using System.Diagnostics;
using System.Windows.Forms.VisualStyles;

namespace ClinicBackupSync;

sealed class MainForm : Form
{
    readonly SyncSettings _settings;
    readonly FolderSync _sync;
    readonly CancellationTokenSource _cancellation = new();
    readonly Task _loop;
    readonly EventWaitHandle _showSignal = new(false, EventResetMode.AutoReset, @"Local\ClinicBackupSync.Show");
    readonly NotifyIcon _tray;
    readonly Label _status;
    readonly Label _summary;
    readonly ListView _files;
    readonly ListView _log;
    readonly SplitContainer _split;
    readonly TextBox _folderBox;
    readonly NumericUpDown _interval;
    readonly UploadProgressBar _uploadBar = new() { Dock = DockStyle.Top, Visible = false };
    const int TryColumn = 4;
    int _shownActivity;
    bool _exit;

    public MainForm(SyncSettings settings)
    {
        _settings = settings;
        Text = "Clinic Pro backup sync";
        StartPosition = FormStartPosition.CenterScreen;
        MinimumSize = new Size(860, 560);
        Size = new Size(980, 720);
        BackColor = Color.FromArgb(231, 238, 242);
        Font = new Font("Segoe UI", 10);

        var header = new Panel
        {
            Dock = DockStyle.Top,
            Height = 78,
            BackColor = Color.FromArgb(16, 40, 58),
        };
        header.Controls.Add(new Label
        {
            Text = "Clinic Pro backups",
            ForeColor = Color.White,
            Font = new Font("Segoe UI", 16, FontStyle.Bold),
            AutoSize = true,
            Location = new Point(20, 12),
        });
        _status = new Label
        {
            ForeColor = Color.FromArgb(183, 198, 211),
            AutoSize = true,
            Location = new Point(22, 44),
            Text = "Starting…",
        };
        header.Controls.Add(_status);

        var tools = new FlowLayoutPanel
        {
            Dock = DockStyle.Top,
            Height = 52,
            Padding = new Padding(16, 10, 16, 8),
            BackColor = Color.FromArgb(231, 238, 242),
            WrapContents = false,
        };
        tools.Controls.Add(MakeButton("Upload now", AccentClick));
        tools.Controls.Add(MakeButton("Open folder", (_, _) => OpenFolder(_settings.WatchFolder), outline: true));

        _folderBox = new TextBox
        {
            Text = _settings.WatchFolder,
            Dock = DockStyle.Fill,
            Margin = new Padding(0, 4, 8, 0),
        };
        _interval = new NumericUpDown
        {
            Minimum = 5,
            Maximum = 86400,
            Value = Math.Clamp(_settings.RetrySeconds, 5, 86400),
            Width = 72,
            Dock = DockStyle.Fill,
            Margin = new Padding(0, 4, 8, 0),
            ThousandsSeparator = true,
        };
        var settingsBar = new TableLayoutPanel
        {
            Dock = DockStyle.Top,
            Height = 44,
            ColumnCount = 7,
            RowCount = 1,
            Padding = new Padding(16, 6, 16, 0),
            BackColor = Color.FromArgb(231, 238, 242),
        };
        settingsBar.RowStyles.Add(new RowStyle(SizeType.Percent, 100));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.Percent, 100));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.Absolute, 84));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
        settingsBar.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
        settingsBar.Controls.Add(SettingsLabel("Folder"), 0, 0);
        settingsBar.Controls.Add(_folderBox, 1, 0);
        settingsBar.Controls.Add(MakeButton("Browse", BrowseFolderClick, outline: true), 2, 0);
        settingsBar.Controls.Add(SettingsLabel("Check every"), 3, 0);
        settingsBar.Controls.Add(_interval, 4, 0);
        settingsBar.Controls.Add(SettingsLabel("seconds"), 5, 0);
        settingsBar.Controls.Add(MakeButton("Save", SaveSettingsClick), 6, 0);

        _summary = new Label
        {
            Dock = DockStyle.Top,
            Height = 28,
            Padding = new Padding(20, 6, 12, 0),
            Text = "Backup files",
            Font = new Font("Segoe UI", 10, FontStyle.Bold),
        };

