using Nonemm.Core;

namespace Nonemm.Contests.Udc;

/// One of a user-defined contest's up-to-three multipliers: where its value
/// comes from and how often it may be counted.
public sealed class UdcMultiplier
{
    private readonly int index;
    private readonly string source;
    private readonly UdcMultiplierScope scope;
    private readonly IReadOnlyList<string> onlyForCountries;

    public UdcMultiplier(
        int index,
        string source,
        UdcMultiplierScope scope,
        IReadOnlyList<string> onlyForCountries)
    {
        this.index = index;
        this.source = source;
        this.scope = scope;
        this.onlyForCountries = onlyForCountries;
    }

    public Multiplier? For(QsoContext qso)
    {
        if (scope == UdcMultiplierScope.None)
        {
            return null;
        }
        if (onlyForCountries.Count > 0 &&
            !onlyForCountries.Contains(qso.CountryPrefix, StringComparer.OrdinalIgnoreCase))
        {
            return null;
        }
        string? value = ValueFor(qso);
        return string.IsNullOrEmpty(value) ? null : new Multiplier(index, value, ScopeKey(qso));
    }

    private string? ValueFor(QsoContext qso) => source.ToUpperInvariant() switch
    {
        "COUNTRYPREFIX" => qso.CountryPrefix,
        "WPXPREFIX" => qso.Qso.Call.WpxPrefix(),
        "SECTION" or "SECT" => Upper(qso.Qso.Section),
        "EXCHANGE" or "EXCH" => Upper(qso.Qso.Exchange1),
        "MISC" or "MISCTEXT" => Upper(qso.Qso.MiscText),
        "CALLSIGN" => qso.Qso.Call.Text,
        "CQZONE" or "ZN" => qso.Qso.Zone > 0 ? qso.Qso.Zone.ToString() : null,
        "GRID" => Truncate(qso.Qso.GridSquare, 4),
        "SGRID" => Truncate(qso.Qso.GridSquare, 6),
        "FIELD" => Truncate(qso.Qso.GridSquare, 2),
        "CONTINENT" => qso.Continent,
        "FIRSTQSO" => "first",
        _ => null,
    };

    private string ScopeKey(QsoContext qso) => scope switch
    {
        UdcMultiplierScope.PerBand => qso.Band?.Name ?? "",
        UdcMultiplierScope.PerMode => qso.ModeCategory.ToString(),
        UdcMultiplierScope.PerBandAndMode => $"{qso.Band?.Name}|{qso.ModeCategory}",
        _ => "",
    };

    private static string Upper(string text) => text.Trim().ToUpperInvariant();

    private static string? Truncate(string text, int length)
    {
        string trimmed = text.Trim().ToUpperInvariant();
        return trimmed.Length < length ? null : trimmed[..length];
    }
}