/**
 * @license
 * Visual Blocks Editor
 *
 * Copyright 2012 Google Inc.
 * https://developers.google.com/blockly/
 *
 * 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 Utility functions for handling variables.
 * @author fraser@google.com (Neil Fraser)
 */
'use strict';

goog.provide('Blockly.Variables');

goog.require('Blockly.Blocks');
goog.require('Blockly.Workspace');
goog.require('goog.string');


/**
 * Category to separate variable names from procedures and generated functions.
 */
Blockly.Variables.NAME_TYPE = 'VARIABLE';

/**
 * Find all user-created variables that are in use in the workspace.
 * For use by generators.
 * @param {!Blockly.Block|!Blockly.Workspace} root Root block or workspace.
 * @return {!Array.<string>} Array of variable names.
 */
Blockly.Variables.allUsedVariables = function(root) {
  var blocks;
  if (root instanceof Blockly.Block) {
    // Root is Block.
    blocks = root.getDescendants();
  } else if (root.getAllBlocks) {
    // Root is Workspace.
    blocks = root.getAllBlocks();
  } else {
    throw 'Not Block or Workspace: ' + root;
  }
  var variableHash = Object.create(null);
  // Iterate through every block and add each variable to the hash.
  for (var x = 0; x < blocks.length; x++) {
    var blockVariables = blocks[x].getVars();
    if (blockVariables) {
      for (var y = 0; y < blockVariables.length; y++) {
        var varName = blockVariables[y];
        // Variable name may be null if the block is only half-built.
        if (varName) {
          variableHash[varName.toLowerCase()] = varName;
        }
      }
    }
  }
  // Flatten the hash into a list.
  var variableList = [];
  for (var name in variableHash) {
    variableList.push(variableHash[name]);
  }
  return variableList;
};

/**
 * Find all variables that the user has created through the workspace or
 * toolbox.  For use by generators.
 * @param {!Blockly.Workspace} root The workspace to inspect.
 * @return {!Array.<string>} Array of variable names.
 */
Blockly.Variables.allVariables = function(root) {
  if (root instanceof Blockly.Block) {
    // Root is Block.
    console.warn('Deprecated call to Blockly.Variables.allVariables ' +
                 'with a block instead of a workspace.  You may want ' +
                 'Blockly.Variables.allUsedVariables');
  }
  return root.variableList;
};

/**
 * Construct the blocks required by the flyout for the variable category.
 * @param {!Blockly.Workspace} workspace The workspace contianing variables.
 * @return {!Array.<!Element>} Array of XML block elements.
 */
Blockly.Variables.flyoutCategory = function(workspace) {
  var variableList = workspace.variableList;
  variableList.sort(goog.string.caseInsensitiveCompare);

  var xmlList = [];
  var button = goog.dom.createDom('button');
  button.setAttribute('text', Blockly.Msg.NEW_VARIABLE);
  xmlList.push(button);

  if (variableList.length > 0) {
    if (Blockly.Blocks['variables_set']) {
      // <block type="variables_set" gap="20">
      //   <field name="VAR">item</field>
      // </block>
      var block = goog.dom.createDom('block');
      block.setAttribute('type', 'variables_set');
      if (Blockly.Blocks['math_change']) {
        block.setAttribute('gap', 8);
      } else {
        block.setAttribute('gap', 24);
      }
      var field = goog.dom.createDom('field', null, variableList[0]);
      field.setAttribute('name', 'VAR');
      block.appendChild(field);
      xmlList.push(block);
    }
    if (Blockly.Blocks['math_change']) {
      // <block type="math_change">
      //   <value name="DELTA">
      //     <shadow type="math_number">
      //       <field name="NUM">1</field>
      //     </shadow>
      //   </value>
      // </block>
      var block = goog.dom.createDom('block');
      block.setAttribute('type', 'math_change');
      if (Blockly.Blocks['variables_get']) {
        block.setAttribute('gap', 20);
      }
      var value = goog.dom.createDom('value');
      value.setAttribute('name', 'DELTA');
      block.appendChild(value);

      var field = goog.dom.createDom('field', null, variableList[0]);
      field.setAttribute('name', 'VAR');
      block.appendChild(field);