        _files = CreateList();
        _files.SmallImageList = new ImageList { ImageSize = new Size(1, 28) };
        _files.OwnerDraw = true;
        _files.Columns.Add("File", 260);
        _files.Columns.Add("Size", 90, HorizontalAlignment.Right);
        _files.Columns.Add("Modified", 150);
        _files.Columns.Add("Status", 110);
        _files.Columns.Add("Try", 78);
        _files.Columns.Add("Details", 240);
        _files.DrawColumnHeader += (_, e) => e.DrawDefault = true;
        _files.DrawItem += (_, _) => { };
        _files.DrawSubItem += DrawFileSubItem;
        _files.MouseClick += OnFileClick;
        _files.MouseMove += (_, e) =>
        {
            var hit = _files.HitTest(e.Location);
            _files.Cursor = IsTryHit(hit, e.Location) ? Cursors.Hand : Cursors.Default;
        };

        _log = CreateList();
        _log.Columns.Add("Time", 150);
        _log.Columns.Add("Result", 90);
        _log.Columns.Add("File", 300);
        _log.Columns.Add("Message", 380);

        _split = new SplitContainer
        {
            Dock = DockStyle.Fill,
            Orientation = Orientation.Horizontal,
            BackColor = Color.FromArgb(231, 238, 242),
        };
        var logHeader = new Panel { Dock = DockStyle.Top, Height = 46, Padding = new Padding(4, 4, 8, 0) };
        var logTitle = new Label
        {
            Text = "Upload log",
            Font = new Font("Segoe UI", 10, FontStyle.Bold),
            AutoSize = true,
            Location = new Point(4, 8),
        };
        var clearLog = MakeButton("Clear log", ClearLogClick, outline: true);
        clearLog.Anchor = AnchorStyles.Top | AnchorStyles.Right;
        logHeader.Controls.Add(logTitle);
        logHeader.Controls.Add(clearLog);
        logHeader.Resize += (_, _) =>
        {
            clearLog.Top = 4;
            clearLog.Left = Math.Max(110, logHeader.ClientSize.Width - clearLog.Width - 4);
        };
        var filesHost = new Panel { Dock = DockStyle.Fill, Padding = new Padding(16, 0, 16, 8) };
        filesHost.Controls.Add(_files);
        var logHost = new Panel { Dock = DockStyle.Fill, Padding = new Padding(16, 0, 16, 16) };
        logHost.Controls.Add(_log);
        logHost.Controls.Add(logHeader);
        _split.Panel1.Controls.Add(filesHost);
        _split.Panel2.Controls.Add(logHost);

        Controls.Add(_split);
        Controls.Add(_summary);
        Controls.Add(settingsBar);
        Controls.Add(tools);
        Controls.Add(_uploadBar);
        Controls.Add(header);

        _sync = new FolderSync(settings);
        var windowIcon = Icon ?? SystemIcons.Application;
        _tray = new NotifyIcon
        {
            Icon = (Icon)windowIcon.Clone(),
            Visible = true,
            Text = "Clinic backup sync",
        };
        var menu = new ContextMenuStrip();
        menu.Items.Add("Show", null, (_, _) => ShowFromSignal());
        menu.Items.Add("Upload now", null, (_, _) => _sync.ScanNow());
        menu.Items.Add(new ToolStripSeparator());
        menu.Items.Add("Exit", null, (_, _) => ExitApp());
        _tray.ContextMenuStrip = menu;
        _tray.DoubleClick += (_, _) => ShowFromSignal();

        _sync.StatusChanged += OnStatus;
        _sync.ViewChanged += OnViewChanged;
        _sync.NewFileFound += OnNewFile;
        _sync.ProgressChanged += OnProgress;
        LoadHistory();
        _loop = Task.Run(() => _sync.RunAsync(_cancellation.Token));
        _ = Task.Run(WaitForShowSignal);
    }

    protected override void OnShown(EventArgs e)
    {
        base.OnShown(e);
        var distance = Math.Max(160, (int)(_split.Height * 0.46));
        if (distance < _split.Height - 120)
        {
            _split.SplitterDistance = distance;
        }

        RefreshLists();
    }

    protected override void OnFormClosing(FormClosingEventArgs e)
    {
        if (!_exit && e.CloseReason == CloseReason.UserClosing)
        {
            e.Cancel = true;
            Hide();
            _tray.ShowBalloonTip(3000, "Clinic backup", "Sync keeps running in the notification area.", ToolTipIcon.Info);
            return;
        }

        _tray.Visible = false;
        _tray.Dispose();
        _cancellation.Cancel();
        try
        {
            _showSignal.Set();
            _loop.Wait(TimeSpan.FromSeconds(3));
        }
        catch (AggregateException)
        {
        }

