IPublished.cs

namespace LabTracker;

/// <summary>
/// Read current published MQTT messages to initialize client state.
/// </summary>
public interface IPublished
{
    /// <summary>
    /// Whether this implementation forces a complete snapshot of all connected clients.
    /// </summary>
    bool ForceSnapshot { get; }

    /// <summary>
    /// Read current published client states from MQTT retained messages.
    /// </summary>
    /// <returns>Dictionary with client ID as key and connection state as value</returns>
    Task<Dictionary<string, ClientState>> ReadCurrentStatesAsync();
}

/// <summary>
/// Current state of a client from published MQTT messages.
/// </summary>
public class ClientState
{
    public string ClientId { get; set; } = string.Empty;
    public string? ApHostname { get; set; }
    public bool IsConnected { get; set; }
    public DateTime LastUpdated { get; set; }
    public string? LastPayload { get; set; }
}

/// <summary>
/// Utility methods for IPublished implementations.
/// </summary>
public static class PublishedUtils
{
    /// <summary>
    /// Creates a standardized client state key combining AP hostname and client ID.
    /// </summary>
    /// <param name="clientId">The client identifier (typically MAC address)</param>
    /// <param name="apHostname">The AP hostname or null for unknown AP</param>
    /// <returns>A formatted key in the format "hostname:clientId"</returns>
    public static string CreateClientStateKey(string clientId, string? apHostname)
    {
        return $"{apHostname ?? "unknown"}:{clientId}";
    }
}