      var shadowBlock = goog.dom.createDom('shadow');
      shadowBlock.setAttribute('type', 'math_number');
      value.appendChild(shadowBlock);

      var numberField = goog.dom.createDom('field', null, '1');
      numberField.setAttribute('name', 'NUM');
      shadowBlock.appendChild(numberField);

      xmlList.push(block);
    }

    for (var i = 0; i < variableList.length; i++) {
      if (Blockly.Blocks['variables_get']) {
        // <block type="variables_get" gap="8">
        //   <field name="VAR">item</field>
        // </block>
        var block = goog.dom.createDom('block');
        block.setAttribute('type', 'variables_get');
        if (Blockly.Blocks['variables_set']) {
          block.setAttribute('gap', 8);
        }
        var field = goog.dom.createDom('field', null, variableList[i]);
        field.setAttribute('name', 'VAR');
        block.appendChild(field);
        xmlList.push(block);
      }
    }
  }
  return xmlList;
};

/**
* Return a new variable name that is not yet being used. This will try to
* generate single letter variable names in the range 'i' to 'z' to start with.
* If no unique name is located it will try 'i' to 'z', 'a' to 'h',
* then 'i2' to 'z2' etc.  Skip 'l'.
 * @param {!Blockly.Workspace} workspace The workspace to be unique in.
* @return {string} New variable name.
*/
Blockly.Variables.generateUniqueName = function(workspace) {
  var variableList = workspace.variableList;
  var newName = '';
  if (variableList.length) {
    var nameSuffix = 1;
    var letters = 'ijkmnopqrstuvwxyzabcdefgh';  // No 'l'.
    var letterIndex = 0;
    var potName = letters.charAt(letterIndex);
    while (!newName) {
      var inUse = false;
      for (var i = 0; i < variableList.length; i++) {
        if (variableList[i].toLowerCase() == potName) {
          // This potential name is already used.
          inUse = true;
          break;
        }
      }
      if (inUse) {
        // Try the next potential name.
        letterIndex++;
        if (letterIndex == letters.length) {
          // Reached the end of the character sequence so back to 'i'.
          // a new suffix.
          letterIndex = 0;
          nameSuffix++;
        }
        potName = letters.charAt(letterIndex);
        if (nameSuffix > 1) {
          potName += nameSuffix;
        }
      } else {
        // We can use the current potential name.
        newName = potName;
      }
    }
  } else {
    newName = 'i';
  }
  return newName;
};

/**
 * Create a new variable on the given workspace.
 * @param {!Blockly.Workspace} workspace The workspace on which to create the
 *     variable.
 * @return {null|undefined|string} An acceptable new variable name, or null if
 *     change is to be aborted (cancel button), or undefined if an existing
 *     variable was chosen.
 */
Blockly.Variables.createVariable = function(workspace) {
  while (true) {
    var text = Blockly.Variables.promptName(Blockly.Msg.NEW_VARIABLE_TITLE, '');
    if (text) {
      if (workspace.variableIndexOf(text) != -1) {
        window.alert(Blockly.Msg.VARIABLE_ALREADY_EXISTS.replace('%1',
            text.toLowerCase()));
      } else {
        workspace.createVariable(text);
        break;
      }
    } else {
      text = null;
      break;
    }
  }
  return text;
};

/**
 * Prompt the user for a new variable name.
 * @param {string} promptText The string of the prompt.
 * @param {string} defaultText The default value to show in the prompt's field.
 * @return {?string} The new variable name, or null if the user picked
 *     something illegal.
 */
Blockly.Variables.promptName = function(promptText, defaultText) {
  var newVar = window.prompt(promptText, defaultText);
  // Merge runs of whitespace.  Strip leading and trailing whitespace.
  // Beyond this, all names are legal.
  if (newVar) {
    newVar = newVar.replace(/[\s\xa0]+/g, ' ').replace(/^ | $/g, '');
    if (newVar == Blockly.Msg.RENAME_VARIABLE ||
        newVar == Blockly.Msg.NEW_VARIABLE) {
      // Ok, not ALL names are legal...
      newVar = null;
    }
  }
  return newVar;
};