text: /**
   * @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 Field.  Used for editable titles, variables, etc.
   * This is an abstract class that defines the UI on the block.  Actual
   * instances would be Blockly.FieldTextInput, Blockly.FieldDropdown, etc.
   * @author fraser@google.com (Neil Fraser)
   */
  'use strict';
  
  goog.provide('Blockly.Field');
  
  goog.require('Blockly.Events.BlockChange');
  goog.require('Blockly.Gesture');
  goog.require('Blockly.utils');
  
  goog.require('goog.math.Size');
  goog.require('goog.style');
  goog.require('goog.userAgent');
  
  
  /**
   * Abstract class for an editable field.
   * @param {string} text The initial content of the field.
   * @param {function(string):(string|null|undefined)=} opt_validator An optional
   *     function that is called to validate user input. See setValidator().
   * @constructor
   */
  Blockly.Field = function(text, opt_validator) {
    this.size_ = new goog.math.Size(0, Blockly.BlockSvg.MIN_BLOCK_Y);
    this.setValue(text);
    this.setValidator(opt_validator);
  };
  
  /**
   * The set of all registered fields, keyed by field type as used in the JSON
   * definition of a block.
   * @type {!Object<string, !{fromJson: Function}>}
   * @private
   */
  Blockly.Field.TYPE_MAP_ = {};
  
  /**
   * Registers a field type. May also override an existing field type.
   * Blockly.Field.fromJson uses this registry to find the appropriate field.
   * @param {string} type The field type name as used in the JSON definition.
   * @param {!{fromJson: Function}} fieldClass The field class containing a
   *     fromJson function that can construct an instance of the field.
   * @throws {Error} if the type name is empty, or the fieldClass is not an
   *     object containing a fromJson function.
   */
  Blockly.Field.register = function(type, fieldClass) {
    if ((typeof type != 'string') || (type.trim() == '')) {
      throw Error('Invalid field type "' + type + '"');
    }
    if (!fieldClass || (typeof fieldClass.fromJson != 'function')) {
      throw Error('Field "' + fieldClass + '" must have a fromJson function');
    }
    Blockly.Field.TYPE_MAP_[type] = fieldClass;
  };
  
  /**
   * Construct a Field from a JSON arg object.
   * Finds the appropriate registered field by the type name as registered using
   * Blockly.Field.register.
   * @param {!Object} options A JSON object with a type and options specific
   *     to the field type.
   * @return {Blockly.Field} The new field instance or null if a field wasn't
   *     found with the given type name
   * @package
   */
  Blockly.Field.fromJson = function(options) {
    var fieldClass = Blockly.Field.TYPE_MAP_[options['type']];
    if (fieldClass) {
      return fieldClass.fromJson(options);
    }
    return null;
  };
  
  /**
   * Temporary cache of text widths.
   * @type {Object}
   * @private
   */
  Blockly.Field.cacheWidths_ = null;
  
  /**
   * Number of current references to cache.
   * @type {number}
   * @private
   */
  Blockly.Field.cacheReference_ = 0;
  
  
  /**
   * Name of field.  Unique within each block.
   * Static labels are usually unnamed.
   * @type {string|undefined}
   */
  Blockly.Field.prototype.name = undefined;
  
  /**
   * Maximum characters of text to display before adding an ellipsis.
   * @type {number}
   */
  Blockly.Field.prototype.maxDisplayLength = 50;
  
  /**
   * Visible text to display.
   * @type {string}
   * @protected
   */
  Blockly.Field.prototype.text_ = '';
  
  /**
   * Block this field is attached to.  Starts as null, then set in init.
   * @type {Blockly.Block}
   * @protected
   */
  Blockly.Field.prototype.sourceBlock_ = null;
  
  /**
   * Does this block need to be re-rendered?
   * @type {boolean}
   * @private
   */
  Blockly.Field.prototype.isDirty_ = true;
  
  /**
   * Is the field visible, or hidden due to the block being collapsed?
   * @type {boolean}
   * @protected
   */
  Blockly.Field.prototype.visible_ = true;
  
  /**
   * Validation function called when user edits an editable field.
   * @type {Function}
   * @protected
   */
  Blockly.Field.prototype.validator_ = null;
  
  /**
   * The element the click handler is bound to.
   * @type {!Element}
   * @private
   */
  Blockly.Field.prototype.clickTarget_ = null;
  
  /**
   * Non-breaking space.
   * @const
   */
  Blockly.Field.NBSP = '\u00A0';
  
