/**
 * Copyright 2013-2014 Facebook, Inc.
 *
 * 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.
 *
 * @providesModule ReactMount
 */

"use strict";

var DOMProperty = require('DOMProperty');
var ReactEventEmitter = require('ReactEventEmitter');
var ReactInstanceHandles = require('ReactInstanceHandles');
var ReactPerf = require('ReactPerf');

var containsNode = require('containsNode');
var getReactRootElementInContainer = require('getReactRootElementInContainer');
var instantiateReactComponent = require('instantiateReactComponent');
var invariant = require('invariant');
var shouldUpdateReactComponent = require('shouldUpdateReactComponent');

var SEPARATOR = ReactInstanceHandles.SEPARATOR;

var ATTR_NAME = DOMProperty.ID_ATTRIBUTE_NAME;
var nodeCache = {};

var ELEMENT_NODE_TYPE = 1;
var DOC_NODE_TYPE = 9;

/** Mapping from reactRootID to React component instance. */
var instancesByReactRootID = {};

/** Mapping from reactRootID to `container` nodes. */
var containersByReactRootID = {};

if (__DEV__) {
  /** __DEV__-only mapping from reactRootID to root elements. */
  var rootElementsByReactRootID = {};
}

// Used to store breadth-first search state in findComponentRoot.
var findComponentRootReusableArray = [];

/**
 * @param {DOMElement} container DOM element that may contain a React component.
 * @return {?string} A "reactRoot" ID, if a React component is rendered.
 */
function getReactRootID(container) {
  var rootElement = getReactRootElementInContainer(container);
  return rootElement && ReactMount.getID(rootElement);
}

/**
 * Accessing node[ATTR_NAME] or calling getAttribute(ATTR_NAME) on a form
 * element can return its control whose name or ID equals ATTR_NAME. All
 * DOM nodes support `getAttributeNode` but this can also get called on
 * other objects so just return '' if we're given something other than a
 * DOM node (such as window).
 *
 * @param {?DOMElement|DOMWindow|DOMDocument|DOMTextNode} node DOM node.
 * @return {string} ID of the supplied `domNode`.
 */
function getID(node) {
  var id = internalGetID(node);
  if (id) {
    if (nodeCache.hasOwnProperty(id)) {
      var cached = nodeCache[id];
      if (cached !== node) {
        invariant(
          !isValid(cached, id),
          'ReactMount: Two valid but unequal nodes with the same `%s`: %s',
          ATTR_NAME, id
        );

        nodeCache[id] = node;
      }
    } else {
      nodeCache[id] = node;
    }
  }

  return id;
}

function internalGetID(node) {
  // If node is something like a window, document, or text node, none of
  // which support attributes or a .getAttribute method, gracefully return
  // the empty string, as if the attribute were missing.
  return node && node.getAttribute && node.getAttribute(ATTR_NAME) || '';
}

/**
 * Sets the React-specific ID of the given node.
 *
 * @param {DOMElement} node The DOM node whose ID will be set.
 * @param {string} id The value of the ID attribute.
 */
function setID(node, id) {
  var oldID = internalGetID(node);
  if (oldID !== id) {
    delete nodeCache[oldID];
  }
  node.setAttribute(ATTR_NAME, id);
  nodeCache[id] = node;
}

/**
 * Finds the node with the supplied React-generated DOM ID.
 *
 * @param {string} id A React-generated DOM ID.
 * @return {DOMElement} DOM node with the suppled `id`.
 * @internal
 */
function getNode(id) {
  if (!nodeCache.hasOwnProperty(id) || !isValid(nodeCache[id], id)) {
    nodeCache[id] = ReactMount.findReactNodeByID(id);
  }
  return nodeCache[id];
}

/**
 * A node is "valid" if it is contained by a currently mounted container.
 *
 * This means that the node does not have to be contained by a document in
 * order to be considered valid.
 *
 * @param {?DOMElement} node The candidate DOM node.
 * @param {string} id The expected ID of the node.
 * @return {boolean} Whether the node is contained by a mounted container.
 */
function isValid(node, id) {
  if (node) {
    invariant(
      internalGetID(node) === id,
      'ReactMount: Unexpected modification of `%s`',
      ATTR_NAME
    );

    var container = ReactMount.findReactContainerForID(id);
    if (container && containsNode(container, node)) {
      return true;
    }
  }

  return false;
}

/**
 * Causes the cache to forget about one React-specific ID.
 *
 * @param {string} id The ID to forget.
 */
function purgeID(id) {
  delete nodeCache[id];
}

var deepestNodeSoFar = null;
function findDeepestCachedAncestorImpl(ancestorID) {
  var ancestor = nodeCache[ancestorID];
  if (ancestor && isValid(ancestor, ancestorID)) {
    deepestNodeSoFar = ancestor;
  } else {
    // This node isn't populated in the cache, so presumably none of its
    // descendants are. Break out of the loop.
    return false;
  }
}

