using System.ComponentModel;
using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using System.Net.NetworkInformation;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Windows.Forms;
using static robospot_camera_finder.MainForm;
using System.Runtime.InteropServices;
using System.Text;

namespace robospot_camera_finder
{
    public partial class MainForm : Form
    {
        private BindingList<Camera> allCameras = new();

        public static string CAM_USERNAME = "admin";
        public static string CAM_PASSWORD = "RoboSpot10";

        // UDP discovery constants
        private const int SEND_PORT = 7701;
        private const int RECEIVE_PORT = 7711;
        private const string BROADCAST_ADDRESS = "10.255.255.255";
        private const byte DEF_REQ_SCAN = 1;
        private const byte RES_REQ_SCAN = 11;

        private UdpClient sendClient;
        private UdpClient receiveClient;
        private bool isDiscovering = false;

        public class Camera
        {
            public Camera(string name, string ip, string location, string serial)
            {
                cameraName = name;
                cameraIP = ip;
                cameraLocation = location;
                cameraSerial = serial;
            }

            public string cameraName { get; set; }

            public string cameraIP { get; set; }

            public string cameraLocation { get; set; }

            public string cameraSerial { get; set; }
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        public struct DataPacketIPv4
        {
            public byte mode;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 18)]
            public byte[] packet_id;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 18)]
            public byte[] mac_addr;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16)]
            public byte[] ip_addr;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16)]
            public byte[] subnetmask;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16)]
            public byte[] gateway;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 20)]
            public byte[] password;

            public byte reserved1;
            public ushort port;
            public byte status;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
            public byte[] device_name;

            public byte reserved2;
            public ushort http_port;
            public ushort device_port;
            public ushort tcp_port;
            public ushort udp_port;
            public ushort upload_port;
            public ushort multicast_port;
            public byte network_mode;

            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 128)]
            public byte[] ddns_url;

            public byte reserved3;
        }

        public MainForm()
        {
            InitializeComponent();

            bool gotProperIP = false;
            foreach (NetworkInterface networkInterface in NetworkInterface.GetAllNetworkInterfaces())
            {
                IPInterfaceProperties interfaceProperties = networkInterface.GetIPProperties();
                foreach (UnicastIPAddressInformation interfaceUnicastAddr in interfaceProperties.UnicastAddresses)
                {
                    if (interfaceUnicastAddr.Address.ToString().StartsWith("10."))
                    {
                        if (interfaceUnicastAddr.IPv4Mask.ToString() == "255.0.0.0")
                        {
                            gotProperIP = true;
                        }
                    }
                }
            }
            if (!gotProperIP)
            {
                DialogResult openNetworkSettings = MessageBox.Show("No Ethernet interface on the 10.0.0.0/8 subnet found. Cameras might not be detected. Do you want to open network settings ?", "Wrong IP configuration", MessageBoxButtons.YesNo, MessageBoxIcon.Warning, MessageBoxDefaultButton.Button1);

                if (openNetworkSettings == DialogResult.Yes)
                {
                    ProcessStartInfo startInfo = new ProcessStartInfo("NCPA.cpl");
                    startInfo.UseShellExecute = true;

                    Process.Start(startInfo);
                }

            }

            lbMain.DataSource = allCameras;
            lbMain.DisplayMember = "cameraName";
            lbMain.ValueMember = "cameraIP";

            // Initialize UDP clients
            InitializeUdpClients();

            // Discover cameras
            DiscoverCameras();
        }

        private void InitializeUdpClients()
        {
            try
            {
                sendClient = new UdpClient();
                sendClient.EnableBroadcast = true;

                receiveClient = new UdpClient(RECEIVE_PORT);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Failed to initialize UDP clients: {ex.Message}", "Network Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void AddCamera(Camera newCamera)
        {
            if (allCameras.Count == 0)
            {
                allCameras.Add(newCamera);
            }
            else
            {
                Camera searchCamera = allCameras.FirstOrDefault(cam => cam.cameraSerial == newCamera.cameraSerial);

                if (searchCamera != null)
                {
                    int i = allCameras.IndexOf(searchCamera);
                    allCameras[i] = newCamera;
                }
                else
                {
                    allCameras.Add(newCamera);
                }
            }
        }

        private void lbMain_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            if (lbMain.SelectedItem != null)
            {
                toolStripStatusLabel.Text = "Loading camera...";
                Camera camera = allCameras.FirstOrDefault<Camera>(cam => cam.cameraIP.ToString() == lbMain.SelectedValue.ToString());
                Form viewer = new StreamViewer(lbMain.GetItemText(lbMain.SelectedItem), lbMain.SelectedValue.ToString(), camera, this);
                viewer.Show();
                toolStripStatusLabel.Text = "";
            }
        }

        private void loadToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string json = "";
            OpenFileDialog openFile = new OpenFileDialog();
            openFile.Filter = "json file (*.json)|*.json";
            openFile.RestoreDirectory = true;

            if (openFile.ShowDialog() == DialogResult.OK)
            {
                json = File.ReadAllText(openFile.FileName);

