// <file>
//     <copyright see="prj:///doc/copyright.txt"/>
//     <license see="prj:///doc/license.txt"/>
//     <owner name="David Srbecký" email="dsrbecky@gmail.com"/>
//     <version>$Revision: 2903 $</version>
// </file>

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Threading;
using System.Windows.Forms;

namespace Debugger.Interop
{
    public delegate T MethodInvokerWithReturnValue<out T>();

    public enum CallMethod
    {
        DirectCall,
        Manual,
        HiddenForm,
        HiddenFormWithTimeout
    };

    public class MTA2STA
    {
        private readonly Form hiddenForm;

        private readonly Thread targetThread;
        private CallMethod callMethod = CallMethod.HiddenFormWithTimeout;

        private readonly Queue<MethodInvoker> pendingCalls = new Queue<MethodInvoker>();
        private readonly ManualResetEvent pendingCallsNotEmpty = new ManualResetEvent(false);

        private WaitHandle EnqueueCall(MethodInvoker callDelegate)
        {
            lock (pendingCalls)
            {
                ManualResetEvent callDone = new ManualResetEvent(false);

                pendingCalls.Enqueue(() =>
                {
                    callDelegate();
                    callDone.Set();
                });

                pendingCallsNotEmpty.Set();
                return callDone;
            }
        }

        /// <summary>
        /// Wait until a call a made
        /// </summary>
        public void WaitForCall()
        {
            pendingCallsNotEmpty.WaitOne();
        }

        public void WaitForCall(TimeSpan timeout)
        {
            pendingCallsNotEmpty.WaitOne(timeout, false);
        }

        /// <summary>
        /// Performs all waiting calls on the current thread
        /// </summary>
        public void PerformAllCalls()
        {
            while (true)
            {
                if (!PerformCall())
                {
                    return;
                }
            }
        }

        /// <summary>
        /// Performs all waiting calls on the current thread
        /// </summary>
        public bool PerformCall()
        {
            MethodInvoker nextMethod;
            lock (pendingCalls)
            {
                if (pendingCalls.Count > 0)
                {
                    nextMethod = pendingCalls.Dequeue();
                }
                else
                {
                    pendingCallsNotEmpty.Reset();
                    return false;
                }
            }
            nextMethod();
            return true;
        }

        public CallMethod CallMethod
        {
            get { return callMethod; }
            set { callMethod = value; }
        }

        public MTA2STA()
        {
            targetThread = Thread.CurrentThread;

            hiddenForm = new Form();
            // Force handle creation
        }

        /// <summary>
        /// SoftWait waits for any of the given WaitHandles and allows processing of calls during the wait
        /// </summary>
        public int SoftWait(params WaitHandle[] waitFor)
        {
            List<WaitHandle> waits = new List<WaitHandle>(waitFor)
            {
                this.pendingCallsNotEmpty
            };

            while (true)
            {
                int i = WaitHandle.WaitAny(waits.ToArray());

                PerformAllCalls();

                if (i < waits.Count - 1)
                {
                    // If not pendingCallsNotEmpty
                    return i;
                }
            }
        }

        /// <summary>
        /// Schedules invocation of method and returns immediately
        /// </summary>
        public WaitHandle AsyncCall(MethodInvoker callDelegate)
        {
            WaitHandle callDone = EnqueueCall(callDelegate);
            TriggerInvoke();
            return callDone;
        }

        public T Call<T>(MethodInvokerWithReturnValue<T> callDelegate)
        {
            T returnValue = default(T);
            Call(delegate { returnValue = callDelegate(); }, true);
            return returnValue;
        }

        public void Call(MethodInvoker callDelegate)
        {
            Call(callDelegate, false);
        }

        private void Call(MethodInvoker callDelegate, bool hasReturnValue)
        {
            // Enqueue the call
            WaitHandle callDone = EnqueueCall(callDelegate);

            if (targetThread == Thread.CurrentThread)
            {
                PerformAllCalls();
                return;
            }

            // We have the call waiting in queue, we need to call it (not waiting for it to finish)
            TriggerInvoke();

            // Wait for the call to finish
            if (!hasReturnValue && callMethod == CallMethod.HiddenFormWithTimeout)
            {
                // Give it 5 seconds to run
                if (!callDone.WaitOne(5000, true))
                {
                    Debug.WriteLine("Call time out! (continuing)");
                    Debug.WriteLine(new StackTrace(true).ToString());
                }
            }
            else
            {
                callDone.WaitOne();
            }
        }

        private void TriggerInvoke()
        {
            switch (callMethod)
            {
                case CallMethod.DirectCall:
                    PerformAllCalls();
                    break;
                case CallMethod.Manual:
                    // Nothing we can do - someone else must call SoftWait or Pulse
                    break;
                case CallMethod.HiddenForm:
                case CallMethod.HiddenFormWithTimeout:
                    hiddenForm.BeginInvoke((MethodInvoker)PerformAllCalls);
                    break;
            }
        }

        public static object MarshalParamTo(object param, Type outputType)
        {
            if (param is IntPtr)
            {
                return MarshalIntPtrTo((IntPtr)param, outputType);
            }

            return param;
        }

        public static T MarshalIntPtrTo<T>(IntPtr param)
        {
            return (T)MarshalIntPtrTo(param, typeof(T));
        }

        public static object MarshalIntPtrTo(IntPtr param, Type outputType)
        {
            // IntPtr requested as output (must be before the null check so that we pass IntPtr.Zero)
            if (outputType == typeof(IntPtr))
            {
                return param;
            }
            // The parameter is null pointer
            if (param == IntPtr.Zero)
            {
                return null;
            }
            // String requested as output
            if (outputType == typeof(string))
            {
                return Marshal.PtrToStringAuto(param);
            }
            // Marshal a COM object
            object comObject = Marshal.GetObjectForIUnknown(param);
            return Activator.CreateInstance(outputType, comObject);
        }

        /// <summary>
        /// Uses reflection to call method. Automaticaly marshals parameters.
        /// </summary>
        /// <param name="targetObject">Targed object which contains the method. In case of static mehod pass the Type</param>
        /// <param name="functionName">The name of the function to call</param>
        /// <param name="functionParameters">Parameters which should be send to the function. Parameters will be marshaled to proper type.</param>
        /// <returns>Return value of the called function</returns>
        public static object InvokeMethod(object targetObject, string functionName, object[] functionParameters)
        {
            MethodInfo method;
            if (targetObject is Type)
            {
                method = ((Type)targetObject).GetMethod(functionName);
            }
            else
            {
                method = targetObject.GetType().GetMethod(functionName);
            }

            ParameterInfo[] methodParamsInfo = method.GetParameters();
            object[] convertedParams = new object[methodParamsInfo.Length];

            for (int i = 0; i < convertedParams.Length; i++)
            {
                convertedParams[i] = MarshalParamTo(functionParameters[i], methodParamsInfo[i].ParameterType);
            }

            try
            {
                if (targetObject is Type)
                {
                    return method.Invoke(null, convertedParams);
                }
                return method.Invoke(targetObject, convertedParams);
            }
            catch (Exception exception)
            {
                throw new Exception("Invoke of " + functionName + " failed.", exception);
            }
        }
    }
}