// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace Aspire.Hosting.ApplicationModel;
 
/// <summary>
/// A resource that represents a RabbitMQ resource.
/// </summary>
[AspireExport(ExposeProperties = true)]
public class RabbitMQServerResource : ContainerResource, IResourceWithConnectionString, IResourceWithEnvironment
{
    internal const string PrimaryEndpointName = "tcp";
    internal const string ManagementEndpointName = "management";
    private const string DefaultUserName = "guest";
    private EndpointReference? _managementEndpoint;
 
    /// <summary>
    /// Initializes a new instance of the <see cref="RabbitMQServerResource"/> class.
    /// </summary>
    /// <param name="name">The name of the resource.</param>
    /// <param name="userName">A parameter that contains the RabbitMQ server user name, or <see langword="null"/> to use a default value.</param>
    /// <param name="password">A parameter that contains the RabbitMQ server password.</param>
    public RabbitMQServerResource(string name, ParameterResource? userName, ParameterResource password) : base(name)
    {
        ArgumentNullException.ThrowIfNull(password);
 
        PrimaryEndpoint = new(this, PrimaryEndpointName);
        UserNameParameter = userName;
        PasswordParameter = password;
    }
 
    /// <summary>
    /// Gets the primary endpoint for the RabbitMQ server.
    /// </summary>
    public EndpointReference PrimaryEndpoint { get; }
 
    /// <summary>
    /// Gets the management endpoint for the RabbitMQ server.
    /// </summary>
    public EndpointReference ManagementEndpoint => _managementEndpoint ??= new(this, ManagementEndpointName);
 
    /// <summary>
    /// Gets the host endpoint reference for this resource.
    /// </summary>
    public EndpointReferenceExpression Host => PrimaryEndpoint.Property(EndpointProperty.Host);
 
    /// <summary>
    /// Gets the port endpoint reference for this resource.
    /// </summary>
    public EndpointReferenceExpression Port => PrimaryEndpoint.Property(EndpointProperty.Port);
 
    /// <summary>
    /// Gets the parameter that contains the RabbitMQ server user name.
    /// </summary>
    public ParameterResource? UserNameParameter { get; }
 
    /// <summary>
    /// Gets a reference to the user name for the RabbitMQ server.
    /// </summary>
    /// <remarks>
    /// Returns the user name parameter if specified, otherwise returns the default user name "guest".
    /// </remarks>
    public ReferenceExpression UserNameReference =>
        UserNameParameter is not null ?
            ReferenceExpression.Create($"{UserNameParameter}") :
            ReferenceExpression.Create($"{DefaultUserName}");
 
    /// <summary>
    /// Gets the parameter that contains the RabbitMQ server password.
    /// </summary>
    public ParameterResource PasswordParameter { get; }
 
    /// <summary>
    /// Gets the connection string expression for the RabbitMQ server.
    /// </summary>
    public ReferenceExpression ConnectionStringExpression => UriExpression;
 
    /// <summary>
    /// Gets the connection URI expression for the RabbitMQ server.
    /// </summary>
    /// <remarks>
    /// Format: <c>amqp://{user}:{password}@{host}:{port}</c>.
    /// </remarks>
    public ReferenceExpression UriExpression
    {
        get
        {
            var builder = new ReferenceExpressionBuilder();
            builder.AppendLiteral("amqp://");
            if (UserNameParameter is not null)
            {
                builder.Append($"{UserNameParameter:uri}");
            }
            else
            {
                builder.Append($"{DefaultUserName:uri}");
            }
            builder.AppendLiteral(":");
            builder.Append($"{PasswordParameter:uri}");
            builder.AppendLiteral("@");
            builder.Append($"{PrimaryEndpoint.Property(EndpointProperty.HostAndPort)}");
 
            return builder.Build();
        }
    }
 
    IEnumerable<KeyValuePair<string, ReferenceExpression>> IResourceWithConnectionString.GetConnectionProperties()
    {
        yield return new("Host", ReferenceExpression.Create($"{Host}"));
        yield return new("Port", ReferenceExpression.Create($"{Port}"));
        yield return new("Username", UserNameReference);
        yield return new("Password", ReferenceExpression.Create($"{PasswordParameter}"));
        yield return new("Uri", UriExpression);
    }
}