                List<Camera>? camerasInFile = JsonSerializer.Deserialize<List<Camera>>(json);

                if (camerasInFile is List<Camera>)
                {
                    foreach (Camera camera in camerasInFile)
                    {
                        AddCamera(camera);
                    }
                }
            }
        }

        private void saveToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string json = JsonSerializer.Serialize<BindingList<Camera>>(allCameras, new JsonSerializerOptions
            {
                WriteIndented = true
            });
            SaveFileDialog saveFile = new SaveFileDialog();
            saveFile.Filter = "json file (*.json)|*.json";
            saveFile.RestoreDirectory = true;

            if (saveFile.ShowDialog() == DialogResult.OK)
            {
                File.WriteAllText(saveFile.FileName, json);
            }
        }

        private void manualAddToolStripMenuItem_Click(object sender, EventArgs e)
        {
            ManualIPForm manualForm = new ManualIPForm();

            if (manualForm.ShowDialog(this) == DialogResult.OK)
            {
                string ipAddress = manualForm.ipAddress;

                Camera cameraToAdd = new Camera("Camera " + ipAddress, ipAddress, "", ipAddress.Replace(".", ""));
                AddCamera(cameraToAdd);
            }
        }

        // Helper method to convert structure to byte array
        private byte[] StructureToByteArray(DataPacketIPv4 packet)
        {
            int size = Marshal.SizeOf(packet);
            byte[] array = new byte[size];
            IntPtr ptr = Marshal.AllocHGlobal(size);

            try
            {
                Marshal.StructureToPtr(packet, ptr, true);
                Marshal.Copy(ptr, array, 0, size);
            }
            finally
            {
                Marshal.FreeHGlobal(ptr);
            }

            return array;
        }

        // Helper method to convert byte array to structure
        private DataPacketIPv4 ByteArrayToStructure(byte[] data)
        {
            DataPacketIPv4 packet = new DataPacketIPv4();
            int size = Marshal.SizeOf(packet);
            IntPtr ptr = Marshal.AllocHGlobal(size);

            try
            {
                Marshal.Copy(data, 0, ptr, size);
                packet = (DataPacketIPv4)Marshal.PtrToStructure(ptr, typeof(DataPacketIPv4));
            }
            finally
            {
                Marshal.FreeHGlobal(ptr);
            }

            return packet;
        }

        // Helper method to create a string array field with null termination
        private byte[] CreateStringField(string value, int fieldSize)
        {
            byte[] field = new byte[fieldSize];
            if (!string.IsNullOrEmpty(value))
            {
                byte[] valueBytes = Encoding.ASCII.GetBytes(value);
                int copyLength = Math.Min(valueBytes.Length, fieldSize - 1); // Leave space for null terminator
                Array.Copy(valueBytes, field, copyLength);
            }
            return field;
        }

        // Helper method to extract string from byte array
        private string ExtractString(byte[] data)
        {
            if (data == null) return "";

            // Find the null terminator
            int nullIndex = Array.IndexOf(data, (byte)0);
            if (nullIndex >= 0)
            {
                return Encoding.ASCII.GetString(data, 0, nullIndex);
            }
            else
            {
                return Encoding.ASCII.GetString(data).TrimEnd('\0');
            }
        }

        // Create discovery packet
        private DataPacketIPv4 CreateDiscoveryPacket()
        {
            DataPacketIPv4 packet = new DataPacketIPv4
            {
                mode = DEF_REQ_SCAN,
                packet_id = CreateStringField("CAM_FINDER_" + DateTime.Now.Ticks.ToString(), 18),
                mac_addr = new byte[18],
                ip_addr = new byte[16],
                subnetmask = new byte[16],
                gateway = new byte[16],
                password = new byte[20],
                reserved1 = 0,
                port = 0,
                status = 0,
                device_name = new byte[10],
                reserved2 = 0,
                http_port = 0,
                device_port = 0,
                tcp_port = 0,
                udp_port = 0,
                upload_port = 0,
                multicast_port = 0,
                network_mode = 1,
                ddns_url = new byte[128],
                reserved3 = 0
            };

            return packet;
        }

        // Send discovery packet
        private async Task<bool> SendDiscoveryPacketAsync(DataPacketIPv4 packet)
        {
            try
            {
                byte[] data = StructureToByteArray(packet);
                IPEndPoint broadcastEndPoint = new IPEndPoint(IPAddress.Parse(BROADCAST_ADDRESS), SEND_PORT);

                int bytesSent = await sendClient.SendAsync(data, data.Length, broadcastEndPoint);
                return bytesSent > 0;
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error sending discovery packet: {ex.Message}", "Network Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return false;
            }
        }

