using System;
using System.Collections.Generic;
using System.Text;
using ScrewTurn.Wiki.PluginFramework;

namespace ScrewTurn.Wiki {

	/// <summary>
	/// Contains instances of the Providers Collectors.
	/// </summary>
	public static class Collectors {

		// The following static instances are "almost" thread-safe because they are set at startup and never changed
		// The ProviderCollector generic class is fully thread-safe

		/// <summary>
		/// Contains the file names of the DLLs containing each provider (provider->file).
		/// </summary>
		public static Dictionary<string, string> FileNames;

		/// <summary>
		/// The settings storage provider.
		/// </summary>
		public static ISettingsStorageProviderV30 SettingsProvider;

		/// <summary>
		/// The Users Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IUsersStorageProviderV30> UsersProviderCollector;

		/// <summary>
		/// The Pages Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IPagesStorageProviderV30> PagesProviderCollector;

		/// <summary>
		/// The Files Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IFilesStorageProviderV30> FilesProviderCollector;

		/// <summary>
		/// The Formatter Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IFormatterProviderV30> FormatterProviderCollector;

		/// <summary>
		/// The Cache Provider Collector instance.
		/// </summary>
		public static ProviderCollector<ICacheProviderV30> CacheProviderCollector;

		/// <summary>
		/// The Disabled Users Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IUsersStorageProviderV30> DisabledUsersProviderCollector;

		/// <summary>
		/// The Disabled Files Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IFilesStorageProviderV30> DisabledFilesProviderCollector;

		/// <summary>
		/// The Disabled Pages Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IPagesStorageProviderV30> DisabledPagesProviderCollector;

		/// <summary>
		/// The Disabled Formatter Provider Collector instance.
		/// </summary>
		public static ProviderCollector<IFormatterProviderV30> DisabledFormatterProviderCollector;

		/// <summary>
		/// The Disabled Cache Provider Collector instance.
		/// </summary>
		public static ProviderCollector<ICacheProviderV30> DisabledCacheProviderCollector;

		/// <summary>
		/// Finds a provider.
		/// </summary>
		/// <param name="typeName">The provider type name.</param>
		/// <param name="enabled">A value indicating whether the provider is enabled.</param>
		/// <param name="canDisable">A value indicating whether the provider can be disabled.</param>
		/// <returns>The provider, or <c>null</c>.</returns>
		public static IProviderV30 FindProvider(string typeName, out bool enabled, out bool canDisable) {
			enabled = true;
			canDisable = true;
			IProviderV30 prov = null;

			prov = PagesProviderCollector.GetProvider(typeName);
			canDisable = typeName != Settings.DefaultPagesProvider;
			if(prov == null) {
				prov = DisabledPagesProviderCollector.GetProvider(typeName);
				if(prov != null) enabled = false;
			}
			if(prov != null) return prov;

			prov = UsersProviderCollector.GetProvider(typeName);
			canDisable = typeName != Settings.DefaultUsersProvider;
			if(prov == null) {
				prov = DisabledUsersProviderCollector.GetProvider(typeName);
				if(prov != null) enabled = false;
			}
			if(prov != null) return prov;

			prov = FilesProviderCollector.GetProvider(typeName);
			canDisable = typeName != Settings.DefaultFilesProvider;
			if(prov == null) {
				prov = DisabledFilesProviderCollector.GetProvider(typeName);
				if(prov != null) enabled = false;
			}
			if(prov != null) return prov;

			prov = CacheProviderCollector.GetProvider(typeName);
			canDisable = typeName != Settings.DefaultCacheProvider;
			if(prov == null) {
				prov = DisabledCacheProviderCollector.GetProvider(typeName);
				if(prov != null) enabled = false;
			}
			if(prov != null) return prov;

			prov = FormatterProviderCollector.GetProvider(typeName);
			if(prov == null) {
				prov = DisabledFormatterProviderCollector.GetProvider(typeName);
				if(prov != null) enabled = false;
			}
			if(prov != null) return prov;
			
			return null;
		}

		/// <summary>
		/// Tries to unload a provider.
		/// </summary>
		/// <param name="typeName">The provider.</param>
		public static void TryUnload(string typeName) {
			bool enabled, canDisable;
			IProviderV30 prov = FindProvider(typeName, out enabled, out canDisable);

			PagesProviderCollector.RemoveProvider(prov as IPagesStorageProviderV30);
			DisabledPagesProviderCollector.RemoveProvider(prov as IPagesStorageProviderV30);

			UsersProviderCollector.RemoveProvider(prov as IUsersStorageProviderV30);
			DisabledUsersProviderCollector.RemoveProvider(prov as IUsersStorageProviderV30);

			FilesProviderCollector.RemoveProvider(prov as IFilesStorageProviderV30);
			DisabledFilesProviderCollector.RemoveProvider(prov as IFilesStorageProviderV30);

			CacheProviderCollector.RemoveProvider(prov as ICacheProviderV30);
			DisabledCacheProviderCollector.RemoveProvider(prov as ICacheProviderV30);