/**
 * Return the deepest cached node whose ID is a prefix of `targetID`.
 */
function findDeepestCachedAncestor(targetID) {
  deepestNodeSoFar = null;
  ReactInstanceHandles.traverseAncestors(
    targetID,
    findDeepestCachedAncestorImpl
  );

  var foundNode = deepestNodeSoFar;
  deepestNodeSoFar = null;
  return foundNode;
}

/**
 * Mounting is the process of initializing a React component by creatings its
 * representative DOM elements and inserting them into a supplied `container`.
 * Any prior content inside `container` is destroyed in the process.
 *
 *   ReactMount.renderComponent(
 *     component,
 *     document.getElementById('container')
 *   );
 *
 *   <div id="container">                   <-- Supplied `container`.
 *     <div data-reactid=".3">              <-- Rendered reactRoot of React
 *       // ...                                 component.
 *     </div>
 *   </div>
 *
 * Inside of `container`, the first element rendered is the "reactRoot".
 */
var ReactMount = {
  /** Time spent generating markup. */
  totalInstantiationTime: 0,

  /** Time spent inserting markup into the DOM. */
  totalInjectionTime: 0,

  /** Whether support for touch events should be initialized. */
  useTouchEvents: false,

  /** Exposed for debugging purposes **/
  _instancesByReactRootID: instancesByReactRootID,

  /**
   * This is a hook provided to support rendering React components while
   * ensuring that the apparent scroll position of its `container` does not
   * change.
   *
   * @param {DOMElement} container The `container` being rendered into.
   * @param {function} renderCallback This must be called once to do the render.
   */
  scrollMonitor: function(container, renderCallback) {
    renderCallback();
  },

  /**
   * Take a component that's already mounted into the DOM and replace its props
   * @param {ReactComponent} prevComponent component instance already in the DOM
   * @param {ReactComponent} nextComponent component instance to render
   * @param {DOMElement} container container to render into
   * @param {?function} callback function triggered on completion
   */
  _updateRootComponent: function(
      prevComponent,
      nextComponent,
      container,
      callback) {
    var nextProps = nextComponent.props;
    ReactMount.scrollMonitor(container, function() {
      prevComponent.replaceProps(nextProps, callback);
    });

    if (__DEV__) {
      // Record the root element in case it later gets transplanted.
      rootElementsByReactRootID[getReactRootID(container)] =
        getReactRootElementInContainer(container);
    }

    return prevComponent;
  },

  /**
   * Register a component into the instance map and starts scroll value
   * monitoring
   * @param {ReactComponent} nextComponent component instance to render
   * @param {DOMElement} container container to render into
   * @return {string} reactRoot ID prefix
   */
  _registerComponent: function(nextComponent, container) {
    invariant(
      container && (
        container.nodeType === ELEMENT_NODE_TYPE ||
        container.nodeType === DOC_NODE_TYPE
      ),
      '_registerComponent(...): Target container is not a DOM element.'
    );

    ReactEventEmitter.ensureScrollValueMonitoring();

    var reactRootID = ReactMount.registerContainer(container);
    instancesByReactRootID[reactRootID] = nextComponent;
    return reactRootID;
  },

  /**
   * Render a new component into the DOM.
   * @param {ReactComponent} nextComponent component instance to render
   * @param {DOMElement} container container to render into
   * @param {boolean} shouldReuseMarkup if we should skip the markup insertion
   * @return {ReactComponent} nextComponent
   */
  _renderNewRootComponent: ReactPerf.measure(
    'ReactMount',
    '_renderNewRootComponent',
    function(
        nextComponent,
        container,
        shouldReuseMarkup) {

      var componentInstance = instantiateReactComponent(nextComponent);
      var reactRootID = ReactMount._registerComponent(
        componentInstance,
        container
      );
      componentInstance.mountComponentIntoNode(
        reactRootID,
        container,
        shouldReuseMarkup
      );

      if (__DEV__) {
        // Record the root element in case it later gets transplanted.
        rootElementsByReactRootID[reactRootID] =
          getReactRootElementInContainer(container);
      }

      return componentInstance;
    }
  ),

  /**
   * Renders a React component into the DOM in the supplied `container`.
   *
   * If the React component was previously rendered into `container`, this will
   * perform an update on it and only mutate the DOM as necessary to reflect the
   * latest React component.
   *
   * @param {ReactComponent} nextComponent Component instance to render.
   * @param {DOMElement} container DOM element to render into.
   * @param {?function} callback function triggered on completion
   * @return {ReactComponent} Component instance rendered in `container`.
   */
  renderComponent: function(nextComponent, container, callback) {
    var prevComponent = instancesByReactRootID[getReactRootID(container)];

