using StellaOps.Router.Gateway.Middleware;
using StellaOps.Router.Gateway.OpenApi;
using StellaOps.Router.Gateway.RateLimit;

namespace StellaOps.Router.Gateway;

/// <summary>
/// Extension methods for configuring the router gateway middleware pipeline.
/// </summary>
public static class ApplicationBuilderExtensions
{
    /// <summary>
    /// Adds the router gateway middleware pipeline.
    /// </summary>
    /// <param name="app">The application builder.</param>
    /// <returns>The application builder for chaining.</returns>
    public static IApplicationBuilder UseRouterGateway(this IApplicationBuilder app)
    {
        // Request logging and error handling wrap the full router pipeline.
        app.UseMiddleware<RequestLoggingMiddleware>();
        app.UseMiddleware<GlobalErrorHandlerMiddleware>();

        // Enforce payload limits first
        app.UseMiddleware<PayloadLimitsMiddleware>();

        // Resolve endpoints from routing state
        app.UseMiddleware<EndpointResolutionMiddleware>();

        // Rate limiting (Sprint 1200_001_001)
        // Runs after endpoint resolution so microservice identity is available.
        app.UseRateLimiting();

        // Make routing decisions (select instance)
        app.UseMiddleware<RoutingDecisionMiddleware>();

        // Dispatch to transport and return response
        app.UseMiddleware<TransportDispatchMiddleware>();

        return app;
    }

    /// <summary>
    /// Adds rate limiting middleware to the pipeline.
    /// Sprint: SPRINT_1200_001_001_router_rate_limiting_core
    /// Task: 1.6 - Wire into Router Pipeline
    /// </summary>
    /// <param name="app">The application builder.</param>
    /// <returns>The application builder for chaining.</returns>
    public static IApplicationBuilder UseRateLimiting(this IApplicationBuilder app)
    {
        // Only add if rate limit service is registered
        var rateLimitService = app.ApplicationServices.GetService<RateLimitService>();
        if (rateLimitService is not null)
        {
            app.UseMiddleware<RateLimitMiddleware>();
        }
        return app;
    }

    /// <summary>
    /// Adds the router gateway middleware pipeline without payload limiting.
    /// </summary>
    /// <param name="app">The application builder.</param>
    /// <returns>The application builder for chaining.</returns>
    public static IApplicationBuilder UseRouterGatewayCore(this IApplicationBuilder app)
    {
        // Request logging and error handling wrap the full router pipeline.
        app.UseMiddleware<RequestLoggingMiddleware>();
        app.UseMiddleware<GlobalErrorHandlerMiddleware>();

        // Resolve endpoints from routing state
        app.UseMiddleware<EndpointResolutionMiddleware>();

        // Rate limiting (Sprint 1200_001_001)
        // Runs after endpoint resolution so microservice identity is available.
        app.UseRateLimiting();

        // Make routing decisions (select instance)
        app.UseMiddleware<RoutingDecisionMiddleware>();

        // Dispatch to transport and return response
        app.UseMiddleware<TransportDispatchMiddleware>();

        return app;
    }

    /// <summary>
    /// Maps OpenAPI endpoints to the application.
    /// Should be called before UseRouterGateway so OpenAPI requests are handled first.
    /// </summary>
    /// <param name="endpoints">The endpoint route builder.</param>
    /// <returns>The endpoint route builder for chaining.</returns>
    public static IEndpointRouteBuilder MapRouterOpenApi(this IEndpointRouteBuilder endpoints)
    {
        return endpoints.MapRouterOpenApiEndpoints();
    }
}