module.exports = function(Blockly){
    'use strict';

Blockly.JavaScript['lists_create_empty'] = function(block) {
    // Create an empty list.
    return ['[]', Blockly.JavaScript.ORDER_ATOMIC];
  };
  
  Blockly.JavaScript['lists_create_with'] = function(block) {
    // Create a list with any number of elements of any type.
    var elements = new Array(block.itemCount_);
    for (var i = 0; i < block.itemCount_; i++) {
      elements[i] = Blockly.JavaScript.valueToCode(block, 'ADD' + i,
          Blockly.JavaScript.ORDER_COMMA) || 'null';
    }
    var code = '[' + elements.join(', ') + ']';
    return [code, Blockly.JavaScript.ORDER_ATOMIC];
  };
  
  Blockly.JavaScript['lists_repeat'] = function(block) {
    // Create a list with one element repeated.
    var functionName = Blockly.JavaScript.provideFunction_(
        'listsRepeat',
        ['function ' + Blockly.JavaScript.FUNCTION_NAME_PLACEHOLDER_ +
            '(value, n) {',
         '  var array = [];',
         '  for (var i = 0; i < n; i++) {',
         '    array[i] = value;',
         '  }',
         '  return array;',
         '}']);
    var element = Blockly.JavaScript.valueToCode(block, 'ITEM',
        Blockly.JavaScript.ORDER_COMMA) || 'null';
    var repeatCount = Blockly.JavaScript.valueToCode(block, 'NUM',
        Blockly.JavaScript.ORDER_COMMA) || '0';
    var code = functionName + '(' + element + ', ' + repeatCount + ')';
    return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
  };
  
  Blockly.JavaScript['lists_length'] = function(block) {
    // String or array length.
    var list = Blockly.JavaScript.valueToCode(block, 'VALUE',
        Blockly.JavaScript.ORDER_MEMBER) || '[]';
    return [list + '.length', Blockly.JavaScript.ORDER_MEMBER];
  };
  
  Blockly.JavaScript['lists_isEmpty'] = function(block) {
    // Is the string null or array empty?
    var list = Blockly.JavaScript.valueToCode(block, 'VALUE',
        Blockly.JavaScript.ORDER_MEMBER) || '[]';
    return ['!' + list + '.length', Blockly.JavaScript.ORDER_LOGICAL_NOT];
  };
  
  Blockly.JavaScript['lists_indexOf'] = function(block) {
    // Find an item in the list.
    var operator = block.getFieldValue('END') == 'FIRST' ?
        'indexOf' : 'lastIndexOf';
    var item = Blockly.JavaScript.valueToCode(block, 'FIND',
        Blockly.JavaScript.ORDER_NONE) || '\'\'';
    var list = Blockly.JavaScript.valueToCode(block, 'VALUE',
        Blockly.JavaScript.ORDER_MEMBER) || '[]';
    var code = list + '.' + operator + '(' + item + ')';
    if (block.workspace.options.oneBasedIndex) {
      return [code + ' + 1', Blockly.JavaScript.ORDER_ADDITION];
    }
    return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
  };
  
  Blockly.JavaScript['lists_getIndex'] = function(block) {
    // Get element at index.
    // Note: Until January 2013 this block did not have MODE or WHERE inputs.
    var mode = block.getFieldValue('MODE') || 'GET';
    var where = block.getFieldValue('WHERE') || 'FROM_START';
    var listOrder = (where == 'RANDOM') ? Blockly.JavaScript.ORDER_COMMA :
        Blockly.JavaScript.ORDER_MEMBER;
    var list = Blockly.JavaScript.valueToCode(block, 'VALUE', listOrder) || '[]';
  
