using Nonemm.Core;

namespace Nonemm.Session;

/// Where the operator was last on each band and mode. The band buttons use it,
/// so moving to 40 metres and back puts the radio where it was rather than at
/// the band edge. N1MM remembers the same thing.
public sealed class BandMemory
{
    private readonly Dictionary<(string Band, ModeCategory Mode), Frequency> places = [];

    public void Remember(Frequency frequency, Mode mode)
    {
        if (Bands.ForFrequency(frequency) is { } band)
        {
            places[(band.Name, mode.Category)] = frequency;
        }
    }

    /// Where to go for that band and mode: where the operator left it, or the
    /// start of that part of the band. A band the plan says nothing about
    /// starts at its bottom edge.
    public Frequency Where(Band band, ModeCategory mode, BandPlan plan)
    {
        if (places.TryGetValue((band.Name, mode), out Frequency remembered))
        {
            return remembered;
        }
        BandSegments? segments = plan.For(band);
        return mode switch
        {
            ModeCategory.Phone when segments is { HasPhone: true } => segments.PhoneLow,
            ModeCategory.Digital when segments is { HasDigital: true } => segments.DigitalLow,
            _ => band.Low,
        };
    }
}