using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;
using Shadowsocks.Model;
using Shadowsocks.Properties;
using Shadowsocks.Util;
using Shadowsocks.Util.ProcessManagement;

namespace Shadowsocks.Controller
{
    class PrivoxyRunner
    {
        private static int Uid;
        private static string UniqueConfigFile;
        private static Job PrivoxyJob;
        private Process _process;
        private int _runningPort;

        static PrivoxyRunner()
        {
            try
            {
                Uid = Application.StartupPath.GetHashCode(); // Currently we use ss's StartupPath to identify different Privoxy instance.
                UniqueConfigFile = $"privoxy_{Uid}.conf";
                PrivoxyJob = new Job();

                FileManager.UncompressFile(Utils.GetTempPath("ss_privoxy.exe"), Resources.privoxy_exe);
                FileManager.UncompressFile(Utils.GetTempPath("mgwz.dll"), Resources.mgwz_dll);
            }
            catch (IOException e)
            {
                Logging.LogUsefulException(e);
            }
        }

        public int RunningPort => _runningPort;

        public void Start(Configuration configuration)
        {
            if (_process == null)
            {
                Process[] existingPrivoxy = Process.GetProcessesByName("ss_privoxy");
                foreach (Process p in existingPrivoxy.Where(IsChildProcess))
                {
                    KillProcess(p);
                }
                string privoxyConfig = Resources.privoxy_conf;
                _runningPort = this.GetFreePort();
                privoxyConfig = privoxyConfig.Replace("__SOCKS_PORT__", configuration.localPort.ToString());
                privoxyConfig = privoxyConfig.Replace("__PRIVOXY_BIND_PORT__", _runningPort.ToString());
                privoxyConfig = privoxyConfig.Replace("__PRIVOXY_BIND_IP__", configuration.shareOverLan ? "0.0.0.0" : "127.0.0.1");
                FileManager.ByteArrayToFile(Utils.GetTempPath(UniqueConfigFile), Encoding.UTF8.GetBytes(privoxyConfig));

                _process = new Process();
                // Configure the process using the StartInfo properties.
                _process.StartInfo.FileName = "ss_privoxy.exe";
                _process.StartInfo.Arguments = UniqueConfigFile;
                _process.StartInfo.WorkingDirectory = Utils.GetTempPath();
                _process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
                _process.StartInfo.UseShellExecute = true;
                _process.StartInfo.CreateNoWindow = true;
                _process.Start();

                /*
                 * Add this process to job obj associated with this ss process, so that
                 * when ss exit unexpectedly, this process will be forced killed by system.
                 */
                PrivoxyJob.AddProcess(_process.Handle);
            }
            RefreshTrayArea();
        }

        public void Stop()
        {
            if (_process != null)
            {
                KillProcess(_process);
                _process.Dispose();
                _process = null;
            }
            RefreshTrayArea();
        }

        private static void KillProcess(Process p)
        {
            try
            {
                p.CloseMainWindow();
                p.WaitForExit(100);
                if (!p.HasExited)
                {
                    p.Kill();
                    p.WaitForExit();
                }
            }
            catch (Exception e)
            {
                Logging.LogUsefulException(e);
            }
        }

        /*
         * We won't like to kill other ss instances' ss_privoxy.exe.
         * This function will check whether the given process is created
         * by this process by checking the module path or command line.
         * 
         * Since it's required to put ss in different dirs to run muti instances,
         * different instance will create their unique "privoxy_UID.conf" where
         * UID is hash of ss's location.
         */

        private static bool IsChildProcess(Process process)
        {
            try
            {
                if (Utils.IsPortableMode())
                {
                    /*
                     * Under PortableMode, we could identify it by the path of ss_privoxy.exe.
                     */
                    var path = process.MainModule.FileName;

                    return Utils.GetTempPath("ss_privoxy.exe").Equals(path);
                }
                else
                {
                    var cmd = process.GetCommandLine();

                    return cmd.Contains(UniqueConfigFile);
                }
            }
            catch (Exception ex)
            {
                /*
                 * Sometimes Process.GetProcessesByName will return some processes that
                 * are already dead, and that will cause exceptions here.
                 * We could simply ignore those exceptions.
                 */
                Logging.LogUsefulException(ex);
                return false;
            }
        }

        private int GetFreePort()
        {
            int defaultPort = 8123;
            try
            {
                // TCP stack please do me a favor
                TcpListener l = new TcpListener(IPAddress.Loopback, 0);
                l.Start();
                var port = ((IPEndPoint)l.LocalEndpoint).Port;
                l.Stop();
                return port;
            }
            catch (Exception e)
            {
                // in case access denied
                Logging.LogUsefulException(e);
                return defaultPort;
            }
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
        }
        [DllImport("user32.dll")]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
        [DllImport("user32.dll")]
        public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);
        [DllImport("user32.dll")]
        public static extern bool GetClientRect(IntPtr hWnd, out RECT lpRect);
        [DllImport("user32.dll")]
        public static extern IntPtr SendMessage(IntPtr hWnd, uint msg, int wParam, int lParam);

        public void RefreshTrayArea()
        {
            IntPtr systemTrayContainerHandle = FindWindow("Shell_TrayWnd", null);
            IntPtr systemTrayHandle = FindWindowEx(systemTrayContainerHandle, IntPtr.Zero, "TrayNotifyWnd", null);
            IntPtr sysPagerHandle = FindWindowEx(systemTrayHandle, IntPtr.Zero, "SysPager", null);
            IntPtr notificationAreaHandle = FindWindowEx(sysPagerHandle, IntPtr.Zero, "ToolbarWindow32", "Notification Area");
            if (notificationAreaHandle == IntPtr.Zero)
            {
                notificationAreaHandle = FindWindowEx(sysPagerHandle, IntPtr.Zero, "ToolbarWindow32", "User Promoted Notification Area");
                IntPtr notifyIconOverflowWindowHandle = FindWindow("NotifyIconOverflowWindow", null);
                IntPtr overflowNotificationAreaHandle = FindWindowEx(notifyIconOverflowWindowHandle, IntPtr.Zero, "ToolbarWindow32", "Overflow Notification Area");
                RefreshTrayArea(overflowNotificationAreaHandle);
            }
            RefreshTrayArea(notificationAreaHandle);
        }

        private static void RefreshTrayArea(IntPtr windowHandle)
        {
            const uint wmMousemove = 0x0200;
            RECT rect;
            GetClientRect(windowHandle, out rect);
            for (var x = 0; x < rect.right; x += 5)
                for (var y = 0; y < rect.bottom; y += 5)
                    SendMessage(windowHandle, wmMousemove, 0, (y << 16) + x);
        }
    }
}