    switch (where) {
      case ('FIRST'):
        if (mode == 'GET') {
          var code = list + '[0]';
          return [code, Blockly.JavaScript.ORDER_MEMBER];
        } else if (mode == 'GET_REMOVE') {
          var code = list + '.shift()';
          return [code, Blockly.JavaScript.ORDER_MEMBER];
        } else if (mode == 'REMOVE') {
          return list + '.shift();\n';
        }
        break;
      case ('LAST'):
        if (mode == 'GET') {
          var code = list + '.slice(-1)[0]';
          return [code, Blockly.JavaScript.ORDER_MEMBER];
        } else if (mode == 'GET_REMOVE') {
          var code = list + '.pop()';
          return [code, Blockly.JavaScript.ORDER_MEMBER];
        } else if (mode == 'REMOVE') {
          return list + '.pop();\n';
        }
        break;
      case ('FROM_START'):
        var at = Blockly.JavaScript.getAdjusted(block, 'AT');
        if (mode == 'GET') {
          var code = list + '[' + at + ']';
          return [code, Blockly.JavaScript.ORDER_MEMBER];
        } else if (mode == 'GET_REMOVE') {
          var code = list + '.splice(' + at + ', 1)[0]';
          return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
        } else if (mode == 'REMOVE') {
          return list + '.splice(' + at + ', 1);\n';
        }
        break;
      case ('FROM_END'):
        var at = Blockly.JavaScript.getAdjusted(block, 'AT', 1, true);
        if (mode == 'GET') {
          var code = list + '.slice(' + at + ')[0]';
          return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
        } else if (mode == 'GET_REMOVE') {
          var code = list + '.splice(' + at + ', 1)[0]';
          return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
        } else if (mode == 'REMOVE') {
          return list + '.splice(' + at + ', 1);';
        }
        break;
      case ('RANDOM'):
        var functionName = Blockly.JavaScript.provideFunction_(
            'listsGetRandomItem',
            ['function ' + Blockly.JavaScript.FUNCTION_NAME_PLACEHOLDER_ +
                '(list, remove) {',
             '  var x = Math.floor(Math.random() * list.length);',
             '  if (remove) {',
             '    return list.splice(x, 1)[0];',
             '  } else {',
             '    return list[x];',
             '  }',
             '}']);
        code = functionName + '(' + list + ', ' + (mode != 'GET') + ')';
        if (mode == 'GET' || mode == 'GET_REMOVE') {
          return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
        } else if (mode == 'REMOVE') {
          return code + ';\n';
        }
        break;
    }
    throw 'Unhandled combination (lists_getIndex).';
  };
  
  Blockly.JavaScript['lists_setIndex'] = function(block) {
    // Set element at index.
    // Note: Until February 2013 this block did not have MODE or WHERE inputs.
    var list = Blockly.JavaScript.valueToCode(block, 'LIST',
        Blockly.JavaScript.ORDER_MEMBER) || '[]';
    var mode = block.getFieldValue('MODE') || 'GET';
    var where = block.getFieldValue('WHERE') || 'FROM_START';
    var value = Blockly.JavaScript.valueToCode(block, 'TO',
        Blockly.JavaScript.ORDER_ASSIGNMENT) || 'null';
    // Cache non-trivial values to variables to prevent repeated look-ups.
    // Closure, which accesses and modifies 'list'.
    function cacheList() {
      if (list.match(/^\w+$/)) {
        return '';
      }
      var listVar = Blockly.JavaScript.variableDB_.getDistinctName(
          'tmpList', Blockly.Variables.NAME_TYPE);
      var code = 'var ' + listVar + ' = ' + list + ';\n';
      list = listVar;
      return code;
    }
    switch (where) {
      case ('FIRST'):
        if (mode == 'SET') {
          return list + '[0] = ' + value + ';\n';
        } else if (mode == 'INSERT') {
          return list + '.unshift(' + value + ');\n';
        }
        break;
      case ('LAST'):
        if (mode == 'SET') {
          var code = cacheList();
          code += list + '[' + list + '.length - 1] = ' + value + ';\n';
          return code;
        } else if (mode == 'INSERT') {
          return list + '.push(' + value + ');\n';
        }
        break;
      case ('FROM_START'):
        var at = Blockly.JavaScript.getAdjusted(block, 'AT');
        if (mode == 'SET') {
          return list + '[' + at + '] = ' + value + ';\n';
        } else if (mode == 'INSERT') {
          return list + '.splice(' + at + ', 0, ' + value + ');\n';
        }
        break;
      case ('FROM_END'):
        var at = Blockly.JavaScript.getAdjusted(block, 'AT', 1, false,
            Blockly.JavaScript.ORDER_SUBTRACTION);
        var code = cacheList();
        if (mode == 'SET') {
          code += list + '[' + list + '.length - ' + at + '] = ' + value + ';\n';
          return code;
        } else if (mode == 'INSERT') {
          code += list + '.splice(' + list + '.length - ' + at + ', 0, ' + value +
              ');\n';
          return code;
        }
        break;
      case ('RANDOM'):
        var code = cacheList();
        var xVar = Blockly.JavaScript.variableDB_.getDistinctName(
            'tmpX', Blockly.Variables.NAME_TYPE);
        code += 'var ' + xVar + ' = Math.floor(Math.random() * ' + list +
            '.length);\n';
        if (mode == 'SET') {
          code += list + '[' + xVar + '] = ' + value + ';\n';
          return code;
        } else if (mode == 'INSERT') {
          code += list + '.splice(' + xVar + ', 0, ' + value + ');\n';
          return code;
        }
        break;
    }
    throw 'Unhandled combination (lists_setIndex).';
  };
  
