package sparseviewer.mda;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;


public class XdrInput {

    private final RandomAccessFile raf;

    public XdrInput(File file) throws IOException {
        this.raf = new RandomAccessFile(file, "r");
    }
    public void close() throws IOException {
        raf.close();
}
    public long getFilePointer() throws IOException {
        return raf.getFilePointer();
    }
    public void seek(long position) throws IOException {
        raf.seek(position);
    }
    public int readInt() throws IOException {
        return raf.readInt();
    }
    public float readFloat() throws IOException {
        return raf.readFloat();
    }
    public double readDouble() throws IOException {
        return raf.readDouble();
    }
    public int[] readIntArray(int n) throws IOException {
        int[] values = new int[n];

        for (int i = 0; i < n; i++) {
            values[i] = readInt();
        }

        return values;
    }

    public String readXdrString() throws IOException {
        int length = readInt();

        if (length <= 0) {
            return "";
        }

        byte[] bytes = new byte[length];
        raf.readFully(bytes);

        int pad = padding(length);
        if (pad > 0) {
            raf.skipBytes(pad);
        }

        return new String(bytes, "UTF-8");
    }

    /**
     * MDA writes many strings as:
     *   int n
     *   if n > 0: xdr_string
     *
     * The xdr_string itself again contains length + bytes + padding.
     */
    public String readStringWithLeadingLength() throws IOException {
        int n = readInt();

        if (n <= 0) {
            return "";
        }

        return readXdrString();
    }

    private int padding(int length) {
        int r = length % 4;

        if (r == 0) {
            return 0;
        }
        return 4 - r;
    }

}