN;

      }

      // best guess: , is thousands separator and . is decimal point

      return toFloatFormat(string, '.', ',');

    }

    function precheckFormat() {

      // only combination of 2 separators allowed

      if (dotCount > 0 && commaCount > 0 && spaceCount > 0) {

        return false;

      }

      // if there is any separator (space, comma, dot) found more than once,

      // all other must not be found more than once

      if (dotCount > 1 && (commaCount > 1 || spaceCount > 1)) {

        return false;

      }

      return !(commaCount > 1 && spaceCount > 1);

    }

    string = string.trim();

    // 1st dot position

    dotPos = string.indexOf('.');

    // 1st comma position

    commaPos = string.indexOf(',');

    // 1st space position

    spacePos = string.indexOf(' ');

    if (dotPos + commaPos + spacePos === -3) {

      // life is good, no separators

      return toFloatFormat(string);

    }

    spaceSplit = string.split(' ');

    spaceCount = spaceSplit.length - 1;

    dotCount = string.split('.').length - 1;

    commaCount = string.split(',').length - 1;

    if (!precheckFormat()) {

      return Number.NaN;

    }

    if (spaceCount > 0) {

      if (!string.match(/^(\d{1,3})?(\s\d{3})*([,\.]\d+)?$/)) {

        return Number.NaN;

      }

      string = spaceSplit.join('');

    }

    if (dotPos !== -1 && commaPos !== -1) {

      return parseMixedSeparators();

    }

    return parseSingleSeparators();

  };

  return parse(str, preferThousandsSeparators);

};

if (typeof exports !== 'undefined') {

  if (typeof module !== 'undefined' && module.exports) {

    exports = module.exports = floatify;

  }

}