using System.EnterpriseServices;
using System.Runtime.InteropServices;

namespace Microsoft.Win32.TaskScheduler
{
	/// <summary>
	/// Virtual base class for a COM-based Task Handler
	/// </summary>
	public abstract class TaskHandlerBase : ServicedComponent, ITaskHandler
	{
		public ITaskHandlerStatus StatusHandler { get; private set; }

		/// <summary>
		/// Called to start the COM handler.
		/// </summary>
		/// <param name="data">Data string passed in from Task Scheduler action.</param>
		public abstract void Start(string data);

		/// <summary>
		/// Called to stop the COM handler.
		/// </summary>
		/// <returns>The return code that the Task Schedule will raise as an event when the COM handler action is completed. Return 0 on success.</returns>
		public virtual int Stop() { return 0; }

		/// <summary>
		/// Called to pause the COM handler.
		/// </summary>
		public virtual void Pause() { }

		/// <summary>
		/// Called to resume the COM handler.
		/// </summary>
		public virtual void Resume() { }

		void ITaskHandler.Start(object pHandlerServices, string Data)
		{
			StatusHandler = pHandlerServices as ITaskHandlerStatus;
			Start(Data);
		}

		void ITaskHandler.Stop(out int pRetCode)
		{
			pRetCode = Stop();
		}

		void ITaskHandler.Pause()
		{
			Pause();
		}

		void ITaskHandler.Resume()
		{
			Resume();
		}
	}

	/// <summary>
	/// Defines the methods that are called by the Task Scheduler service to manage a COM handler.
	/// </summary>
	/// <remarks>
	/// This interface must be implemented for a task to perform a COM handler action. When the Task Scheduler performs a COM handler action, it creates and activates the handler and calls the methods of this interface as needed. For information on specifying a COM handler action, see the <see cref="ComHandlerAction"/> class.
	/// </remarks>
	[ComImport, Guid("839D7762-5121-4009-9234-4F0D19394F04"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), System.Security.SuppressUnmanagedCodeSecurity]
	public interface ITaskHandler
	{
		/// <summary>
		/// Called to start the COM handler. This method must be implemented by the handler.
		/// </summary>
		/// <param name="pHandlerServices">An <c>IUnkown</c> interface that is used to communicate back with the Task Scheduler.</param>
		/// <param name="Data">The arguments that are required by the handler. These arguments are defined in the <see cref="ComHandlerAction.Data"/> property of the COM handler action.</param>
		void Start([In, MarshalAs(UnmanagedType.IUnknown)] object pHandlerServices, [In, MarshalAs(UnmanagedType.BStr)] string Data);
		/// <summary>
		/// Called to stop the COM handler. This method must be implemented by the handler.
		/// </summary>
		/// <param name="pRetCode">The return code that the Task Schedule will raise as an event when the COM handler action is completed.</param>
		void Stop([MarshalAs(UnmanagedType.Error)] out int pRetCode);
		/// <summary>
		/// Called to pause the COM handler. This method is optional and should only be implemented to give the Task Scheduler the ability to pause and restart the handler.
		/// </summary>
		void Pause();
		/// <summary>
		/// Called to resume the COM handler. This method is optional and should only be implemented to give the Task Scheduler the ability to resume the handler.
		/// </summary>
		void Resume();
	}

	/// <summary>
	/// Provides the methods that are used by COM handlers to notify the Task Scheduler about the status of the handler.
	/// </summary>
	[ComImport, Guid("EAEC7A8F-27A0-4DDC-8675-14726A01A38A"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), System.Security.SuppressUnmanagedCodeSecurity]
	public interface ITaskHandlerStatus
	{
		/// <summary>
		/// Tells the Task Scheduler about the percentage of completion of the COM handler.
		/// </summary>
		/// <param name="percentComplete">A value that indicates the percentage of completion for the COM handler.</param>
		/// <param name="statusMessage">The message that is displayed in the Task Scheduler UI.</param>
		void UpdateStatus([In] short percentComplete, [In, MarshalAs(UnmanagedType.BStr)] string statusMessage);
		/// <summary>
		/// Tells the Task Scheduler that the COM handler is completed.
		/// </summary>
		/// <param name="taskErrCode">The error code that the Task Scheduler will raise as an event.</param>
		void TaskCompleted([In, MarshalAs(UnmanagedType.Error)] int taskErrCode);
	}
}