package de.nclazz.commons.io;

import de.nclazz.commons.StringUtils;
import lombok.NonNull;

import java.io.*;
import java.security.MessageDigest;

public abstract class StreamUtils {

    private StreamUtils() { /* no-op */ }

    /**
     * Pipes all the input from {@code streamIn} to {@code streamOut}.
     * This method does not close any of the streams!
     *
     * @param streamIn InputStream
     * @param streamOut OutputStream
     * @throws IOException on Error
     */
    public static void pipeStream(InputStream streamIn, OutputStream streamOut) throws IOException {
        byte[] bytes = new byte[4096]; //TODO make configurable? maybe as a sys property?
        int length;
        while ((length = streamIn.read(bytes)) >= 0) {
            streamOut.write(bytes, 0, length);
        }
    }

    /**
     * Loads an InputStream into a new byte array.
     * This method does not close the stream after processing!
     * @param stream InputStream
     * @return new {@code byte[]}
     */
    public static byte[] inputStreamToByteArray(InputStream stream) throws IOException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] buffer = new byte[4096]; //TODO make configurable? maybe as a sys property?
        int length;
        while((length = stream.read(buffer)) != -1) {
            bos.write(buffer, 0, length);
        }
        return bos.toByteArray();
    }

    /**
     * Digest an InputStream with given MessageDigest.
     * The stream will not be closed after processing!
     * @param stream to hash
     * @param md hash algorithm
     * @return new String hash
     */
    public static String digestStream(@NonNull InputStream stream, @NonNull MessageDigest md) {
        try {
            byte[] buffer = new byte[2048];
            int len;
            while((len = stream.read(buffer)) != -1) {
                md.update(buffer, 0, len);
            }
            byte[] digest = md.digest();
            return StringUtils.toHex(digest);
        }catch(Exception e) {
            throw new RuntimeException(e);
        }
    }


}