// 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;
 
namespace Aspire.Hosting.ApplicationModel;
 
/// <summary>
/// Represents the hidden terminal host process for one parent-resource replica.
/// </summary>
[DebuggerDisplay("Type = {GetType().Name,nq}, Name = {Name}, Parent = {Parent.Name}, ParentReplicaIndex = {ParentReplicaIndex}")]
internal sealed class TerminalHostResource : ExecutableResource, IResourceWithParent<IResource>
{
    // The host is created before its real binary path is known (DcpOptions is not yet
    // configured at WithTerminal time). A BeforeStartEvent subscriber rewrites the
    // ExecutableAnnotation.Command before DCP launches the resource. This sentinel makes
    // misconfiguration easy to spot if the BeforeStart hook is somehow skipped.
    internal const string UnresolvedCommand = "<unresolved-aspire-terminalhost>";
 
    /// <summary>
    /// Initializes a new instance of the <see cref="TerminalHostResource"/> class for one
    /// parent-resource replica.
    /// </summary>
    /// <param name="name">The name of the terminal host resource (typically <c>{parent}-terminalhost-{i}</c>).</param>
    /// <param name="parent">The target resource that this terminal host serves.</param>
    /// <param name="layout">The Unix domain socket layout this host will own (single producer/consumer/control triple).</param>
    public TerminalHostResource(string name, IResource parent, TerminalHostLayout layout)
        : base(name, UnresolvedCommand, string.Empty)
    {
        ArgumentNullException.ThrowIfNull(parent);
        ArgumentNullException.ThrowIfNull(layout);
 
        Parent = parent;
        Layout = layout;
    }
 
    /// <summary>
    /// Gets the target resource that this terminal host serves.
    /// </summary>
    public IResource Parent { get; }
 
    /// <summary>
    /// Gets the Unix domain socket layout this host owns. Always describes a single
    /// producer/consumer/control triple for one parent replica.
    /// </summary>
    public TerminalHostLayout Layout { get; }
 
    /// <summary>
    /// Gets the zero-based index of the parent replica this host serves. Convenience
    /// alias for <see cref="TerminalHostLayout.ParentReplicaIndex"/>.
    /// </summary>
    public int ParentReplicaIndex => Layout.ParentReplicaIndex;
}