/*
 * Copyright (C) ManTech International Corporation 2010
 * Copyright (C) 2013 Helmut Grohne <helmut@subdivi.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Earlier versions of this code can be found at:
 *     http://ssdeep.sf.net/
 */

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

#ifndef FUZZY_H
#define FUZZY_H

/**
 * @brief Compute the fuzzy hash of a buffer
 *
 * The computes the fuzzy hash of the first buf_len bytes of the buffer.
 * It is the caller's responsibility to append the filename,
 * if any, to result after computation. 
 * @param buf The data to be fuzzy hashed
 * @param buf_len The length of the data being hashed
 * @param result Where the fuzzy hash of buf is stored. This variable
 * must be allocated to hold at least FUZZY_MAX_RESULT bytes.
 * @return Returns zero on success, non-zero on error.
 */
extern int fuzzy_hash_buf(const unsigned char *buf, uint32_t buf_len,
		/*@out@*/ char *result);

/**
 * @brief Compute the fuzzy hash of a file using an open handle
 *
 * Computes the fuzzy hash of the contents of the open file, starting
 * at the beginning of the file. When finished, the file pointer is
 * returned to its original position. If an error occurs, the file 
 * pointer's value is undefined.
 * It is the callers's responsibility to append the filename
 * to the result after computation.
 * @param handle Open handle to the file to be hashed
 * @param result Where the fuzzy hash of the file is stored. This 
 * variable must be allocated to hold at least FUZZY_MAX_RESULT bytes.
 * @return Returns zero on success, non-zero on error
 */
extern int fuzzy_hash_file(FILE *handle, /*@out@*/ char *result);

/**
 * @brief Compute the fuzzy hash of a stream using an open handle
 *
 * Computes the fuzzy hash of the contents of the open stream, starting at the
 * current file position until reaching EOF. Unlike fuzzy_hash_file the stream
 * is never seeked. If an error occurs, the result as well as the file position
 * are undefined.
 * It is the callers's responsibility to append the filename
 * to the result after computation.
 * @param handle Open handle to the stream to be hashed
 * @param result Where the fuzzy hash of the file is stored. This 
 * variable must be allocated to hold at least FUZZY_MAX_RESULT bytes.
 * @return Returns zero on success, non-zero on error
 */
extern int fuzzy_hash_stream(FILE *handle, /*@out@*/ char *result);

/**
 * @brief Compute the fuzzy hash of a file
 *
 * Opens, reads, and hashes the contents of the file 'filename' 
 * The result must be allocated to hold FUZZY_MAX_RESULT characters. 
 * It is the caller's responsibility to append the filename
 * to the result after computation. 
 * @param filename The file to be hashed
 * @param result Where the fuzzy hash of the file is stored. This 
 * variable must be allocated to hold at least FUZZY_MAX_RESULT bytes.
 * @return Returns zero on success, non-zero on error. 
 */
extern int fuzzy_hash_filename(const char *filename, /*@out@*/ char * result);

/** Length of an individual fuzzy hash signature component. */
#define SPAMSUM_LENGTH 64

/** The longest possible length for a fuzzy hash signature
 * (without the filename) */
#define FUZZY_MAX_RESULT    (SPAMSUM_LENGTH + (SPAMSUM_LENGTH/2 + 20))

#ifdef __cplusplus
} 
#endif

#endif