using System.Globalization;
using Avalonia.Controls;
using Avalonia.Interactivity;
using Avalonia.Threading;
using Nonemm.App.Configuration;
using Nonemm.App.Dialogs;
using Nonemm.Network;

namespace Nonemm.App.Windows;

/// The other computers of this entry: who they are, where they are on the
/// bands, how fast they are working people, and whether anything is arriving
/// from them. N1MM's network status window, with its tabs and its columns.
///
/// A row per station, this computer included, which is how N1MM shows it: the
/// operator reads its own station number and the version it is claiming off the
/// same window as everybody else's.
///
/// Five of N1MM's tabs are here. Its Options tab and its call-stacking target
/// tab are not: the transmit interlocks behind Options are not written, and a
/// tab of controls that do nothing is worse than no tab.
///
/// The window redraws once a second and on every message, which on a busy
/// network is several a second. That is what a status window is for, and the
/// table is a dozen rows.
public sealed partial class NetworkStatusWindow : RefreshableWindow
{
    /// How much of the messages pane is kept.
    private const int MessageLines = 200;

    private readonly AppSession session;
    private readonly List<string> messages = [];
    private readonly Dictionary<string, TimeSpan> echoes = new(StringComparer.OrdinalIgnoreCase);
    private readonly DispatcherTimer clock;
    private StationLink? link;
    /// Set while a resync that was asked to rescore when it finishes is
    /// running. It holds the start of the period, which is what gets rescored.
    private DateTime? rescoreAfterResync;

    public NetworkStatusWindow(AppSession session)
    {
        this.session = session;
        InitializeComponent();
        Rows.LoadingRow += (_, e) =>
        {
            if (e.Row.DataContext is StationRow row)
            {
                e.Row.Foreground = row.Colour;
            }
        };
        // the two Since boxes start at the contest, which is the period an
        // operator asks for most often
        string start = (session.Logging?.Instance.StartDate ?? DateTime.UtcNow)
            .ToString("yyyy-MM-dd HH:mm", CultureInfo.InvariantCulture);
        ResyncSinceBox.Text = start;
        RescoreSinceBox.Text = start;
        Attach();
        // the Receive column is a countdown, so it has to redraw with nothing
        // arriving
        clock = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
        clock.Tick += (_, _) => Refresh();
        clock.Start();
        Closed += (_, _) =>
        {
            clock.Stop();
            Detach();
        };
        Refresh();
    }

    public override void Refresh()
    {
        Attach();
        NetworkingButton.Content = link is null ? "Start Networking" : "Stop Networking";
        if (link is null)
        {
            Rows.ItemsSource = Array.Empty<StationRow>();
            StateText.Text =
                "the link to the other logging computers is off — Edit Computer Addresses turns it on";
            ShowMessages();
            return;
        }
        DateTime now = DateTime.UtcNow;
        string? selected = (Rows.SelectedItem as StationRow)?.Station.ComputerName;
        List<StationRow> rows = link.Stations
            .OrderBy(s => s.StationNumber)
            .ThenBy(s => s.ComputerName, StringComparer.OrdinalIgnoreCase)
            .Select(s => new StationRow(s, now))
            .ToList();
        Rows.ItemsSource = rows;
        Rows.SelectedItem = rows.FirstOrDefault(r =>
            string.Equals(r.Station.ComputerName, selected, StringComparison.OrdinalIgnoreCase));
        ResyncRows.ItemsSource = rows.Where(r => !r.Station.IsMine).ToList();
        RescoreWhenResyncDone();
        ReportEchoes();
        StateText.Text = State();
        ShowMessages();
    }

    /// What the link is doing, under the tabs. A station that broadcast the
    /// wrong version is named here: it is the one fault that leaves everything
    /// looking connected and nothing arriving.
    private string State()
    {
        if (link is null)
        {
            return "";
        }
        List<NetworkedStation> others = link.Stations.Where(s => !s.IsMine).ToList();
        int connected = others.Count(s => s.IsConnected);
        string what = $"station {link.StationNumber} as {link.ComputerName}, "
            + $"claiming version {session.Settings.StationLinkVersion} — "
            + $"{connected} of {others.Count} other stations connected";
        List<string> refused = others
            .Where(s => s.Refused.Length > 0)
            .Select(s => $"{s.ComputerName}: {s.Refused}")
            .ToList();
        return refused.Count > 0 ? $"{what}\n{string.Join("\n", refused)}" : what;
    }