  /**
   * Returns an expression calculating the index into a list.
   * @private
   * @param {string} listName Name of the list, used to calculate length.
   * @param {string} where The method of indexing, selected by dropdown in Blockly
   * @param {string=} opt_at The optional offset when indexing from start/end.
   * @return {string} Index expression.
   */
  Blockly.JavaScript.lists.getIndex_ = function(listName, where, opt_at) {
    if (where == 'FIRST') {
      return '0';
    } else if (where == 'FROM_END') {
      return listName + '.length - 1 - ' + opt_at;
    } else if (where == 'LAST') {
      return listName + '.length - 1';
    } else {
      return opt_at;
    }
  };
  
  Blockly.JavaScript['lists_getSublist'] = function(block) {
    // Get sublist.
    var list = Blockly.JavaScript.valueToCode(block, 'LIST',
        Blockly.JavaScript.ORDER_MEMBER) || '[]';
    var where1 = block.getFieldValue('WHERE1');
    var where2 = block.getFieldValue('WHERE2');
    if (where1 == 'FIRST' && where2 == 'LAST') {
      var code = list + '.slice(0)';
    } else if (list.match(/^\w+$/) ||
        (where1 != 'FROM_END' && where2 == 'FROM_START')) {
      // If the list is a variable or doesn't require a call for length, don't
      // generate a helper function.
      switch (where1) {
        case 'FROM_START':
          var at1 = Blockly.JavaScript.getAdjusted(block, 'AT1');
          break;
        case 'FROM_END':
          var at1 = Blockly.JavaScript.getAdjusted(block, 'AT1', 1, false,
              Blockly.JavaScript.ORDER_SUBTRACTION);
          at1 = list + '.length - ' + at1;
          break;
        case 'FIRST':
          var at1 = '0';
          break;
        default:
          throw 'Unhandled option (lists_getSublist).';
      }
      switch (where2) {
        case 'FROM_START':
          var at2 = Blockly.JavaScript.getAdjusted(block, 'AT2', 1);
          break;
        case 'FROM_END':
          var at2 = Blockly.JavaScript.getAdjusted(block, 'AT2', 0, false,
              Blockly.JavaScript.ORDER_SUBTRACTION);
          at2 = list + '.length - ' + at2;
          break;
        case 'LAST':
          var at2 = list + '.length';
          break;
        default:
          throw 'Unhandled option (lists_getSublist).';
      }
      code = list + '.slice(' + at1 + ', ' + at2 + ')';
    } else {
      var at1 = Blockly.JavaScript.getAdjusted(block, 'AT1');
      var at2 = Blockly.JavaScript.getAdjusted(block, 'AT2');
      var getIndex_ = Blockly.JavaScript.lists.getIndex_;
      var wherePascalCase = {'FIRST': 'First', 'LAST': 'Last',
          'FROM_START': 'FromStart', 'FROM_END': 'FromEnd'};
      var functionName = Blockly.JavaScript.provideFunction_(
          'subsequence' + wherePascalCase[where1] + wherePascalCase[where2],
          ['function ' + Blockly.JavaScript.FUNCTION_NAME_PLACEHOLDER_ +
              '(sequence' +
              // The value for 'FROM_END' and'FROM_START' depends on `at` so
              // we add it as a parameter.
              ((where1 == 'FROM_END' || where1 == 'FROM_START') ? ', at1' : '') +
              ((where2 == 'FROM_END' || where2 == 'FROM_START') ? ', at2' : '') +
              ') {',
            '  var start = ' + getIndex_('sequence', where1, 'at1') + ';',
            '  var end = ' + getIndex_('sequence', where2, 'at2') + ' + 1;',
            '  return sequence.slice(start, end);',
            '}']);
      var code = functionName + '(' + list +
          // The value for 'FROM_END' and 'FROM_START' depends on `at` so we
          // pass it.
          ((where1 == 'FROM_END' || where1 == 'FROM_START') ? ', ' + at1 : '') +
          ((where2 == 'FROM_END' || where2 == 'FROM_START') ? ', ' + at2 : '') +
          ')';
    }
    return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
  };
  
