/*
    This file is part of Mitsuba, a physically based rendering system.

    Copyright (c) 2007-2014 by Wenzel Jakob and others.

    Mitsuba is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License Version 3
    as published by the Free Software Foundation.

    Mitsuba 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, see <http://www.gnu.org/licenses/>.
*/

#pragma once
#if !defined(__MITSUBA_CORE_RANDOM_H_)
#define __MITSUBA_CORE_RANDOM_H_

#include <mitsuba/mitsuba.h>
#include <mitsuba/core/cobject.h>

/*
   SIMD oriented Fast Mersenne Twister (SFMT) pseudorandom number generator
   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/

   Copyright (c) 2006,2007 Mutsuo Saito, Makoto Matsumoto and Hiroshima
   University. All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:

       * Redistributions of source code must retain the above copyright
         notice, this list of conditions and the following disclaimer.
       * Redistributions in binary form must reproduce the above
         copyright notice, this list of conditions and the following
         disclaimer in the documentation and/or other materials provided
         with the distribution.
       * Neither the name of the Hiroshima University nor the names of
         its contributors may be used to endorse or promote products
         derived from this software without specific prior written
         permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

   References:
   M. Saito and M. Matsumoto,
     ``SIMD-oriented Fast Mersenne Twister:
       a 128-bit Pseudorandom Number Generator''
     Monte Carlo and Quasi-Monte Carlo Method 2006.
     Springer (2008) 607--622.
     DOI: 10.1007/978-3-540-74496-2_36
   T. Nishimura, ``Tables of 64-bit Mersenne Twisters''
     ACM Transactions on Modeling and
     Computer Simulation 10. (2000) 348--357.
   M. Matsumoto and T. Nishimura,
     ``Mersenne Twister: a 623-dimensionally equidistributed
       uniform pseudorandom number generator''
     ACM Transactions on Modeling and
     Computer Simulation 8. (Jan. 1998) 3--30.
 * \ingroup libcore
*/

MTS_NAMESPACE_BEGIN

/**
 * \brief %Random number generator based on SIMD-oriented Fast Mersenne Twister
 *
 * \author Mutsuo Saito and Makoto Matsumoto at Hiroshima University.
 *
 * \ingroup libcore
 * \ingroup libpython
 */
class MTS_EXPORT_CORE Random : public SerializableObject {
public:
    /**
     * \brief Construct a new seeded random generator.
     *
     * Uses the default seed on Windows and '/dev/urandom'
     * on OSX and Linux.
     */
    Random();

    /**
     * \brief Construct a random generator with a custom seed
     */
    Random(uint64_t seed);

    /// Construct a new random generator seeded from a pre-existing one
    Random(Random *random);

    /// Unserialize a random generator
    Random(Stream *stream, InstanceManager *manager);

    /// Copy the state from another random generator
    void set(Random *random);

    /// Seed the random generator with a single 64bit value
    void seed(uint64_t value = 5489ULL);

    /// Seed the random generator from another random generator
    void seed(Random *random);

    /**
     * \brief Seed the random generator from an array
     * \remark This function is currently not exposed
     * by the Python bindings
     */
    void seed(uint64_t *values, uint64_t length);

    /// Return an integer on the [0, 2^63-1]-interval
    uint64_t nextULong();

    /// Return an integer on the [0, n)-interval
    uint32_t nextUInt(uint32_t n);

    /// Return an integer on the [0, n)-interval
    size_t nextSize(size_t n);

    /// Return a floating point value on the [0, 1) interval
    Float nextFloat();

    /// Return a normally distributed value
    Float nextStandardNormal();

    /**
     * \brief Draw a uniformly distributed permutation and permute the
     * given STL container.
     *
     * See Knuth, TAoCP Vol. 2 (3rd 3d), Section 3.4.2.
     *
     * \remark This function is currently not exposed
     * by the Python bindings
     */
    template <typename Iterator> void shuffle(Iterator it1, Iterator it2) {
        for (Iterator it = it2 - 1; it > it1; --it)
            std::iter_swap(it, it1 + nextSize((size_t) (it-it1)));
    }

    /// Serialize a random generator to a binary data stream
    void serialize(Stream *stream, InstanceManager *manager) const;

    MTS_DECLARE_CLASS()
protected:
    /// Virtual destructor
    virtual ~Random();
private:
    struct State;
    State *mt;
};


MTS_NAMESPACE_END

#endif /* __MITSUBA_CORE_RANDOM_H_ */
