/* xoreos-tools - Tools to help with xoreos development
 *
 * xoreos-tools is the legal property of its developers, whose names
 * can be found in the AUTHORS file distributed with this source
 * distribution.
 *
 * xoreos-tools 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 3
 * of the License, or (at your option) any later version.
 *
 * xoreos-tools 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 xoreos-tools. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file
 *  Utility hash functions.
 */

#ifndef COMMON_HASH_H
#define COMMON_HASH_H

#include "src/common/types.h"
#include "src/common/scopedptr.h"
#include "src/common/ustring.h"
#include "src/common/encoding.h"
#include "src/common/memreadstream.h"

namespace Common {

/** The algorithm used for hashing. */
enum HashAlgo {
	kHashNone  = -1, ///< No hashing at all.
	kHashDJB2  =  0, ///< djb2 hash function by Daniel J. Bernstein.
	kHashFNV32 =  1, ///< 32bit Fowler-Noll-Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo.
	kHashFNV64 =  2, ///< 64bit Fowler-Noll-Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo.
	kHashCRC32 =  3, ///< 32bit CRC.
	kHashMAX         ///< For range checks.
};

// .--- djb2 hash function by Daniel J. Bernstein ---.
static inline uint32 hashDJB2(uint32 hash, uint32 c) {
	return ((hash << 5) + hash) + c;
}

static inline uint32 hashStringDJB2(const UString &string) {
	uint32 hash = 5381;

	for (UString::iterator it = string.begin(); it != string.end(); ++it)
		hash = hashDJB2(hash, *it);

	return hash;
}

static inline uint32 hashStringDJB2(const UString &string, Encoding encoding) {
	uint32 hash = 5381;

	ScopedPtr<SeekableReadStream> data(convertString(string, encoding, false));
	if (!data)
		return hash;

	uint32 c;
	while ((c = data->readChar()) != ReadStream::kEOF)
		hash = hashDJB2(hash, c);

	return hash;
}
// '--- djb2 hash function by Daniel J. Bernstein ---'

// .--- 32bit Fowler-Noll-Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo ---.
static inline uint32 hashFNV32(uint32 hash, uint32 c) {
	return (hash * 16777619) ^ c;
}

static inline uint32 hashStringFNV32(const UString &string) {
	uint32 hash = 0x811C9DC5;

	for (UString::iterator it = string.begin(); it != string.end(); ++it)
		hash = hashFNV32(hash, *it);

	return hash;
}

static inline uint32 hashStringFNV32(const UString &string, Encoding encoding) {
	uint32 hash = 0x811C9DC5;

	ScopedPtr<SeekableReadStream> data(convertString(string, encoding, false));
	if (!data)
		return hash;

	uint32 c;
	while ((c = data->readChar()) != ReadStream::kEOF)
		hash = hashFNV32(hash, c);

	return hash;
}
// '--- 32bit Fowler-Noll-Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo ---'

// .--- 64bit Fowler-Noll-Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo ---.
static inline uint64 hashFNV64(uint64 hash, uint32 c) {
	return (hash * 1099511628211LL) ^ c;
}

static inline uint64 hashStringFNV64(const UString &string) {
	uint64 hash = 0xCBF29CE484222325LL;

	for (UString::iterator it = string.begin(); it != string.end(); ++it)
		hash = hashFNV64(hash, *it);

	return hash;
}

static inline uint64 hashStringFNV64(const UString &string, Encoding encoding) {
	uint64 hash = 0xCBF29CE484222325LL;

	ScopedPtr<SeekableReadStream> data(convertString(string, encoding, false));
	if (!data)
		return hash;

	uint32 c;
	while ((c = data->readChar()) != ReadStream::kEOF)
		hash = hashFNV64(hash, c);

	return hash;
}
// '--- 64bit Fowler-Noll-Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo ---'

/* .--- CRC32, based on the implementation by Gary S. Brown ---.
 *
 * The original copyright note stated as follows:
 * You may use this program, or code or tables extracted from it,
 * as desired without restriction.
 *
 * See also <http://web.mit.edu/freebsd/head/sys/libkern/crc32.c>
 */

/** Table of CRC32 polynomial feedback terms. */
static const uint32 kCRC32Tab[] = {
	0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
	0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
	0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
	0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
	0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
	0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
	0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
	0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
	0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
	0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
	0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
	0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
	0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
	0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
	0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
	0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
	0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
	0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
	0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
	0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
	0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
	0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
	0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
	0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
	0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
	0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
	0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
	0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
	0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
	0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
	0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
	0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
	0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
	0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
	0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
	0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
	0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
	0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
	0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
	0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
	0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
	0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
	0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

static inline uint32 hashCRC32(uint32 hash, uint32 c) {
	return kCRC32Tab[(hash ^ c) & 0xFF] ^ (hash >> 8);
}

static inline uint32 hashStringCRC32(const UString &string) {
	uint32 hash = 0xFFFFFFFF;

	for (UString::iterator it = string.begin(); it != string.end(); ++it)
		hash = hashCRC32(hash, *it);

	return hash ^ 0xFFFFFFFF;
}

static inline uint32 hashStringCRC32(const UString &string, Encoding encoding) {
	uint32 hash = 0xFFFFFFFF;

	ScopedPtr<SeekableReadStream> data(convertString(string, encoding, false));
	if (!data)
		return hash;

	uint32 c;
	while ((c = data->readChar()) != ReadStream::kEOF)
		hash = hashCRC32(hash, c);

	return hash ^ 0xFFFFFFFF;
}
// '--- CRC32, based on the implementation by Gary S. Brown ---'

/** Hash the string with the given algorithm, as a series of UTF-8 characters. */
static inline uint64 hashString(const UString &string, HashAlgo algo) {
	switch (algo) {
		case kHashDJB2:
			return hashStringDJB2(string);

		case kHashFNV32:
			return hashStringFNV32(string);

		case kHashFNV64:
			return hashStringFNV64(string);

		case kHashCRC32:
			return hashStringCRC32(string);

		default:
			break;
	}

	return 0;
}

/** Hash the string with the given algorithm, as a series of bytes in the given encoding. */
static inline uint64 hashString(const UString &string, HashAlgo algo, Encoding encoding) {
	switch (algo) {
		case kHashDJB2:
			return hashStringDJB2(string, encoding);

		case kHashFNV32:
			return hashStringFNV32(string, encoding);

		case kHashFNV64:
			return hashStringFNV64(string, encoding);

		case kHashCRC32:
			return hashStringCRC32(string, encoding);

		default:
			break;
	}

	return 0;
}

static inline UString formatHash(uint64 hash) {
	return UString::format("0x%04X%04X%04X%04X",
			(uint) ((hash >> 48) & 0xFFFF),
			(uint) ((hash >> 32) & 0xFFFF),
			(uint) ((hash >> 16) & 0xFFFF),
			(uint) ( hash        & 0xFFFF));
}

} // End of namespace Common

#endif // COMMON_HASH_H