        _sync.Dispose();
        base.OnFormClosing(e);
    }

    void DrawFileSubItem(object? sender, DrawListViewSubItemEventArgs e)
    {
        if (e.Item is null)
        {
            return;
        }

        var selected = e.Item.Selected;
        var background = selected ? SystemColors.Highlight : Color.White;
        var foreground = selected ? SystemColors.HighlightText : e.Item.ForeColor;
        using (var brush = new SolidBrush(background))
        {
            e.Graphics.FillRectangle(brush, e.Bounds);
        }

        using (var pen = new Pen(Color.FromArgb(220, 228, 232)))
        {
            e.Graphics.DrawLine(pen, e.Bounds.Left, e.Bounds.Bottom - 1, e.Bounds.Right, e.Bounds.Bottom - 1);
        }

        if (e.ColumnIndex == TryColumn)
        {
            if (e.SubItem?.Text == "Try")
            {
                var bounds = TryButtonBounds(e.Bounds);
                ButtonRenderer.DrawButton(e.Graphics, bounds, "Try", _files.Font, false, PushButtonState.Normal);
            }

            return;
        }

        var flags = TextFormatFlags.VerticalCenter | TextFormatFlags.EndEllipsis | TextFormatFlags.NoPrefix
            | (e.ColumnIndex == 1 ? TextFormatFlags.Right : TextFormatFlags.Left);
        var textBounds = Rectangle.Inflate(e.Bounds, -4, 0);
        TextRenderer.DrawText(e.Graphics, e.SubItem?.Text ?? "", e.SubItem?.Font ?? _files.Font, textBounds, foreground, flags);
    }

    void OnFileClick(object? sender, MouseEventArgs e)
    {
        var hit = _files.HitTest(e.Location);
        if (!IsTryHit(hit, e.Location) || hit.Item is null)
        {
            return;
        }

        _sync.RetryFile(hit.Item.Text);
    }

    static bool IsTryHit(ListViewHitTestInfo hit, Point location)
    {
        if (hit.Item is null || hit.SubItem is null || hit.Item.SubItems.IndexOf(hit.SubItem) != TryColumn)
        {
            return false;
        }

        return hit.SubItem.Text == "Try" && TryButtonBounds(hit.SubItem.Bounds).Contains(location);
    }

    static Rectangle TryButtonBounds(Rectangle cell)
    {
        var width = Math.Min(64, Math.Max(40, cell.Width - 12));
        var height = Math.Min(24, Math.Max(18, cell.Height - 6));
        return new Rectangle(cell.X + 6, cell.Y + ((cell.Height - height) / 2), width, height);
    }

    void BrowseFolderClick(object? sender, EventArgs e)
    {
        using var dialog = new FolderBrowserDialog
        {
            Description = "Choose the backup folder to watch",
            UseDescriptionForTitle = true,
            SelectedPath = Directory.Exists(_folderBox.Text) ? _folderBox.Text : _settings.WatchFolder,
        };
        if (dialog.ShowDialog(this) == DialogResult.OK)
        {
            _folderBox.Text = dialog.SelectedPath;
        }
    }

    void SaveSettingsClick(object? sender, EventArgs e)
    {
        var folder = _folderBox.Text.Trim();
        if (folder.Length == 0)
        {
            _status.Text = "Choose a backup folder.";
            return;
        }

        try
        {
            folder = Path.GetFullPath(folder);
        }
        catch (Exception ex) when (ex is ArgumentException or NotSupportedException or PathTooLongException)
        {
            _status.Text = "That folder path is not valid.";
            return;
        }

        var interval = (int)_interval.Value;
        _settings.WatchFolder = folder;
        _settings.RetrySeconds = interval;
        try
        {
            _settings.Save();
        }
        catch (Exception ex) when (ex is IOException or UnauthorizedAccessException)
        {
            _status.Text = "Could not save settings.";
            return;
        }

        _folderBox.Text = folder;
        _sync.ApplyWatch(folder, interval);
    }

    void ClearLogClick(object? sender, EventArgs e)
    {
        _sync.ClearActivity();
        var cleared = AppLog.Clear();
        _log.Items.Clear();
        _shownActivity = 0;
        _status.Text = cleared ? "Log cleared." : "Could not clear the log file.";
    }

    void OnNewFile(string name)
    {
        if (IsDisposed || !IsHandleCreated)
        {
            return;
        }

