Campaign_Tracker/Campaign_Tracker.Server/Audit/IAuditService.cs

namespace Campaign_Tracker.Server.Audit;

/// <summary>
/// Shared audit event type constants used across all application features.
/// </summary>
public static class AuditEventType
{
    public const string SessionLogin = "SESSION_LOGIN";
    public const string SessionLoginFailure = "SESSION_LOGIN_FAILURE";
    public const string SessionRefresh = "SESSION_REFRESH";
    public const string SessionRefreshFailure = "SESSION_REFRESH_FAILURE";
    public const string SessionLogout = "SESSION_LOGOUT";
    public const string AuthorizationAllowed = "AUTHORIZATION_ALLOWED";
    public const string AuthorizationDenied = "AUTHORIZATION_DENIED";
}

/// <summary>
/// A general-purpose audit event record written by any application feature.
/// All fields are required; no nullable properties to prevent incomplete records.
/// </summary>
public sealed record AuditEvent(
    string EventType,
    string ActorIdentity,
    string Resource,
    string Outcome,
    string TraceIdentifier,
    DateTimeOffset RecordedAt);

/// <summary>
/// Shared audit logging service contract. All application features record
/// security-relevant events through this interface — features must not
/// implement their own audit persistence (AC #3).
///
/// Record() is synchronous and throws if the underlying store is unavailable.
/// Callers must not silently swallow these exceptions; failed audit writes
/// must block or surface the originating action (AC #5).
/// </summary>
public interface IAuditService
{
    /// <summary>
    /// Appends an audit event to the durable store.
    /// Throws <see cref="AuditServiceUnavailableException"/> if the store cannot be written to.
    /// </summary>
    void Record(AuditEvent auditEvent);

    /// <summary>
    /// Returns the most recent events from the in-process cache for review and testing.
    /// For full historical queries spanning 365+ days, read the underlying store directly.
    /// </summary>
    IReadOnlyCollection<AuditEvent> GetRecent(int maxCount = 200);
}

public sealed class AuditServiceUnavailableException : Exception
{
    public AuditServiceUnavailableException(string message, Exception innerException)
        : base(message, innerException) { }
}