namespace StellaOps.Plugin.Abstractions.Lifecycle;

/// <summary>
/// Represents the current state of a plugin in its lifecycle.
/// </summary>
public enum PluginLifecycleState
{
    /// <summary>
    /// Plugin has been discovered but not yet loaded.
    /// This is the initial state after manifest parsing.
    /// </summary>
    Discovered = 0,

    /// <summary>
    /// Plugin assembly is being loaded into the application domain.
    /// </summary>
    Loading = 1,

    /// <summary>
    /// Plugin is being initialized via <see cref="IPlugin.InitializeAsync"/>.
    /// </summary>
    Initializing = 2,

    /// <summary>
    /// Plugin is fully initialized and ready to handle requests.
    /// This is the normal operating state.
    /// </summary>
    Active = 3,

    /// <summary>
    /// Plugin is functioning but with reduced capability or performance.
    /// May transition back to Active or to Unhealthy.
    /// </summary>
    Degraded = 4,

    /// <summary>
    /// Plugin is being stopped gracefully.
    /// </summary>
    Stopping = 5,

    /// <summary>
    /// Plugin has been stopped and is no longer servicing requests.
    /// </summary>
    Stopped = 6,

    /// <summary>
    /// Plugin initialization or operation failed.
    /// Check status message for details.
    /// </summary>
    Failed = 7,

    /// <summary>
    /// Plugin is being unloaded from the application domain.
    /// </summary>
    Unloading = 8
}

/// <summary>
/// Extension methods for <see cref="PluginLifecycleState"/>.
/// </summary>
public static class PluginLifecycleStateExtensions
{
    /// <summary>
    /// Returns true if the plugin is in an operational state that can handle requests.
    /// </summary>
    public static bool IsOperational(this PluginLifecycleState state) =>
        state is PluginLifecycleState.Active or PluginLifecycleState.Degraded;

    /// <summary>
    /// Returns true if the plugin is in a terminal state (stopped, failed, unloading).
    /// </summary>
    public static bool IsTerminal(this PluginLifecycleState state) =>
        state is PluginLifecycleState.Stopped or PluginLifecycleState.Failed or PluginLifecycleState.Unloading;

    /// <summary>
    /// Returns true if the plugin is in a transitional state (loading, initializing, stopping).
    /// </summary>
    public static bool IsTransitioning(this PluginLifecycleState state) =>
        state is PluginLifecycleState.Loading or PluginLifecycleState.Initializing or
               PluginLifecycleState.Stopping or PluginLifecycleState.Unloading;

    /// <summary>
    /// Returns the storage string representation.
    /// </summary>
    public static string ToStorageString(this PluginLifecycleState state) =>
        state.ToString().ToLowerInvariant();

    /// <summary>
    /// Parses a storage string back to enum value.
    /// </summary>
    public static PluginLifecycleState ParseFromStorage(string value) =>
        Enum.Parse<PluginLifecycleState>(value, ignoreCase: true);
}