  /**
   * Editable fields usually show some sort of UI indicating they are editable.
   * They will also be saved by the XML renderer.
   * @type {boolean}
   * @const
   * @default
   */
  Blockly.Field.prototype.EDITABLE = true;
  
  /**
   * Serializable fields are saved by the XML renderer, non-serializable fields
   * are not. Editable fields should also be serializable. This is not the
   * case by default so that SERIALIZABLE is backwards compatible.
   * @type {boolean}
   * @const
   * @default
   */
  Blockly.Field.prototype.SERIALIZABLE = false;
  
  /**
   * Attach this field to a block.
   * @param {!Blockly.Block} block The block containing this field.
   */
  Blockly.Field.prototype.setSourceBlock = function(block) {
    if (this.sourceBlock_) {
      throw Error('Field already bound to a block.');
    }
    this.sourceBlock_ = block;
  };
  
  /**
   * Get the source block for this field.
   * @return {Blockly.Block} The source block, or null if there is none.
   */
  Blockly.Field.prototype.getSourceBlock = function() {
    return this.sourceBlock_;
  };
  
  /**
   * Install this field on a block.
   */
  Blockly.Field.prototype.init = function() {
    if (this.fieldGroup_) {
      // Field has already been initialized once.
      return;
    }
    // Build the DOM.
    this.fieldGroup_ = Blockly.utils.createSvgElement('g', {}, null);
    if (!this.visible_) {
      this.fieldGroup_.style.display = 'none';
    }
    this.borderRect_ = Blockly.utils.createSvgElement('rect',
        {
          'rx': 4,
          'ry': 4,
          'x': -Blockly.BlockSvg.SEP_SPACE_X / 2,
          'y': 0,
          'height': 16
        }, this.fieldGroup_);
    /** @type {!Element} */
    this.textElement_ = Blockly.utils.createSvgElement('text',
        {'class': 'blocklyText', 'y': this.size_.height - 12.5},
        this.fieldGroup_);
  
    this.updateEditable();
  
    this.clickTarget_ = this.getSvgRoot();
    this.sourceBlock_.getSvgRoot().appendChild(this.fieldGroup_);
    this.mouseDownWrapper_ =
        Blockly.bindEventWithChecks_(
            this.clickTarget_, 'mousedown', this, this.onMouseDown_);
  };
  
  /**
   * Initializes the model of the field after it has been installed on a block.
   * No-op by default.
   */
  Blockly.Field.prototype.initModel = function() {
  };
  
  /**
   * Sets the field's value based on the given XML element. Should only be
   * called by Blockly.Xml.
   * @param {!Element} fieldElement The element containing info about the
   *    field's state.
   * @package
   */
  Blockly.Field.prototype.fromXml = function(fieldElement) {
    this.setValue(fieldElement.textContent);
  };
  
  /**
   * Serializes this field's value to XML. Should only be called by Blockly.Xml.
   * @param {!Element} fieldElement The element to populate with info about the
   *    field's state.
   * @return {!Element} The element containing info about the field's state.
   * @package
   */
  Blockly.Field.prototype.toXml = function(fieldElement) {
    fieldElement.setAttribute('name', this.name);
    fieldElement.textContent = this.getValue();
    return fieldElement;
  };
  
  /**
   * Dispose of all DOM objects belonging to this editable field.
   */
  Blockly.Field.prototype.dispose = function() {
    if (this.mouseDownWrapper_) {
      Blockly.unbindEvent_(this.mouseDownWrapper_);
      this.mouseDownWrapper_ = null;
    }
    this.sourceBlock_ = null;
    if (this.fieldGroup_) {
      Blockly.utils.removeNode(this.fieldGroup_);
      this.fieldGroup_ = null;
    }
    this.textElement_ = null;
    this.borderRect_ = null;
    this.validator_ = null;
  };
  
  /**
   * Add or remove the UI indicating if this field is editable or not.
   */
  Blockly.Field.prototype.updateEditable = function() {
    var group = this.getClickTarget_();
    if (!this.EDITABLE || !group) {
      return;
    }
    if (this.sourceBlock_.isEditable()) {
      Blockly.utils.addClass(group, 'blocklyEditableText');
      Blockly.utils.removeClass(group, 'blocklyNonEditableText');
      group.style.cursor = this.CURSOR;
    } else {
      Blockly.utils.addClass(group, 'blocklyNonEditableText');
      Blockly.utils.removeClass(group, 'blocklyEditableText');
      group.style.cursor = '';
    }
  };
  
