package org.lidar;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * Util
 * @author Andrej Cimpersek
 */
public class Util {

    public static byte CalcXOR(byte[] data, int offset, int count) {
        byte x = data[offset];
        for (int i = 1; i < count; i++) {
            x ^= data[offset + i];
        }
        return x;
    }

    private static byte CalcXOR(String data) {
        byte x = (byte) (data.charAt(0));
        for (int i = 1; i < data.length(); i++) {
            x ^= (byte) (data.charAt(i));
        }
        return x;
    }

    public static byte[] GetBytesFromFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);

        // Get the size of the file
        long length = file.length();

        if (length > Integer.MAX_VALUE) {
            throw new IOException("File is too large!");
        }

        // Create the byte array to hold the data
        byte[] bytes = new byte[(int) length];

        // Read in the bytes
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
                && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
            offset += numRead;
        }

        // Ensure all the bytes have been read in
        if (offset < bytes.length) {
            throw new IOException("Could not completely read file " + file.getName());
        }

        // Close the input stream and return bytes
        is.close();
        return bytes;
    }
}