/**
 * @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 Dropdown input field.  Used for editable titles and variables.
 * In the interests of a consistent UI, the toolbox shares some functions and
 * properties with the context menu.
 * @author fraser@google.com (Neil Fraser)
 */
'use strict';

goog.provide('Blockly.FieldDropdown');

goog.require('Blockly.Field');
goog.require('goog.dom');
goog.require('goog.events');
goog.require('goog.style');
goog.require('goog.ui.Menu');
goog.require('goog.ui.MenuItem');
goog.require('goog.userAgent');


/**
 * Class for an editable dropdown field.
 * @param {(!Array.<!Array>|!Function)} menuGenerator An array of options
 *     for a dropdown list, or a function which generates these options.
 * @param {Function=} opt_validator A function that is executed when a new
 *     option is selected, with the newly selected value as its sole argument.
 *     If it returns a value, that value (which must be one of the options) will
 *     become selected in place of the newly selected option, unless the return
 *     value is null, in which case the change is aborted.
 * @extends {Blockly.Field}
 * @constructor
 */
Blockly.FieldDropdown = function(menuGenerator, opt_validator) {
  this.menuGenerator_ = menuGenerator;
  this.trimOptions_();
  var firstTuple = this.getOptions_()[0];

  // Call parent's constructor.
  Blockly.FieldDropdown.superClass_.constructor.call(this, firstTuple[1],
      opt_validator);
};
goog.inherits(Blockly.FieldDropdown, Blockly.Field);

/**
 * Horizontal distance that a checkmark overhangs the dropdown.
 */
Blockly.FieldDropdown.CHECKMARK_OVERHANG = 25;

/**
 * Android can't (in 2014) display "▾", so use "▼" instead.
 */
Blockly.FieldDropdown.ARROW_CHAR = goog.userAgent.ANDROID ? '\u25BC' : '\u25BE';

/**
 * Mouse cursor style when over the hotspot that initiates the editor.
 */
Blockly.FieldDropdown.prototype.CURSOR = 'default';

/**
 * Language-neutral currently selected string or image object.
 * @type {string|!Object}
 * @private
 */
Blockly.FieldDropdown.prototype.value_ = '';

/**
 * SVG image element if currently selected option is an image, or null.
 * @type {SVGElement}
 * @private
 */
Blockly.FieldDropdown.prototype.imageElement_ = null;

/**
 * Object with src, height, width, and alt attributes if currently selected
 * option is an image, or null.
 * @type {Object}
 * @private
 */
Blockly.FieldDropdown.prototype.imageJson_ = null;

/**
 * Install this dropdown on a block.
 */
Blockly.FieldDropdown.prototype.init = function() {
  if (this.fieldGroup_) {
    // Dropdown has already been initialized once.
    return;
  }
  // Add dropdown arrow: "option ▾" (LTR) or "▾ אופציה" (RTL)
  this.arrow_ = Blockly.utils.createSvgElement('tspan', {}, null);
  this.arrow_.appendChild(document.createTextNode(this.sourceBlock_.RTL ?
      Blockly.FieldDropdown.ARROW_CHAR + ' ' :
      ' ' + Blockly.FieldDropdown.ARROW_CHAR));

  Blockly.FieldDropdown.superClass_.init.call(this);
  // Force a reset of the text to add the arrow.
  var text = this.text_;
  this.text_ = null;
  this.setText(text);
};

/**
 * Create a dropdown menu under the text.
 * @private
 */
Blockly.FieldDropdown.prototype.showEditor_ = function() {
  Blockly.WidgetDiv.show(this, this.sourceBlock_.RTL, null);
  var thisField = this;

  function callback(e) {
    var menu = this;
    var menuItem = e.target;
    if (menuItem) {
      thisField.onItemSelected(menu, menuItem);
    }
    Blockly.WidgetDiv.hideIfOwner(thisField);
    Blockly.Events.setGroup(false);
  }

