/* Copyright (C) 2016 Tal Aloni <tal.aloni.il@gmail.com>. All rights reserved.
 *
 * You can redistribute this program and/or modify it under the terms of
 * the GNU Lesser Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
 */

using ISCSI.Server;
using ISCSIConsole.Mods;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Windows.Forms;
using DiskAccessLibrary;
using SCSI;
using Utilities;

namespace ISCSIConsole
{
    public partial class MainForm : BaseForm
    {
        private ISCSIServer m_server = new ISCSIServer();
        private List<ISCSITarget> m_targets = new List<ISCSITarget>();
        private UsageCounter m_usageCounter = new UsageCounter();
        private bool m_started = false;

        public MainForm()
        {
            InitializeComponent();
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            var version = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version;
            Text += " v" + version.ToString(3);
            m_server.OnLogEntry += Program.OnLogEntry;

            var localIPs = GetHostIPAddresses();
            var list = new KeyValuePairList<string, IPAddress>();
            list.Add("Any", IPAddress.Any);
            foreach (var address in localIPs)
            {
                list.Add(address.ToString(), address);
            }
            comboIPAddress.DataSource = list;
            comboIPAddress.DisplayMember = "Key";
            comboIPAddress.ValueMember = "Value";
            lblStatus.Text = "Author: Tal Aloni (tal.aloni.il@gmail.com)";
#if Win32
            if (!SecurityHelper.IsAdministrator())
            {
                lblStatus.Text = "Some features require administrator privileges and have been disabled";
            }
#endif
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            if (!m_started)
            {
                var serverAddress = (IPAddress)comboIPAddress.SelectedValue;
                var port = Conversion.ToInt32(txtPort.Text, 0);
                if (port <= 0 || port > UInt16.MaxValue)
                {
                    MessageBox.Show("Invalid TCP port", "Error");
                    return;
                }
                var endpoint = new IPEndPoint(serverAddress, port);
                try
                {
                    m_server.Start(endpoint);
                }
                catch (SocketException ex)
                {
                    MessageBox.Show("Cannot start server, " + ex.Message, "Error");
                    return;
                }
                btnStart.Text = "Stop";
                txtPort.Enabled = false;
                comboIPAddress.Enabled = false;
                m_started = true;
                UpdateUI();
            }
            else
            {
                m_server.Stop();
                lblStatus.Text = String.Empty;
                m_started = false;
                btnStart.Text = "Start";
                txtPort.Enabled = true;
                comboIPAddress.Enabled = true;
            }
        }

        private void btnAddTarget_Click(object sender, EventArgs e)
        {
            var addTarget = new AddTargetForm();
            var addTargetResult = addTarget.ShowDialog();
            if (addTargetResult == DialogResult.OK)
            {
                var target = addTarget.Target;
                try
                {
                    AddTarget(target);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "Error");
                }
            }
        }

        private void AddTarget(ISCSITarget target)
        {
            ((SCSI.VirtualSCSITarget)target.SCSITarget).OnLogEntry += Program.OnLogEntry;
            target.OnAuthorizationRequest += ISCSITarget_OnAuthorizationRequest;
            target.OnSessionTermination += ISCSITarget_OnSessionTermination;
            m_targets.Add(target);
            m_server.AddTarget(target);
            listTargets.Items.Add(target.TargetName);
        }

        private void btnRemoveTarget_Click(object sender, EventArgs e)
        {
            if (listTargets.SelectedIndices.Count > 0)
            {
                var targetIndex = listTargets.SelectedIndices[0];
                var target = m_targets[targetIndex];
                var isTargetRemoved = m_server.RemoveTarget(target.TargetName);
                if (!isTargetRemoved)
                {
                    MessageBox.Show("Could not remove iSCSI target", "Error");
                    return;
                }
                var disks = ((SCSI.VirtualSCSITarget)target.SCSITarget).Disks;
                LockUtils.ReleaseDisks(disks);
                m_targets.RemoveAt(targetIndex);
                listTargets.Items.RemoveAt(targetIndex);
            }
        }

        private void ISCSITarget_OnAuthorizationRequest(object sender, AuthorizationRequestArgs e)
        {
            var targetName = ((ISCSITarget)sender).TargetName;
            m_usageCounter.NotifySessionStart(targetName);
            UpdateUI();
        }

        private void ISCSITarget_OnSessionTermination(object sender, SessionTerminationArgs e)
        {
            var targetName = ((ISCSITarget)sender).TargetName;
            m_usageCounter.NotifySessionTermination(targetName);
            UpdateUI();
        }

