var Hammer = require('../../../module/hammer');
var Item = require('./Item');
var RangeItem = require('./RangeItem');

/**
 * @constructor BackgroundItem
 * @extends Item
 * @param {Object} data             Object containing parameters start, end
 *                                  content, className.
 * @param {{toScreen: function, toTime: function}} conversion
 *                                  Conversion functions from time to screen and vice versa
 * @param {Object} [options]        Configuration options
 *                                  // TODO: describe options
 */
// TODO: implement support for the BackgroundItem just having a start, then being displayed as a sort of an annotation
function BackgroundItem (data, conversion, options) {
  this.props = {
    content: {
      width: 0
    }
  };
  this.overflow = false; // if contents can overflow (css styling), this flag is set to true

  // validate data
  if (data) {
    if (data.start == undefined) {
      throw new Error('Property "start" missing in item ' + data.id);
    }
    if (data.end == undefined) {
      throw new Error('Property "end" missing in item ' + data.id);
    }
  }

  Item.call(this, data, conversion, options);
}

BackgroundItem.prototype = new Item (null, null, null);

BackgroundItem.prototype.baseClassName = 'item background';

/**
 * Check whether this item is visible inside given range
 * @returns {{start: Number, end: Number}} range with a timestamp for start and end
 * @returns {boolean} True if visible
 */
BackgroundItem.prototype.isVisible = function(range) {
  // determine visibility
  return (this.data.start < range.end) && (this.data.end > range.start);
};

/**
 * Repaint the item
 */
BackgroundItem.prototype.redraw = function() {
  var dom = this.dom;
  if (!dom) {
    // create DOM
    this.dom = {};
    dom = this.dom;

      // background box
    dom.box = document.createElement('div');
    // className is updated in redraw()

    // contents box
    dom.content = document.createElement('div');
    dom.content.className = 'content';
    dom.box.appendChild(dom.content);

    // attach this item as attribute
    dom.box['timeline-item'] = this;

    this.dirty = true;
  }

  // append DOM to parent DOM
  if (!this.parent) {
    throw new Error('Cannot redraw item: no parent attached');
  }
  if (!dom.box.parentNode) {
    var background = this.parent.dom.background;
    if (!background) {
      throw new Error('Cannot redraw time axis: parent has no background container element');
    }
    background.appendChild(dom.box);
  }
  this.displayed = true;

  // Update DOM when item is marked dirty. An item is marked dirty when:
  // - the item is not yet rendered
  // - the item's data is changed
  // - the item is selected/deselected
  if (this.dirty) {
    this._updateContents(this.dom.content);
    this._updateTitle(this.dom.content);
    this._updateDataAttributes(this.dom.content);

    // update class
    var className = (this.data.className ? (' ' + this.data.className) : '') +
        (this.selected ? ' selected' : '');
    dom.box.className = this.baseClassName + className;

    // determine from css whether this box has overflow
    this.overflow = window.getComputedStyle(dom.content).overflow !== 'hidden';

    // recalculate size
    this.props.content.width = this.dom.content.offsetWidth;
    this.height = 0; // set height zero, so this item will be ignored when stacking items

    this.dirty = false;
  }
};

/**
 * Show the item in the DOM (when not already visible). The items DOM will
 * be created when needed.
 */
BackgroundItem.prototype.show = RangeItem.prototype.show;

/**
 * Hide the item from the DOM (when visible)
 * @return {Boolean} changed
 */
BackgroundItem.prototype.hide = RangeItem.prototype.hide;

/**
 * Reposition the item horizontally
 * @Override
 */
BackgroundItem.prototype.repositionX = RangeItem.prototype.repositionX;

/**
 * Reposition the item vertically
 * @Override
 */
BackgroundItem.prototype.repositionY = function() {
  var onTop = this.options.orientation === 'top';
  this.dom.content.style.top = onTop ? '' : '0';
  this.dom.content.style.bottom = onTop ? '0' : '';
};

module.exports = BackgroundItem;