/**
 * Copyright 2016-present, 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 ReactComponentTreeDevtool
 */

'use strict';

var invariant = require('invariant');

var tree = {};
var unmountedIDs = {};
var rootIDs = {};

function updateTree(id, update) {
  if (!tree[id]) {
    tree[id] = {
      element: null,
      parentID: null,
      ownerID: null,
      text: null,
      childIDs: [],
      displayName: 'Unknown',
      isMounted: false,
      updateCount: 0,
    };
    // TODO: We need to do this awkward dance because TopLevelWrapper "never
    // gets mounted" but its display name gets set in instantiateReactComponent
    // before its debug ID is set to 0.
    unmountedIDs[id] = true;
  }
  update(tree[id]);
}

function purgeDeep(id) {
  var item = tree[id];
  if (item) {
    var {childIDs} = item;
    delete tree[id];
    childIDs.forEach(purgeDeep);
  }
}

var ReactComponentTreeDevtool = {
  onSetDisplayName(id, displayName) {
    updateTree(id, item => item.displayName = displayName);
  },

  onSetChildren(id, nextChildIDs) {
    updateTree(id, item => {
      var prevChildIDs = item.childIDs;
      item.childIDs = nextChildIDs;

      nextChildIDs.forEach(nextChildID => {
        var nextChild = tree[nextChildID];
        invariant(
          nextChild,
          'Expected devtool events to fire for the child ' +
          'before its parent includes it in onSetChildren().'
        );
        invariant(
          nextChild.displayName != null,
          'Expected onSetDisplayName() to fire for the child ' +
          'before its parent includes it in onSetChildren().'
        );
        invariant(
          nextChild.childIDs != null || nextChild.text != null,
          'Expected onSetChildren() or onSetText() to fire for the child ' +
          'before its parent includes it in onSetChildren().'
        );
        invariant(
          nextChild.isMounted,
          'Expected onMountComponent() to fire for the child ' +
          'before its parent includes it in onSetChildren().'
        );

        if (prevChildIDs.indexOf(nextChildID) === -1) {
          nextChild.parentID = id;
        }
      });
    });
  },

  onSetOwner(id, ownerID) {
    updateTree(id, item => item.ownerID = ownerID);
  },

  onSetText(id, text) {
    updateTree(id, item => item.text = text);
  },

  onBeforeMountComponent(id, element) {
    updateTree(id, item => item.element = element);
  },

  onBeforeUpdateComponent(id, element) {
    updateTree(id, item => item.element = element);
  },

  onMountComponent(id) {
    updateTree(id, item => item.isMounted = true);
    delete unmountedIDs[id];
  },

  onMountRootComponent(id) {
    rootIDs[id] = true;
  },

  onUpdateComponent(id) {
    updateTree(id, item => item.updateCount++);
  },

  onUnmountComponent(id) {
    updateTree(id, item => item.isMounted = false);
    unmountedIDs[id] = true;
    delete rootIDs[id];
  },

  purgeUnmountedComponents() {
    if (ReactComponentTreeDevtool._preventPurging) {
      // Should only be used for testing.
      return;
    }

    for (var id in unmountedIDs) {
      purgeDeep(id);
    }
    unmountedIDs = {};
  },

  isMounted(id) {
    var item = tree[id];
    return item ? item.isMounted : false;
  },

  getChildIDs(id) {
    var item = tree[id];
    return item ? item.childIDs : [];
  },

  getDisplayName(id) {
    var item = tree[id];
    return item ? item.displayName : 'Unknown';
  },

  getOwnerID(id) {
    var item = tree[id];
    return item ? item.ownerID : null;
  },

  getParentID(id) {
    var item = tree[id];
    return item ? item.parentID : null;
  },

  getSource(id) {
    var item = tree[id];
    var element = item ? item.element : null;
    var source = element != null ? element._source : null;
    return source;
  },

  getText(id) {
    var item = tree[id];
    return item ? item.text : null;
  },

  getUpdateCount(id) {
    var item = tree[id];
    return item ? item.updateCount : 0;
  },

  getRootIDs() {
    return Object.keys(rootIDs);
  },

  getRegisteredIDs() {
    return Object.keys(tree);
  },
};

module.exports = ReactComponentTreeDevtool;