using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using TestStack.White.InputDevices;
using TestStack.White.WindowsAPI;

namespace Tango.BuildExtensions
{
    public class WindowInfo
    {
        [DllImport("user32.dll", EntryPoint = "GetDesktopWindow")]
        static extern IntPtr GetDesktopWindow();

        [DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
        static extern int SendMessage(IntPtr hwndControl, uint Msg, int wParam, StringBuilder strBuffer); // get text

        [DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
        static extern int SendMessage(IntPtr hwndControl, uint Msg, int wParam, int lParam);  // text length

        [DllImport("user32.dll", EntryPoint = "FindWindowEx", CharSet = CharSet.Auto)]
        static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

        [DllImport("user32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);

        private static List<IntPtr> GetAllChildrenHandles(IntPtr hParent, int maxCount)
        {
            List<IntPtr> result = new List<IntPtr>();
            int ct = 0;
            IntPtr prevChild = IntPtr.Zero;
            IntPtr currChild = IntPtr.Zero;
            while (true && ct < maxCount)
            {
                currChild = FindWindowEx(hParent, prevChild, null, null);
                if (currChild == IntPtr.Zero) break;
                result.Add(currChild);
                prevChild = currChild;
                ++ct;
            }
            return result;
        }

        private static int GetCaptionTextLength(IntPtr hTextBox)
        {
            // helper for GetCaptionText
            uint WM_GETTEXTLENGTH = 0x000E;
            int result = SendMessage(hTextBox, WM_GETTEXTLENGTH,
              0, 0);
            return result;
        }

        private static string GetCaptionText(IntPtr hTextBox)
        {
            uint WM_GETTEXT = 0x000D;
            int len = GetCaptionTextLength(hTextBox);
            if (len <= 0) return null;  // no text. consider empty string instead.
            StringBuilder sb = new StringBuilder(len + 1);
            SendMessage(hTextBox, WM_GETTEXT, len + 1, sb);
            return sb.ToString();
        }

        public IntPtr Handle { get; set; }
        public int Level { get; set; }
        public String Caption { get; set; }
        public WindowInfo Parent { get; set; }
        public List<WindowInfo> Children { get; set; }

        public WindowInfo()
        {
            Children = new List<WindowInfo>();
        }

        public void SetActive()
        {
            SetForegroundWindow(Handle);
        }

        public void PressKey(KeyboardInput.SpecialKeys key)
        {
            SetActive();
            Keyboard.Instance.PressSpecialKey(key);
        }

        public override string ToString()
        {
            return Caption;
        }

        public static List<WindowInfo> GetAllWindows()
        {
            List<WindowInfo> windows = new List<WindowInfo>();

            IntPtr hDesktop = GetDesktopWindow();
            WindowInfo desktop = new WindowInfo();
            desktop.Handle = hDesktop;
            desktop.Level = 0;
            desktop.Caption = "(Desktop)";
            desktop.Parent = null;
            windows.Add(desktop);

            FillWindows(desktop, desktop.Children);

            return windows;
        }

        private static void FlattenWindows(WindowInfo parent, List<WindowInfo> windows)
        {
            windows.Add(parent);

            foreach (var window in parent.Children)
            {
                windows.Add(window);
                FlattenWindows(window, windows);
            }
        }

        public static WindowInfo GetWindow(String title)
        {
            var windows = GetAllWindows();

            List<WindowInfo> flatList = new List<WindowInfo>();
            FlattenWindows(windows.First(), flatList);

            return flatList.FirstOrDefault(x => x.Caption == title);
        }

        private static void FillWindows(WindowInfo parent, List<WindowInfo> windows)
        {
            foreach (var handle in GetAllChildrenHandles(parent.Handle, 5000))
            {
                WindowInfo child = new WindowInfo();
                child.Handle = handle;
                child.Level = parent.Level + 1;
                child.Caption = GetCaptionText(handle);
                child.Parent = parent;

                if (child.Caption != null)
                {
                    windows.Add(child);
                }

                FillWindows(child, child.Children);
            }
        }
    }
}