  /**
   * Check whether this field is currently editable.  Some fields are never
   * EDITABLE (e.g. text labels). Other fields may be EDITABLE but may exist on
   * non-editable blocks.
   * @return {boolean} Whether this field is editable and on an editable block
   */
  Blockly.Field.prototype.isCurrentlyEditable = function() {
    return this.EDITABLE && !!this.sourceBlock_ && this.sourceBlock_.isEditable();
  };
  
  /**
   * Check whether this field should be serialized by the XML renderer.
   * Handles the logic for backwards compatibility and incongruous states.
   * @return {boolean} Whether this field should be serialized or not.
   */
  Blockly.Field.prototype.isSerializable = function() {
    var isSerializable = false;
    if (this.name) {
      if (this.SERIALIZABLE) {
        isSerializable = true;
      } else if (this.EDITABLE) {
        console.warn('Detected an editable field that was not serializable.' +
          ' Please define SERIALIZABLE property as true on all editable custom' +
          ' fields. Proceeding with serialization.');
        isSerializable = true;
      }
    }
    return isSerializable;
  };
  
  /**
   * Gets whether this editable field is visible or not.
   * @return {boolean} True if visible.
   */
  Blockly.Field.prototype.isVisible = function() {
    return this.visible_;
  };
  
  /**
   * Sets whether this editable field is visible or not. Should only be called
   * by input.setVisible.
   * @param {boolean} visible True if visible.
   * @package
   */
  Blockly.Field.prototype.setVisible = function(visible) {
    if (this.visible_ == visible) {
      return;
    }
    this.visible_ = visible;
    var root = this.getSvgRoot();
    if (root) {
      root.style.display = visible ? 'block' : 'none';
      this.size_.width = 0;
    }
  };
  
  /**
   * Sets a new validation function for editable fields, or clears a previously
   * set validator.
   *
   * The validator function takes in the text form of the users input, and
   * optionally returns the accepted field text. Alternatively, if the function
   * returns null, the field value change aborts. If the function does not return
   * anything (or returns undefined), the input value is accepted as valid. This
   * is a shorthand for fields using the validator function call as a field-level
   * change event notification.
   *
   * @param {?function(string):(string|null|undefined)} handler The validator
   *     function or null to clear a previous validator.
   */
  Blockly.Field.prototype.setValidator = function(handler) {
    this.validator_ = handler;
  };
  
  /**
   * Gets the validation function for editable fields, or null if not set.
   * @return {Function} Validation function, or null.
   */
  Blockly.Field.prototype.getValidator = function() {
    return this.validator_;
  };
  
  /**
   * Validates a change.  Does nothing.  Subclasses may override this.
   * @param {string} text The user's text.
   * @return {string} No change needed.
   */
  Blockly.Field.prototype.classValidator = function(text) {
    return text;
  };
  
  /**
   * Calls the validation function for this field, as well as all the validation
   * function for the field's class and its parents.
   * @param {string} text Proposed text.
   * @return {?string} Revised text, or null if invalid.
   */
  Blockly.Field.prototype.callValidator = function(text) {
    var classResult = this.classValidator(text);
    if (classResult === null) {
      // Class validator rejects value.  Game over.
      return null;
    } else if (classResult !== undefined) {
      text = classResult;
    }
    var userValidator = this.getValidator();
    if (userValidator) {
      var userResult = userValidator.call(this, text);
      if (userResult === null) {
        // User validator rejects value.  Game over.
        return null;
      } else if (userResult !== undefined) {
        text = userResult;
      }
    }
    return text;
  };
  
  /**
   * Gets the group element for this editable field.
   * Used for measuring the size and for positioning.
   * @return {!Element} The group element.
   */
  Blockly.Field.prototype.getSvgRoot = function() {
    return /** @type {!Element} */ (this.fieldGroup_);
  };
  
  /**
   * Draws the border with the correct width.
   * Saves the computed width in a property.
   * @protected
   */
  Blockly.Field.prototype.render_ = function() {
    // Replace the text.
    this.textElement_.textContent = this.getDisplayText_();
    this.updateWidth();
    this.isDirty_ = false;
  };
  
