using Avalonia.Controls;
using Avalonia.Input;
using Avalonia.Input.Platform;
using Avalonia.Interactivity;
using Avalonia.Media;
using Avalonia.Threading;
using Nonemm.App.Configuration;
using Nonemm.Core;
using Nonemm.Session;
using Nonemm.Spotting;

namespace Nonemm.App.Windows;

/// The cluster node's traffic as it arrived, a line to send commands on, and
/// the tabs that say which node to talk to and which spots to keep. Double
/// clicking a spot line puts the radio on it.
public sealed partial class TelnetWindow : RefreshableWindow
{
    private const int LinesKept = 500;

    private static readonly IBrush SpotColour = new SolidColorBrush(Color.FromRgb(0x27, 0xAE, 0x60));
    private static readonly IBrush SentColour = new SolidColorBrush(Color.FromRgb(0x29, 0x80, 0xB9));
    private static readonly IBrush NoticeColour = new SolidColorBrush(Color.FromRgb(0x7F, 0x8C, 0x8D));

    private readonly AppSession session;
    private readonly Action<Frequency, string> tune;
    private readonly List<string> history = [];
    private int recalled = -1;
    private bool paused;

    public TelnetWindow(AppSession session, Action<Frequency, string> tune)
    {
        this.session = session;
        this.tune = tune;
        InitializeComponent();
        LoadButtons();
        LoadButtonRows();
        LoadClusters();
        LoadFilters();
        Listen(session.Cluster);
        Closed += (_, _) => Forget(session.Cluster);
        Refresh();
    }

    /// Config ▸ Cluster opens the window here, because this is where the node
    /// is chosen.
    public void ShowClusters() => Tabs.SelectedIndex = 1;

    public void ShowButtons() => Tabs.SelectedIndex = 3;

    public override void Refresh()
    {
        ClusterClient? cluster = session.Cluster;
        string kind = cluster?.Kind switch
        {
            ClusterKind.DxSpider => " · DXSpider",
            ClusterKind.ArCluster => " · AR-Cluster",
            ClusterKind.CcCluster => " · CC Cluster",
            ClusterKind.GoCluster => " · GoCluster",
            _ => "",
        };
        StateText.Text = cluster is null
            ? "not connected — pick a node on the Clusters tab"
            : cluster.IsConnected
                ? $"connected to {cluster.Host}:{cluster.Port}{kind}"
                : $"connecting to {cluster.Host}:{cluster.Port}…";
        ReconnectButton.Content = cluster is null ? "Connect" : "Reconnect";
    }

    /// The traffic so far is put up first, so a window opened mid-contest is
    /// not blank. Taking it before subscribing keeps a line from appearing
    /// twice.
    private void Listen(ClusterClient? cluster)
    {
        if (cluster is null)
        {
            return;
        }
        IReadOnlyList<ClusterLine> already = cluster.Recent;
        cluster.LineArrived += OnLineArrived;
        cluster.LineSent += OnLineSent;
        cluster.ConnectionChanged += OnConnectionChanged;
        foreach (ClusterLine line in already)
        {
            if (line.WasSent)
            {
                OnLineSent(cluster, line.Text);
            }
            else
            {
                OnLineArrived(cluster, line.Text);
            }
        }
    }

    private void Forget(ClusterClient? cluster)
    {
        if (cluster is null)
        {
            return;
        }
        cluster.LineArrived -= OnLineArrived;
        cluster.LineSent -= OnLineSent;
        cluster.ConnectionChanged -= OnConnectionChanged;
    }

    private void OnLineArrived(object? sender, string line)
    {
        if (line.StartsWith("***", StringComparison.Ordinal))
        {
            Show(line, NoticeColour);
            return;
        }
        if (SpotLine.Parse(line, DateTime.UtcNow) is not { } spot)
        {
            Show(line, Foreground);
            return;
        }
        Show(line, SpotColour, IsPreferred(spot.Spotter));
    }

    /// A spotter the operator listed on the Filters tab. N1MM matches on the
    /// start of the call, so `W3LPL` also covers `W3LPL-#`.
    private bool IsPreferred(string spotter) =>
        session.Settings.SpotFilter.PreferredSpotters.Any(one =>
            one.Length > 0 && spotter.StartsWith(one, StringComparison.OrdinalIgnoreCase));

    private void OnLineSent(object? sender, string line) => Show($"> {line}", SentColour);

    private void OnConnectionChanged(object? sender, bool connected) =>
        Dispatcher.UIThread.Post(Refresh);

    /// `strong` marks the lines from a preferred spotter.
    private void Show(string line, IBrush? colour, bool strong = false) => Dispatcher.UIThread.Post(() =>
    {
        while (Traffic.Items.Count >= LinesKept)
        {
            Traffic.Items.RemoveAt(0);
        }
        Traffic.Items.Add(new TextBlock
        {
            Text = line,
            Foreground = colour,
            FontWeight = strong ? FontWeight.Bold : FontWeight.Normal,
        });
        if (!paused && Traffic.Items.Count > 0)
        {
            Traffic.ScrollIntoView(Traffic.Items.Count - 1);
        }
        Refresh();
    });