        BeginInvoke(() =>
        {
            RefreshLists();
            _status.Text = $"New file found: {name}";
            var tip = name.Length <= 60 ? name : name[..60];
            _tray.ShowBalloonTip(4000, "New backup file", tip, ToolTipIcon.Info);
        });
    }

    void AccentClick(object? sender, EventArgs e)
    {
        _sync.ScanNow();
        _status.Text = "Looking for new backup files…";
    }

    void OnStatus(string message)
    {
        if (IsDisposed || !IsHandleCreated)
        {
            return;
        }

        BeginInvoke(() =>
        {
            _status.Text = message;
            var tip = message.Length <= 63 ? message : message[..63];
            _tray.Text = tip;
            if (message.StartsWith("Uploading ", StringComparison.Ordinal))
            {
                _uploadBar.ShowUpload(message["Uploading ".Length..]);
            }
            else
            {
                _uploadBar.HideIdle();
            }
        });
    }

    void OnProgress(UploadProgress progress)
    {
        if (IsDisposed || !IsHandleCreated)
        {
            return;
        }

        BeginInvoke(() =>
        {
            var percent = progress.Total <= 0 ? 0 : (int)Math.Clamp(progress.Sent * 100 / progress.Total, 0, 100);
            _uploadBar.SetProgress(progress.FileName, percent);
            _status.Text = $"Uploading {progress.FileName}  {percent}%";
            var tip = _status.Text.Length <= 63 ? _status.Text : _status.Text[..63];
            _tray.Text = tip;
            foreach (ListViewItem item in _files.Items)
            {
                if (item.SubItems.Count > 5
                    && item.Text == progress.FileName
                    && item.SubItems[3].Text == "Uploading")
                {
                    item.SubItems[5].Text = $"{percent}% sent";
                    break;
                }
            }
        });
    }

    void OnViewChanged()
    {
        if (IsDisposed || !IsHandleCreated)
        {
            return;
        }

        BeginInvoke(RefreshLists);
    }

    void RefreshLists()
    {
        var rows = _sync.ListFiles();
        _files.BeginUpdate();
        _files.Items.Clear();
        var uploaded = 0;
        var failed = 0;
        foreach (var row in rows)
        {
            if (row.Status == "Uploaded")
            {
                uploaded++;
            }
            else if (row.Status == "Failed")
            {
                failed++;
            }

            var item = new ListViewItem(row.Name);
            item.SubItems.Add(FormatSize(row.Length));
            item.SubItems.Add(row.ModifiedLocal.ToString("dd MMM yyyy HH:mm"));
            item.SubItems.Add(row.Status);
            item.SubItems.Add(row.Status == "Failed" ? "Try" : "");
            item.SubItems.Add(row.Detail);
            item.ForeColor = StatusColor(row.Status);
            _files.Items.Add(item);
        }

        _files.EndUpdate();
        _summary.Text = rows.Length == 0
            ? $"No backup files in {_settings.WatchFolder}"
            : $"{rows.Length} files    {uploaded} uploaded    {failed} failed";

        var activity = _sync.ActivitySnapshot();
        if (activity.Length < _shownActivity)
        {
            _shownActivity = 0;
            _log.Items.Clear();
        }

        _log.BeginUpdate();
        for (var index = _shownActivity; index < activity.Length; index++)
        {
            var entry = activity[index];
            var item = new ListViewItem(entry.WhenLocal.ToString("dd MMM yyyy HH:mm:ss"));
            item.SubItems.Add(entry.Result == "Uploaded" ? "Success" : "Failed");
            item.SubItems.Add(entry.FileName);
            item.SubItems.Add(entry.Message);
            item.ForeColor = StatusColor(entry.Result);
            _log.Items.Add(item);
            item.EnsureVisible();
        }

        _log.EndUpdate();
        _shownActivity = activity.Length;
    }

    void LoadHistory()
    {
        if (!File.Exists(AppPaths.LogFile))
        {
            return;
        }

        string text;
        try
        {
            using var stream = new FileStream(AppPaths.LogFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            using var reader = new StreamReader(stream);
            text = reader.ReadToEnd();
        }
        catch (IOException)
        {
            return;
        }

        var lines = text.Split(["\r\n", "\n"], StringSplitOptions.RemoveEmptyEntries);
        var start = Math.Max(0, lines.Length - 200);
        for (var index = start; index < lines.Length; index++)
        {
            if (!TryParseHistory(lines[index], out var item))
            {
                continue;
            }

