/*
 * Copyright 2014 Google 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.
 */
package com.google.gwt.lang;

import com.google.gwt.core.client.JavaScriptObject;

/**
 * This is an intrinsic class that contains helper methods for module startup.
 * <p>
 * This class should contain only static methods or fields.
 */
public final class ModuleUtils {
  /**
   * Module startup glue.
   * <p>
   * This function is responsible for calling the module entry points.
   * <p>
   * {@link ModuleUtils#gwtOnLoad} will have a global alias gwtOnLoad called
   * to startup the application.
   */
  public static native void gwtOnLoad(JavaScriptObject errFn, JavaScriptObject modName,
      JavaScriptObject modBase, JavaScriptObject softPermutationId) /*-{
    @ModuleUtils::ensureModuleInit()();
    var initFnList = @ModuleUtils::initFnList;
    $moduleName = modName;
    $moduleBase = modBase;
    @CollapsedPropertyHolder::permutationId = softPermutationId;

    function initializeModules() {
      for (var i = 0; i < initFnList.length; i++) {
        initFnList[i]();
      }
    }

    if (errFn) {
      try {
        $entry(initializeModules)();
      } catch(e) {
        errFn(modName, e);
      }
    } else {
      $entry(initializeModules)();
    }
  }-*/;

  /**
   * Adds entry points to call during gwtOnLoad, uses JS arguments.
   */
  public static native void addInitFunctions() /*-{
    @ModuleUtils::ensureModuleInit()();
    var initFnList = @ModuleUtils::initFnList;
    for (var i = 0;  i < arguments.length; i++) {
      initFnList.push(arguments[i]);
    }
  }-*/;

  public static native JavaScriptObject registerEntry() /*-{
    return @com.google.gwt.core.client.impl.Impl::registerEntry()();
  }-*/;

  public static native void setGwtProperty(String propertyName, JavaScriptObject propertyValue) /*-{
    // Access $gwt as a global object property so that it does not get optimized out when
    // using the closure backend.

    // The linker should create the $gwt variable. If not, do nothing.
    if (typeof(window) === "object" && typeof(window["$gwt"]) === "object") {
        window["$gwt"][propertyName] = propertyValue;
    }
  }-*/;

  private static native void ensureModuleInit() /*-{
    if (@ModuleUtils::initFnList == null ) {
      @ModuleUtils::initFnList = [];
    }
   }-*/;

  private static JavaScriptObject initFnList;

  private ModuleUtils() {
  }
}