// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics.CodeAnalysis;
using Aspire.Hosting.ApplicationModel;
 
namespace Aspire.Hosting.Azure.DurableTask;
 
/// <summary>
/// Represents a Durable Task scheduler resource used in Aspire hosting that provides endpoints
/// and a connection string for Durable Task orchestration scheduling.
/// </summary>
/// <param name="name">The unique resource name.</param>
[Experimental("ASPIREDURABLETASK001", UrlFormat = "https://aka.ms/aspire/diagnostics/{0}")]
public sealed class DurableTaskSchedulerResource(string name) : Resource(name), IResourceWithEndpoints, IResourceWithConnectionString
{
    /// <summary>
    /// Gets the expression that resolves to the connection string for the Durable Task scheduler.
    /// </summary>
    public ReferenceExpression ConnectionStringExpression => CreateConnectionString();
 
    internal ReferenceExpression EmulatorDashboardEndpoint => CreateDashboardEndpoint();
 
    /// <summary>
    /// Gets a value indicating whether the Durable Task scheduler is running using the local
    /// emulator (container) instead of a cloud-hosted service.
    /// </summary>
    public bool IsEmulator => this.IsContainer();
 
    private ReferenceExpression CreateConnectionString()
    {
        if (IsEmulator)
        {
            var grpcEndpoint = new EndpointReference(this, "grpc");
 
            return ReferenceExpression.Create($"Endpoint={grpcEndpoint.Property(EndpointProperty.Scheme)}://{grpcEndpoint.Property(EndpointProperty.Host)}:{grpcEndpoint.Property(EndpointProperty.Port)};Authentication=None");
        }
 
        if (this.TryGetLastAnnotation<DurableTaskSchedulerConnectionStringAnnotation>(out var connectionStringAnnotation))
        {
            return connectionStringAnnotation.ConnectionString switch
            {
                ParameterResource parameterResource => ReferenceExpression.Create($"{parameterResource}"),
                string value => ReferenceExpression.Create($"{value}"),
                _ => throw new InvalidOperationException($"Unexpected connection string type: {connectionStringAnnotation.ConnectionString.GetType().Name}"),
            };
        }
 
        throw new InvalidOperationException($"Unable to resolve the Durable Task Scheduler connection string. Configure the scheduler using {nameof(DurableTaskResourceExtensions.RunAsEmulator)}() or {nameof(DurableTaskResourceExtensions.RunAsExisting)}(connectionString) before accessing {nameof(ConnectionStringExpression)}.");
    }
 
    private ReferenceExpression CreateDashboardEndpoint()
    {
        if (IsEmulator)
        {
            var dashboardEndpoint = new EndpointReference(this, "dashboard");
 
            return ReferenceExpression.Create($"{dashboardEndpoint.Property(EndpointProperty.Url)}");
        }
 
        throw new InvalidOperationException("Dashboard endpoint is only available when running as an emulator.");
    }
}