using System.Globalization;
using System.Text;
using Nonemm.Contests;
using Nonemm.Core;

namespace Nonemm.Formats.Cabrillo;

/// Writes a Cabrillo 3.0 log: the header the sponsor's robot reads, then one
/// line per contact.
public sealed class CabrilloWriter
{
    private readonly Contest contest;
    private readonly StationInfo me;
    private readonly ContestEntry entry;

    public CabrilloWriter(Contest contest, StationInfo me, ContestEntry? entry = null)
    {
        this.contest = contest;
        this.me = me;
        this.entry = entry ?? new ContestEntry();
    }

    public string Write(CabrilloHeader header, IEnumerable<Qso> qsos)
    {
        StringBuilder text = new();
        text.Append("START-OF-LOG: ").Append(contest.CabrilloVersion).Append("\r\n");
        Line(text, "CONTEST", header.Contest);
        Line(text, "CALLSIGN", header.Callsign);
        Line(text, "CATEGORY-OPERATOR", header.OperatorCategory);
        Line(text, "CATEGORY-ASSISTED", header.AssistedCategory);
        Line(text, "CATEGORY-BAND", header.BandCategory);
        Line(text, "CATEGORY-MODE", header.ModeCategory);
        Line(text, "CATEGORY-POWER", header.PowerCategory);
        Line(text, "CATEGORY-STATION", header.StationCategory);
        Line(text, "CATEGORY-TRANSMITTER", header.TransmitterCategory);
        Line(text, "CATEGORY-OVERLAY", header.OverlayCategory);
        Line(text, "CATEGORY-TIME", header.TimeCategory);
        text.Append(CultureInfo.InvariantCulture, $"CLAIMED-SCORE: {header.ClaimedScore}\r\n");
        Line(text, "CLUB", header.Club);
        Line(text, "NAME", header.Name);
        foreach (string line in header.Address)
        {
            Line(text, "ADDRESS", line);
        }
        Line(text, "ADDRESS-CITY", header.AddressCity);
        Line(text, "ADDRESS-STATE-PROVINCE", header.AddressStateProvince);
        Line(text, "ADDRESS-POSTALCODE", header.AddressPostalcode);
        Line(text, "ADDRESS-COUNTRY", header.AddressCountry);
        Line(text, "EMAIL", header.Email);
        Line(text, "OPERATORS", header.Operators);
        foreach (string line in SplitLines(header.Soapbox))
        {
            Line(text, "SOAPBOX", line);
        }
        Line(text, "CREATED-BY", header.CreatedBy);

        foreach (Qso qso in qsos.OrderBy(q => q.TimestampUtc))
        {
            text.Append(QsoLine(qso)).Append("\r\n");
        }
        text.Append("END-OF-LOG:\r\n");
        return text.ToString();
    }

    public string QsoLine(Qso qso)
    {
        CabrilloExchange exchange = contest.CabrilloExchange(qso, me, entry);
        StringBuilder line = new(RecordName(qso));
        line.Append(CabrilloBands.Designator(qso.Frequency).PadLeft(5)).Append(' ');
        line.Append(qso.Mode.CabrilloCode.PadRight(2)).Append(' ');
        line.Append(qso.TimestampUtc.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture)).Append(' ');
        line.Append(qso.TimestampUtc.ToString("HHmm", CultureInfo.InvariantCulture)).Append(' ');
        Append(line, exchange.Sent);
        Append(line, exchange.Received);
        if (contest.IsContact(qso) && exchange.AddsTransmitter)
        {
            line.Append(qso.RadioNumber > 1 ? '1' : '0');
        }
        return line.ToString();
    }

    /// A contact the operator has excluded from the claimed score is still
    /// written, under `X-QSO:` rather than `QSO:`. That is what N1MM writes,
    /// and the sponsors read it as a contact the entrant is not claiming.
    private string RecordName(Qso qso)
    {
        if (!contest.IsContact(qso))
        {
            return "QTC: ";
        }
        return qso.IsClaimed ? "QSO: " : "X-QSO: ";
    }

    /// Every column is the width the sponsor asks for and one space, and a
    /// value longer than its column is cut, which is what N1MM writes.
    private static void Append(StringBuilder line, IReadOnlyList<CabrilloField> fields)
    {
        foreach (CabrilloField field in fields)
        {
            string value = field.Value.Length > field.Width
                ? field.Value[..field.Width]
                : field.Value.PadRight(field.Width);
            line.Append(value).Append(' ');
        }
    }

    private static void Line(StringBuilder text, string tag, string value)
    {
        if (value.Length > 0)
        {
            text.Append(tag).Append(": ").Append(value).Append("\r\n");
        }
    }

    private static IEnumerable<string> SplitLines(string text) =>
        text.Length == 0 ? [] : text.Split('\n').Select(l => l.TrimEnd('\r'));
}