text: /**
   * @license
   * Visual Blocks Language
   *
   * Copyright 2014 Google Inc.
   * https://blockly.googlecode.com/
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /**
   * @fileoverview Generating Dart for math blocks.
   * @author q.neutron@gmail.com (Quynh Neutron)
   */
  'use strict';
  
  goog.provide('Blockly.Dart.math');
  
  goog.require('Blockly.Dart');
  
  
  Blockly.Dart.addReservedWords('Math');
  
  Blockly.Dart['math_number'] = function(block) {
    // Numeric value.
    var code = window.parseFloat(block.getFieldValue('NUM'));
    // -4.abs() returns -4 in Dart due to strange order of operation choices.
    // -4 is actually an operator and a number.  Reflect this in the order.
    var order = code < 0 ?
        Blockly.Dart.ORDER_UNARY_PREFIX : Blockly.Dart.ORDER_ATOMIC;
    return [code, order];
  };
  
  Blockly.Dart['math_arithmetic'] = function(block) {
    // Basic arithmetic operators, and power.
    var OPERATORS = {
      ADD: [' + ', Blockly.Dart.ORDER_ADDITIVE],
      MINUS: [' - ', Blockly.Dart.ORDER_ADDITIVE],
      MULTIPLY: [' * ', Blockly.Dart.ORDER_MULTIPLICATIVE],
      DIVIDE: [' / ', Blockly.Dart.ORDER_MULTIPLICATIVE],
      POWER: [null, Blockly.Dart.ORDER_NONE]  // Handle power separately.
    };
    var tuple = OPERATORS[block.getFieldValue('OP')];
    var operator = tuple[0];
    var order = tuple[1];
    var argument0 = Blockly.Dart.valueToCode(block, 'A', order) || '0';
    var argument1 = Blockly.Dart.valueToCode(block, 'B', order) || '0';
    var code;
    // Power in Dart requires a special case since it has no operator.
    if (!operator) {
      Blockly.Dart.definitions_['import_dart_math'] =
          'import \'dart:math\' as Math;';
      code = 'Math.pow(' + argument0 + ', ' + argument1 + ')';
      return [code, Blockly.Dart.ORDER_UNARY_POSTFIX];
    }
    code = argument0 + operator + argument1;
    return [code, order];
  };
  
  Blockly.Dart['math_single'] = function(block) {
    // Math operators with single operand.
    var operator = block.getFieldValue('OP');
    var code;
    var arg;
    if (operator == 'NEG') {
      // Negation is a special case given its different operator precedence.
      arg = Blockly.Dart.valueToCode(block, 'NUM',
          Blockly.Dart.ORDER_UNARY_PREFIX) || '0';
      if (arg[0] == '-') {
        // --3 is not legal in Dart.
        arg = ' ' + arg;
      }
      code = '-' + arg;
      return [code, Blockly.Dart.ORDER_UNARY_PREFIX];
    }
    Blockly.Dart.definitions_['import_dart_math'] =
        'import \'dart:math\' as Math;';
    if (operator == 'ABS' || operator.substring(0, 5) == 'ROUND') {
      arg = Blockly.Dart.valueToCode(block, 'NUM',
          Blockly.Dart.ORDER_UNARY_POSTFIX) || '0';
    } else if (operator == 'SIN' || operator == 'COS' || operator == 'TAN') {
      arg = Blockly.Dart.valueToCode(block, 'NUM',
          Blockly.Dart.ORDER_MULTIPLICATIVE) || '0';
    } else {
      arg = Blockly.Dart.valueToCode(block, 'NUM',
          Blockly.Dart.ORDER_NONE) || '0';
    }
    // First, handle cases which generate values that don't need parentheses
    // wrapping the code.
    switch (operator) {
      case 'ABS':
        code = arg + '.abs()';
        break;
      case 'ROOT':
        code = 'Math.sqrt(' + arg + ')';
        break;
      case 'LN':
        code = 'Math.log(' + arg + ')';
        break;
      case 'EXP':
        code = 'Math.exp(' + arg + ')';
        break;
      case 'POW10':
        code = 'Math.pow(10,' + arg + ')';
        break;
      case 'ROUND':
        code = arg + '.round()';
        break;
      case 'ROUNDUP':
        code = arg + '.ceil()';
        break;
      case 'ROUNDDOWN':
        code = arg + '.floor()';
        break;
      case 'SIN':
        code = 'Math.sin(' + arg + ' / 180 * Math.PI)';
        break;
      case 'COS':
        code = 'Math.cos(' + arg + ' / 180 * Math.PI)';
        break;
      case 'TAN':
        code = 'Math.tan(' + arg + ' / 180 * Math.PI)';
        break;
    }
    if (code) {
      return [code, Blockly.Dart.ORDER_UNARY_POSTFIX];
    }
    // Second, handle cases which generate values that may need parentheses
    // wrapping the code.
    switch (operator) {
      case 'LOG10':
        code = 'Math.log(' + arg + ') / Math.log(10)';
        break;
      case 'ASIN':
        code = 'Math.asin(' + arg + ') / Math.PI * 180';
        break;
      case 'ACOS':
        code = 'Math.acos(' + arg + ') / Math.PI * 180';
        break;
      case 'ATAN':
        code = 'Math.atan(' + arg + ') / Math.PI * 180';
        break;
      default:
        throw 'Unknown math operator: ' + operator;
    }
    return [code, Blockly.Dart.ORDER_MULTIPLICATIVE];
  };
  
