using Avalonia.Threading;
using Nonemm.App.Dialogs;
using Nonemm.Core;
using Nonemm.Keying;
using Nonemm.Session;
using Nonemm.Spotting;

namespace Nonemm.App.Windows;

/// Running a function key message: the action macros in it, the text that goes
/// on the air, and the actions N1MM's `{END}` holds back until the message has
/// gone out.
public sealed partial class EntryWindow
{
    /// A keyer that says nothing after this long is taken as finished, so the
    /// actions after `{END}` still run.
    private static readonly TimeSpan SendingPatience = TimeSpan.FromMinutes(2);

    /// What sends this radio's messages: the digital engine on a digital mode,
    /// and the CW or voice keyer otherwise. A message therefore goes out the
    /// way the mode needs without the caller choosing.
    private MessageSender? Sender =>
        Logging?.Mode.Category == ModeCategory.Digital && session.DigitalKeyer is { IsReady: true } engine
            ? engine
            : session.Keyer;

    /// What to say when a message has nowhere to go. The mode decides which
    /// keyer a message uses, so the mode is part of the answer: an operator on
    /// a data mode who sees "no keyer for USB" knows to move the radio or the
    /// band panel rather than to look at the keyer settings.
    private string NoKeyer() =>
        Logging is { } logging
            ? $"no keyer for {logging.Mode.Name} — Config ▸ Keyer"
            : "no keyer — Config ▸ Keyer";

    /// The twelve keys for this radio, which are a different twelve while
    /// running and while searching, as N1MM's file holds them.
    private IReadOnlyList<FunctionKey> Keys() =>
        Messages
            .For(
                Logging?.Mode.Category ?? Core.ModeCategory.Cw,
                session.Settings.CwMessageFile,
                session.Settings.PhoneMessageFile)
            .Keys(Logging?.IsRunning ?? false);

    /// Right-clicking a function key button opens the messages for the mode the
    /// radio is in, which is where import and export live too.
    private Task EditMessages() => EditMessages(Logging?.Mode.Category ?? ModeCategory.Cw);

    private async Task EditMessages(ModeCategory mode)
    {
        string stored = mode == ModeCategory.Phone
            ? session.Settings.PhoneMessageFile
            : session.Settings.CwMessageFile;
        if (await new MessagesDialog(mode, stored, folder: session.Paths.FunctionKeyMessages).ShowDialog<string?>(this) is not { } edited)
        {
            return;
        }
        session.Save(mode == ModeCategory.Phone
            ? session.Settings with { PhoneMessageFile = edited }
            : session.Settings with { CwMessageFile = edited });
        BuildFunctionKeys();
        Refresh();
    }

    private void SendMessage(int index) => _ = SendKeyAsync(index);

    /// Sends one function key's message. The task finishes when the text has
    /// been handed to the keyer, not when it has gone out on the air, so a
    /// second key can be queued behind it. `prefix` carries the corrected call
    /// that ESM puts in front of the message that ends a contact.
    private async Task SendKeyAsync(int index, string prefix = "")
    {
        if (Logging is null)
        {
            return;
        }
        string template = Keys()[index].Message;
        if (template.Length == 0)
        {
            return;
        }
        MessagePlan plan = MessagePlan.Read(template, Logging, session.Other(Logging));
        foreach (MessageAction action in plan.Before)
        {
            Run(action);
        }
        Refresh();
        if (plan.Text.Length == 0)
        {
            // a key that only acts: {WIPE}, {RUN}, {TELNET sh/dx}
            return;
        }
        if (Sender is null)
        {
            Status(NoKeyer());
            return;
        }
        if (index == Esm.Exchange)
        {
            // the BARTG contest sends the time, and logs the one it sent
            Logging.StampSentTime();
        }
        // only a CQ carries alternating CQ on to the other radio
        if (index == Esm.CallCq)
        {
            session.Alternating?.CarryOn();
            CqSent?.Invoke(this, EventArgs.Empty);
        }
        else
        {
            session.Alternating?.Hold();
        }
        string text = prefix + plan.Text;
        // the box has to point at this radio before the key does
        await session.PointTransmitAtAsync(radioNumber);
        Status($"sending {text}");
        await SendThenAsync(Sender, text, plan.After);
    }

