h-school/src/HSchool.Content/DiseaseDefs.cs

namespace HSchool.Content;

/// <summary>Stable family ids for immunity grouping and realism labels.</summary>
public static class DiseaseFamilies
{
    public const string Respiratory = "respiratory";

    public const string Gastrointestinal = "gastrointestinal";

    public const string Ent = "ent";
}

/// <summary>One severity band on a <see cref="DiseaseDef"/> curve.</summary>
public sealed class DiseaseStage
{
    /// <summary>Inclusive lower bound of severity for this stage.</summary>
    public float MinSeverity { get; init; }

    public float SeverityPerDay { get; init; }

    public float ProgressPerDay { get; init; }

    /// <summary>Multiplies lesson skill gain while this stage is active (after incubation).</summary>
    public float LessonLearningFactor { get; init; } = 1f;

    /// <summary>Per-day chance the person stays off campus while in this stage (after incubation).</summary>
    public float StayHomeChance { get; init; }

    /// <summary>Multiplies Warmth decay. 1 = unchanged.</summary>
    public float WarmthDecayFactor { get; init; } = 1f;
}

/// <summary>
/// A named disease: stages, weather vectors, lesson/attendance effects, temporary immunity,
/// and optional person-to-person contagion (node and/or class).
/// </summary>
public sealed class DiseaseDef : Def
{
    /// <summary><see cref="DiseaseFamilies"/> id. Required on concrete defs.</summary>
    public string Family { get; init; } = "";

    /// <summary>Game days after onset before stage effects (lesson / stay-home) apply.</summary>
    public float IncubationDays { get; init; }

    public IReadOnlyList<DiseaseStage> Stages { get; init; } = [];

    /// <summary>Base daily onset chance before weather vectors and <see cref="BehaviorDef.DiseaseVectorScale"/>.</summary>
    public float BaseChancePerDay { get; init; }

    /// <summary>Street °C at or below this adds <see cref="ColdChancePerDay"/>. Null — no cold vector.</summary>
    public float? ColdBelowC { get; init; }

    public float ColdChancePerDay { get; init; }

    public float RainChancePerDay { get; init; }

    public float SnowChancePerDay { get; init; }

    /// <summary>Days of immunity to this def after recovery.</summary>
    public float ImmunityDays { get; init; }

    /// <summary>
    /// Daily chance to infect each other person sharing the same map node. 0 — no node contagion.
    /// </summary>
    public float NodeContagionChancePerDay { get; init; }

    /// <summary>
    /// Daily chance to infect each classmate (same <c>ClassId</c>) while both are on campus.
    /// 0 — no class contagion.
    /// </summary>
    public float ClassContagionChancePerDay { get; init; }

    /// <summary>When true, the carrier can infect during incubation before stage effects apply.</summary>
    public bool ContagiousDuringIncubation { get; init; }
}