  Blockly.Dart['math_constant'] = function(block) {
    // Constants: PI, E, the Golden Ratio, sqrt(2), 1/sqrt(2), INFINITY.
    var CONSTANTS = {
      PI: ['Math.PI', Blockly.Dart.ORDER_UNARY_POSTFIX],
      E: ['Math.E', Blockly.Dart.ORDER_UNARY_POSTFIX],
      GOLDEN_RATIO: ['(1 + Math.sqrt(5)) / 2', Blockly.Dart.ORDER_MULTIPLICATIVE],
      SQRT2: ['Math.SQRT2', Blockly.Dart.ORDER_UNARY_POSTFIX],
      SQRT1_2: ['Math.SQRT1_2', Blockly.Dart.ORDER_UNARY_POSTFIX],
      INFINITY: ['double.INFINITY', Blockly.Dart.ORDER_ATOMIC]
    };
    var constant = block.getFieldValue('CONSTANT');
    if (constant != 'INFINITY') {
      Blockly.Dart.definitions_['import_dart_math'] =
          'import \'dart:math\' as Math;';
    }
    return CONSTANTS[constant];
  };
  
  Blockly.Dart['math_number_property'] = function(block) {
    // Check if a number is even, odd, prime, whole, positive, or negative
    // or if it is divisible by certain number. Returns true or false.
    var number_to_check = Blockly.Dart.valueToCode(block, 'NUMBER_TO_CHECK',
        Blockly.Dart.ORDER_MULTIPLICATIVE);
    if (!number_to_check) {
      return ['false', Blockly.Python.ORDER_ATOMIC];
    }
    var dropdown_property = block.getFieldValue('PROPERTY');
    var code;
    if (dropdown_property == 'PRIME') {
      // Prime is a special case as it is not a one-liner test.
      Blockly.Dart.definitions_['import_dart_math'] =
          'import \'dart:math\' as Math;';
      var functionName = Blockly.Dart.provideFunction_(
          'math_isPrime',
          [ 'bool ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ + '(n) {',
            '  // https://en.wikipedia.org/wiki/Primality_test#Naive_methods',
            '  if (n == 2 || n == 3) {',
            '    return true;',
            '  }',
            '  // False if n is null, negative, is 1, or not whole.',
            '  // And false if n is divisible by 2 or 3.',
            '  if (n == null || n <= 1 || n % 1 != 0 || n % 2 == 0 ||' +
              ' n % 3 == 0) {',
            '    return false;',
            '  }',
            '  // Check all the numbers of form 6k +/- 1, up to sqrt(n).',
            '  for (var x = 6; x <= Math.sqrt(n) + 1; x += 6) {',
            '    if (n % (x - 1) == 0 || n % (x + 1) == 0) {',
            '      return false;',
            '    }',
            '  }',
            '  return true;',
            '}']);
      code = functionName + '(' + number_to_check + ')';
      return [code, Blockly.Dart.ORDER_UNARY_POSTFIX];
    }
    switch (dropdown_property) {
      case 'EVEN':
        code = number_to_check + ' % 2 == 0';
        break;
      case 'ODD':
        code = number_to_check + ' % 2 == 1';
        break;
      case 'WHOLE':
        code = number_to_check + ' % 1 == 0';
        break;
      case 'POSITIVE':
        code = number_to_check + ' > 0';
        break;
      case 'NEGATIVE':
        code = number_to_check + ' < 0';
        break;
      case 'DIVISIBLE_BY':
        var divisor = Blockly.Dart.valueToCode(block, 'DIVISOR',
            Blockly.Dart.ORDER_MULTIPLICATIVE);
        if (!divisor) {
          return ['false', Blockly.Python.ORDER_ATOMIC];
        }
        code = number_to_check + ' % ' + divisor + ' == 0';
        break;
    }
    return [code, Blockly.Dart.ORDER_EQUALITY];
  };
  