    if (prevComponent) {
      if (shouldUpdateReactComponent(prevComponent, nextComponent)) {
        return ReactMount._updateRootComponent(
          prevComponent,
          nextComponent,
          container,
          callback
        );
      } else {
        ReactMount.unmountComponentAtNode(container);
      }
    }

    var reactRootElement = getReactRootElementInContainer(container);
    var containerHasReactMarkup =
      reactRootElement && ReactMount.isRenderedByReact(reactRootElement);

    var shouldReuseMarkup = containerHasReactMarkup && !prevComponent;

    var component = ReactMount._renderNewRootComponent(
      nextComponent,
      container,
      shouldReuseMarkup
    );
    callback && callback.call(component);
    return component;
  },

  /**
   * Constructs a component instance of `constructor` with `initialProps` and
   * renders it into the supplied `container`.
   *
   * @param {function} constructor React component constructor.
   * @param {?object} props Initial props of the component instance.
   * @param {DOMElement} container DOM element to render into.
   * @return {ReactComponent} Component instance rendered in `container`.
   */
  constructAndRenderComponent: function(constructor, props, container) {
    return ReactMount.renderComponent(constructor(props), container);
  },

  /**
   * Constructs a component instance of `constructor` with `initialProps` and
   * renders it into a container node identified by supplied `id`.
   *
   * @param {function} componentConstructor React component constructor
   * @param {?object} props Initial props of the component instance.
   * @param {string} id ID of the DOM element to render into.
   * @return {ReactComponent} Component instance rendered in the container node.
   */
  constructAndRenderComponentByID: function(constructor, props, id) {
    var domNode = document.getElementById(id);
    invariant(
      domNode,
      'Tried to get element with id of "%s" but it is not present on the page.',
      id
    );
    return ReactMount.constructAndRenderComponent(constructor, props, domNode);
  },

  /**
   * Registers a container node into which React components will be rendered.
   * This also creates the "reactRoot" ID that will be assigned to the element
   * rendered within.
   *
   * @param {DOMElement} container DOM element to register as a container.
   * @return {string} The "reactRoot" ID of elements rendered within.
   */
  registerContainer: function(container) {
    var reactRootID = getReactRootID(container);
    if (reactRootID) {
      // If one exists, make sure it is a valid "reactRoot" ID.
      reactRootID = ReactInstanceHandles.getReactRootIDFromNodeID(reactRootID);
    }
    if (!reactRootID) {
      // No valid "reactRoot" ID found, create one.
      reactRootID = ReactInstanceHandles.createReactRootID();
    }
    containersByReactRootID[reactRootID] = container;
    return reactRootID;
  },

  /**
   * Unmounts and destroys the React component rendered in the `container`.
   *
   * @param {DOMElement} container DOM element containing a React component.
   * @return {boolean} True if a component was found in and unmounted from
   *                   `container`
   */
  unmountComponentAtNode: function(container) {
    var reactRootID = getReactRootID(container);
    var component = instancesByReactRootID[reactRootID];
    if (!component) {
      return false;
    }
    ReactMount.unmountComponentFromNode(component, container);
    delete instancesByReactRootID[reactRootID];
    delete containersByReactRootID[reactRootID];
    if (__DEV__) {
      delete rootElementsByReactRootID[reactRootID];
    }
    return true;
  },

  /**
   * Unmounts a component and removes it from the DOM.
   *
   * @param {ReactComponent} instance React component instance.
   * @param {DOMElement} container DOM element to unmount from.
   * @final
   * @internal
   * @see {ReactMount.unmountComponentAtNode}
   */
  unmountComponentFromNode: function(instance, container) {
    instance.unmountComponent();

    if (container.nodeType === DOC_NODE_TYPE) {
      container = container.documentElement;
    }

    // http://jsperf.com/emptying-a-node
    while (container.lastChild) {
      container.removeChild(container.lastChild);
    }
  },

  /**
   * Finds the container DOM element that contains React component to which the
   * supplied DOM `id` belongs.
   *
   * @param {string} id The ID of an element rendered by a React component.
   * @return {?DOMElement} DOM element that contains the `id`.
   */
  findReactContainerForID: function(id) {
    var reactRootID = ReactInstanceHandles.getReactRootIDFromNodeID(id);
    var container = containersByReactRootID[reactRootID];

    if (__DEV__) {
      var rootElement = rootElementsByReactRootID[reactRootID];
      if (rootElement && rootElement.parentNode !== container) {
        invariant(
          // Call internalGetID here because getID calls isValid which calls
          // findReactContainerForID (this function).
          internalGetID(rootElement) === reactRootID,
          'ReactMount: Root element ID differed from reactRootID.'
        );

