// Copyright (c) 2026 The MoonBite Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <crypto/randomx_hasher.h>

#include <crypto/randomx/randomx.h>

#include <cstring>
#include <mutex>

// Nothing-up-my-sleeve consensus seed (ADR-001, revised for the standard-miner
// launch). RandomX keys its cache from this value; a value distinct from
// Monero's live seed means rented Monero hashpower cannot point at MoonBite
// without first recomputing the dataset for this key.
//
// It is exactly 32 bytes so it matches the Monero/XMRig job "seed_hash" format:
// the pool advertises these 32 bytes, stock XMRig calls randomx_init_cache with
// them, and this node keys its cache identically, so every party computes the
// same hash. The bytes are SHA-256("MBITE-RX-1") - derived from the original
// 10-byte salt, so the provenance is verifiable and nothing is hidden:
//   python3 -c 'import hashlib;print(hashlib.sha256(b"MBITE-RX-1").hexdigest())'
//   -> 00f960e6d9e1d7255dc2ae70d8cd44e6ceb69d9a924ffc34e2c94d46bf496953
const unsigned char MBITE_RX_SEED[MBITE_RX_SEED_LEN] = {
    0x00,0xf9,0x60,0xe6,0xd9,0xe1,0xd7,0x25,0x5d,0xc2,0xae,0x70,0xd8,0xcd,0x44,0xe6,
    0xce,0xb6,0x9d,0x9a,0x92,0x4f,0xfc,0x34,0xe2,0xc9,0x4d,0x46,0xbf,0x49,0x69,0x53,
};

namespace {

std::mutex g_mutex;
randomx_cache* g_cache = nullptr;
randomx_vm* g_vm = nullptr;

// Initialise the shared light-mode VM once. Light mode (cache only, no ~2 GB
// dataset) keeps validation RAM near ~256 MB; miners may opt into fast mode
// separately. The produced hash is identical in either mode.
void EnsureInit()
{
    if (g_vm) return;

    randomx_flags flags = randomx_get_flags(); // JIT/AES autodetect; hash is flag-independent
    g_cache = randomx_alloc_cache(flags);
    if (g_cache == nullptr) {
        // JIT/large-page allocation can fail on locked-down hosts; fall back to
        // the portable interpreter path so validation never wedges.
        flags = RANDOMX_FLAG_DEFAULT;
        g_cache = randomx_alloc_cache(flags);
    }
    randomx_init_cache(g_cache, MBITE_RX_SEED, MBITE_RX_SEED_LEN);
    g_vm = randomx_create_vm(flags, g_cache, nullptr); // light mode
}

} // namespace

void RandomXHashBytes(const void* input, size_t inputSize, unsigned char output[32])
{
    std::lock_guard<std::mutex> lock(g_mutex);
    EnsureInit();
    randomx_calculate_hash(g_vm, input, inputSize, output);
}