  Blockly.Dart['math_change'] = function(block) {
    // Add to a variable in place.
    var argument0 = Blockly.Dart.valueToCode(block, 'DELTA',
        Blockly.Dart.ORDER_ADDITIVE) || '0';
    var varName = Blockly.Dart.variableDB_.getName(block.getFieldValue('VAR'),
        Blockly.Variables.NAME_TYPE);
    return varName + ' = (' + varName + ' is num ? ' + varName + ' : 0) + ' +
        argument0 + ';\n';
  };
  
  // Rounding functions have a single operand.
  Blockly.Dart['math_round'] = Blockly.Dart['math_single'];
  // Trigonometry functions have a single operand.
  Blockly.Dart['math_trig'] = Blockly.Dart['math_single'];
  
  Blockly.Dart['math_on_list'] = function(block) {
    // Math functions for lists.
    var func = block.getFieldValue('OP');
    var list = Blockly.Dart.valueToCode(block, 'LIST',
        Blockly.Dart.ORDER_NONE) || '[]';
    var code;
    switch (func) {
      case 'SUM':
        var functionName = Blockly.Dart.provideFunction_(
            'math_sum',
            [ 'num ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  num sumVal = 0;',
              '  myList.forEach((num entry) {sumVal += entry;});',
              '  return sumVal;',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'MIN':
        Blockly.Dart.definitions_['import_dart_math'] =
            'import \'dart:math\' as Math;';
        var functionName = Blockly.Dart.provideFunction_(
            'math_min',
            [ 'num ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  if (myList.isEmpty) return null;',
              '  num minVal = myList[0];',
              '  myList.forEach((num entry) ' +
                '{minVal = Math.min(minVal, entry);});',
              '  return minVal;',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'MAX':
        Blockly.Dart.definitions_['import_dart_math'] =
            'import \'dart:math\' as Math;';
        var functionName = Blockly.Dart.provideFunction_(
            'math_max',
            [ 'num ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  if (myList.isEmpty) return null;',
              '  num maxVal = myList[0];',
              '  myList.forEach((num entry) ' +
                    '{maxVal = Math.max(maxVal, entry);});',
              '  return maxVal;',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'AVERAGE':
        // This operation exclude null and values that are not int or float:
        //   math_mean([null,null,"aString",1,9]) == 5.0.
        var functionName = Blockly.Dart.provideFunction_(
            'math_average',
            [ 'num ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  // First filter list for numbers only.',
              '  List localList = new List.from(myList);',
              '  localList.removeMatching((a) => a is! num);',
              '  if (localList.isEmpty) return null;',
              '  num sumVal = 0;',
              '  localList.forEach((num entry) {sumVal += entry;});',
              '  return sumVal / localList.length;',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'MEDIAN':
        var functionName = Blockly.Dart.provideFunction_(
            'math_median',
            [ 'num ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  // First filter list for numbers only, then sort, ' +
                'then return middle value',
              '  // or the average of two middle values if list has an ' +
                'even number of elements.',
              '  List localList = new List.from(myList);',
              '  localList.removeMatching((a) => a is! num);',
              '  if (localList.isEmpty) return null;',
              '  localList.sort((a, b) => (a - b));',
              '  int index = localList.length ~/ 2;',
              '  if (localList.length % 2 == 1) {',
              '    return localList[index];',
              '  } else {',
              '    return (localList[index - 1] + localList[index]) / 2;',
              '  }',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'MODE':
        Blockly.Dart.definitions_['import_dart_math'] =
            'import \'dart:math\' as Math;';
        // As a list of numbers can contain more than one mode,
        // the returned result is provided as an array.
        // Mode of [3, 'x', 'x', 1, 1, 2, '3'] -> ['x', 1].
        var functionName = Blockly.Dart.provideFunction_(
            'math_modes',
            [ 'List ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List values) {',
              '  List modes = [];',
              '  List counts = [];',
              '  int maxCount = 0;',
              '  for (int i = 0; i < values.length; i++) {',
              '    var value = values[i];',
              '    bool found = false;',
              '    int thisCount;',
              '    for (int j = 0; j < counts.length; j++) {',
              '      if (counts[j][0] == value) {',
              '        thisCount = ++counts[j][1];',
              '        found = true;',
              '        break;',
              '      }',
              '    }',
              '    if (!found) {',
              '      counts.add([value, 1]);',
              '      thisCount = 1;',
              '    }',
              '    maxCount = Math.max(thisCount, maxCount);',
              '  }',
              '  for (int j = 0; j < counts.length; j++) {',
              '    if (counts[j][1] == maxCount) {',
              '        modes.add(counts[j][0]);',
              '    }',
              '  }',
              '  return modes;',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'STD_DEV':
        Blockly.Dart.definitions_['import_dart_math'] =
            'import \'dart:math\' as Math;';
        var functionName = Blockly.Dart.provideFunction_(
            'math_standard_deviation',
            [ 'num ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  // First filter list for numbers only.',
              '  List numbers = new List.from(myList);',
              '  numbers.removeMatching((a) => a is! num);',
              '  if (numbers.isEmpty) return null;',
              '  num n = numbers.length;',
              '  num sum = 0;',
              '  numbers.forEach((x) => sum += x);',
              '  num mean = sum / n;',
              '  num sumSquare = 0;',
              '  numbers.forEach((x) => sumSquare += ' +
                    'Math.pow(x - mean, 2));',
              '  return Math.sqrt(sumSquare / n);',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      case 'RANDOM':
        Blockly.Dart.definitions_['import_dart_math'] =
            'import \'dart:math\' as Math;';
        var functionName = Blockly.Dart.provideFunction_(
            'math_random_item',
            [ 'dynamic ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ +
                '(List myList) {',
              '  int x = new Math.Random().nextInt(myList.length);',
              '  return myList[x];',
              '}']);
        code = functionName + '(' + list + ')';
        break;
      default:
        throw 'Unknown operator: ' + func;
    }
    return [code, Blockly.Dart.ORDER_UNARY_POSTFIX];
  };
  
