/*
  This file is part of cpp-ethereum.

  cpp-ethereum 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.

  cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file dash.cpp
* @author Tim Hughes <tim@twistedfury.com>
* @author Matthew Wampler-Doty
* @date 2015
*/

#include <assert.h>
#include <inttypes.h>
#include <stddef.h>
#include "ethash.h"
#include "fnv.h"
#include "endian.h"
#include "internal.h"
#include "data_sizes.h"

#ifdef WITH_CRYPTOPP

#include "sha3_cryptopp.h"

#else
#include "sha3.h"
#endif // WITH_CRYPTOPP

size_t ethash_get_datasize(const uint32_t block_number) {
    assert(block_number / EPOCH_LENGTH < 500);
    return dag_sizes[block_number / EPOCH_LENGTH];
}

size_t ethash_get_cachesize(const uint32_t block_number) {
    assert(block_number / EPOCH_LENGTH < 500);
    return cache_sizes[block_number / EPOCH_LENGTH];
}

// Follows Sergio's "STRICT MEMORY HARD HASHING FUNCTIONS" (2014)
// https://bitslog.files.wordpress.com/2013/12/memohash-v0-3.pdf
// SeqMemoHash(s, R, N)
void static ethash_compute_cache_nodes(
        node *const nodes,
        ethash_params const *params,
        const uint8_t seed[32]) {
    assert((params->cache_size % sizeof(node)) == 0);
    uint32_t const num_nodes = (uint32_t)(params->cache_size / sizeof(node));

    SHA3_512(nodes[0].bytes, seed, 32);

    for (unsigned i = 1; i != num_nodes; ++i) {
        SHA3_512(nodes[i].bytes, nodes[i - 1].bytes, 64);
    }

    for (unsigned j = 0; j != CACHE_ROUNDS; j++) {
        for (unsigned i = 0; i != num_nodes; i++) {
            uint32_t const idx = nodes[i].words[0] % num_nodes;
            node data;
            data = nodes[(num_nodes - 1 + i) % num_nodes];
			for (unsigned w = 0; w != NODE_WORDS; ++w)
			{
				data.words[w] ^= nodes[idx].words[w];
			}
            SHA3_512(nodes[i].bytes, data.bytes, sizeof(data));
        }
    }

    // now perform endian conversion
#if BYTE_ORDER != LITTLE_ENDIAN
    for (unsigned w = 0; w != (num_nodes*NODE_WORDS); ++w)
    {
        nodes->words[w] = fix_endian32(nodes->words[w]);
    }
#endif
}

void ethash_mkcache(
  ethash_cache *cache,
        ethash_params const *params,
        const uint8_t seed[32]) {
    node *nodes = (node *) cache->mem;
    ethash_compute_cache_nodes(nodes, params, seed);
}

void ethash_calculate_dag_item(
        node *const ret,
        const unsigned node_index,
        const struct ethash_params *params,
        const struct ethash_cache *cache) {

    uint32_t num_parent_nodes = (uint32_t)(params->cache_size / sizeof(node));
    node const *cache_nodes = (node const *) cache->mem;
    node const *init = &cache_nodes[node_index % num_parent_nodes];

	memcpy(ret, init, sizeof(node));
	ret->words[0] ^= node_index;
	SHA3_512(ret->bytes, ret->bytes, sizeof(node));

#if defined(_M_X64) && ENABLE_SSE
    __m128i const fnv_prime = _mm_set1_epi32(FNV_PRIME);
    __m128i xmm0 = ret->xmm[0];
    __m128i xmm1 = ret->xmm[1];
    __m128i xmm2 = ret->xmm[2];
    __m128i xmm3 = ret->xmm[3];
#endif

    for (unsigned i = 0; i != DAG_PARENTS; ++i)
	{
        uint32_t parent_index = ((node_index ^ i)*FNV_PRIME ^ ret->words[i % NODE_WORDS]) % num_parent_nodes;
        node const *parent = &cache_nodes[parent_index];

		#if defined(_M_X64) && ENABLE_SSE
        {
            xmm0 = _mm_mullo_epi32(xmm0, fnv_prime);
            xmm1 = _mm_mullo_epi32(xmm1, fnv_prime);
            xmm2 = _mm_mullo_epi32(xmm2, fnv_prime);
            xmm3 = _mm_mullo_epi32(xmm3, fnv_prime);
            xmm0 = _mm_xor_si128(xmm0, parent->xmm[0]);
            xmm1 = _mm_xor_si128(xmm1, parent->xmm[1]);
            xmm2 = _mm_xor_si128(xmm2, parent->xmm[2]);
            xmm3 = _mm_xor_si128(xmm3, parent->xmm[3]);

            // have to write to ret as values are used to compute index
            ret->xmm[0] = xmm0;
            ret->xmm[1] = xmm1;
            ret->xmm[2] = xmm2;
            ret->xmm[3] = xmm3;
        }
        #else
        {
            for (unsigned w = 0; w != NODE_WORDS; ++w) {
                ret->words[w] = fnv_hash(ret->words[w], parent->words[w]);
            }
        }
		#endif
    }

	SHA3_512(ret->bytes, ret->bytes, sizeof(node));
}

void ethash_compute_full_data(
        void *mem,
        ethash_params const *params,
        ethash_cache const *cache) {
    assert((params->full_size % (sizeof(uint32_t) * MIX_WORDS)) == 0);
    assert((params->full_size % sizeof(node)) == 0);
    node *full_nodes = mem;

