// 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;
 
namespace Aspire.Hosting;
 
/// <summary>
/// Provides extension methods for adding YARP resources to the application model.
/// </summary>
public static class YarpServiceExtensions
{
    private const int Port = 5000;
 
    private const string ConfigDirectory = "/etc";
 
    private const string ConfigFileName = "yarp.config";
 
    /// <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(targetPort: Port)
                      .WithImage(YarpContainerImageTags.Image)
                      .WithImageRegistry(YarpContainerImageTags.Registry)
                      .WithEnvironment("ASPNETCORE_ENVIRONMENT", builder.Environment.EnvironmentName)
                      .WithOtlpExporter();
 
        if (builder.ExecutionContext.IsRunMode)
        {
            // YARP will not trust the cert used by Aspire otlp endpoint when running locally
            // The Aspire otlp endpoint uses the dev cert, 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.
            yarpBuilder.WithEnvironment("YARP_UNSAFE_OLTP_CERT_ACCEPT_ANY_SERVER_CERTIFICATE", "true");
        }
 
        // Map the configuration file
        yarpBuilder.WithContainerFiles(ConfigDirectory, async (context, ct) =>
        {
            string contents;
            if (yarpBuilder.Resource.ConfigFilePath != null)
            {
                try
                {
                    contents = await File.ReadAllTextAsync(yarpBuilder.Resource.ConfigFilePath, ct).ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    throw new DistributedApplicationException($"Error when reading the YARP config file '{yarpBuilder.Resource.ConfigFilePath}'", ex);
                }
            }
            else
            {
                // TODO: build dynamically the config file if none provided.
                throw new DistributedApplicationException($"No configuration provided for YARP instance \"{yarpBuilder.Resource.Name}\"");
            }
 
            var configFile = new ContainerFile
            {
                Name = ConfigFileName,
                Contents = contents
            };
 
            return [configFile];
        });
 
        return yarpBuilder;
    }
 
    /// <summary>
    /// Set explicitly the config file to use for YARP.
    /// </summary>
    /// <param name="builder">The YARP resource to configure.</param>
    /// <param name="configFilePath">The path to the YARP config file.</param>
    /// <returns>A reference to the <see cref="IResourceBuilder{T}"/>.</returns>
    public static IResourceBuilder<YarpResource> WithConfigFile(this IResourceBuilder<YarpResource> builder, string configFilePath)
    {
        builder.Resource.ConfigFilePath = configFilePath;
        return builder;
    }
}