			FormatterProviderCollector.RemoveProvider(prov as IFormatterProviderV30);
			DisabledFormatterProviderCollector.RemoveProvider(prov as IFormatterProviderV30);
		}

		/// <summary>
		/// Tries to disable a provider.
		/// </summary>
		/// <param name="typeName">The provider.</param>
		public static void TryDisable(string typeName) {
			IProviderV30 prov = null;

			prov = PagesProviderCollector.GetProvider(typeName);
			if(prov != null) {
				DisabledPagesProviderCollector.AddProvider((IPagesStorageProviderV30)prov);
				PagesProviderCollector.RemoveProvider((IPagesStorageProviderV30)prov);
				return;
			}

			prov = UsersProviderCollector.GetProvider(typeName);
			if(prov != null) {
				DisabledUsersProviderCollector.AddProvider((IUsersStorageProviderV30)prov);
				UsersProviderCollector.RemoveProvider((IUsersStorageProviderV30)prov);
				return;
			}

			prov = FilesProviderCollector.GetProvider(typeName);
			if(prov != null) {
				DisabledFilesProviderCollector.AddProvider((IFilesStorageProviderV30)prov);
				FilesProviderCollector.RemoveProvider((IFilesStorageProviderV30)prov);
				return;
			}

			prov = CacheProviderCollector.GetProvider(typeName);
			if(prov != null) {
				DisabledCacheProviderCollector.AddProvider((ICacheProviderV30)prov);
				CacheProviderCollector.RemoveProvider((ICacheProviderV30)prov);
				return;
			}

			prov = FormatterProviderCollector.GetProvider(typeName);
			if(prov != null) {
				DisabledFormatterProviderCollector.AddProvider((IFormatterProviderV30)prov);
				FormatterProviderCollector.RemoveProvider((IFormatterProviderV30)prov);
				return;
			}
		}

		/// <summary>
		/// Tries to enable a provider.
		/// </summary>
		/// <param name="typeName">The provider.</param>
		public static void TryEnable(string typeName) {
			IProviderV30 prov = null;

			prov = DisabledPagesProviderCollector.GetProvider(typeName);
			if(prov != null) {
				PagesProviderCollector.AddProvider((IPagesStorageProviderV30)prov);
				DisabledPagesProviderCollector.RemoveProvider((IPagesStorageProviderV30)prov);
				return;
			}

			prov = DisabledUsersProviderCollector.GetProvider(typeName);
			if(prov != null) {
				UsersProviderCollector.AddProvider((IUsersStorageProviderV30)prov);
				DisabledUsersProviderCollector.RemoveProvider((IUsersStorageProviderV30)prov);
				return;
			}

			prov = DisabledFilesProviderCollector.GetProvider(typeName);
			if(prov != null) {
				FilesProviderCollector.AddProvider((IFilesStorageProviderV30)prov);
				DisabledFilesProviderCollector.RemoveProvider((IFilesStorageProviderV30)prov);
				return;
			}

			prov = DisabledCacheProviderCollector.GetProvider(typeName);
			if(prov != null) {
				CacheProviderCollector.AddProvider((ICacheProviderV30)prov);
				DisabledCacheProviderCollector.RemoveProvider((ICacheProviderV30)prov);
				return;
			}

			prov = DisabledFormatterProviderCollector.GetProvider(typeName);
			if(prov != null) {
				FormatterProviderCollector.AddProvider((IFormatterProviderV30)prov);
				DisabledFormatterProviderCollector.RemoveProvider((IFormatterProviderV30)prov);
				return;
			}
		}

		/// <summary>
		/// Gets the names of all known providers, both enabled and disabled.
		/// </summary>
		/// <returns>The names of the known providers.</returns>
		public static string[] GetAllProviders() {
			List<string> result = new List<string>(20);

			foreach(IProviderV30 prov in PagesProviderCollector.AllProviders) result.Add(prov.GetType().FullName);
			foreach(IProviderV30 prov in DisabledPagesProviderCollector.AllProviders) result.Add(prov.GetType().FullName);

			foreach(IProviderV30 prov in UsersProviderCollector.AllProviders) result.Add(prov.GetType().FullName);
			foreach(IProviderV30 prov in DisabledUsersProviderCollector.AllProviders) result.Add(prov.GetType().FullName);

			foreach(IProviderV30 prov in FilesProviderCollector.AllProviders) result.Add(prov.GetType().FullName);
			foreach(IProviderV30 prov in DisabledFilesProviderCollector.AllProviders) result.Add(prov.GetType().FullName);

			foreach(IProviderV30 prov in CacheProviderCollector.AllProviders) result.Add(prov.GetType().FullName);
			foreach(IProviderV30 prov in DisabledCacheProviderCollector.AllProviders) result.Add(prov.GetType().FullName);

			foreach(IProviderV30 prov in FormatterProviderCollector.AllProviders) result.Add(prov.GetType().FullName);
			foreach(IProviderV30 prov in DisabledFormatterProviderCollector.AllProviders) result.Add(prov.GetType().FullName);

			return result.ToArray();
		}

	}

}