    // now compute full nodes
    for (unsigned n = 0; n != (params->full_size / sizeof(node)); ++n) {
        ethash_calculate_dag_item(&(full_nodes[n]), n, params, cache);
    }
}

static void ethash_hash(
        ethash_return_value * ret,
        node const *full_nodes,
        ethash_cache const *cache,
        ethash_params const *params,
        const uint8_t header_hash[32],
        const uint64_t nonce) {

    assert((params->full_size % MIX_WORDS) == 0);

    // pack hash and nonce together into first 40 bytes of s_mix
    assert(sizeof(node)*8 == 512);
    node s_mix[MIX_NODES + 1];
    memcpy(s_mix[0].bytes, header_hash, 32);

#if BYTE_ORDER != LITTLE_ENDIAN
    s_mix[0].double_words[4] = fix_endian64(nonce);
#else
    s_mix[0].double_words[4] = nonce;
#endif

    // compute sha3-512 hash and replicate across mix
    SHA3_512(s_mix->bytes, s_mix->bytes, 40);

#if BYTE_ORDER != LITTLE_ENDIAN
    for (unsigned w = 0; w != 16; ++w) {
        s_mix[0].words[w] = fix_endian32(s_mix[0].words[w]);
    }
#endif

    node* const mix = s_mix + 1;
    for (unsigned w = 0; w != MIX_WORDS; ++w) {
        mix->words[w] = s_mix[0].words[w % NODE_WORDS];
    }

    unsigned const
            page_size = sizeof(uint32_t) * MIX_WORDS,
            num_full_pages = (unsigned)(params->full_size / page_size);


    for (unsigned i = 0; i != ACCESSES; ++i)
	{
        uint32_t const index = ((s_mix->words[0] ^ i)*FNV_PRIME ^ mix->words[i % MIX_WORDS]) % num_full_pages;

        for (unsigned n = 0; n != MIX_NODES; ++n)
		{
            const node * dag_node = &full_nodes[MIX_NODES * index + n];

            if (!full_nodes) {
                node tmp_node;
                ethash_calculate_dag_item(&tmp_node, index * MIX_NODES + n, params, cache);
                dag_node = &tmp_node;
            }

			#if defined(_M_X64) && ENABLE_SSE
            {
                __m128i fnv_prime = _mm_set1_epi32(FNV_PRIME);
                __m128i xmm0 = _mm_mullo_epi32(fnv_prime, mix[n].xmm[0]);
                __m128i xmm1 = _mm_mullo_epi32(fnv_prime, mix[n].xmm[1]);
                __m128i xmm2 = _mm_mullo_epi32(fnv_prime, mix[n].xmm[2]);
                __m128i xmm3 = _mm_mullo_epi32(fnv_prime, mix[n].xmm[3]);
                mix[n].xmm[0] = _mm_xor_si128(xmm0, dag_node->xmm[0]);
                mix[n].xmm[1] = _mm_xor_si128(xmm1, dag_node->xmm[1]);
                mix[n].xmm[2] = _mm_xor_si128(xmm2, dag_node->xmm[2]);
                mix[n].xmm[3] = _mm_xor_si128(xmm3, dag_node->xmm[3]);
            }
            #else
            {
                for (unsigned w = 0; w != NODE_WORDS; ++w) {
                    mix[n].words[w] = fnv_hash(mix[n].words[w], dag_node->words[w]);
                }
            }
            #endif
        }

    }

	// compress mix
	for (unsigned w = 0; w != MIX_WORDS; w += 4)
	{
		uint32_t reduction = mix->words[w+0];
		reduction = reduction*FNV_PRIME ^ mix->words[w+1];
		reduction = reduction*FNV_PRIME ^ mix->words[w+2];
		reduction = reduction*FNV_PRIME ^ mix->words[w+3];
		mix->words[w/4] = reduction;
	}

#if BYTE_ORDER != LITTLE_ENDIAN
    for (unsigned w = 0; w != MIX_WORDS/4; ++w) {
        mix->words[w] = fix_endian32(mix->words[w]);
    }
#endif

    memcpy(ret->mix_hash, mix->bytes, 32);
    // final Keccak hash
    SHA3_256(ret->result, s_mix->bytes, 64+32);	// Keccak-256(s + compressed_mix)
}

void ethash_quick_hash(
        uint8_t return_hash[32],
        const uint8_t header_hash[32],
        const uint64_t nonce,
        const uint8_t mix_hash[32]) {

    uint8_t buf[64+32];
    memcpy(buf, header_hash, 32);
#if BYTE_ORDER != LITTLE_ENDIAN
    nonce = fix_endian64(nonce);
#endif
    memcpy(&(buf[32]), &nonce, 8);
    SHA3_512(buf, buf, 40);
    memcpy(&(buf[64]), mix_hash, 32);
    SHA3_256(return_hash, buf, 64+32);
}

int ethash_quick_check_difficulty(
        const uint8_t header_hash[32],
        const uint64_t nonce,
        const uint8_t mix_hash[32],
        const uint8_t difficulty[32]) {

    uint8_t return_hash[32];
    ethash_quick_hash(return_hash, header_hash, nonce, mix_hash);
    return ethash_check_difficulty(return_hash, difficulty);
}

void ethash_full(ethash_return_value * ret, void const *full_mem, ethash_params const *params, const uint8_t previous_hash[32], const uint64_t nonce) {
    ethash_hash(ret, (node const *) full_mem, NULL, params, previous_hash, nonce);
}

void ethash_light(ethash_return_value * ret, ethash_cache const *cache, ethash_params const *params, const uint8_t previous_hash[32], const uint64_t nonce) {
    ethash_hash(ret, NULL, cache, params, previous_hash, nonce);
}