  /**
   * Updates the width of the field. This calls getCachedWidth which won't cache
   * the approximated width on IE/Edge when `getComputedTextLength` fails. Once
   * it eventually does succeed, the result will be cached.
   */
  Blockly.Field.prototype.updateWidth = function() {
    var width = Blockly.Field.getCachedWidth(this.textElement_);
    if (this.borderRect_) {
      this.borderRect_.setAttribute('width',
          width + Blockly.BlockSvg.SEP_SPACE_X);
    }
    this.size_.width = width;
  };
  
  /**
   * Gets the width of a text element, caching it in the process.
   * @param {!Element} textElement An SVG 'text' element.
   * @return {number} Width of element.
   */
  Blockly.Field.getCachedWidth = function(textElement) {
    var key = textElement.textContent + '\n' + textElement.className.baseVal;
    var width;
  
    // Return the cached width if it exists.
    if (Blockly.Field.cacheWidths_) {
      width = Blockly.Field.cacheWidths_[key];
      if (width) {
        return width;
      }
    }
  
    // Attempt to compute fetch the width of the SVG text element.
    try {
      if (goog.userAgent.IE || goog.userAgent.EDGE) {
        width = textElement.getBBox().width;
      } else {
        width = textElement.getComputedTextLength();
      }
    } catch (e) {
      // In other cases where we fail to geth the computed text. Instead, use an
      // approximation and do not cache the result. At some later point in time
      // when the block is inserted into the visible DOM, this method will be
      // called again and, at that point in time, will not throw an exception.
      return textElement.textContent.length * 8;
    }
  
    // Cache the computed width and return.
    if (Blockly.Field.cacheWidths_) {
      Blockly.Field.cacheWidths_[key] = width;
    }
    return width;
  };
  
  /**
   * Start caching field widths.  Every call to this function MUST also call
   * stopCache.  Caches must not survive between execution threads.
   */
  Blockly.Field.startCache = function() {
    Blockly.Field.cacheReference_++;
    if (!Blockly.Field.cacheWidths_) {
      Blockly.Field.cacheWidths_ = {};
    }
  };
  
  /**
   * Stop caching field widths.  Unless caching was already on when the
   * corresponding call to startCache was made.
   */
  Blockly.Field.stopCache = function() {
    Blockly.Field.cacheReference_--;
    if (!Blockly.Field.cacheReference_) {
      Blockly.Field.cacheWidths_ = null;
    }
  };
  
  /**
   * Returns the height and width of the field.
   *
   * This should *in general* be the only place render_ gets called from.
   * @return {!goog.math.Size} Height and width.
   */
  Blockly.Field.prototype.getSize = function() {
    if (this.isDirty_) {
      this.render_();
    } else if (this.visible_ && this.size_.width == 0) {
      // If the field is not visible the width will be 0 as well, one of the
      // problems with the old system.
      console.warn('Deprecated use of setting size_.width to 0 to rerender a' +
        ' field. Set field.isDirty_ to true instead.');
      this.render_();
    }
    return this.size_;
  };
  
  /**
   * Returns the bounding box of the rendered field, accounting for workspace
   * scaling.
   * @return {!Object} An object with top, bottom, left, and right in pixels
   *     relative to the top left corner of the page (window coordinates).
   * @protected
   */
  Blockly.Field.prototype.getScaledBBox_ = function() {
    var bBox = this.borderRect_.getBBox();
    var scaledHeight = bBox.height * this.sourceBlock_.workspace.scale;
    var scaledWidth = bBox.width * this.sourceBlock_.workspace.scale;
    var xy = this.getAbsoluteXY_();
    return {
      top: xy.y,
      bottom: xy.y + scaledHeight,
      left: xy.x,
      right: xy.x + scaledWidth
    };
  };
  
  /**
   * Get the text from this field as displayed on screen.  May differ from getText
   * due to ellipsis, and other formatting.
   * @return {string} Currently displayed text.
   * @protected
   */
  Blockly.Field.prototype.getDisplayText_ = function() {
    var text = this.text_;
    if (!text) {
      // Prevent the field from disappearing if empty.
      return Blockly.Field.NBSP;
    }
    if (text.length > this.maxDisplayLength) {
      // Truncate displayed string and add an ellipsis ('...').
      text = text.substring(0, this.maxDisplayLength - 2) + '\u2026';
    }
    // Replace whitespace with non-breaking spaces so the text doesn't collapse.
    text = text.replace(/\s/g, Blockly.Field.NBSP);
    if (this.sourceBlock_.RTL) {
      // The SVG is LTR, force text to be RTL.
      text += '\u200F';
    }
    return text;
  };
  
  /**
   * Get the text from this field.
   * @return {string} Current text.
   */
  Blockly.Field.prototype.getText = function() {
    return this.text_;
  };
  
