// 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;
 
namespace Aspire.Hosting.Azure;
 
/// <summary>
/// Represents an Azure Event Hubs resource.
/// </summary>
/// <param name="name">The name of the resource.</param>
/// <param name="configureInfrastructure">Callback to configure the Azure Event Hubs resource.</param>
public class AzureEventHubsResource(string name, Action<AzureResourceInfrastructure> configureInfrastructure)
    : AzureProvisioningResource(name, configureInfrastructure), IResourceWithConnectionString, IResourceWithEndpoints, IResourceWithAzureFunctionsConfig
{
    private static readonly string[] s_eventHubClientNames =
    [
        "EventHubProducerClient",
        "EventHubConsumerClient",
        "EventProcessorClient",
        "PartitionReceiver",
        "EventHubBufferedProducerClient"
    ];
 
    private const string ConnectionKeyPrefix = "Aspire__Azure__Messaging__EventHubs";
 
    internal List<AzureEventHubResource> Hubs { get; } = [];
 
    /// <summary>
    /// Gets the "eventHubsEndpoint" output reference from the bicep template for the Azure Event Hubs resource.
    /// </summary>
    public BicepOutputReference EventHubsEndpoint => new("eventHubsEndpoint", this);
 
    internal EndpointReference EmulatorEndpoint => new(this, "emulator");
 
    /// <summary>
    /// Gets a value indicating whether the Azure Event Hubs resource is running in the local emulator.
    /// </summary>
    public bool IsEmulator => this.IsContainer();
 
    /// <summary>
    /// Gets the connection string template for the manifest for the Azure Event Hubs endpoint.
    /// </summary>
    public ReferenceExpression ConnectionStringExpression => GetConnectionString();
 
    internal ReferenceExpression GetConnectionString(string? eventHub = null, string? consumerGroup = null)
    {
        var builder = new ReferenceExpressionBuilder();
 
        if (IsEmulator)
        {
            builder.Append($"Endpoint=sb://{EmulatorEndpoint.Property(EndpointProperty.HostAndPort)};SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=SAS_KEY_VALUE;UseDevelopmentEmulator=true");
        }
        else
        {
            if (eventHub is null && consumerGroup is null)
            {
                // for backwards compatibility - if there is no event hub or consumer group, return just the endpoint
                builder.AppendFormatted(EventHubsEndpoint);
            }
            else
            {
                builder.Append($"Endpoint={EventHubsEndpoint}");
            }
        }
 
        if (eventHub is not null)
        {
            builder.Append($";EntityPath={eventHub}");
        }
 
        if (consumerGroup is not null)
        {
            builder.Append($";ConsumerGroup={consumerGroup}");
        }
 
        return builder.Build();
    }
 
    void IResourceWithAzureFunctionsConfig.ApplyAzureFunctionsConfiguration(IDictionary<string, object> target, string connectionName) =>
        ApplyAzureFunctionsConfiguration(target, connectionName);
 
    internal void ApplyAzureFunctionsConfiguration(IDictionary<string, object> target, string connectionName, string? eventHub = null, string? consumerGroup = null)
    {
        if (IsEmulator)
        {
            // Injected to support Azure Functions listener initialization.
            target[connectionName] = ConnectionStringExpression;
            // Injected to support Aspire client integration for each EventHubs client in Azure Functions projects.
            foreach (var clientName in s_eventHubClientNames)
            {
                target[$"{ConnectionKeyPrefix}__{clientName}__{connectionName}__ConnectionString"] = ConnectionStringExpression;
            }
        }
        else
        {
            // Injected to support Azure Functions listener initialization.
            target[$"{connectionName}__fullyQualifiedNamespace"] = EventHubsEndpoint;
            // Injected to support Aspire client integration for each EventHubs client in Azure Functions projects.
            foreach (var clientName in s_eventHubClientNames)
            {
                target[$"{ConnectionKeyPrefix}__{clientName}__{connectionName}__FullyQualifiedNamespace"] = EventHubsEndpoint;
            }
        }
 
        // Injected to support Aspire client integration for each EventHubs client in Azure Functions projects.
        foreach (var clientName in s_eventHubClientNames)
        {
            if (eventHub is not null)
            {
                target[$"{ConnectionKeyPrefix}__{clientName}__{connectionName}__EventHubName"] = eventHub;
            }
            if (consumerGroup is not null)
            {
                target[$"{ConnectionKeyPrefix}__{clientName}__{connectionName}__ConsumerGroup"] = consumerGroup;
            }
        }
    }
}