using Nonemm.Core;

namespace Nonemm.Contests.Rules;

/// Worked All Europe DX, CW, SSB and RTTY. Europe works the rest of the world
/// and the rest of the world works Europe; on RTTY everybody works everybody.
///
/// Two things make it unlike the other contests here. A multiplier is worth
/// more on the low bands — four times on 80 metres, three on 40, twice on 20,
/// 15 and 10 — and the contest is half about QTC traffic: a station reports
/// contacts it has already made to the station it is working, and each line
/// reported is a point for both of them. Those lines live in the log as rows of
/// their own; see `WaeQtc`.
public sealed class Wae : Contest
{
    /// The countries whose call areas count separately, so W1 and W2 are two
    /// multipliers rather than one.
    private static readonly IReadOnlySet<string> CallAreaCountries =
        new HashSet<string>(StringComparer.OrdinalIgnoreCase)
        {
            "K", "VE", "VK", "ZL", "ZS", "JA", "PY", "BY",
        };

    /// Asiatic Russia is split by call area too, and the multiplier is written
    /// `UA` and the call area digit whatever the prefix on the air, so RM0W and
    /// UA0AB are one multiplier.
    private static readonly IReadOnlySet<string> AsiaticRussia =
        new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "UA8", "UA9", "UA0" };

    private readonly ModeCategory mode;

    public Wae(ModeCategory mode) => this.mode = mode;

    public string Name => mode switch
    {
        ModeCategory.Phone => "WAESSB",
        ModeCategory.Digital => "WAERTTY",
        _ => "WAECW",
    };

    public string DisplayName => $"Worked All Europe DX {ModeLabel()}";

    public string CabrilloName => mode switch
    {
        ModeCategory.Phone => "WAE-SSB",
        ModeCategory.Digital => "WAE-RTTY",
        _ => "WAE-CW",
    };

    public IReadOnlyList<ExchangeField> ExchangeFieldsFor(StationInfo me) =>
    [
        new ExchangeField("RST", ExchangeSlot.ReceivedReport, ExchangeFieldKind.Report),
        new ExchangeField("Nr", ExchangeSlot.SerialNumber, ExchangeFieldKind.Number),
    ];

    public IReadOnlyList<string> MultiplierNames => ["Mults"];

    public DupeScope DupeScope => DupeScope.PerBand;

    public bool HasSerialNumbers => true;

    public IReadOnlyList<ModeCategory> Modes => [mode];

    public bool HasQtcTraffic => true;

    public string SentExchangeFor(StationInfo me) => "001";

    /// A QTC line counts, and so does every contact on a contest band. The
    /// WARC bands are not in this contest, so a contact there is worth nothing.
    public int PointsFor(QsoContext qso)
    {
        if (!IsWorkable(qso))
        {
            return 0;
        }
        return WaeQtc.IsQtc(qso.Qso) || WeightFor(qso.Band) > 0 ? 1 : 0;
    }

    public bool IsContact(Qso qso) => !WaeQtc.IsQtc(qso);

    /// One multiplier per band, worth more the lower the band. For a station in
    /// Europe it is the other station's country or call area; for a station
    /// outside it, the European country worked.
    public IReadOnlyList<Multiplier> MultipliersFor(QsoContext qso)
    {
        int weight = WeightFor(qso.Band);
        if (weight == 0 || !IsWorkable(qso) || !qso.Qso.Call.CountsForEntity)
        {
            return [];
        }
        string value = MultiplierValue(qso);
        return value.Length == 0
            ? []
            : [new Multiplier(1, value, qso.Band?.Name ?? "", weight)];
    }

    public int TotalScore(ScoreTally tally) => tally.Points * tally.TotalMultipliers;

    /// A QTC is written as its own Cabrillo record: the station that received
    /// the traffic, the series, the station that sent it, and then the contact
    /// being reported.
    public CabrilloExchange CabrilloExchange(Qso qso, StationInfo me)
    {
        if (WaeQtc.From(qso) is not { } qtc)
        {
            return new CabrilloExchange(
                [
                    new CabrilloField(me.Callsign, 13),
                    new CabrilloField(qso.SentReport, 3),
                    new CabrilloField($"{qso.SentNumber:0000}", 4),
                ],
                [
                    new CabrilloField(qso.Call.Text, 13),
                    new CabrilloField(qso.ReceivedReport, 3),
                    new CabrilloField($"{qso.ReceivedNumber:0000}", 4),
                ]);
        }
        string receiver = qtc.IsSent ? qtc.Station.Text : me.Callsign;
        string sender = qtc.IsSent ? me.Callsign : qtc.Station.Text;
        return new CabrilloExchange(
            [
                new CabrilloField(receiver, 13),
                new CabrilloField(qtc.SeriesText, 10),
                new CabrilloField(sender, 13),
            ],
            [
                new CabrilloField(qtc.TimeUtc, 4),
                new CabrilloField(qtc.Call.Text, 13),
                new CabrilloField($"{qtc.Number:0000}", 4),
            ]);
    }

    /// On CW and SSB the contest is Europe against the rest of the world, so a
    /// contact with your own side of that line is worth nothing. RTTY drops the
    /// rule and everybody works everybody.
    public bool IsWorkable(QsoContext qso)
    {
        if (mode == ModeCategory.Digital)
        {
            return true;
        }
        return qso.Me.Continent == "EU" ? qso.Continent != "EU" : qso.Continent == "EU";
    }

    /// 80 metres is worth four, 40 three, and 20, 15 and 10 two. Everything
    /// else is not in the contest.
    public static int WeightFor(Band? band) => band?.Name switch
    {
        "80M" => 4,
        "40M" => 3,
        "20M" or "15M" or "10M" => 2,
        _ => 0,
    };

    private string MultiplierValue(QsoContext qso)
    {
        string prefix = qso.CountryPrefix;
        if (prefix.Length == 0)
        {
            return "";
        }
        // outside Europe on CW and SSB, only European countries are worked and
        // the country alone is the multiplier
        if (mode != ModeCategory.Digital && qso.Me.Continent != "EU")
        {
            return prefix;
        }
        if (AsiaticRussia.Contains(prefix))
        {
            return $"UA{CallAreaDigit(qso) ?? '9'}";
        }
        return CallAreaCountries.Contains(prefix) ? CallArea(qso) : prefix;
    }

    /// The country prefix with the call area digit on the end: W1AW is `K1`.
    private static string CallArea(QsoContext qso) =>
        CallAreaDigit(qso) is { } digit ? $"{qso.CountryPrefix}{digit}" : qso.CountryPrefix;

    private static char? CallAreaDigit(QsoContext qso)
    {
        string? wpx = qso.Qso.Call.WpxPrefix();
        return wpx is { Length: > 0 } && char.IsAsciiDigit(wpx[^1]) ? wpx[^1] : null;
    }

    private string ModeLabel() => mode switch
    {
        ModeCategory.Cw => "CW",
        ModeCategory.Phone => "SSB",
        _ => "RTTY",
    };
}