  /**
   * Set the text in this field.  Trigger a rerender of the source block.
   * @param {*} newText New text.
   */
  Blockly.Field.prototype.setText = function(newText) {
    if (newText === null) {
      // No change if null.
      return;
    }
    newText = String(newText);
    if (newText === this.text_) {
      // No change.
      return;
    }
    this.text_ = newText;
    this.forceRerender();
  };
  
  /**
   * Force a rerender of the block that this field is installed on, which will
   * rerender this field and adjust for any sizing changes.
   * Other fields on the same block will not rerender, because their sizes have
   * already been recorded.
   * @package
   */
  Blockly.Field.prototype.forceRerender = function() {
    this.isDirty_ = true;
    if (this.sourceBlock_ && this.sourceBlock_.rendered) {
      this.sourceBlock_.render();
      this.sourceBlock_.bumpNeighbours_();
    }
  };
  
  /**
   * By default there is no difference between the human-readable text and
   * the language-neutral values.  Subclasses (such as dropdown) may define this.
   * @return {string} Current value.
   */
  Blockly.Field.prototype.getValue = function() {
    return this.getText();
  };
  
  /**
   * By default there is no difference between the human-readable text and
   * the language-neutral values.  Subclasses (such as dropdown) may define this.
   * @param {string} newValue New value.
   */
  Blockly.Field.prototype.setValue = function(newValue) {
    if (newValue === null) {
      // No change if null.
      return;
    }
    // Validate input.
    var validated = this.callValidator(newValue);
    if (validated !== null) {
      newValue = validated;
    }
    // Check for change.
    var oldValue = this.getValue();
    if (oldValue == newValue) {
      return;
    }
    if (this.sourceBlock_ && Blockly.Events.isEnabled()) {
      Blockly.Events.fire(new Blockly.Events.BlockChange(
          this.sourceBlock_, 'field', this.name, oldValue, newValue));
    }
    this.setText(newValue);
  };
  
  /**
   * Handle a mouse down event on a field.
   * @param {!Event} e Mouse down event.
   * @protected
   */
  Blockly.Field.prototype.onMouseDown_ = function(e) {
    if (!this.sourceBlock_ || !this.sourceBlock_.workspace) {
      return;
    }
    var gesture = this.sourceBlock_.workspace.getGesture(e);
    if (gesture) {
      gesture.setStartField(this);
    }
  };
  
  /**
   * Change the tooltip text for this field.
   * @param {string|!Element} _newTip Text for tooltip or a parent element to
   *     link to for its tooltip.
   */
  Blockly.Field.prototype.setTooltip = function(_newTip) {
    // Non-abstract sub-classes may wish to implement this.  See FieldLabel.
  };
  
  /**
   * The element to bind the click handler to. If not set explicitly, defaults
   * to the SVG root of the field. When this element is
   * clicked on an editable field, the editor will open.
   * @return {!Element} Element to bind click handler to.
   * @private
   */
  Blockly.Field.prototype.getClickTarget_ = function() {
    return this.clickTarget_ || this.getSvgRoot();
  };
  
  /**
   * Return the absolute coordinates of the top-left corner of this field.
   * The origin (0,0) is the top-left corner of the page body.
   * @return {!goog.math.Coordinate} Object with .x and .y properties.
   * @private
   */
  Blockly.Field.prototype.getAbsoluteXY_ = function() {
    return goog.style.getPageOffset(this.borderRect_);
  };
  
  /**
   * Whether this field references any Blockly variables.  If true it may need to
   * be handled differently during serialization and deserialization.  Subclasses
   * may override this.
   * @return {boolean} True if this field has any variable references.
   * @package
   */
  Blockly.Field.prototype.referencesVariables = function() {
    return false;
  };
  
  /**
   * Search through the list of inputs and their fields in order to find the
   * parent input of a field.
   * @return {Blockly.Input} The input that the field belongs to.
   * @package
   */
  Blockly.Field.prototype.getParentInput = function() {
    var parentInput = null;
    var block = this.sourceBlock_;
    var inputs = block.inputList;
  
    for (var idx = 0; idx < block.inputList.length; idx++) {
      var input = inputs[idx];
      var fieldRows = input.fieldRow;
      for (var j = 0; j < fieldRows.length; j++) {
        if (fieldRows[j] === this) {
          parentInput = input;
          break;
        }
      }
    }
    return parentInput;
  };
  