package com.tangem.wallet;

/**
 * Created by Ilia on 18.12.2017.
 */

public interface Digest{

    /**
     * Insert one more input data byte.
     *
     * @param in   the input byte
     */
    void update(byte in);

    /**
     * Insert some more bytes.
     *
     * @param inbuf   the data bytes
     */
    void update(byte[] inbuf);

    /**
     * Insert some more bytes.
     *
     * @param inbuf   the data buffer
     * @param off     the data offset in {@code inbuf}
     * @param len     the data length (in bytes)
     */
    void update(byte[] inbuf, int off, int len);

    /**
     * Finalize the current hash computation and return the hash value
     * in a newly-allocated array. The object is resetted.
     *
     * @return  the hash output
     */
    byte[] digest();

    /**
     * Input some bytes, then finalize the current hash computation
     * and return the hash value in a newly-allocated array. The object
     * is resetted.
     *
     * @param inbuf   the input data
     * @return  the hash output
     */
    byte[] digest(byte[] inbuf);

    /**
     * Finalize the current hash computation and store the hash value
     * in the provided output buffer. The {@code len} parameter
     * contains the maximum number of bytes that should be written;
     * no more bytes than the natural hash function output length will
     * be produced. If {@code len} is smaller than the natural
     * hash output length, the hash output is truncated to its first
     * {@code len} bytes. The object is resetted.
     *
     * @param outbuf   the output buffer
     * @param off      the output offset within {@code outbuf}
     * @param len      the requested hash output length (in bytes)
     * @return  the number of bytes actually written in {@code outbuf}
     */
    int digest(byte[] outbuf, int off, int len);

    /**
     * Get the natural hash function output length (in bytes).
     *
     * @return  the digest output length (in bytes)
     */
    int getDigestLength();

    /**
     * Reset the object: this makes it suitable for a new hash
     * computation. The current computation, if any, is discarded.
     */
    void reset();

    /**
     * Clone the current state. The returned object evolves independantly
     * of this object.
     *
     * @return  the clone
     */
    Digest copy();

    /**
     * <p>Return the "block length" for the hash function. This
     * value is naturally defined for iterated hash functions
     * (Merkle-Damgard). It is used in HMAC (that's what the
     * <a href="http://tools.ietf.org/html/rfc2104">HMAC specification</a>
     * names the "{@code B}" parameter).</p>
     *
     * <p>If the function is "block-less" then this function may
     * return {@code -n} where {@code n} is an integer such that the
     * block length for HMAC ("{@code B}") will be inferred from the
     * key length, by selecting the smallest multiple of {@code n}
     * which is no smaller than the key length. For instance, for
     * the Fugue-xxx hash functions, this function returns -4: the
     * virtual block length B is the HMAC key length, rounded up to
     * the next multiple of 4.</p>
     *
     * @return  the internal block length (in bytes), or {@code -n}
     */
    int getBlockLength();

    /**
     * <p>Get the display name for this function (e.g. {@code "SHA-1"}
     * for SHA-1).</p>
     *
     * @see Object
     */
    String toString();
}