using System;
using System.IO;
using System.Windows.Forms;
namespace Festel
{
    public class ProcessFile
    {

	    private static FileStream fsi, fso;
        private static int size;
        private static long inLength;
        private static byte[] buffForRead = new byte[(int)Math.Pow(10, 7)];
        private static byte[] buffForWrite;
        private static ulong[] block;

        //Noi cac so ulong thang mot mang byte[]
        public static byte[] AppendBuffers(params ulong[] block)
        {
            int i, size, length;
            
            size = block.Length;
            byte [][] subbuff = new byte[size][];
            for (i=0;i<size;i++)
            {
                subbuff[i] = BitConverter.GetBytes(block[i]);
                              
            }
            length = subbuff[0].Length * size;  
            byte [] buff = new byte[length];
            for (i=0;i<size;i++)
            {
                Array.Copy(subbuff[i],0,buff,i*subbuff[i].Length,subbuff[i].Length);
            }
            return buff;

        }
        // tra ve mang ulong[] tu mot phan cua mang byte[]
        public static ulong[] ReadArrayIntegerFromArrayByte(byte[] buffer,int offset, int size)
        {
            ulong[] block = new ulong[size];
            for (int j = 0; j < size; j++)
            {
                int ind = offset + 8 * j;
                block[j] = BitConverter.ToUInt64(buffer, ind);
            }
            return block;
        }
        //================================================================
        //Mo file chuan bi cho viec doc, tra ve bo dem file va 
        //do dai tinh theo byte cua file
        //================================================================
        public static byte[] ReturnBuffer(string filename, int s)
        {
            long length;
            try
            {
                fsi = new FileStream(filename, FileMode.Open, FileAccess.ReadWrite);         
                
                size = s;
                length = fsi.Length;
                if (length % size != 0)
                {
                    int r = size - (int)length % size;
                    inLength = length + r;
                    fsi.SetLength(inLength);
                }
                else
                    inLength = length;

                buffForRead = new byte[inLength];
                fsi.Read(buffForRead, 0, (int)inLength);
                fsi.Close();
                return buffForRead;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                return null;
            }
        }

        //================================================================
        //Xu li file
        //================================================================
        public static void Encode(string filename,string outfile,int flag)
        {
            int i;
            try
            {
                fso = new FileStream(outfile, FileMode.Create);
                if (flag == 0)
                {
                    size = 16;                //

                    buffForRead = ReturnBuffer(filename, size);

                    for (i = 0; i < (int)inLength; i += size)
                    {

                        block = new ulong[2];
                        block = ProcessFile.ReadArrayIntegerFromArrayByte(buffForRead, i, 2);
                        FestelAlg.FestelClassis(block);
                        buffForWrite = new byte[size];
                        buffForWrite = ProcessFile.AppendBuffers(block);

                        fso.Write(buffForWrite, 0, size);
                        // 
                    }

                }
                else
                {
                    // fso = new FileStream(filename, FileMode.Create);
                    size = 32;
                    //

                    buffForRead = ReturnBuffer(filename, size);// ProcessFile.ReadFile(inName, size, out buffForRead);//
                    //
                    for (i = 0; i < inLength; i += size)
                    {

                        block = new ulong[4];
                        block = ProcessFile.ReadArrayIntegerFromArrayByte(buffForRead, i, 4);
                        FestelAlg.FestelModif(block, flag);
                        buffForWrite = new byte[size];
                        buffForWrite = ProcessFile.AppendBuffers(block);
                        fso.Write(buffForWrite, 0, size);

                    }


                }
                fso.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

        }

    }
}