using System;
using System.IO;
using System.Net;
using System.Text;

namespace SocketHttpListener.Net
{
    public sealed unsafe partial class HttpListenerResponse : IDisposable
    {
        private BoundaryType _boundaryType = BoundaryType.None;
        private CookieCollection _cookies;
        private HttpListenerContext _httpContext;
        private bool _keepAlive = true;
        private HttpResponseStream _responseStream;
        private string _statusDescription;
        private WebHeaderCollection _webHeaders = new WebHeaderCollection();

        public WebHeaderCollection Headers => _webHeaders;

        public Encoding ContentEncoding { get; set; }

        public string ContentType
        {
            get => Headers["Content-Type"];
            set
            {
                CheckDisposed();
                if (string.IsNullOrEmpty(value))
                {
                    Headers.Remove("Content-Type");
                }
                else
                {
                    Headers.Set("Content-Type", value);
                }
            }
        }

        private HttpListenerContext HttpListenerContext => _httpContext;

        private HttpListenerRequest HttpListenerRequest => HttpListenerContext.Request;

        internal EntitySendFormat EntitySendFormat
        {
            get => (EntitySendFormat)_boundaryType;
            set
            {
                CheckDisposed();
                CheckSentHeaders();
                if (value == EntitySendFormat.Chunked && HttpListenerRequest.ProtocolVersion.Minor == 0)
                {
                    throw new ProtocolViolationException("net_nochunkuploadonhttp10");
                }
                _boundaryType = (BoundaryType)value;
                if (value != EntitySendFormat.ContentLength)
                {
                    _contentLength = -1;
                }
            }
        }

        public bool SendChunked
        {
            get => EntitySendFormat == EntitySendFormat.Chunked;
            set => EntitySendFormat = value ? EntitySendFormat.Chunked : EntitySendFormat.ContentLength;
        }

        // We MUST NOT send message-body when we send responses with these Status codes
        private static readonly int[] s_noResponseBody = { 100, 101, 204, 205, 304 };

        private static bool CanSendResponseBody(int responseCode)
        {
            for (int i = 0; i < s_noResponseBody.Length; i++)
            {
                if (responseCode == s_noResponseBody[i])
                {
                    return false;
                }
            }
            return true;
        }

        public long ContentLength64
        {
            get => _contentLength;
            set
            {
                CheckDisposed();
                CheckSentHeaders();
                if (value >= 0)
                {
                    _contentLength = value;
                    _boundaryType = BoundaryType.ContentLength;
                }
                else
                {
                    throw new ArgumentOutOfRangeException(nameof(value));
                }
            }
        }

        public CookieCollection Cookies
        {
            get => _cookies ?? (_cookies = new CookieCollection());
            set => _cookies = value;
        }

        public bool KeepAlive
        {
            get => _keepAlive;
            set
            {
                CheckDisposed();
                _keepAlive = value;
            }
        }

        public Stream OutputStream
        {
            get
            {
                CheckDisposed();
                EnsureResponseStream();
                return _responseStream;
            }
        }

        public string RedirectLocation
        {
            get => Headers["Location"];
            set
            {
                // note that this doesn't set the status code to a redirect one
                CheckDisposed();
                if (string.IsNullOrEmpty(value))
                {
                    Headers.Remove("Location");
                }
                else
                {
                    Headers.Set("Location", value);
                }
            }
        }

        public string StatusDescription
        {
            get
            {
                if (_statusDescription == null)
                {
                    // if the user hasn't set this, generated on the fly, if possible.
                    // We know this one is safe, no need to verify it as in the setter.
                    _statusDescription = HttpStatusDescription.Get(StatusCode);
                }
                if (_statusDescription == null)
                {
                    _statusDescription = string.Empty;
                }
                return _statusDescription;
            }
            set
            {
                CheckDisposed();
                if (value == null)
                {
                    throw new ArgumentNullException(nameof(value));
                }

                // Need to verify the status description doesn't contain any control characters except HT.  We mask off the high
                // byte since that's how it's encoded.
                for (int i = 0; i < value.Length; i++)
                {
                    char c = (char)(0x000000ff & (uint)value[i]);
                    if ((c <= 31 && c != (byte)'\t') || c == 127)
                    {
                        throw new ArgumentException("net_WebHeaderInvalidControlChars");
                    }
                }

                _statusDescription = value;
            }
        }

        public void AddHeader(string name, string value)
        {
            Headers.Set(name, value);
        }

        public void AppendHeader(string name, string value)
        {
            Headers.Add(name, value);
        }

        public void AppendCookie(Cookie cookie)
        {
            if (cookie == null)
            {
                throw new ArgumentNullException(nameof(cookie));
            }
            Cookies.Add(cookie);
        }

        private void ComputeCookies()
        {
            if (_cookies != null)
            {
                // now go through the collection, and concatenate all the cookies in per-variant strings
                //string setCookie2 = null, setCookie = null;
                //for (int index = 0; index < _cookies.Count; index++)
                //{
                //    Cookie cookie = _cookies[index];
                //    string cookieString = cookie.ToServerString();
                //    if (cookieString == null || cookieString.Length == 0)
                //    {
                //        continue;
                //    }

                //    if (cookie.IsRfc2965Variant())
                //    {
                //        setCookie2 = setCookie2 == null ? cookieString : setCookie2 + ", " + cookieString;
                //    }
                //    else
                //    {
                //        setCookie = setCookie == null ? cookieString : setCookie + ", " + cookieString;
                //    }
                //}

                //if (!string.IsNullOrEmpty(setCookie))
                //{
                //    Headers.Set(HttpKnownHeaderNames.SetCookie, setCookie);
                //    if (string.IsNullOrEmpty(setCookie2))
                //    {
                //        Headers.Remove(HttpKnownHeaderNames.SetCookie2);
                //    }
                //}

                //if (!string.IsNullOrEmpty(setCookie2))
                //{
                //    Headers.Set(HttpKnownHeaderNames.SetCookie2, setCookie2);
                //    if (string.IsNullOrEmpty(setCookie))
                //    {
                //        Headers.Remove(HttpKnownHeaderNames.SetCookie);
                //    }
                //}
            }
        }

        public void Redirect(string url)
        {
            Headers["Location"] = url;
            StatusCode = (int)HttpStatusCode.Redirect;
            StatusDescription = "Found";
        }

        public void SetCookie(Cookie cookie)
        {
            if (cookie == null)
            {
                throw new ArgumentNullException(nameof(cookie));
            }

            //Cookie newCookie = cookie.Clone();
            //int added = Cookies.InternalAdd(newCookie, true);

            //if (added != 1)
            //{
            //    // The Cookie already existed and couldn't be replaced.
            //    throw new ArgumentException("Cookie exists");
            //}
        }

        void IDisposable.Dispose()
        {
            Dispose();
        }

        private void CheckDisposed()
        {
            if (Disposed)
            {
                throw new ObjectDisposedException(GetType().FullName);
            }
        }

        private void CheckSentHeaders()
        {
            if (SentHeaders)
            {
                throw new InvalidOperationException();
            }
        }
    }
}