    /// An echo that has come back since the last redraw goes into the messages
    /// pane, because that is where the operator who pressed the button is
    /// looking.
    private void ReportEchoes()
    {
        foreach (NetworkedStation station in link!.Stations)
        {
            if (station.EchoTime is not { } echo
                || (echoes.TryGetValue(station.ComputerName, out TimeSpan last) && last == echo))
            {
                continue;
            }
            echoes[station.ComputerName] = echo;
            Say($"{station.ComputerName} answered in {echo.TotalMilliseconds:0} ms");
        }
    }

    private void Attach()
    {
        if (ReferenceEquals(link, session.Link))
        {
            return;
        }
        Detach();
        link = session.Link;
        if (link is null)
        {
            return;
        }
        link.StationsChanged += WhenStationsChanged;
        link.TalkArrived += WhenTalkArrived;
        link.Failed += WhenFailed;
        link.MessageArrived += WhenMessageArrived;
    }

    private void Detach()
    {
        if (link is null)
        {
            return;
        }
        link.StationsChanged -= WhenStationsChanged;
        link.TalkArrived -= WhenTalkArrived;
        link.Failed -= WhenFailed;
        link.MessageArrived -= WhenMessageArrived;
        link = null;
    }

    /// The link raises its events on a socket thread, so everything that draws
    /// is posted.
    private void WhenStationsChanged(object? sender, EventArgs e) =>
        Dispatcher.UIThread.Post(Refresh);

    private void WhenTalkArrived(object? sender, string text) =>
        Dispatcher.UIThread.Post(() => Say(text));

    private void WhenFailed(object? sender, string why) =>
        Dispatcher.UIThread.Post(() => Say(why));

    private void WhenMessageArrived(object? sender, StationRecord record) =>
        Dispatcher.UIThread.Post(() =>
        {
            if (TraceBox.IsChecked == true)
            {
                Say($"{record.ComputerName} {record.Type} {string.Join(" ", record.Fields)}".TrimEnd());
            }
        });

    private void Say(string text)
    {
        messages.Add($"{DateTime.UtcNow:HH:mm:ss} {text}");
        if (messages.Count > MessageLines)
        {
            messages.RemoveRange(0, messages.Count - MessageLines);
        }
        ShowMessages();
    }

    private void ShowMessages()
    {
        MessageText.Text = string.Join("\n", messages);
        MessageScroll.ScrollToEnd();
    }

    /// The rescore an operator asked for when the resync is done, once every
    /// station has stopped.
    private void RescoreWhenResyncDone()
    {
        if (rescoreAfterResync is not { } from
            || link is null
            || link.Stations.Any(s => s.IsResyncing))
        {
            return;
        }
        rescoreAfterResync = null;
        Say($"rescored {session.Rescore(from)} contacts");
    }

    /// The start of the period the resync and rescore buttons work on.
    /// `Since` reads the box, which is a time of day in UTC the way the rest of
    /// the program writes one.
    private DateTime? Since(TextBox box)
    {
        if (DateTime.TryParseExact(
            (box.Text ?? "").Trim(),
            ["yyyy-MM-dd HH:mm", "yyyy-MM-dd HH:mm:ss", "yyyy-MM-dd"],
            CultureInfo.InvariantCulture,
            DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal,
            out DateTime when))
        {
            return when;
        }
        Say($"{box.Text} is not a time — write it as 2026-09-03 14:00");
        return null;
    }

    private static DateTime HoursAgo(TextBox box) =>
        DateTime.UtcNow.AddHours(-Math.Max(1, int.TryParse((box.Text ?? "").Trim(), out int hours) ? hours : 4));

    /// The whole contest, from three hours before it started. N1MM allows the
    /// same margin either side, for a clock that is out and for the contacts
    /// entered after the contest ended.
    private DateTime ContestStart() =>
        (session.Logging?.Instance.StartDate ?? DateTime.UtcNow.AddDays(-1)).AddHours(-3);

    private void OnResyncContest(object? sender, RoutedEventArgs e) => Resync(ContestStart());

    private void OnResyncSince(object? sender, RoutedEventArgs e)
    {
        if (Since(ResyncSinceBox) is { } from)
        {
            Resync(from);
        }
    }

    private void OnResyncLast(object? sender, RoutedEventArgs e) => Resync(HoursAgo(ResyncHoursBox));

