'use strict';

var common = require('../common');
var Type   = require('../type');

var YAML_FLOAT_PATTERN = new RegExp(
  '^(?:[-+]?(?:[0-9][0-9_]*)\\.[0-9_]*(?:[eE][-+][0-9]+)?' +
  '|\\.[0-9_]+(?:[eE][-+][0-9]+)?' +
  '|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]*' +
  '|[-+]?\\.(?:inf|Inf|INF)' +
  '|\\.(?:nan|NaN|NAN))$');

function resolveYamlFloat(data) {
  var value, sign, base, digits;

  if (!YAML_FLOAT_PATTERN.test(data)) {
    return false;
  }
  return true;
}

function constructYamlFloat(data) {
  var value, sign, base, digits;

  value  = data.replace(/_/g, '').toLowerCase();
  sign   = '-' === value[0] ? -1 : 1;
  digits = [];

  if (0 <= '+-'.indexOf(value[0])) {
    value = value.slice(1);
  }

  if ('.inf' === value) {
    return (1 === sign) ? Number.POSITIVE_INFINITY : Number.NEGATIVE_INFINITY;

  } else if ('.nan' === value) {
    return NaN;

  } else if (0 <= value.indexOf(':')) {
    value.split(':').forEach(function (v) {
      digits.unshift(parseFloat(v, 10));
    });

    value = 0.0;
    base = 1;

    digits.forEach(function (d) {
      value += d * base;
      base *= 60;
    });

    return sign * value;

  } else {
    return sign * parseFloat(value, 10);
  }
}

function representYamlFloat(object, style) {
  if (isNaN(object)) {
    switch (style) {
    case 'lowercase':
      return '.nan';
    case 'uppercase':
      return '.NAN';
    case 'camelcase':
      return '.NaN';
    }
  } else if (Number.POSITIVE_INFINITY === object) {
    switch (style) {
    case 'lowercase':
      return '.inf';
    case 'uppercase':
      return '.INF';
    case 'camelcase':
      return '.Inf';
    }
  } else if (Number.NEGATIVE_INFINITY === object) {
    switch (style) {
    case 'lowercase':
      return '-.inf';
    case 'uppercase':
      return '-.INF';
    case 'camelcase':
      return '-.Inf';
    }
  } else if (common.isNegativeZero(object)) {
    return '-0.0';
  } else {
    return object.toString(10);
  }
}

function isFloat(object) {
  return ('[object Number]' === Object.prototype.toString.call(object)) &&
         (0 !== object % 1 || common.isNegativeZero(object));
}

module.exports = new Type('tag:yaml.org,2002:float', {
  kind: 'scalar',
  resolve: resolveYamlFloat,
  construct: constructYamlFloat,
  predicate: isFloat,
  represent: representYamlFloat,
  defaultStyle: 'lowercase'
});
