using Avalonia.Controls;
using Nonemm.Session;

namespace Nonemm.App.Windows;

/// Enter sends the message the contact has got to, which is how most operators
/// run N1MM. What goes out is decided by `Esm`; this keeps the state that
/// decision needs and sends what it asks for.
public sealed partial class EntryWindow
{
    private bool callSent;
    private bool exchangeSent;

    /// The call as it was when it last went out, for the corrected call.
    private string sentCall = "";

    /// What the last Enter sent, so `=` can send it again.
    private IReadOnlyList<int> lastKeys = [];

    private bool IsEsmOn => session.Settings.EsmEnabled;

    /// The keys the next Enter would send. The entry window highlights them, so
    /// the operator can see what is about to happen.
    private EsmAction NextEsmAction()
    {
        if (Logging is null)
        {
            return EsmAction.Nothing;
        }
        return Esm.Decide(new EsmSituation
        {
            IsRunning = Logging.IsRunning,
            HasCall = Logging.Entry.Call.Trim().Length > 0,
            IsDupe = Logging.Verdict()?.IsDupe == true,
            HasExchange = Logging.Entry.IsComplete,
            CallSent = callSent,
            ExchangeSent = exchangeSent,
            SendsCallOnce = session.Settings.EsmSendsCallOnce,
            WorksDupes = session.Settings.EsmWorksDupes,
        });
    }

    private async Task RunEsmAsync()
    {
        EsmAction action = NextEsmAction();
        if (action.IsNothing)
        {
            Status("nothing to send — the station is already in the log");
            return;
        }
        await SendKeysAsync(action.Keys);
        if (action.Logs)
        {
            LogContact();
        }
        Refresh();
    }

    private async Task SendKeysAsync(IReadOnlyList<int> keys)
    {
        if (Logging is null)
        {
            return;
        }
        lastKeys = keys;
        foreach (int key in keys)
        {
            await SendKeyAsync(key, CorrectedCall(key));
            if (key == Esm.CallCq)
            {
                RememberCqFrequency();
            }
            Remember(key);
        }
    }

    /// N1MM's "send corrected call": while running, a call that has changed
    /// since it went out is sent again in front of the message that ends the
    /// contact, so the station hears the call we are logging.
    private string CorrectedCall(int key)
    {
        if (Logging is null
            || key != Esm.EndQso
            || !Logging.IsRunning
            || !session.Settings.EsmSendsCorrectedCall)
        {
            return "";
        }
        string call = Logging.Entry.Call.Trim();
        return call.Length > 0 && sentCall.Length > 0 && call != sentCall ? call + " " : "";
    }

    private void Remember(int key)
    {
        if (key is Esm.MyCall or Esm.HisCall)
        {
            callSent = true;
            sentCall = Logging is null ? "" : Logging.Entry.Call.Trim();
        }
        if (key == Esm.Exchange)
        {
            exchangeSent = true;
        }
    }

    /// The contact is over, or the boxes have been cleared: the next station
    /// starts from nothing sent.
    private void ResetEsm()
    {
        callSent = false;
        exchangeSent = false;
        sentCall = "";
        lastKeys = [];
    }

    /// `=` sends whatever Enter last sent, without deciding again.
    private void RepeatLastMessage()
    {
        if (lastKeys.Count == 0)
        {
            Status("nothing has been sent yet");
            return;
        }
        _ = SendKeysAsync(lastKeys);
    }

    /// The buttons say what the file says, which is a different twelve labels
    /// while running and while searching, and the ones ESM would send next are
    /// highlighted.
    private void ShowFunctionKeys()
    {
        EsmItem.IsChecked = IsEsmOn;
        IReadOnlyList<int> next = IsEsmOn ? NextEsmAction().Keys : [];
        IReadOnlyList<FunctionKey> keys = Keys();
        for (int at = 0; at < functionButtons.Count; at++)
        {
            functionButtons[at].Content = keys[at].Label.Length > 0 ? keys[at].Label : $"F{at + 1}";
            functionButtons[at].Classes.Set("esm", next.Contains(at));
        }
    }
}