using System;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Windows.Automation;

namespace KeeWebHelper
{
    class WindowHelper
    {
        static readonly string[] BrowserProcessNames = new[] { "chrome", "firefox", "opera", "browser",
            "applicationframehost", "iexplore", "edge" };
        static readonly string[] BrowserWindowClasses = new[] { "Chrome_WidgetWin_1" };

        [DllImport("user32.dll")]
        static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll")]
        static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);

        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);

        [DllImport("user32.dll", SetLastError = true)]
        static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint processId);

        public static WindowInfo GetActiveWindowInfo()
        {
            const int nChars = 2048;
            var buff = new StringBuilder(nChars);
            IntPtr hwnd = GetForegroundWindow();

            var result = new WindowInfo();
            if (GetWindowText(hwnd, buff, nChars) > 0)
            {
                result.Title = buff.ToString();
            }

            try
            {
                result.Url = GetUrl(hwnd);
            }
            catch { }

            return result;
        }

        static string GetUrl(IntPtr hwnd)
        {
            uint pid = 0;
            GetWindowThreadProcessId(hwnd, out pid);
            if (pid <= 0)
            {
                return null;
            }
            var process = Process.GetProcessById((int)pid);

            if (!IsBrowser(process.ProcessName))
            {
                const int maxChars = 64;
                var cls = new StringBuilder(maxChars);
                var clsId = GetClassName(hwnd, cls, maxChars);
                if (Array.IndexOf(BrowserWindowClasses, cls.ToString()) < 0) {
                    return null;
                }
            }

            var el = AutomationElement.FromHandle(process.MainWindowHandle);
            if (el == null)
            {
                return null;
            }

            if (process.ProcessName.IndexOf("chrome", StringComparison.OrdinalIgnoreCase) >= 0)
            {
                var elChr = el.FindFirst(TreeScope.Children, new PropertyCondition(AutomationElement.NameProperty, "Google Chrome"));
                if (elChr != null)
                {
                    el = elChr;
                }
            }

            var controlCondition = new PropertyCondition(AutomationElement.ControlTypeProperty, ControlType.Edit);
            var valueCondition = new PropertyCondition(AutomationElement.IsValuePatternAvailableProperty, true);
            var condition = new AndCondition(controlCondition, valueCondition);
            AutomationElement urlEl = el.FindFirst(TreeScope.Descendants, condition);
            if (urlEl == null)
            {
                return null;
            }

            var val = (ValuePattern)urlEl.GetCurrentPattern(ValuePattern.Pattern);
            return val.Current.Value;
        }

        static bool IsBrowser(string processName)
        {
            processName = processName.ToLower();
            foreach (var br in BrowserProcessNames)
            {
                if (processName.IndexOf(br) >= 0)
                {
                    return true;
                }
            }
            return false;
        }
    }
}