    /// Sends a message that did not come from a function key. The QTC window
    /// hands its traffic over this way, as N1MM's does through its own entry
    /// window, so it goes out through the same keyer with the same macros
    /// expanded.
    /// `through` is the keyer the caller insists on: the digital window keys
    /// its own engine whatever mode the entry window is on, which is what
    /// N1MM's digital window does. Everyone else passes null and gets the keyer
    /// the mode calls for. False when nothing went out, with the reason already
    /// in the status line.
    internal async Task<bool> SendTextAsync(string template, MessageSender? through = null)
    {
        if (Logging is null || template.Trim().Length == 0)
        {
            return false;
        }
        MessagePlan plan = MessagePlan.Read(template, Logging, session.Other(Logging));
        foreach (MessageAction action in plan.Before)
        {
            Run(action);
        }
        if (plan.Text.Length == 0)
        {
            // a button that only acts: {WIPE}, {LOG}, {RUN}
            return true;
        }
        if ((through ?? Sender) is not { } keyer)
        {
            Status(NoKeyer());
            return false;
        }
        await session.PointTransmitAtAsync(radioNumber);
        Status($"sending {plan.Text}");
        await SendThenAsync(keyer, plan.Text, plan.After);
        return true;
    }

    /// Hands the text to the keyer, and leaves what follows `{END}` to run on
    /// its own once the keyer says the message has gone out.
    private async Task SendThenAsync(MessageSender keyer, string text, IReadOnlyList<MessageAction> after)
    {
        try
        {
            sending = true;
            Refresh();
            await keyer.SendAsync(text);
        }
        catch (InvalidOperationException e)
        {
            sending = false;
            Status(e.Message);
            return;
        }
        _ = RunWhenSentAsync(keyer, after);
    }

    /// Waits for the keyer, turns the transmit light off, and runs whatever
    /// stood after `{END}`.
    private async Task RunWhenSentAsync(MessageSender keyer, IReadOnlyList<MessageAction> after)
    {
        await WhenSentAsync(keyer);
        Dispatcher.UIThread.Post(() =>
        {
            sending = false;
            foreach (MessageAction action in after)
            {
                Run(action);
            }
            Refresh();
        });
    }

    /// Waits for the keyer to say the message has gone out. A keyer that does
    /// not report completion is taken at its word as soon as the text is sent,
    /// because the alternative is never running what follows `{END}`.
    private static async Task WhenSentAsync(MessageSender keyer)
    {
        if (!keyer.ReportsCompletion)
        {
            return;
        }
        TaskCompletionSource sent = new();
        void Finished(object? sender, EventArgs e) => sent.TrySetResult();
        keyer.Finished += Finished;
        try
        {
            await sent.Task.WaitAsync(SendingPatience);
        }
        catch (TimeoutException)
        {
        }
        finally
        {
            keyer.Finished -= Finished;
        }
    }

    private void Run(MessageAction action)
    {
        if (Logging is null)
        {
            return;
        }
        switch (action.Command)
        {
            case MessageCommand.Wipe:
                Logging.Wipe();
                SyncBoxes();
                boxes[0].Focus();
                break;
            case MessageCommand.Log:
                LogContact();
                break;
            case MessageCommand.Run:
                Logging.IsRunning = true;
                break;
            case MessageCommand.SearchAndPounce:
                Logging.IsRunning = false;
                break;
            case MessageCommand.Space:
                MoveFocus(forward: true);
                break;
            case MessageCommand.SpotMe:
                SpotMe();
                break;
            case MessageCommand.ExchangeSent:
                exchangeSent = true;
                break;
            // the manual's table has the two page macros the other way round;
            // the keys they are named after move the frequency this way
            case MessageCommand.FrequencyUp:
                Step(session.Settings.FrequencyStepHertz);
                break;
            case MessageCommand.FrequencyDown:
                Step(-session.Settings.FrequencyStepHertz);
                break;
            case MessageCommand.PageUp:
                Step(session.Settings.PageStepHertz);
                break;
            case MessageCommand.PageDown:
                Step(-session.Settings.PageStepHertz);
                break;
            case MessageCommand.StopSending:
                sending = false;
                _ = Sender?.AbortAsync();
                break;
            case MessageCommand.Telnet:
                SendToCluster(action.Argument);
                break;
            case MessageCommand.JumpToOtherRadio:
                session.SwapRadio();
                break;
            case MessageCommand.JumpToOtherRadioWithTransmit:
                session.SwapRadio();
                _ = session.PointTransmitAtAsync(session.ActiveRadioNumber);
                break;
            case MessageCommand.SendOnOtherRadio:
                SendOnOtherRadio(action.Argument);
                break;
            case MessageCommand.Otrsp:
                _ = session.Box?.SendCommandAsync(action.Argument);
                break;
            case MessageCommand.StackAnother:
                StackAnother();
                break;
            case MessageCommand.SwapWithStack:
                SwapWithStack();
                break;
            case MessageCommand.LogThenPop:
                LogThenPop();
                break;
            case MessageCommand.ClearStack:
                Logging.Stack.Clear();
                ShowCallStack();
                break;
            // the digital engine keys itself while it has text to send, so
            // {TX} and {RX} only matter when a macro wants the transmitter
            // held open around what it sends
            case MessageCommand.StartTransmit:
                _ = session.Digital?.SetPttAsync(true);
                break;
            case MessageCommand.ReturnToReceive:
                _ = session.Digital?.ReturnToReceiveAsync();
                break;
        }
    }

