// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Aspire.Hosting.ApplicationModel;
using Aspire.Hosting.Yarp;
using Microsoft.Extensions.DependencyInjection;
 
namespace Aspire.Hosting;
 
/// <summary>
/// Provides extension methods for adding YARP resources to the application model.
/// </summary>
public static class YarpResourceExtensions
{
    private const int Port = 5000;
 
    /// <summary>
    /// Adds a YARP container to the application model.
    /// </summary>
    /// <param name="builder">The <see cref="IDistributedApplicationBuilder"/>.</param>
    /// <param name="name">The name of the resource. This name will be used as the connection string name when referenced in a dependency.</param>
    /// <returns>A reference to the <see cref="IResourceBuilder{T}"/>.</returns>
    public static IResourceBuilder<YarpResource> AddYarp(
        this IDistributedApplicationBuilder builder,
        [ResourceName] string name)
    {
        var resource = new YarpResource(name);
 
        var yarpBuilder = builder.AddResource(resource)
                      .WithHttpEndpoint(name: "http", targetPort: Port)
                      .WithImage(YarpContainerImageTags.Image)
                      .WithImageRegistry(YarpContainerImageTags.Registry)
                      .WithImageTag(YarpContainerImageTags.Tag)
                      .WithEnvironment("ASPNETCORE_ENVIRONMENT", builder.Environment.EnvironmentName)
                      .WithEntrypoint("dotnet")
                      .WithArgs("/app/yarp.dll")
                      .WithOtlpExporter();
 
        if (builder.ExecutionContext.IsRunMode)
        {
            yarpBuilder.WithEnvironment(ctx =>
            {
                var developerCertificateService = ctx.ExecutionContext.ServiceProvider.GetRequiredService<IDeveloperCertificateService>();
                if (!developerCertificateService.SupportsContainerTrust)
                {
                    // On systems without the ASP.NET DevCert updates introduced in .NET 10, YARP will not trust the cert used
                    // by Aspire otlp endpoint when running locally. The Aspire otlp endpoint uses the dev cert, and prior to
                    // .NET 10, it was only valid for localhost, but from the container perspective, the url will be something
                    // like https://docker.host.internal, so it will NOT be valid. This is not necessary when using the latest
                    // dev cert.
                    ctx.EnvironmentVariables["YARP_UNSAFE_OLTP_CERT_ACCEPT_ANY_SERVER_CERTIFICATE"] = "true";
                }
            });
        }
 
        yarpBuilder.WithEnvironment(ctx =>
        {
            YarpEnvConfigGenerator.PopulateEnvVariables(ctx.EnvironmentVariables, yarpBuilder.Resource.Routes, yarpBuilder.Resource.Clusters);
        });
 
        return yarpBuilder;
    }
 
    /// <summary>
    /// Configure the YARP resource.
    /// </summary>
    /// <param name="builder">The YARP resource to configure.</param>
    /// <param name="configurationBuilder">The delegate to configure YARP.</param>
    public static IResourceBuilder<YarpResource> WithConfiguration(this IResourceBuilder<YarpResource> builder, Action<IYarpConfigurationBuilder> configurationBuilder)
    {
        var configBuilder = new YarpConfigurationBuilder(builder);
        configurationBuilder(configBuilder);
        return builder;
    }
 
    /// <summary>
    /// Configures the host port that the YARP resource is exposed on instead of using randomly assigned port.
    /// </summary>
    /// <param name="builder">The resource builder for YARP.</param>
    /// <param name="port">The port to bind on the host. If <see langword="null"/> is used random port will be assigned.</param>
    public static IResourceBuilder<YarpResource> WithHostPort(this IResourceBuilder<YarpResource> builder, int? port)
    {
        ArgumentNullException.ThrowIfNull(builder);
 
        return builder.WithEndpoint("http", endpoint =>
        {
            endpoint.Port = port;
        });
    }
 
    /// <summary>
    /// Enables static file serving in the YARP resource. Static files are served from the wwwroot folder.
    /// </summary>
    /// <param name="builder">The resource builder for YARP.</param>
    /// <returns>The <see cref="IResourceBuilder{T}"/>.</returns>
    public static IResourceBuilder<YarpResource> WithStaticFiles(this IResourceBuilder<YarpResource> builder)
    {
        ArgumentNullException.ThrowIfNull(builder);
 
        return builder.WithEnvironment("YARP_ENABLE_STATIC_FILES", "true");
    }
 
    /// <summary>
    /// Enables static file serving. In run mode: bind mounts <paramref name="sourcePath"/> to /wwwroot.
    /// In publish mode: generates a Dockerfile whose build context is <paramref name="sourcePath"/> and
    /// copies its contents into /app/wwwroot baked into the image.
    /// </summary>
    /// <param name="builder">The resource builder for YARP.</param>
    /// <param name="sourcePath">The source path containing static files to serve.</param>
    /// <returns>The <see cref="IResourceBuilder{T}"/>.</returns>
    public static IResourceBuilder<YarpResource> WithStaticFiles(this IResourceBuilder<YarpResource> builder, string sourcePath)
    {
        ArgumentNullException.ThrowIfNull(builder);
        ArgumentNullException.ThrowIfNull(sourcePath);
 
        builder = builder.WithStaticFiles();
 
        if (builder.ApplicationBuilder.ExecutionContext.IsPublishMode)
        {
            builder.WithDockerfileFactory(sourcePath, ctx =>
            {
                if (!ctx.Resource.TryGetContainerImageName(useBuiltImage: false, out var imageName) || string.IsNullOrEmpty(imageName))
                {
                    imageName = $"{YarpContainerImageTags.Image}:{YarpContainerImageTags.Tag}";
                }
 
                return $"""
                FROM {imageName} AS yarp
                WORKDIR /app
                COPY . /app/wwwroot
                """;
            });
        }
        else
        {
            builder = builder.WithContainerFiles("/wwwroot", sourcePath);
        }
 
        return builder;
    }
}