    /// Asks every connected station whether it and this one hold the same
    /// contacts, an hour at a time, from `fromUtc` until now.
    private void Resync(DateTime fromUtc)
    {
        if (link is null)
        {
            return;
        }
        bool everyStation = ResyncAllBox.IsChecked == true;
        bool rescore = RescoreWhenDoneBox.IsChecked == true;
        rescoreAfterResync = rescore ? fromUtc : null;
        link.StartResyncAll(fromUtc, DateTime.UtcNow, everyStation, rescore);
        Say($"resync from {fromUtc:yyyy-MM-dd HH:mm}Z");
        Tabs.SelectedIndex = 2;
    }

    private void OnRescoreContest(object? sender, RoutedEventArgs e) => Rescore(DateTime.MinValue);

    private void OnRescoreSince(object? sender, RoutedEventArgs e)
    {
        if (Since(RescoreSinceBox) is { } from)
        {
            Rescore(from);
        }
    }

    private void OnRescoreLast(object? sender, RoutedEventArgs e) => Rescore(HoursAgo(RescoreHoursBox));

    /// Scores the log again and writes the points and multiplier flags back.
    /// Nothing is sent: the other stations score their own logs.
    private void Rescore(DateTime fromUtc)
    {
        int written = session.Rescore(fromUtc);
        RescoreText.Text = $"wrote {written} contacts at {DateTime.UtcNow:HH:mm:ss}Z";
        Say($"rescored {written} contacts");
    }

    /// The station the operator right-clicked, or null when the row is this
    /// computer's own: nothing in the menu is worth doing to yourself.
    private NetworkedStation? Chosen() =>
        Rows.SelectedItem is StationRow row && !row.Station.IsMine ? row.Station : null;

    private async void OnTalk(object? sender, RoutedEventArgs e)
    {
        if (link is null || (TalkBox.Text ?? "").Trim() is not { Length: > 0 } text)
        {
            return;
        }
        TalkBox.Text = "";
        Say($"[{link.ComputerName}] {text}");
        if (await link.SendTalkAsync(text) == 0)
        {
            Say("nobody is connected");
        }
    }

    private void OnTalkTo(object? sender, RoutedEventArgs e)
    {
        Tabs.SelectedIndex = 1;
        TalkBox.Focus();
    }

    private void OnShowMessages(object? sender, RoutedEventArgs e) => Tabs.SelectedIndex = 4;

    private async void OnEcho(object? sender, RoutedEventArgs e)
    {
        if (link is not null)
        {
            await link.SendEchoRequestAsync();
        }
    }

    /// This station's pass frequency: where it is now, and the callsign in the
    /// entry window if there is one. The other operators see it in their Pass
    /// column and know where to send a station that belongs on this band.
    private async void OnSetPass(object? sender, RoutedEventArgs e)
    {
        if (link is null || session.Position is not { } position)
        {
            return;
        }
        await link.SendPassAsync(position.Frequency, position.Entry.Call);
        Say($"passing on {position.Frequency.Kilohertz:0.0}");
    }

    /// The contact being worked, handed to one station. N1MM's Pass
    /// Current/Last QSO: the frequency this radio is on and the callsign in the
    /// entry window, to the position that is going to work it.
    private async void OnPassToStation(object? sender, RoutedEventArgs e)
    {
        if (link is null || Chosen() is not { } station || session.Position is not { } position)
        {
            return;
        }
        await link.SendPassAsync(position.Frequency, position.Entry.Call, station);
        Say($"passed {position.Entry.Call} on {position.Frequency.Kilohertz:0.0} to {station.ComputerName}");
    }

    private void OnCloseConnection(object? sender, RoutedEventArgs e)
    {
        if (link is not null && Chosen() is { } station)
        {
            link.Close(station);
            Say($"closed the connection to {station.ComputerName}");
            Refresh();
        }
    }

    private void OnOpenConnection(object? sender, RoutedEventArgs e)
    {
        if (link is not null && Chosen() is { } station)
        {
            link.Open(station);
            Say($"opening a connection to {station.ComputerName}");
            Refresh();
        }
    }

    /// Turns the link off, or back on. N1MM warns that stopping it during a
    /// contest is not a good idea, and it is right: the contacts made while it
    /// is off have to be resynchronised by hand.
    private void OnStopNetworking(object? sender, RoutedEventArgs e)
    {
        session.Save(session.Settings with { StationLinkEnabled = link is null });
        session.ApplyStationLinkSettings();
        Refresh();
    }

    private void OnClearMessages(object? sender, RoutedEventArgs e)
    {
        messages.Clear();
        ShowMessages();
    }

    private async void OnSetup(object? sender, RoutedEventArgs e)
    {
        NetworkDialog dialog = new(session.Settings);
        if (await dialog.ShowDialog<Settings?>(this) is { } updated)
        {
            session.Save(updated);
            session.ApplyNetworkSettings();
            session.ApplyStationLinkSettings();
            Refresh();
        }
    }
}