    /// N1MM's {STACKANOTHER} and Ctrl+Alt+G.
    private void StackAnother()
    {
        if (Logging is null || !Logging.StackAnother())
        {
            return;
        }
        SyncBoxes();
        boxes[0].Focus();
        ShowCallStack();
        Status($"{Logging.Stack.Count} stacked");
    }

    /// N1MM's Alt+G.
    private void GrabStacked()
    {
        if (Logging is null || !Logging.GrabStacked())
        {
            return;
        }
        SyncBoxes();
        boxes[0].Focus();
        ShowCallStack();
    }

    /// N1MM's Alt+D: the call on top of the stack is dropped without being
    /// worked.
    private void DropStacked()
    {
        if (Logging is null || Logging.Stack.IsEmpty)
        {
            return;
        }
        Status($"{Logging.Stack.Next()} dropped");
        ShowCallStack();
    }

    /// N1MM's {SOCALLSTACK}.
    private void SwapWithStack()
    {
        if (Logging is null)
        {
            return;
        }
        Logging.SwapWithStack();
        SyncBoxes();
        boxes[0].Focus();
        ShowCallStack();
    }

    /// N1MM's {LOGTHENPOP} and {LOGTHENNEXT}: one key logs the contact and
    /// brings the next caller into the boxes, so a run does not stop between
    /// callers.
    private void LogThenPop()
    {
        if (Logging is null || !Logging.IsRunning)
        {
            return;
        }
        LogContact();
        GrabStacked();
    }

    private void Step(int hertz)
    {
        if (Logging is null)
        {
            return;
        }
        Frequency moved = Frequency.FromHertz(Logging.Frequency.Hertz + hertz);
        Logging.Tune(moved);
        _ = session.Radio?.TuneAsync(moved);
        Refresh();
    }

    /// N1MM only self-spots while running, and so does this: a station that is
    /// not calling CQ has nothing to tell the cluster.
    private void SpotMe()
    {
        if (Logging is null || session.Cluster is not { IsConnected: true } cluster)
        {
            Status("not connected to a cluster node");
            return;
        }
        if (!Logging.IsRunning)
        {
            Status("self-spotting is for running only");
            return;
        }
        Callsign me = Callsign.Parse(Logging.Me.Callsign);
        string comment = MessageExpander.Expand(
            session.Settings.SpotComment, Logging, session.Other(Logging));
        _ = cluster.SendSpotAsync(Logging.Frequency, me, comment);
        session.Bandmap.Add(new Spot(me, Logging.Frequency, DateTime.UtcNow, SpotSource.Operator));
        Status($"spotted {me.Text} on {Logging.Frequency.Kilohertz:0.0}");
    }

    private void SendToCluster(string command)
    {
        if (session.Cluster is not { } cluster)
        {
            Status("not connected to a cluster node");
            return;
        }
        _ = cluster.SendAsync(command);
        Status($"cluster: {command}");
    }

    /// `{CTRLFn}` sends the other radio's message n while the keyboard stays
    /// here, which is how an SO2R station CQs on the other radio.
    private void SendOnOtherRadio(string key)
    {
        if (Logging is null
            || session.Other(Logging) is not { } other
            || Sender is null
            || !int.TryParse(key, out int number))
        {
            return;
        }
        string template = Messages
            .For(other.Mode.Category, session.Settings.CwMessageFile, session.Settings.PhoneMessageFile)
            .Keys(other.IsRunning)[number - 1]
            .Message;
        if (template.Length == 0)
        {
            return;
        }
        string text = MessageExpander.Expand(template, other, Logging);
        _ = SendOnOtherRadioAsync(other.RadioNumber, text);
        Status($"radio {other.RadioNumber}: {text}");
    }

    private async Task SendOnOtherRadioAsync(int radio, string text)
    {
        await session.PointTransmitAtAsync(radio);
        try
        {
            await Sender!.SendAsync(text);
        }
        catch (InvalidOperationException e)
        {
            Status(e.Message);
        }
    }
}