    /// Scrolling stops while the pointer is over the traffic, so a line can be
    /// read or copied while the node keeps sending.
    private void OnTrafficEntered(object? sender, PointerEventArgs e)
    {
        paused = true;
        PausedText.IsVisible = true;
    }

    private void OnTrafficExited(object? sender, PointerEventArgs e)
    {
        paused = false;
        PausedText.IsVisible = false;
        if (Traffic.Items.Count > 0)
        {
            Traffic.ScrollIntoView(Traffic.Items.Count - 1);
        }
    }

    /// The label takes the macros as well, expanded once here, which is what
    /// N1MM does when it loads its buttons.
    private void LoadButtons()
    {
        ButtonRow.Children.Clear();
        foreach (StoredTelnetButton stored in Buttons())
        {
            Button button = new()
            {
                Content = Expanded(stored.Label),
                FontSize = 11,
                Padding = new Avalonia.Thickness(6, 3),
                Margin = new Avalonia.Thickness(0, 0, 3, 3),
                Tag = stored,
            };
            ToolTip.SetTip(button, $"{stored.Command}\nright-click to edit the buttons");
            button.Click += OnButtonPressed;
            button.PointerReleased += OnButtonRightClick;
            ButtonRow.Children.Add(button);
        }
    }

    /// Right-clicking a button opens the editor, as it does in N1MM.
    private void OnButtonRightClick(object? sender, PointerReleasedEventArgs e)
    {
        if (e.InitialPressMouseButton == MouseButton.Right)
        {
            ShowButtons();
        }
    }

    private IReadOnlyList<StoredTelnetButton> Buttons() =>
        session.Settings.TelnetButtons.Count > 0
            ? session.Settings.TelnetButtons
            : StoredTelnetButton.Default;

    /// A button's text is N1MM's: the message macros, and `{CONN}node` to
    /// connect to a favourite instead of sending anything. Several commands are
    /// separated by semicolons and go out one after the other.
    private async void OnButtonPressed(object? sender, RoutedEventArgs e)
    {
        if (sender is not Button { Tag: StoredTelnetButton stored })
        {
            return;
        }
        if (ConnectToFavourite(stored.Command))
        {
            return;
        }
        foreach (string command in Expanded(stored.Command).Split(';', StringSplitOptions.RemoveEmptyEntries))
        {
            await SendAsync(command.Trim());
        }
    }

    /// The same macros the function keys take. With no contest open there is
    /// nothing to fill them from, so the text goes out as it was typed.
    private string Expanded(string text) =>
        session.Position is { } position
            ? MessageExpander.Expand(text, position, session.Other(position))
            : text;

    private async void OnSend(object? sender, RoutedEventArgs e)
    {
        if (CommandBox.Text is not { Length: > 0 } command)
        {
            return;
        }
        history.Add(command);
        recalled = -1;
        CommandBox.Text = "";
        // what is typed goes out as it was typed, the way N1MM sends it
        await SendAsync(command);
    }

    /// Up and down walk back through what has been typed, the way a terminal
    /// does.
    private void OnCommandKey(object? sender, KeyEventArgs e)
    {
        if (history.Count == 0 || (e.Key != Key.Up && e.Key != Key.Down))
        {
            return;
        }
        recalled = e.Key == Key.Up
            ? Math.Min(recalled + 1, history.Count - 1)
            : Math.Max(recalled - 1, -1);
        CommandBox.Text = recalled < 0 ? "" : history[history.Count - 1 - recalled];
        CommandBox.CaretIndex = CommandBox.Text.Length;
        e.Handled = true;
    }

    private async Task SendAsync(string command)
    {
        if (session.Cluster is not { } cluster)
        {
            Show("*** not connected to a node", NoticeColour);
            return;
        }
        // N1MM refuses this one too: asking the node for spots is what an
        // unassisted entry may not do, and the category is what the log claims
        if (command.Contains("SH/DX", StringComparison.OrdinalIgnoreCase) && !IsAssisted)
        {
            Show("*** you cannot use sh/dx while unassisted", NoticeColour);
            return;
        }
        await cluster.SendAsync(command);
    }

    /// True while no contest is open: nothing is being claimed yet.
    private bool IsAssisted => session.Logging?.Instance.IsAssisted ?? true;

    private void OnReconnect(object? sender, RoutedEventArgs e) => Connect();

    /// Tunes the radio to the spot on the selected line, which is what N1MM's
    /// "Jump to this spot" does.
    private void OnJumpToSpot(object? sender, RoutedEventArgs e)
    {
        if (Traffic.SelectedItem is not TextBlock { Text: { } line })
        {
            return;
        }
        if (SpotLine.Parse(line, DateTime.UtcNow) is not { } spot)
        {
            Show("*** that line is not a spot", NoticeColour);
            return;
        }
        tune(spot.Frequency, spot.Call.Text);
    }

    private async void OnCopyLine(object? sender, RoutedEventArgs e)
    {
        if (Traffic.SelectedItem is TextBlock { Text: { } line } && Clipboard is { } clipboard)
        {
            await clipboard.SetTextAsync(line);
        }
    }

    private void OnClearTraffic(object? sender, RoutedEventArgs e) => Traffic.Items.Clear();
}