using System.Text.Json.Serialization;

namespace StellaOps.Policy.Determinization.Models;

/// <summary>
/// Describes a missing signal that contributes to uncertainty.
/// </summary>
public sealed record SignalGap
{
    /// <summary>
    /// Signal name (e.g., "epss", "vex", "reachability").
    /// </summary>
    [JsonPropertyName("signal")]
    public required string Signal { get; init; }

    /// <summary>
    /// Reason the signal is missing.
    /// </summary>
    [JsonPropertyName("reason")]
    public required SignalGapReason Reason { get; init; }

    /// <summary>
    /// Prior assumption used in absence of signal.
    /// </summary>
    [JsonPropertyName("prior")]
    public double? Prior { get; init; }

    /// <summary>
    /// Weight this signal contributes to total uncertainty.
    /// </summary>
    [JsonPropertyName("weight")]
    public double Weight { get; init; }

    /// <summary>
    /// Human-readable description.
    /// </summary>
    [JsonPropertyName("description")]
    public string? Description { get; init; }
}

/// <summary>
/// Reason a signal is missing.
/// </summary>
public enum SignalGapReason
{
    /// <summary>Signal not yet queried.</summary>
    NotQueried,

    /// <summary>Signal legitimately does not exist (e.g., EPSS not published yet).</summary>
    NotAvailable,

    /// <summary>Signal query failed due to external error.</summary>
    QueryFailed,

    /// <summary>Signal not applicable for this artifact type.</summary>
    NotApplicable
}