// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Net.Sockets;
using Aspire.Hosting.ApplicationModel;
 
namespace Aspire.Hosting.Maui.Otlp;
 
/// <summary>
/// Represents a synthetic OTLP resource that acts as a loopback endpoint for service discovery.
/// </summary>
/// <remarks>
/// This resource is used internally for MAUI OTLP configurations (especially with dev tunnels).
/// It creates an endpoint annotation that can be referenced by MAUI platform resources through service discovery.
/// The endpoint points to localhost at a configured or dashboard-allocated port and can be tunneled externally.
/// </remarks>
internal sealed class OtlpLoopbackResource : Resource, IResourceWithEndpoints
{
    /// <summary>
    /// Initializes a new instance of <see cref="OtlpLoopbackResource"/>.
    /// </summary>
    /// <param name="name">The name of the resource.</param>
    /// <param name="port">The port number for the OTLP endpoint.</param>
    /// <param name="scheme">The URI scheme (http or https).</param>
    public OtlpLoopbackResource(string name, int? port, string scheme) : base(name)
    {
        // File-based AppHosts commonly use dynamic dashboard ports, so the port can start as
        // null and be filled from ResourceEndpointsAllocatedEvent once the dashboard OTLP
        // endpoint is known. Configured OTLP endpoint URLs are already concrete and can be
        // allocated immediately.
        OtlpEndpoint = new EndpointAnnotation(
            ProtocolType.Tcp,
            uriScheme: scheme,
            name: "otlp",
            port: port,
            isProxied: false)
        {
            // TargetHost = localhost means this resource is running on the local machine
            // When tunneled through dev tunnels, the service discovery will rewrite this to the tunnel URL
            TargetHost = "localhost"
        };
 
        if (port is int configuredPort)
        {
            OtlpEndpoint.AllocatedEndpoint = new AllocatedEndpoint(OtlpEndpoint, "localhost", configuredPort);
        }
 
        Annotations.Add(OtlpEndpoint);
    }
 
    /// <summary>
    /// Gets the synthetic endpoint that targets the local dashboard OTLP listener.
    /// </summary>
    internal EndpointAnnotation OtlpEndpoint { get; }
}