C:/Private/OSS/n2cms/github/n2cms/src/Framework/N2/Context.cs

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#region License
/* Copyright (C) Cristian Libardo
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 */
#endregion

using System.Diagnostics;
using System.Runtime.CompilerServices;
using System;
using System.Configuration;
using System.Web.Configuration;
using System.Security;
using N2.Configuration;
using N2.Engine;
using N2.Engine.MediumTrust;
using System.IO;

namespace N2
{
    public class Context
    {
                #region Initialization Methods


                [MethodImpl(MethodImplOptions.Synchronized)]
                public static IEngine Initialize(bool forceRecreate)
                {
                        if (Singleton<IEngine>.Instance == null || forceRecreate)
                        {
                Debug.WriteLine("Constructing engine " + DateTime.Now);
                                Singleton<IEngine>.Instance = CreateEngineInstance();
                                Debug.WriteLine("Initializing engine " + DateTime.Now);
                                Singleton<IEngine>.Instance.Initialize();
                        }
                        return Singleton<IEngine>.Instance;
                }

                [Obsolete("Use Context.Replace(IEngine)", false)]
                public static void Initialize(IEngine engine)
                {
                        Singleton<IEngine>.Instance = engine;
                }

                public static void Replace(IEngine engine)
                {
                        Singleton<IEngine>.Instance = engine;
                }

        private static System.Configuration.Configuration GetConfiguration()
        {
            try
            {
                return System.Web.Hosting.HostingEnvironment.IsHosted
                    ? WebConfigurationManager.OpenWebConfiguration("~")
                    : ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            }
            catch (Exception ex)
            {
                Trace.TraceWarning("Error reading configuration. This has happened when running a web site project in a virtual directory (reason unknown). " + ex);
                return null;
            }
        }

                public static IEngine CreateEngineInstance()
                {
            try
            {
                                var config = ConfigurationManager.GetSection("n2/engine") as EngineSection;
                                if (config != null && !string.IsNullOrEmpty(config.EngineType))
                                {
                                        Type engineType = Type.GetType(config.EngineType);
                                        if(engineType == null)
                                                throw new ConfigurationErrorsException("The type '" + engineType + "' could not be found. Please check the configuration at /configuration/n2/engine[@engineType] or check for missing assemblies.");
                                        if(!typeof(IEngine).IsAssignableFrom(engineType))
                                                throw new ConfigurationErrorsException("The type '" + engineType + "' doesn't implement 'N2.Engines.IEngine' and cannot be configured in /configuration/n2/engine[@engineType] for that purpose.");
                                        return Activator.CreateInstance(engineType) as IEngine;
                                }

                                return new ContentEngine();
                        }
                        catch (SecurityException ex)
                        {
                                Trace.TraceInformation("Caught SecurityException, reverting to MediumTrustEngine. " + ex);
                                return new ContentEngine(new MediumTrustServiceContainer(), EventBroker.Instance, new ContainerConfigurer());
                        }
                        catch (Exception ex)
                        {
                                if (ex.GetType().Name != "ComponentActivatorException")
                                        throw;

                                Trace.TraceInformation("Caught ComponentActivatorException, reverting to MediumTrustEngine. " + ex);
                                return new ContentEngine(new MediumTrustServiceContainer(), EventBroker.Instance, new ContainerConfigurer());
                        }
                }

                #endregion

                #region Properties: Persister, Definitions, Integrity, UrlParser, CurrentPage

                public static IEngine Current
                {
                        get
                        {
                                if (Singleton<IEngine>.Instance == null)
                                {
                                        Initialize(false);
                                }
                                return Singleton<IEngine>.Instance;
                        }
                }

                public static Persistence.IPersister Persister
                {
                        get { return Current.Persister; }
                }

                public static Definitions.IDefinitionManager Definitions
                {
                        get { return Current.Definitions; }
                }
        
                public static Integrity.IIntegrityManager IntegrityManager
        {
                        get { return Current.IntegrityManager; }
        }

                public static Security.ISecurityManager SecurityManager
                {
                        get { return Current.SecurityManager; }
                }

                public static Web.IUrlParser UrlParser
                {
                        get { return Current.UrlParser; }
                }

        public static ContentItem CurrentPage
        {
            get { return Current.UrlParser.CurrentPage; }
        }
        #endregion
        }
}