  Blockly.Dart['math_modulo'] = function(block) {
    // Remainder computation.
    var argument0 = Blockly.Dart.valueToCode(block, 'DIVIDEND',
        Blockly.Dart.ORDER_MULTIPLICATIVE) || '0';
    var argument1 = Blockly.Dart.valueToCode(block, 'DIVISOR',
        Blockly.Dart.ORDER_MULTIPLICATIVE) || '0';
    var code = argument0 + ' % ' + argument1;
    return [code, Blockly.Dart.ORDER_MULTIPLICATIVE];
  };
  
  Blockly.Dart['math_constrain'] = function(block) {
    // Constrain a number between two limits.
    Blockly.Dart.definitions_['import_dart_math'] =
        'import \'dart:math\' as Math;';
    var argument0 = Blockly.Dart.valueToCode(block, 'VALUE',
        Blockly.Dart.ORDER_NONE) || '0';
    var argument1 = Blockly.Dart.valueToCode(block, 'LOW',
        Blockly.Dart.ORDER_NONE) || '0';
    var argument2 = Blockly.Dart.valueToCode(block, 'HIGH',
        Blockly.Dart.ORDER_NONE) || 'double.INFINITY';
    var code = 'Math.min(Math.max(' + argument0 + ', ' + argument1 + '), ' +
        argument2 + ')';
    return [code, Blockly.Dart.ORDER_UNARY_POSTFIX];
  };
  
  Blockly.Dart['math_random_int'] = function(block) {
    // Random integer between [X] and [Y].
    Blockly.Dart.definitions_['import_dart_math'] =
        'import \'dart:math\' as Math;';
    var argument0 = Blockly.Dart.valueToCode(block, 'FROM',
        Blockly.Dart.ORDER_NONE) || '0';
    var argument1 = Blockly.Dart.valueToCode(block, 'TO',
        Blockly.Dart.ORDER_NONE) || '0';
    var functionName = Blockly.Dart.provideFunction_(
        'math_random_int',
        [ 'int ' + Blockly.Dart.FUNCTION_NAME_PLACEHOLDER_ + '(num a, num b) {',
          '  if (a > b) {',
          '    // Swap a and b to ensure a is smaller.',
          '    num c = a;',
          '    a = b;',
          '    b = c;',
          '  }',
          '  return new Math.Random().nextInt(b - a + 1) + a;',
          '}']);
    var code = functionName + '(' + argument0 + ', ' + argument1 + ')';
    return [code, Blockly.Dart.ORDER_UNARY_POSTFIX];
  };
  
  Blockly.Dart['math_random_float'] = function(block) {
    // Random fraction between 0 and 1.
    Blockly.Dart.definitions_['import_dart_math'] =
        'import \'dart:math\' as Math;';
    return ['new Math.Random().nextDouble()', Blockly.Dart.ORDER_UNARY_POSTFIX];
  };
  