promiscuity/microservices/WorldApi/Services/WorldCycleService.cs

using WorldApi.Models;

namespace WorldApi.Services;

public class WorldCycleService
{
    private readonly double _dayLengthSeconds;
    private readonly DateTime _epochUtc;

    public WorldCycleService(IConfiguration configuration)
    {
        _dayLengthSeconds = Math.Max(1.0, configuration.GetValue<double?>("WorldCycle:DayLengthSeconds") ?? 1200.0);

        var configuredEpoch = configuration["WorldCycle:EpochUtc"];
        _epochUtc = DateTime.TryParse(
            configuredEpoch,
            null,
            System.Globalization.DateTimeStyles.AdjustToUniversal | System.Globalization.DateTimeStyles.AssumeUniversal,
            out var parsedEpoch)
            ? parsedEpoch
            : new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
    }

    public WorldCycleResponse GetCurrentCycle()
    {
        var now = DateTime.UtcNow;
        var elapsedSeconds = Math.Max(0.0, (now - _epochUtc).TotalSeconds);
        var timeOfDaySeconds = elapsedSeconds % _dayLengthSeconds;
        var normalized = timeOfDaySeconds / _dayLengthSeconds;
        var solarCurve = Math.Sin(normalized * Math.PI);
        var lightLevel = Math.Clamp(solarCurve, 0.0, 1.0);

        return new WorldCycleResponse
        {
            CurrentUtc = now,
            DayLengthSeconds = _dayLengthSeconds,
            TimeOfDaySeconds = timeOfDaySeconds,
            TimeOfDayNormalized = normalized,
            Phase = ResolvePhase(normalized),
            IsDay = lightLevel > 0.0,
            LightLevel = lightLevel
        };
    }

    private static string ResolvePhase(double normalized)
    {
        return normalized switch
        {
            < 0.20 => "night",
            < 0.30 => "dawn",
            < 0.70 => "day",
            < 0.80 => "dusk",
            _ => "night"
        };
    }
}