/**
 * Copyright 2013-2014, 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 ReactCompositeComponent = require('ReactCompositeComponent');
var ReactElement = require('ReactElement');
var ReactDOM = require('ReactDOM');
var ReactUpdates = require('ReactUpdates');

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

// Store a reference to the <select> `ReactDOMComponent`. TODO: use string
var select = ReactElement.createFactory(ReactDOM.select.type);

function updateWithPendingValueIfMounted() {
  /*jshint validthis:true */
  if (this.isMounted()) {
    this.setState({value: this._pendingValue});
    this._pendingValue = 0;
  }
}

/**
 * Validation function for `value` and `defaultValue`.
 * @private
 */
function selectValueType(props, propName, componentName) {
  if (props[propName] == null) {
    return;
  }
  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.`
      );
    }
  }
}

/**
 * If `value` is supplied, updates <option> elements on mount and update.
 * @param {ReactComponent} component Instance of ReactDOMSelect
 * @param {?*} propValue For uncontrolled components, null/undefined. For
 * controlled components, a string (or with `multiple`, a list of strings).
 * @private
 */
function updateOptions(component, propValue) {
  var multiple = component.props.multiple;
  var value = propValue != null ? propValue : component.state.value;
  var options = component.getDOMNode().options;
  var selectedValue, i, l;
  if (multiple) {
    selectedValue = {};
    for (i = 0, l = value.length; i < l; ++i) {
      selectedValue['' + value[i]] = true;
    }
  } else {
    selectedValue = '' + value;
  }
  for (i = 0, l = options.length; i < l; i++) {
    var selected = multiple ?
      selectedValue.hasOwnProperty(options[i].value) :
      options[i].value === selectedValue;

    if (selected !== options[i].selected) {
      options[i].selected = selected;
    }
  }
}

/**
 * Implements a <select> native component that allows optionally setting the
 * props `value` and `defaultValue`. If `multiple` is false, the prop must be a
 * string. If `multiple` is true, the prop must be an array of strings.
 *
 * 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 = ReactCompositeComponent.createClass({
  displayName: 'ReactDOMSelect',

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

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

  getInitialState: function() {
    return {value: this.props.defaultValue || (this.props.multiple ? [] : '')};
  },

  componentWillMount: function() {
    this._pendingValue = null;
  },

  componentWillReceiveProps: function(nextProps) {
    if (!this.props.multiple && nextProps.multiple) {
      this.setState({value: [this.state.value]});
    } else if (this.props.multiple && !nextProps.multiple) {
      this.setState({value: this.state.value[0]});
    }
  },

  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);
  },

  componentDidMount: function() {
    updateOptions(this, LinkedValueUtils.getValue(this));
  },

  componentDidUpdate: function(prevProps) {
    var value = LinkedValueUtils.getValue(this);
    var prevMultiple = !!prevProps.multiple;
    var multiple = !!this.props.multiple;
    if (value != null || prevMultiple !== multiple) {
      updateOptions(this, value);
    }
  },

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

    var selectedValue;
    if (this.props.multiple) {
      selectedValue = [];
      var options = event.target.options;
      for (var i = 0, l = options.length; i < l; i++) {
        if (options[i].selected) {
          selectedValue.push(options[i].value);
        }
      }
    } else {
      selectedValue = event.target.value;
    }

    this._pendingValue = selectedValue;
    ReactUpdates.asap(updateWithPendingValueIfMounted, this);
    return returnValue;
  }

});

module.exports = ReactDOMSelect;