  Blockly.JavaScript['lists_sort'] = function(block) {
    // Block for sorting a list.
    var list = Blockly.JavaScript.valueToCode(block, 'LIST',
        Blockly.JavaScript.ORDER_FUNCTION_CALL) || '[]';
    var direction = block.getFieldValue('DIRECTION') === '1' ? 1 : -1;
    var type = block.getFieldValue('TYPE');
    var getCompareFunctionName = Blockly.JavaScript.provideFunction_(
        'listsGetSortCompare',
        ['function ' + Blockly.JavaScript.FUNCTION_NAME_PLACEHOLDER_ +
            '(type, direction) {',
         '  var compareFuncs = {',
         '    "NUMERIC": function(a, b) {',
         '        return parseFloat(a) - parseFloat(b); },',
         '    "TEXT": function(a, b) {',
         '        return a.toString() > b.toString() ? 1 : -1; },',
         '    "IGNORE_CASE": function(a, b) {',
         '        return a.toString().toLowerCase() > ' +
            'b.toString().toLowerCase() ? 1 : -1; },',
         '  };',
         '  var compare = compareFuncs[type];',
         '  return function(a, b) { return compare(a, b) * direction; }',
         '}']);
    return [list + '.slice().sort(' +
        getCompareFunctionName + '("' + type + '", ' + direction + '))',
        Blockly.JavaScript.ORDER_FUNCTION_CALL];
  };
  
  Blockly.JavaScript['lists_split'] = function(block) {
    // Block for splitting text into a list, or joining a list into text.
    var input = Blockly.JavaScript.valueToCode(block, 'INPUT',
        Blockly.JavaScript.ORDER_MEMBER);
    var delimiter = Blockly.JavaScript.valueToCode(block, 'DELIM',
        Blockly.JavaScript.ORDER_NONE) || '\'\'';
    var mode = block.getFieldValue('MODE');
    if (mode == 'SPLIT') {
      if (!input) {
        input = '\'\'';
      }
      var functionName = 'split';
    } else if (mode == 'JOIN') {
      if (!input) {
        input = '[]';
      }
      var functionName = 'join';
    } else {
      throw 'Unknown mode: ' + mode;
    }
    var code = input + '.' + functionName + '(' + delimiter + ')';
    return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
  };
  
  Blockly.JavaScript['lists_reverse'] = function(block) {
    // Block for reversing a list.
    var list = Blockly.JavaScript.valueToCode(block, 'LIST',
        Blockly.JavaScript.ORDER_FUNCTION_CALL) || '[]';
    var code = list + '.slice().reverse()';
    return [code, Blockly.JavaScript.ORDER_FUNCTION_CALL];
  };

}