package arithmetic_coding;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class ArithmeticCoding {
	public static int ReadBits;
	public static int SentBits;

	public static void encode (String inFilename, String outFilename) {
		try {
			FileInputStream		in = new FileInputStream (inFilename);
			FileOutputStream	out = outFilename != null ?
										new FileOutputStream (outFilename) :
										null;

			double		CharsOverall = 0.0,
						Length,
						Lower = 0.0,
						Upper = 10;

			int[] 		CharsCounter = new int[256];

			double[]	Possibilities = new double[CharsCounter.length+1];
			int			CurrentChar,
						Fillers = 0,
						Sent = 0;


			while ((CurrentChar = in.read ()) > -1)
				CharsCounter [CurrentChar]++;
			for (int Char : CharsCounter)
				CharsOverall += (double) Char;

			for (int i = 0; i < CharsCounter.length; i++)
				Possibilities [i+1] = Possibilities [i] + ((double) CharsCounter [i])/CharsOverall;


			in.close ();
			in = new FileInputStream (inFilename);

			while ((CurrentChar = in.read ()) > -1) {
				Length	= Upper - Lower;
				Upper	= Lower + Length * Possibilities [CurrentChar+1];
				Lower	= Lower + Length * Possibilities [CurrentChar];

				if (Upper < 0.5) {
					Upper *= 2.0;
					Lower *= 2.0;

					Sent += send01s (out, Fillers);
					Fillers = 0;
				} else if (Lower >= 0.5) {
					Lower	= (Lower - 0.5) * 2.0;
					Upper	= (Upper - 0.5) * 2.0;

					Sent += send10s (out, Fillers);
					Fillers = 0;
				} else if (Lower >= 0.25 && Upper < 0.75) {
					Lower	= (Lower - 0.25) * 2.0;
					Upper	= (Upper - 0.25) * 2.0;

					Fillers++;
				}

				if (Lower == Upper) {
					System.out.println ("[fail]");
				}
			}

			// wyślij resztę
		} catch (IOException e) {
			e.printStackTrace ();
		}
	}

	private static int send01s (FileOutputStream out, int noOf1) {
		if (out != null)
			try {
				out.write (0);
				for (int i = 0; i < noOf1; i++)
					out.write (1);
			} catch (IOException e) {}

		return 1+noOf1;
	}

	private static int send10s (FileOutputStream out, int noOf0) {
		if (out != null)
			try {
				out.write (1);
				for (int i = 0; i < noOf0; i++)
					out.write (0);
			} catch (IOException e) {}

		return 1+noOf0;
	}
}