using System.Globalization;
using Nonemm.Core;

namespace Nonemm.Session;

/// The fields N1MM's statistics window offers, in N1MM's own order. Every one
/// of them can go down the rows; nine of them cannot go across the columns,
/// because a column per call or per five minutes is wider than any screen.
public static class StatisticsFields
{
    private static readonly string[] NotColumns =
    [
        "Hour", "CountryPrefix", "CK", "WPXPrefix", "MiscText",
        "5 Minute", "10 Minute", "15 Minute", "Call",
    ];

    public static readonly IReadOnlyList<StatisticsField> Rows =
    [
        new("Band", (q, _) => BandKey(q)),
        Text("Operator", q => q.Operator),
        new("Hour",
            (q, _) => new PivotKey(
                DayText(q),
                q.TimestampUtc.ToString("HH", CultureInfo.InvariantCulture),
                SecondOrder: q.TimestampUtc.Hour),
            "Day",
            "Hr"),
        Number("RadioNr", q => q.RadioNumber),
        Text("Mode", q => q.Mode.Name),
        Text("CountryPrefix", q => q.CountryPrefix),
        Number("Zone", q => q.Zone),
        Text("Section", q => q.Section),
        Number("CK", q => q.Check),
        Text("Prec", q => q.Precedence),
        Number("Points", q => q.Points),
        Flag("Mult1", q => q.IsMultiplier1),
        Flag("Mult2", q => q.IsMultiplier2),
        Flag("Mult3", q => q.IsMultiplier3),
        Text("WPXPrefix", q => q.WpxPrefix),
        // N1MM counts a four-character field, so every station in a square
        // lands in one row however precise a grid it sent
        Text("GridSquare", q => q.GridSquare.Length > 4 ? q.GridSquare[..4] : q.GridSquare),
        Number("Run1Run2", q => q.RunPosition),
        Text("MiscText", q => q.MiscText),
        Text("ContactType", q => q.ContactType),
        Flag("IsRunQSO", q => q.IsRunQso),
        new("Day", (q, _) => new PivotKey(DayText(q))),
        Minutes(5),
        Minutes(10),
        Minutes(15),
        new("Mode & Band",
            (q, _) => new PivotKey(
                q.Mode.Name,
                q.Band?.Name ?? "",
                SecondOrder: q.Band?.MegahertzLabel ?? 0),
            "Mode",
            "Band"),
        Text("Exchange1", q => q.Exchange1),
        Text("Call", q => q.Call.Text),
        Text("RoverLocation", q => q.RoverLocation),
        Text("Computer Name", q => q.StationName),
    ];

    public static readonly IReadOnlyList<StatisticsField> Columns =
        Rows.Where(f => !NotColumns.Contains(f.Name)).ToList();

    /// The field of that name, or the first field when there is none: a name
    /// read back out of the settings can be one this version no longer has.
    public static StatisticsField Find(IReadOnlyList<StatisticsField> among, string name) =>
        among.FirstOrDefault(f => f.Name == name) ?? among[0];

    private static PivotKey BandKey(Qso qso) =>
        new(qso.Band?.Name ?? "", Order: qso.Band?.MegahertzLabel ?? 0);

    private static string DayText(Qso qso) =>
        qso.TimestampUtc.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture);

    private static StatisticsField Text(string name, Func<Qso, string> value) =>
        new(name, (q, _) => new PivotKey(value(q)));

    private static StatisticsField Number(string name, Func<Qso, int> value) =>
        new(name, (q, _) =>
        {
            int found = value(q);
            return new PivotKey(found.ToString(CultureInfo.InvariantCulture), Order: found);
        });

    /// N1MM reads the flag columns back as VB booleans, so the labels are
    /// `True` and `False` and False sorts first.
    private static StatisticsField Flag(string name, Func<Qso, bool> value) =>
        new(name, (q, _) => value(q) ? new PivotKey("True", Order: 1) : new PivotKey("False"));

    /// Minutes since the contest started, in steps of `span`. N1MM works this
    /// out in SQLite with integer division, which cuts towards zero.
    private static StatisticsField Minutes(int span) =>
        new($"{span} Minute", (q, start) =>
        {
            long seconds = (long)(q.TimestampUtc - start).TotalSeconds;
            long bucket = span * (seconds / (span * 60));
            return new PivotKey(bucket.ToString(CultureInfo.InvariantCulture), Order: bucket);
        });
}