        private void UpdateUI()
        {
            if (InvokeRequired)
            {
                Invoke((MethodInvoker)UpdateUI);
            }
            else
            {
                if (m_started)
                {
                    lblStatus.Text = String.Format("{0} Active Sessions", m_usageCounter.SessionCount);
                }

                if (listTargets.SelectedIndices.Count > 0)
                {
                    var targetIndex = listTargets.SelectedIndices[0];
                    var target = m_targets[targetIndex];
                    var isInUse = m_usageCounter.IsTargetInUse(target.TargetName);
                    btnRemoveTarget.Enabled = !isInUse;
                }
                else
                {
                    btnRemoveTarget.Enabled = false;
                }
            }
        }

        private static List<IPAddress> GetHostIPAddresses()
        {
            var result = new List<IPAddress>();
            foreach (var netInterface in NetworkInterface.GetAllNetworkInterfaces())
            {
                var ipProperties = netInterface.GetIPProperties();
                foreach (var addressInfo in ipProperties.UnicastAddresses)
                {
                    if (addressInfo.Address.AddressFamily == AddressFamily.InterNetwork)
                    {
                        result.Add(addressInfo.Address);
                    }
                }
            }
            return result;
        }

        private void listTargets_SelectedIndexChanged(object sender, EventArgs e)
        {
            UpdateUI();
        }

        private void LoadConfigButton_Click(object sender, EventArgs e)
        {
            LoadFromConfig();
        }

        private void LoadFromConfig()
        {
            var entries = ((List<AutoLoadEntry>)ConfigurationManager.GetSection("autoLoad")).Where(p => p.Enable).ToArray();
            if (entries.Length != entries.Select(p => p.Iqn).Distinct().Count())
            {
                MessageBox.Show("Config error: Iqn should no duplicate");
                return;
            }

            foreach (var entry in entries)
            {
                if (m_targets.Any(p => p.TargetName == entry.Iqn)) continue;
                AddTarget(entry.CreateTarget());
            }
        }

        private void MainForm_Shown(object sender, EventArgs e)
        {
            if (IPAddress.TryParse(ConfigurationManager.AppSettings["Listen"], out var ipAddress)) comboIPAddress.Text = ipAddress.ToString();
            if (int.TryParse(ConfigurationManager.AppSettings["Port"], out var port)) txtPort.Text = port.ToString();
            if ("true" == ConfigurationManager.AppSettings["AutoLoadConfig"]) LoadFromConfig();
            if ("true" == ConfigurationManager.AppSettings["AutoStart"]) btnStart_Click(null, null);
        }

        private void listTargets_DoubleClick(object sender, EventArgs e)
        {
            if (listTargets.SelectedIndices.Count == 0) return;

            var targetIndex = listTargets.SelectedIndices[0];
            var target = m_targets[targetIndex];

            if (target.Target is VirtualSCSITarget v)
            {
                if (v.Disks.Count == 0)
                {
                    MainContextMenuStrip.Items.Add("(no Disks)").Enabled = false;
                }
                else
                {
                    var dic = new Dictionary<string, ToolStripItem[]>();

                    foreach (var disk in v.Disks)
                    {
                        switch (disk)
                        {
                            case BlockDifferencingDiskImage bdd:
                                if (false == bdd.IsNoBaseImage)
                                {
                                    var toolStripMenuItem = new ToolStripMenuItem("Clean");
                                    toolStripMenuItem.Click += (o, args) =>
                                    {
                                        var dr = MessageBox.Show($"Are you sure to clean `{bdd.Path}'", "Clean snapshot", MessageBoxButtons.YesNo, MessageBoxIcon.Warning, MessageBoxDefaultButton.Button2);
                                        if (dr == DialogResult.Yes) bdd.Clean();
                                    };
                                    dic[bdd.Path] = new ToolStripItem[] { toolStripMenuItem };
                                }
                                break;
                        }
                    }

                    if (dic.Count == 0) MainContextMenuStrip.Items.Add("(no option able Disks)").Enabled = false;
                    else
                    {
                        foreach (var item in dic)
                        {
                            var m = new ToolStripMenuItem(item.Key);
                            m.DropDownItems.AddRange(item.Value);
                            MainContextMenuStrip.Items.Add(m);
                        }
                    }
                }
                MainContextMenuStrip.Show(MousePosition);
            }
            else
            {
                MainContextMenuStrip.Items.Add("(non Virtual SCSI Target)").Enabled = false;
                MainContextMenuStrip.Show(MousePosition);
            }
        }

        private void MainContextMenuStrip_Closed(object sender, ToolStripDropDownClosedEventArgs e)
        {
            MainContextMenuStrip.Items.Clear();
        }
    }
}