using System.Globalization;
using Nonemm.Core;

namespace Nonemm.Contests;

/// One row of N1MM's score query: the contacts of one band and mode, or of all
/// of them when `Band` is `ScoreBreakdown.TotalBand`. `Kind` is empty except in
/// WAE, which gives contacts and traffic a row each.
public sealed record ScoreBreakdownRow(
    double Band,
    string Mode,
    string Kind,
    int Qsos,
    int Points,
    IReadOnlyList<int> Multipliers);

/// The score the way N1MM's database query splits it: a row per band and mode
/// of the contact, with the multiplier flags added up, and a total row last
/// when there is any contact.
/// `ContestLog.Rows` splits by band alone, which is what the score window shows.
public static class ScoreBreakdown
{
    /// The band N1MM gives the total row.
    public const double TotalBand = 900_000_000;

    public const string TotalMode = "Both";

    /// Ordered the way the query orders them: by the band as text, so `10.0`
    /// comes before `3.5`, then by mode. Only contacts in the claimed score
    /// are counted.
    public static IReadOnlyList<ScoreBreakdownRow> For(IEnumerable<Qso> qsos, Contest contest)
    {
        List<Qso> counted = qsos.Where(q => q.IsInScore).ToList();
        List<ScoreBreakdownRow> rows = counted
            .Where(q => q.Mode.Name.Length > 0)
            .GroupBy(q => (Band: Rounded(q), Mode: q.Mode.Name, Kind: contest.RowKindFor(q)))
            .OrderBy(g => BandText(g.Key.Band), StringComparer.Ordinal)
            .ThenBy(g => g.Key.Mode, StringComparer.Ordinal)
            .ThenBy(g => g.Key.Kind, StringComparer.Ordinal)
            .Select(g => Row(g.Key.Band, g.Key.Mode, g.Key.Kind, g))
            .ToList();
        // the query's total is a group of the same rows, so an empty log has none
        if (counted.Count > 0)
        {
            rows.Add(Row(TotalBand, TotalMode, contest.HasQtcTraffic ? "All" : "", counted));
        }
        return rows;
    }

    /// The band as the database stores it: the megahertz label to one decimal.
    private static double Rounded(Qso qso) =>
        Math.Round(qso.Band?.MegahertzLabel ?? 0, 1, MidpointRounding.AwayFromZero);

    /// What SQLite writes for a real number cast to text.
    private static string BandText(double band) => band.ToString("0.0", CultureInfo.InvariantCulture);

    private static ScoreBreakdownRow Row(double band, string mode, string kind, IEnumerable<Qso> qsos)
    {
        List<Qso> rows = [.. qsos];
        return new ScoreBreakdownRow(
            band,
            mode,
            kind,
            rows.Count,
            rows.Sum(q => q.Points),
            [
                rows.Count(q => q.IsMultiplier1),
                rows.Count(q => q.IsMultiplier2),
                rows.Count(q => q.IsMultiplier3),
            ]);
    }
}