  var menu = new goog.ui.Menu();
  menu.setRightToLeft(this.sourceBlock_.RTL);
  var options = this.getOptions_();
  for (var i = 0; i < options.length; i++) {
    var content = options[i][0]; // Human-readable text or image.
    var value = options[i][1];   // Language-neutral value.
    if (typeof content == 'object') {
      // An image, not text.
      var image = new Image(content['width'], content['height']);
      image.src = content['src'];
      image.alt = content['alt'] || '';
      content = image;
    }
    var menuItem = new goog.ui.MenuItem(content);
    menuItem.setRightToLeft(this.sourceBlock_.RTL);
    menuItem.setValue(value);
    menuItem.setCheckable(true);
    menu.addChild(menuItem, true);
    menuItem.setChecked(value == this.value_);
  }
  // Listen for mouse/keyboard events.
  goog.events.listen(menu, goog.ui.Component.EventType.ACTION, callback);
  // Listen for touch events (why doesn't Closure handle this already?).
  function callbackTouchStart(e) {
    var control = this.getOwnerControl(/** @type {Node} */ (e.target));
    // Highlight the menu item.
    control.handleMouseDown(e);
  }
  function callbackTouchEnd(e) {
    var control = this.getOwnerControl(/** @type {Node} */ (e.target));
    // Activate the menu item.
    control.performActionInternal(e);
  }
  menu.getHandler().listen(menu.getElement(), goog.events.EventType.TOUCHSTART,
                           callbackTouchStart);
  menu.getHandler().listen(menu.getElement(), goog.events.EventType.TOUCHEND,
                           callbackTouchEnd);

  // Record windowSize and scrollOffset before adding menu.
  var windowSize = goog.dom.getViewportSize();
  var scrollOffset = goog.style.getViewportPageOffset(document);
  var xy = this.getAbsoluteXY_();
  var borderBBox = this.getScaledBBox_();
  var div = Blockly.WidgetDiv.DIV;
  menu.render(div);
  var menuDom = menu.getElement();
  Blockly.utils.addClass(menuDom, 'blocklyDropdownMenu');
  // Record menuSize after adding menu.
  var menuSize = goog.style.getSize(menuDom);
  // Recalculate height for the total content, not only box height.
  menuSize.height = menuDom.scrollHeight;

  // Position the menu.
  // Flip menu vertically if off the bottom.
  if (xy.y + menuSize.height + borderBBox.height >=
      windowSize.height + scrollOffset.y) {
    xy.y -= menuSize.height + 2;
  } else {
    xy.y += borderBBox.height;
  }
  if (this.sourceBlock_.RTL) {
    xy.x += borderBBox.width;
    xy.x += Blockly.FieldDropdown.CHECKMARK_OVERHANG;
    // Don't go offscreen left.
    if (xy.x < scrollOffset.x + menuSize.width) {
      xy.x = scrollOffset.x + menuSize.width;
    }
  } else {
    xy.x -= Blockly.FieldDropdown.CHECKMARK_OVERHANG;
    // Don't go offscreen right.
    if (xy.x > windowSize.width + scrollOffset.x - menuSize.width) {
      xy.x = windowSize.width + scrollOffset.x - menuSize.width;
    }
  }
  Blockly.WidgetDiv.position(xy.x, xy.y, windowSize, scrollOffset,
                             this.sourceBlock_.RTL);
  menu.setAllowAutoFocus(true);
  menuDom.focus();
};

/**
 * Handle the selection of an item in the dropdown menu.
 * @param {!goog.ui.Menu} menu The Menu component clicked.
 * @param {!goog.ui.MenuItem} menuItem The MenuItem selected within menu.
 */
Blockly.FieldDropdown.prototype.onItemSelected = function(menu, menuItem) {
  var value = menuItem.getValue();
  if (this.sourceBlock_) {
    // Call any validation function, and allow it to override.
    value = this.callValidator(value);
  }
  if (value !== null) {
    this.setValue(value);
  }
}

/**
 * Factor out common words in statically defined options.
 * Create prefix and/or suffix labels.
 * @private
 */
Blockly.FieldDropdown.prototype.trimOptions_ = function() {
  this.prefixField = null;
  this.suffixField = null;
  var options = this.menuGenerator_;
  if (!goog.isArray(options) || options.length < 2) {
    return;
  }
  var strings = [];
  for (var i = 0; i < options.length; i++) {
    var text = options[i][0];
    if (typeof text != 'string') {
      return;  // No text splitting if there is an image in the list.
    }
    strings.push(text);
  }
  var shortest = Blockly.utils.shortestStringLength(strings);
  var prefixLength = Blockly.utils.commonWordPrefix(strings, shortest);
  var suffixLength = Blockly.utils.commonWordSuffix(strings, shortest);
  if (!prefixLength && !suffixLength) {
    return;
  }
  if (shortest <= prefixLength + suffixLength) {
    // One or more strings will entirely vanish if we proceed.  Abort.
    return;
  }
  if (prefixLength) {
    this.prefixField = strings[0].substring(0, prefixLength - 1);
  }
  if (suffixLength) {
    this.suffixField = strings[0].substr(1 - suffixLength);
  }
  // Remove the prefix and suffix from the options.
  var newOptions = [];
  for (var i = 0; i < options.length; i++) {
    var text = options[i][0];
    var value = options[i][1];
    text = text.substring(prefixLength, text.length - suffixLength);
    newOptions[i] = [text, value];
  }
  this.menuGenerator_ = newOptions;
};

