// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Net;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal;
using Microsoft.Extensions.Logging;
 
namespace Microsoft.AspNetCore.Server.Kestrel.Core;
 
internal sealed class LocalhostListenOptions : ListenOptions
{
    private readonly string? _hostPrefix;
 
    internal LocalhostListenOptions(int port, string hostPrefix)
        : this(port)
    {
        _hostPrefix = hostPrefix ?? throw new ArgumentNullException(nameof(hostPrefix));
    }
 
    internal LocalhostListenOptions(int port)
        : base(new IPEndPoint(IPAddress.Loopback, port))
    {
        if (port == 0)
        {
            throw new InvalidOperationException(CoreStrings.DynamicPortOnLocalhostNotSupported);
        }
    }
 
    /// <summary>
    /// Gets the name of this endpoint to display on command-line when the web server starts.
    /// </summary>
    internal override string GetDisplayName()
    {
        var host = _hostPrefix is { } prefix ? $"{prefix}.localhost" : "localhost";
        return $"{Scheme}://{host}:{IPEndPoint!.Port}";
    }
 
    internal override async Task BindAsync(AddressBindContext context, CancellationToken cancellationToken)
    {
        var exceptions = new List<Exception>();
 
        try
        {
            var v4Options = Clone(IPAddress.Loopback);
            await AddressBinder.BindEndpointAsync(v4Options, context, cancellationToken).ConfigureAwait(false);
        }
        catch (Exception ex) when (!(ex is IOException or OperationCanceledException))
        {
            if (context.Logger.IsEnabled(LogLevel.Information))
            {
                context.Logger.LogInformation(0, CoreStrings.NetworkInterfaceBindingFailed, GetDisplayName(), "IPv4 loopback", ex.Message);
            }
            exceptions.Add(ex);
        }
 
        try
        {
            var v6Options = Clone(IPAddress.IPv6Loopback);
            await AddressBinder.BindEndpointAsync(v6Options, context, cancellationToken).ConfigureAwait(false);
        }
        catch (Exception ex) when (!(ex is IOException or OperationCanceledException))
        {
            if (context.Logger.IsEnabled(LogLevel.Information))
            {
                context.Logger.LogInformation(0, CoreStrings.NetworkInterfaceBindingFailed, GetDisplayName(), "IPv6 loopback", ex.Message);
            }
            exceptions.Add(ex);
        }
 
        if (exceptions.Count == 2)
        {
            throw new IOException(CoreStrings.FormatAddressBindingFailed(GetDisplayName()), new AggregateException(exceptions));
        }
 
        // If StartLocalhost doesn't throw, there is at least one listener.
        // The port cannot change for "localhost".
        context.Addresses.Add(GetDisplayName());
    }
}