/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Copyright 2015 Danny Robson <danny@nerdcruft.net>
 */


#ifdef __UTIL_NOISE_RAND_IPP
#error
#endif
#define __UTIL_NOISE_RAND_IPP

#include "../hash/murmur/murmur2.hpp"


namespace util { namespace noise {
    //-------------------------------------------------------------------------
    template <
        typename U,
        size_t S,
        typename T,
        template <size_t,typename> class Q
    >
    U
    rand (uint64_t seed, Q<S,T> query)
    {
        static_assert (std::is_integral<T>::value,
                       "mixing only works on integral types");

        uint64_t accum = seed;
        for (auto i: query)
            accum = hash::murmur2::mix (accum, i);

        U result = (accum & 0xFFFF) / U{0xFFFF};

        result *= 2;
        result -= 1;

        return result;
    }


    //-------------------------------------------------------------------------
    template <
        template <size_t,typename> class R,
        typename U,
        size_t S,
        typename T,
        template <size_t,typename> class Q
    >
    R<S,U>
    rand (uint64_t seed, Q<S,T> query)
    {
        uint64_t accum = seed;
        for (auto i: query)
            accum = hash::murmur2::mix (accum, i);

        R<S,U> result;
        for (auto &i: result) {
            i = (accum & 0xFFFF) / U{0xFFFF};
            accum = hash::murmur2::mix (accum, seed);
        }

        return result * 2 - 1;
    }
} }