// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.IO;
using System.Net.Quic;
 
namespace System.Net.Http
{
    /// <summary>
    /// The exception thrown when an HTTP/2 or an HTTP/3 protocol error occurs.
    /// </summary>
    /// <remarks>
    /// When calling <see cref="HttpClient"/> or <see cref="SocketsHttpHandler"/> methods, <see cref="HttpProtocolException"/> will be the inner exception of
    /// <see cref="HttpRequestException"/> if a protocol error occurs.
    /// When calling <see cref="Stream"/> methods on the stream returned by <see cref="HttpContent.ReadAsStream()"/> or
    /// <see cref="HttpContent.ReadAsStreamAsync(Threading.CancellationToken)"/>, <see cref="HttpProtocolException"/> can be thrown directly.
    /// </remarks>
    public sealed class HttpProtocolException : HttpIOException
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="HttpProtocolException"/> class with the specified error code,
        /// message, and inner exception.
        /// </summary>
        /// <param name="errorCode">The HTTP/2 or HTTP/3 error code.</param>
        /// <param name="message">The error message that explains the reason for the exception.</param>
        /// <param name="innerException">The exception that is the cause of the current exception.</param>
        public HttpProtocolException(long errorCode, string message, Exception? innerException)
            : base(Http.HttpRequestError.HttpProtocolError, message, innerException)
        {
            ErrorCode = errorCode;
        }
 
        /// <summary>
        /// Gets the HTTP/2 or HTTP/3 error code associated with this exception.
        /// </summary>
        public long ErrorCode { get; }
 
#if !TARGET_BROWSER && !TARGET_WASI
        internal static HttpProtocolException CreateHttp2StreamException(Http2ProtocolErrorCode protocolError)
        {
            string message = SR.Format(SR.net_http_http2_stream_error, GetName(protocolError), ((int)protocolError).ToString("x"));
            return new HttpProtocolException((long)protocolError, message, null);
        }
 
        internal static HttpProtocolException CreateHttp2ConnectionException(Http2ProtocolErrorCode protocolError, string? message = null)
        {
            message = SR.Format(message ?? SR.net_http_http2_connection_error, GetName(protocolError), ((int)protocolError).ToString("x"));
            return new HttpProtocolException((long)protocolError, message, null);
        }
 
        internal static HttpProtocolException CreateHttp3StreamException(Http3ErrorCode protocolError, QuicException innerException)
        {
            string message = SR.Format(SR.net_http_http3_stream_error, GetName(protocolError), ((int)protocolError).ToString("x"));
            return new HttpProtocolException((long)protocolError, message, innerException);
        }
 
        internal static HttpProtocolException CreateHttp3ConnectionException(Http3ErrorCode protocolError, string? message = null)
        {
            message = SR.Format(message ?? SR.net_http_http3_connection_error, GetName(protocolError), ((int)protocolError).ToString("x"));
            return new HttpProtocolException((long)protocolError, message, null);
        }
 
        private static string GetName(Http2ProtocolErrorCode code) =>
            // These strings are the names used in the HTTP2 spec and should not be localized.
            code switch
            {
                Http2ProtocolErrorCode.NoError => "NO_ERROR",
                Http2ProtocolErrorCode.ProtocolError => "PROTOCOL_ERROR",
                Http2ProtocolErrorCode.InternalError => "INTERNAL_ERROR",
                Http2ProtocolErrorCode.FlowControlError => "FLOW_CONTROL_ERROR",
                Http2ProtocolErrorCode.SettingsTimeout => "SETTINGS_TIMEOUT",
                Http2ProtocolErrorCode.StreamClosed => "STREAM_CLOSED",
                Http2ProtocolErrorCode.FrameSizeError => "FRAME_SIZE_ERROR",
                Http2ProtocolErrorCode.RefusedStream => "REFUSED_STREAM",
                Http2ProtocolErrorCode.Cancel => "CANCEL",
                Http2ProtocolErrorCode.CompressionError => "COMPRESSION_ERROR",
                Http2ProtocolErrorCode.ConnectError => "CONNECT_ERROR",
                Http2ProtocolErrorCode.EnhanceYourCalm => "ENHANCE_YOUR_CALM",
                Http2ProtocolErrorCode.InadequateSecurity => "INADEQUATE_SECURITY",
                Http2ProtocolErrorCode.Http11Required => "HTTP_1_1_REQUIRED",
                _ => "(unknown error)",
            };
 
        private static string GetName(Http3ErrorCode code) =>
            // These strings come from the H3 spec and should not be localized.
            code switch
            {
                Http3ErrorCode.NoError => "H3_NO_ERROR",
                Http3ErrorCode.ProtocolError => "H3_GENERAL_PROTOCOL_ERROR",
                Http3ErrorCode.InternalError => "H3_INTERNAL_ERROR",
                Http3ErrorCode.StreamCreationError => "H3_STREAM_CREATION_ERROR",
                Http3ErrorCode.ClosedCriticalStream => "H3_CLOSED_CRITICAL_STREAM",
                Http3ErrorCode.UnexpectedFrame => "H3_FRAME_UNEXPECTED",
                Http3ErrorCode.FrameError => "H3_FRAME_ERROR",
                Http3ErrorCode.ExcessiveLoad => "H3_EXCESSIVE_LOAD",
                Http3ErrorCode.IdError => "H3_ID_ERROR",
                Http3ErrorCode.SettingsError => "H3_SETTINGS_ERROR",
                Http3ErrorCode.MissingSettings => "H3_MISSING_SETTINGS",
                Http3ErrorCode.RequestRejected => "H3_REQUEST_REJECTED",
                Http3ErrorCode.RequestCancelled => "H3_REQUEST_CANCELLED",
                Http3ErrorCode.RequestIncomplete => "H3_REQUEST_INCOMPLETE",
                Http3ErrorCode.ConnectError => "H3_CONNECT_ERROR",
                Http3ErrorCode.VersionFallback => "H3_VERSION_FALLBACK",
                _ => "(unknown error)"
            };
#endif
    }
}