using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Interop;
using Monolith.Models;

namespace Monolith.View
{
    public class HostingPanel : HwndHost
    {
        private Process m_hostedProcess;

        private const int GWL_STYLE = -16;
        private const int WS_CAPTION = 0x00C00000;
        private const int WS_THICKFRAME = 0x00040000;
        private const int WS_CHILD = 0x40000000;

        public HostingPanel()
        {
            DataContextChanged += OnDataContextChanged;
        }

        private void OnDataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            HostedProcessModel model = DataContext as HostedProcessModel;
            if (model != null)
                m_hostedProcess = model.RequestProcessHandle(this);
        }

        public static void OnHostedProcessFullPathChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (e.NewValue == null)
                throw new NotSupportedException("This control does not support changing its running process in runtime. ");
        }
            
        protected override System.Runtime.InteropServices.HandleRef BuildWindowCore(System.Runtime.InteropServices.HandleRef hwndParent)
        {
            // The main window handle may be unavailable for a while, just wait for it
            while (m_hostedProcess.MainWindowHandle == IntPtr.Zero)
            {
                Thread.Yield();
            }

            IntPtr notepadHandle = m_hostedProcess.MainWindowHandle;

            int style = GetWindowLong(notepadHandle, GWL_STYLE);
            style = style & ~((int)WS_CAPTION) & ~((int)WS_THICKFRAME); // Removes Caption bar and the sizing border
            style |= ((int)WS_CHILD); // Must be a child window to be hosted

            SetWindowLong(notepadHandle, GWL_STYLE, style);
            SetParent(notepadHandle, hwndParent.Handle);

            this.InvalidateVisual();

            HandleRef hwnd = new HandleRef(this, notepadHandle);
            return hwnd;
        }

        protected override void DestroyWindowCore(System.Runtime.InteropServices.HandleRef hwnd)
        {
            m_hostedProcess = null;
            HostedProcessModel model = DataContext as HostedProcessModel;
            if (model != null)
                model.DisposeProcessHandle(this);
        }

        [DllImport("user32.dll")]
        private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

        [DllImport("user32.dll", SetLastError = true)]
        private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

        [DllImport("user32")]
        private static extern IntPtr SetParent(IntPtr hWnd, IntPtr hWndParent);
    }
}