        // Listen for camera responses
        private async Task ListenForResponsesAsync(int timeoutMs = 5000)
        {
            var startTime = DateTime.Now;
            var endTime = startTime.AddMilliseconds(timeoutMs);

            try
            {
                while (DateTime.Now < endTime && isDiscovering)
                {
                    var receiveTask = receiveClient.ReceiveAsync();
                    var timeoutTask = Task.Delay(1000); // Check every second

                    var completedTask = await Task.WhenAny(receiveTask, timeoutTask);

                    if (completedTask == receiveTask)
                    {
                        var result = await receiveTask;
                        ProcessCameraResponse(result.Buffer, result.RemoteEndPoint);
                    }
                }
            }
            catch (Exception ex)
            {
                if (isDiscovering) // Only show error if we're still supposed to be discovering
                {
                    this.Invoke(new Action(() =>
                    {
                        MessageBox.Show($"Error listening for responses: {ex.Message}", "Network Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }));
                }
            }
        }

        // Process received camera response
        private void ProcessCameraResponse(byte[] data, IPEndPoint remoteEndPoint)
        {
            try
            {
                if (data.Length == Marshal.SizeOf<DataPacketIPv4>())
                {
                    DataPacketIPv4 response = ByteArrayToStructure(data);

                    // Check if this is a valid camera response
                    if (response.mode == RES_REQ_SCAN)
                    {
                        string cameraIP = ExtractString(response.ip_addr);
                        string deviceName = ExtractString(response.device_name);
                        string macAddress = ExtractString(response.mac_addr);
                        string packetId = ExtractString(response.packet_id);

                        // Use the IP from the response or fall back to the sender's IP
                        if (string.IsNullOrEmpty(cameraIP))
                        {
                            cameraIP = remoteEndPoint.Address.ToString();
                        }

                        // Create camera name
                        string cameraName = !string.IsNullOrEmpty(deviceName) ? deviceName : $"Camera {cameraIP}";

                        // Create camera object
                        Camera discoveredCamera = new Camera(
                            $"{deviceName} - ({cameraIP})",
                            cameraIP,
                            $"MAC: {macAddress}",
                            packetId // Using packet_id as serial for uniqueness
                        );

                        // Add camera to list (must be done on UI thread)
                        this.Invoke(new Action(() =>
                        {
                            AddCamera(discoveredCamera);
                            toolStripStatusLabel.Text = $"Found camera: {cameraName} ({cameraIP})";
                        }));
                    }
                }
            }
            catch (Exception ex)
            {
                this.Invoke(new Action(() =>
                {
                    MessageBox.Show($"Error processing camera response: {ex.Message}", "Processing Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }));
            }
        }

        // Main discovery method
        private async void DiscoverCameras()
        {
            if (isDiscovering)
            {
                MessageBox.Show("Discovery is already in progress.", "Discovery", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return;
            }

            if (sendClient == null || receiveClient == null)
            {
                InitializeUdpClients();
                if (sendClient == null || receiveClient == null)
                {
                    MessageBox.Show("Failed to initialize network clients.", "Network Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
            }

            isDiscovering = true;
            toolStripStatusLabel.Text = "Discovering cameras...";

            try
            {
                // Create and send discovery packet
                DataPacketIPv4 discoveryPacket = CreateDiscoveryPacket();
                bool sent = await SendDiscoveryPacketAsync(discoveryPacket);

                if (sent)
                {
                    // Listen for responses for 10 seconds
                    await ListenForResponsesAsync(10000);
                }
                else
                {
                    MessageBox.Show("Failed to send discovery packet.", "Network Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Discovery error: {ex.Message}", "Discovery Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            finally
            {
                isDiscovering = false;
                toolStripStatusLabel.Text = $"Discovery complete. Found {allCameras.Count} cameras.";
            }
        }

        // Clean up resources when form is closing
        protected override void OnFormClosing(FormClosingEventArgs e)
        {
            isDiscovering = false;

            try
            {
                sendClient?.Close();
                receiveClient?.Close();
            }
            catch { }

            base.OnFormClosing(e);
        }
    }
}