/**
 * Return a list of the options for this dropdown.
 * @return {!Array.<!Array>} Array of option tuples:
 *     (human-readable text or image, language-neutral name).
 * @private
 */
Blockly.FieldDropdown.prototype.getOptions_ = function() {
  if (goog.isFunction(this.menuGenerator_)) {
    return this.menuGenerator_.call(this);
  }
  return /** @type {!Array.<!Array.<string>>} */ (this.menuGenerator_);
};

/**
 * Get the language-neutral value from this dropdown menu.
 * @return {string} Current text.
 */
Blockly.FieldDropdown.prototype.getValue = function() {
  return this.value_;
};

/**
 * Set the language-neutral value for this dropdown menu.
 * @param {string} newValue New value to set.
 */
Blockly.FieldDropdown.prototype.setValue = function(newValue) {
  if (newValue === null || newValue === this.value_) {
    return;  // No change if null.
  }
  if (this.sourceBlock_ && Blockly.Events.isEnabled()) {
    Blockly.Events.fire(new Blockly.Events.Change(
        this.sourceBlock_, 'field', this.name, this.value_, newValue));
  }
  this.value_ = newValue;
  // Look up and display the human-readable text.
  var options = this.getOptions_();
  for (var i = 0; i < options.length; i++) {
    // Options are tuples of human-readable text and language-neutral values.
    if (options[i][1] == newValue) {
      var content = options[i][0];
      if (typeof content == 'object') {
        this.imageJson_ = content;
        this.setText(content.alt);
      } else {
        this.imageJson_ = null;
        this.setText(content);
      }
      return;
    }
  }
  // Value not found.  Add it, maybe it will become valid once set
  // (like variable names).
  this.setText(newValue);
};

/**
 * Draws the border with the correct width.
 * @private
 */
Blockly.FieldDropdown.prototype.render_ = function() {
  if (!this.visible_) {
    this.size_.width = 0;
    return;
  }
  if (this.sourceBlock_ && this.arrow_) {
    // Update arrow's colour.
    this.arrow_.style.fill = this.sourceBlock_.getColour();
  }
  goog.dom.removeChildren(/** @type {!Element} */ (this.textElement_));
  goog.dom.removeNode(this.imageElement_);
  this.imageElement_ = null;

  if (this.imageJson_) {
    // Image option is selected.
    this.imageElement_ = Blockly.utils.createSvgElement('image',
        {'y': 5,
         'height': this.imageJson_.height + 'px',
         'width': this.imageJson_.width + 'px'}, this.fieldGroup_);
    this.imageElement_.setAttributeNS('http://www.w3.org/1999/xlink',
                                      'xlink:href', this.imageJson_.src);
    // Insert dropdown arrow.
    this.textElement_.appendChild(this.arrow_);
    var arrowWidth = Blockly.Field.getCachedWidth(this.arrow_);
    this.size_.height = Number(this.imageJson_.height) + 19;
    this.size_.width = Number(this.imageJson_.width) + arrowWidth;
    if (this.sourceBlock_.RTL) {
      this.imageElement_.setAttribute('x', arrowWidth);
      this.textElement_.setAttribute('x', -1);
    } else {
      this.textElement_.setAttribute('text-anchor', 'end');
      this.textElement_.setAttribute('x', this.size_.width + 1);
    }

  } else {
    // Text option is selected.
    // Replace the text.
    var textNode = document.createTextNode(this.getDisplayText_());
    this.textElement_.appendChild(textNode);
    // Insert dropdown arrow.
    if (this.sourceBlock_.RTL) {
      this.textElement_.insertBefore(this.arrow_, this.textElement_.firstChild);
    } else {
      this.textElement_.appendChild(this.arrow_);
    }
    this.textElement_.setAttribute('text-anchor', 'start');
    this.textElement_.setAttribute('x', 0);

    this.size_.height = Blockly.BlockSvg.MIN_BLOCK_Y;
    this.size_.width = Blockly.Field.getCachedWidth(this.textElement_);
  }
  this.borderRect_.setAttribute('height', this.size_.height - 9);
  this.borderRect_.setAttribute('width',
      this.size_.width + Blockly.BlockSvg.SEP_SPACE_X);
};

/**
 * Close the dropdown menu if this input is being deleted.
 */
Blockly.FieldDropdown.prototype.dispose = function() {
  Blockly.WidgetDiv.hideIfOwner(this);
  Blockly.FieldDropdown.superClass_.dispose.call(this);
};