        var containerChild = container.firstChild;
        if (containerChild &&
            reactRootID === internalGetID(containerChild)) {
          // If the container has a new child with the same ID as the old
          // root element, then rootElementsByReactRootID[reactRootID] is
          // just stale and needs to be updated. The case that deserves a
          // warning is when the container is empty.
          rootElementsByReactRootID[reactRootID] = containerChild;
        } else {
          console.warn(
            'ReactMount: Root element has been removed from its original ' +
            'container. New container:', rootElement.parentNode
          );
        }
      }
    }

    return container;
  },

  /**
   * Finds an element rendered by React with the supplied ID.
   *
   * @param {string} id ID of a DOM node in the React component.
   * @return {DOMElement} Root DOM node of the React component.
   */
  findReactNodeByID: function(id) {
    var reactRoot = ReactMount.findReactContainerForID(id);
    return ReactMount.findComponentRoot(reactRoot, id);
  },

  /**
   * True if the supplied `node` is rendered by React.
   *
   * @param {*} node DOM Element to check.
   * @return {boolean} True if the DOM Element appears to be rendered by React.
   * @internal
   */
  isRenderedByReact: function(node) {
    if (node.nodeType !== 1) {
      // Not a DOMElement, therefore not a React component
      return false;
    }
    var id = ReactMount.getID(node);
    return id ? id.charAt(0) === SEPARATOR : false;
  },

  /**
   * Traverses up the ancestors of the supplied node to find a node that is a
   * DOM representation of a React component.
   *
   * @param {*} node
   * @return {?DOMEventTarget}
   * @internal
   */
  getFirstReactDOM: function(node) {
    var current = node;
    while (current && current.parentNode !== current) {
      if (ReactMount.isRenderedByReact(current)) {
        return current;
      }
      current = current.parentNode;
    }
    return null;
  },

  /**
   * Finds a node with the supplied `targetID` inside of the supplied
   * `ancestorNode`.  Exploits the ID naming scheme to perform the search
   * quickly.
   *
   * @param {DOMEventTarget} ancestorNode Search from this root.
   * @pararm {string} targetID ID of the DOM representation of the component.
   * @return {DOMEventTarget} DOM node with the supplied `targetID`.
   * @internal
   */
  findComponentRoot: function(ancestorNode, targetID) {
    var firstChildren = findComponentRootReusableArray;
    var childIndex = 0;

    var deepestAncestor = findDeepestCachedAncestor(targetID) || ancestorNode;

    firstChildren[0] = deepestAncestor.firstChild;
    firstChildren.length = 1;

    while (childIndex < firstChildren.length) {
      var child = firstChildren[childIndex++];
      var targetChild;

      while (child) {
        var childID = ReactMount.getID(child);
        if (childID) {
          // Even if we find the node we're looking for, we finish looping
          // through its siblings to ensure they're cached so that we don't have
          // to revisit this node again. Otherwise, we make n^2 calls to getID
          // when visiting the many children of a single node in order.

          if (targetID === childID) {
            targetChild = child;
          } else if (ReactInstanceHandles.isAncestorIDOf(childID, targetID)) {
            // If we find a child whose ID is an ancestor of the given ID,
            // then we can be sure that we only want to search the subtree
            // rooted at this child, so we can throw out the rest of the
            // search state.
            firstChildren.length = childIndex = 0;
            firstChildren.push(child.firstChild);
          }

        } else {
          // If this child had no ID, then there's a chance that it was
          // injected automatically by the browser, as when a `<table>`
          // element sprouts an extra `<tbody>` child as a side effect of
          // `.innerHTML` parsing. Optimistically continue down this
          // branch, but not before examining the other siblings.
          firstChildren.push(child.firstChild);
        }

        child = child.nextSibling;
      }

      if (targetChild) {
        // Emptying firstChildren/findComponentRootReusableArray is
        // not necessary for correctness, but it helps the GC reclaim
        // any nodes that were left at the end of the search.
        firstChildren.length = 0;

        return targetChild;
      }
    }

    firstChildren.length = 0;

    invariant(
      false,
      'findComponentRoot(..., %s): Unable to find element. This probably ' +
      'means the DOM was unexpectedly mutated (e.g., by the browser), ' +
      'usually due to forgetting a <tbody> when using tables or nesting <p> ' +
      'or <a> tags. Try inspecting the child nodes of the element with React ' +
      'ID `%s`.',
      targetID,
      ReactMount.getID(ancestorNode)
    );
  },


  /**
   * React ID utilities.
   */

  getReactRootID: getReactRootID,

  getID: getID,

  setID: setID,

  getNode: getNode,

  purgeID: purgeID
};

module.exports = ReactMount;
