// /**
//  * File: Message.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Globalization;
using ln.http.io;
using ln.type;
using ln.http.message.parser;
namespace ln.http.message
{
    public class Message
    {
        public HeaderContainer Headers { get; private set; }

        byte[] bodyData;
        int bodyOffset;
        int bodyLength;

        List<Message> parts;

        bool isMultipart;
        public bool IsMultipart => isMultipart;

        public Message()
        {
            Setup(new HeaderContainer(), new byte[0], 0, 0);
        }

        public Message(HeaderContainer headers, byte[] body)
            : this(headers, body, 0, body.Length) { }

        public Message(HeaderContainer headers, byte[] body, int offset, int length)
        {
            Setup(headers, body, offset, length);
        }

        public Message(byte[] body, int offset, int length)
        {
            MemoryStream memoryStream = new MemoryStream(body, offset, length);
            HeaderContainer headers = MIME.ReadHeader(new UnbufferedStreamReader(memoryStream));

            if (memoryStream.Position >= length)
                throw new FormatException("MIME header section too long");
                
            Setup(headers, body, offset + (int)memoryStream.Position, length - (int)memoryStream.Position);
        }

        public Message(Stream stream)
        {
            HeaderContainer headers = MIME.ReadHeader(new UnbufferedStreamReader(stream));

            byte[] data = stream.ReadToEnd();

            Setup(headers, data, 0, data.Length);
        }

        private void Setup(HeaderContainer headers, byte[] body, int offset, int length)
        {
            Headers = headers;

            bodyData = body;
            bodyOffset = offset;
            bodyLength = length;

            string ct = Headers["Content-Type"].Value;
            isMultipart = ct.StartsWith("multipart/", StringComparison.InvariantCulture) || ct.StartsWith("message/", StringComparison.InvariantCulture);
        }

        public void ReadParts()
        {
            parts = new List<Message>();

            if (isMultipart)
            {
                string boundary = Headers["Content-Type"].GetParameter("boundary");
                string delimiter = "--" + boundary;
                int[] indeces = FindIndeces(bodyData, bodyOffset, bodyLength, Encoding.ASCII.GetBytes(delimiter));

                for (int n = 1; n < indeces.Length; n++)
                {
                    Message part = new Message(bodyData, indeces[n - 1], indeces[n] - indeces[n - 1]);
                    parts.Add(part);
                }

            }
        }

        int[] FindIndeces(byte[] data,int offset,int length,byte[] pattern)
        {
            List<int> offsets = new List<int>();
            List<int> validated = new List<int>();

            for (int n = offset; n < (length - pattern.Length); n++)
            {
                int p = 0;
                while ((p < pattern.Length) && (data[n + p] == pattern[p]))
                    p++;

                if (p == pattern.Length)
                {
                    if ((n == offset) || ((n >= (offset + 2)) && (data[offset + n - 2] == '\r') && (data[offset + n - 1] == '\n')))
                    {
                        n += pattern.Length;

                        while ((n < (offset + length)) && (data[n - 2] != '\r') && (data[n - 1] != '\n'))
                            n++;

                        validated.Add(n);


                        if (((offset + length) > (n + 1)) && (data[n] == '-') && (data[n + 1] == '-'))
                            break;
                    }
                }
            }

            return validated.ToArray();
        }


        public Stream OpenBodyStream() => new MemoryStream(bodyData, bodyOffset, bodyLength);

        public IEnumerable<Message> Parts
        {
            get
            {
                if (parts == null)
                    ReadParts();
                return parts;
            }
        }

        public bool HasHeader(string name) => Headers.Contains(name);
        public Header GetHeader(string name) => Headers[name];
        public void SetHeader(string name, string value) => Headers.Set(name, value);
        public void RemoveHeader(String name) => Headers.Remove(name);

        public override string ToString()
        {
            return base.ToString();
        }

    }
}