/**
 * Copyright 2013-2015, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactDOMSelect
 */

'use strict';

var AutoFocusMixin = require('AutoFocusMixin');
var LinkedValueUtils = require('LinkedValueUtils');
var ReactBrowserComponentMixin = require('ReactBrowserComponentMixin');
var ReactClass = require('ReactClass');
var ReactElement = require('ReactElement');
var ReactUpdates = require('ReactUpdates');

var assign = require('Object.assign');

var select = ReactElement.createFactory('select');

function updateOptionsIfPendingUpdateAndMounted() {
  /*jshint validthis:true */
  if (this._pendingUpdate) {
    this._pendingUpdate = false;
    var value = LinkedValueUtils.getValue(this);
    if (value != null && this.isMounted()) {
      updateOptions(this, value);
    }
  }
}

/**
 * Validation function for `value` and `defaultValue`.
 * @private
 */
function selectValueType(props, propName, componentName) {
  if (props[propName] == null) {
    return null;
  }
  if (props.multiple) {
    if (!Array.isArray(props[propName])) {
      return new Error(
        `The \`${propName}\` prop supplied to <select> must be an array if ` +
        `\`multiple\` is true.`
      );
    }
  } else {
    if (Array.isArray(props[propName])) {
      return new Error(
        `The \`${propName}\` prop supplied to <select> must be a scalar ` +
        `value if \`multiple\` is false.`
      );
    }
  }
}

/**
 * @param {ReactComponent} component Instance of ReactDOMSelect
 * @param {*} propValue A stringable (with `multiple`, a list of stringables).
 * @private
 */
function updateOptions(component, propValue) {
  var selectedValue, i, l;
  var options = component.getDOMNode().options;

  if (component.props.multiple) {
    selectedValue = {};
    for (i = 0, l = propValue.length; i < l; i++) {
      selectedValue['' + propValue[i]] = true;
    }
    for (i = 0, l = options.length; i < l; i++) {
      var selected = selectedValue.hasOwnProperty(options[i].value);
      if (options[i].selected !== selected) {
        options[i].selected = selected;
      }
    }
  } else {
    // Do not set `select.value` as exact behavior isn't consistent across all
    // browsers for all cases.
    selectedValue = '' + propValue;
    for (i = 0, l = options.length; i < l; i++) {
      if (options[i].value === selectedValue) {
        options[i].selected = true;
        return;
      }
    }
    if (options.length) {
      options[0].selected = true;
    }
  }
}

/**
 * Implements a <select> native component that allows optionally setting the
 * props `value` and `defaultValue`. If `multiple` is false, the prop must be a
 * stringable. If `multiple` is true, the prop must be an array of stringables.
 *
 * If `value` is not supplied (or null/undefined), user actions that change the
 * selected option will trigger updates to the rendered options.
 *
 * If it is supplied (and not null/undefined), the rendered options will not
 * update in response to user actions. Instead, the `value` prop must change in
 * order for the rendered options to update.
 *
 * If `defaultValue` is provided, any options with the supplied values will be
 * selected.
 */
var ReactDOMSelect = ReactClass.createClass({
  displayName: 'ReactDOMSelect',
  tagName: 'SELECT',

  mixins: [AutoFocusMixin, LinkedValueUtils.Mixin, ReactBrowserComponentMixin],

  propTypes: {
    defaultValue: selectValueType,
    value: selectValueType
  },

  render: function() {
    // Clone `this.props` so we don't mutate the input.
    var props = assign({}, this.props);

    props.onChange = this._handleChange;
    props.value = null;

    return select(props, this.props.children);
  },

  componentWillMount: function() {
    this._pendingUpdate = false;
  },

  componentDidMount: function() {
    var value = LinkedValueUtils.getValue(this);
    if (value != null) {
      updateOptions(this, value);
    } else if (this.props.defaultValue != null) {
      updateOptions(this, this.props.defaultValue);
    }
  },

  componentDidUpdate: function(prevProps) {
    var value = LinkedValueUtils.getValue(this);
    if (value != null) {
      this._pendingUpdate = false;
      updateOptions(this, value);
    } else if (!prevProps.multiple !== !this.props.multiple) {
      // For simplicity, reapply `defaultValue` if `multiple` is toggled.
      if (this.props.defaultValue != null) {
        updateOptions(this, this.props.defaultValue);
      } else {
        // Revert the select back to its default unselected state.
        updateOptions(this, this.props.multiple ? [] : '');
      }
    }
  },

  _handleChange: function(event) {
    var returnValue;
    var onChange = LinkedValueUtils.getOnChange(this);
    if (onChange) {
      returnValue = onChange.call(this, event);
    }

    this._pendingUpdate = true;
    ReactUpdates.asap(updateOptionsIfPendingUpdateAndMounted, this);
    return returnValue;
  }

});

module.exports = ReactDOMSelect;