            _log.Items.Add(item);
        }

        if (_log.Items.Count > 0)
        {
            _log.Items[^1].EnsureVisible();
        }
    }

    static bool TryParseHistory(string line, out ListViewItem item)
    {
        item = null!;
        if (line.Length < 20)
        {
            return false;
        }

        var uploaded = line.IndexOf(" Uploaded ", StringComparison.Ordinal);
        var failed = line.IndexOf(" Upload failed for ", StringComparison.Ordinal);
        if (uploaded < 0 && failed < 0)
        {
            return false;
        }

        var timeText = line[..19];
        if (failed >= 0)
        {
            var rest = line[(failed + " Upload failed for ".Length)..];
            var split = rest.IndexOf(':');
            var name = split >= 0 ? rest[..split] : rest;
            var message = split >= 0 ? rest[(split + 1)..].Trim() : "";
            item = new ListViewItem(timeText);
            item.SubItems.Add("Failed");
            item.SubItems.Add(name.Trim());
            item.SubItems.Add(message);
            item.ForeColor = StatusColor("Failed");
            return true;
        }

        var body = line[(uploaded + " Uploaded ".Length)..];
        var colon = body.IndexOf(':');
        var fileName = colon >= 0 ? body[..colon] : body;
        var detail = colon >= 0 ? body[(colon + 1)..].Trim() : "";
        item = new ListViewItem(timeText);
        item.SubItems.Add("Success");
        item.SubItems.Add(fileName.Trim());
        item.SubItems.Add(detail);
        item.ForeColor = StatusColor("Uploaded");
        return true;
    }

    void WaitForShowSignal()
    {
        while (!_cancellation.IsCancellationRequested)
        {
            if (!_showSignal.WaitOne(500))
            {
                continue;
            }

            if (_cancellation.IsCancellationRequested || IsDisposed)
            {
                break;
            }

            try
            {
                BeginInvoke(ShowFromSignal);
            }
            catch (InvalidOperationException)
            {
                break;
            }
        }
    }

    void ShowFromSignal()
    {
        Show();
        WindowState = FormWindowState.Normal;
        Activate();
    }

    void ExitApp()
    {
        _exit = true;
        Close();
    }

    static ListView CreateList()
    {
        var list = new ListView
        {
            Dock = DockStyle.Fill,
            View = View.Details,
            FullRowSelect = true,
            GridLines = true,
            HeaderStyle = ColumnHeaderStyle.Nonclickable,
            BorderStyle = BorderStyle.None,
        };
        typeof(ListView).GetProperty("DoubleBuffered", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)
            ?.SetValue(list, true);
        return list;
    }

    static Label SettingsLabel(string text)
    {
        return new Label
        {
            Text = text,
            AutoSize = true,
            Margin = new Padding(0, 8, 8, 0),
            TextAlign = System.Drawing.ContentAlignment.MiddleLeft,
        };
    }

    static Button MakeButton(string text, EventHandler click, bool outline = false)
    {
        var button = new Button
        {
            Text = text,
            AutoSize = true,
            Padding = new Padding(12, 4, 12, 4),
            Margin = new Padding(0, 0, 8, 0),
            FlatStyle = FlatStyle.Flat,
            BackColor = outline ? Color.White : Color.FromArgb(12, 110, 105),
            ForeColor = outline ? Color.FromArgb(16, 40, 58) : Color.White,
            Cursor = Cursors.Hand,
        };
        button.FlatAppearance.BorderColor = Color.FromArgb(180, 196, 206);
        button.Click += click;
        return button;
    }

    static Color StatusColor(string status)
    {
        return status switch
        {
            "Uploaded" => Color.FromArgb(8, 110, 100),
            "Failed" => Color.FromArgb(154, 52, 18),
            "Uploading" => Color.FromArgb(20, 84, 140),
            _ => Color.FromArgb(20, 36, 51),
        };
    }

    static string FormatSize(long size)
    {
        var value = (double)size;
        foreach (var unit in new[] { "B", "KB", "MB", "GB" })
        {
            if (value < 1024 || unit == "GB")
            {
                return unit == "B" ? $"{size} B" : $"{value:0.#} {unit}";
            }

            value /= 1024;
        }

        return $"{size} B";
    }

    static void OpenFolder(string folder)
    {
        if (!Directory.Exists(folder))
        {
            return;
        }

        Process.Start(new ProcessStartInfo
        {
            FileName = "explorer.exe",
            Arguments = $"\"{folder}\"",
            UseShellExecute = true,
        });
    }

}