using System;
using System.IO;
using System.Text;
using System.Collections.Generic;
using System.Net;
using ln.types.net;

namespace ln.http
{
    public class HttpReader
    {
        delegate bool ReadCondition(int b);

        public Stream Stream { get; }

        private byte[] buffer = new byte[8192];
        private int hlen;
        private int blen;
        private int bptr;

        public Endpoint RemoteEndpoint { get; private set; }

        public String Method { get; private set; }
        public String URL { get; private set; }
        public String Protocol { get; private set; }

        public Dictionary<string, string> Headers { get; } = new Dictionary<string, string>();

        public bool Valid { get; private set; } = false;

        public HttpReader(Stream stream)
        {
            Stream = stream;
        }
        public HttpReader(Stream stream,Endpoint remoteEndpoint)
        {
            Stream = stream;
            RemoteEndpoint = remoteEndpoint;
        }

        public void Read()
        {
            ReadRequestHead();

            if (blen == 0)
                return;

            Method = ReadToken();
            SkipWhiteSpace();
            URL = ReadToken();
            SkipWhiteSpace();
            Protocol = ReadToken();
            ReadLine();

            ReadHeaders();

            Valid = true;
        }

        public int ReadByte()
        {
            if (bptr >= blen)
                return -1;
            return buffer[bptr++];
        }

        public int Current
        {
            get
            {
                if (bptr >= blen)
                    return -1;
                return buffer[bptr];
            }
        }

        public void Reverse()
        {
            if ((bptr > 0) && (bptr < blen))
                bptr--;
        }

        public void ReadRequestHead()
        {
            bptr = 0;
            do
            {
                int rlen = Stream.Read(buffer, blen, buffer.Length - blen);
                if (rlen == 0)
                    throw new IOException();

                blen += rlen;
                while (bptr <= (blen - 4))
                {
                    if (
                            (buffer[bptr + 0] == '\r') &&
                            (buffer[bptr + 1] == '\n') &&
                            (buffer[bptr + 2] == '\r') &&
                            (buffer[bptr + 3] == '\n')
                        )
                    {
                        hlen = bptr;
                        bptr = 0;
                        return;
                    }
                    bptr++;
                }

                byte[] nbuffer = new byte[buffer.Length << 1];
                Array.Copy(buffer, nbuffer, buffer.Length);
                buffer = nbuffer;
            } while (blen >= buffer.Length);
            bptr = 0;
        }

        private String ReadConditional(ReadCondition readCondition,bool reverse = true)
        {
            StringBuilder stringBuilder = new StringBuilder();
            int b = ReadByte();
            while ((b != -1) && (readCondition(b)) )
            {
                stringBuilder.Append((char)b);
                b = ReadByte();
            }
            if (reverse)
                Reverse();

            return stringBuilder.ToString();
        }

        public void SkipWhiteSpace()
        {
            while (Char.IsWhiteSpace((char)ReadByte())) { };
            Reverse();
        }

        public String ReadToken()
        {
            return ReadConditional((b) => !Char.IsWhiteSpace((char)b));
        }

        public String ReadLine()
        {
            int p = bptr;
            while (p < blen - 1)
            {
                if ((buffer[p] == '\r') && (buffer[p + 1] == '\n'))
                {
                    break;
                }
                p++;
            }

            string result = Encoding.ASCII.GetString(buffer, bptr, p - bptr);
            bptr = p + 2;
            return result;
        }

        public String ReadHeaderName()
        {
            return ReadConditional((b) => b != ':', false).ToUpper();
        }
        public String ReadHeaderValue()
        {
            String value = ReadLine();
            while (Char.IsWhiteSpace((char)Current))
            {
                value = value + ReadLine();
            }
            return value.Trim();
        }

        public void ReadHeaders()
        {
            while (bptr < hlen)
            {
                String name = ReadHeaderName();
                String value = ReadHeaderValue();

                Headers.Add(name, value);
            }
        }

        public int ReadRequestBody(byte[] dst,int offset,int length)
        {
            int nRead = 0;
            if (bptr < blen)
            {
                int len = Math.Min(length, blen - bptr);
                Array.Copy(buffer, bptr, dst, offset, len);
                bptr += len;
                length -= len;
                offset += len;
                nRead += len;
            }
            if (length > 0)
            {
                nRead += Stream.Read(dst, offset, length);
            }
            return nRead;
        }



        /*
                byte[] buffer;
                int blen = 0;
                int bptr = 0;

                public HttpReader(Stream stream)
                {
                    Stream = stream;
                    buffer = new byte[1024];
                }
                public HttpReader(Stream stream, int buffersize)
                {
                    Stream = stream;
                    buffer = new byte[buffersize];
                }

                private int read()
                {
                    if (bptr >= blen)
                    {
                        bptr = 0;
                        blen = Stream.Read(buffer, 0, buffer.Length);
                        if (blen <= 0)
                            throw new EndOfStreamException();
                    }
                    return buffer[bptr++];
                }

                private int ReadTo(byte[] b,int offset,byte[] mark)
                {
                    int pm = 0;
                    int p = offset;
                    while (p < b.Length)
                    {
                        b[p] = (byte)read();
                        if (b[p] == mark[pm])
                        {
                            pm++;
                            if (pm >= mark.Length)
                            {
                                p++;
                                break;
                            }
                        }
                        else
                        {
                            pm = 0;
                        }
                        p++;
                    }
                    return p;
                }


                public String ReadRequestLine(int maxSize = 1024)
                {
                    byte[] b = new byte[maxSize];
                    int l = ReadTo(b, 0, new byte[] { 0x0d, 0x0a });
                    return Encoding.ASCII.GetString(b, 0, l);
                }

                public Dictionary<string,string> ReadHTTPHeaders()
                {
                    byte[] b = new byte[8192];
                    int hlen = ReadTo(b, 0, new byte[] { 0x0d, 0x0a, 0x0d, 0x0a });

                    Dictionary<string, string> headers = new Dictionary<string, string>();

                    string rawHeaders = Encoding.ASCII.GetString(b, 0, hlen);
                    String[] rawLines = rawHeaders.Split(new String[] { "\r\n" }, StringSplitOptions.None);

                    for (int n = rawLines.Length-1; n >= 0 ; n--)
                    {
                        if ((rawLines[n].Length > 0) && (Char.IsWhiteSpace(rawLines[n][0])))
                        {
                            rawLines[n - 1] = rawLines[n - 1] + rawLines[n];
                            rawLines[n] = null;
                        }
                    }

                    foreach (String rawLine in rawLines)
                    {
                        if (rawLine != null)
                        {
                            int colon = rawLine.IndexOf(':');
                            if (colon > 0)
                            {
                                String name = rawLine.Substring(0, colon).Trim().ToUpper();
                                String value = rawLine.Substring(colon + 1).Trim();
                                headers.Add(name, value);
                            }
                        }
                    }

                    return headers;
                }

                public byte[] ReadRequestBody(byte[] buffer)
                {
                    return null;
                }
                */
    }

}