cxx/engine_bridge.cpp

// AutomatedOperator FFI Bridge Implementation
// Integrates Circom witness calculator + Rapidsnark CUDA prover

#include "automated_operator/include/engine_bridge.hpp"
#include <stdexcept>
#include <cstring>
#include <array>

// Mock implementation for compilation without full Circom/Rapidsnark toolchain
// Replace with actual implementation when toolchain is available

namespace algorithm_engine {

// Mock BN254 field element operations
struct FrElement {
    std::array<uint8_t, 32> data;
};

inline void Fr_fromBin(FrElement* out, const uint8_t* in) {
    std::memcpy(out->data.data(), in, 32);
}

inline void Fr_from32(FrElement* out, uint32_t val) {
    out->data.fill(0);
    std::memcpy(out->data.data(), &val, 4);
}

// Mock Circom witness calculator interface
class Circom_CalcWit {
public:
    Circom_CalcWit() {}
    ~Circom_CalcWit() {}
    
    void setSignal(const char* name, const FrElement& val) {
        // In real implementation: store signal value for witness generation
        (void)name; (void)val;
    }
    
    void generate() {
        // In real implementation: execute witness generation
        // Throws if constraints violated (e.g., entropy > 200000)
    }
    
    const std::vector<uint8_t>& getWitness() const {
        static std::vector<uint8_t> dummy(1024);
        return dummy;
    }
};

// Mock Rapidsnark CUDA prover
namespace rapidsnark {

struct Groth16Proof {
    std::array<uint8_t, 64> pi_a;
    std::array<uint8_t, 128> pi_b;
    std::array<uint8_t, 64> pi_c;
};

inline Groth16Proof groth16_prove_cuda(const std::vector<uint8_t>& witness, const char* zkey_path) {
    (void)witness; (void)zkey_path;
    // In real implementation: call Rapidsnark CUDA prover
    Groth16Proof proof;
    proof.pi_a.fill(0xAA);
    proof.pi_b.fill(0xBB);
    proof.pi_c.fill(0xCC);
    return proof;
}

} // namespace rapidsnark

// Mock BLAKE3 hash for proof/result commitments
std::array<uint8_t, 32> blake3_hash(const std::vector<uint8_t>& data) {
    std::array<uint8_t, 32> out;
    out.fill(0);
    // In real implementation: use blake3 crate
    for (size_t i = 0; i < std::min(data.size(), size_t(32)); ++i) {
        out[i] = data[i];
    }
    return out;
}

ZkProof execute_circuit_and_prove(
    const std::array<uint8_t, 32>& target_space,
    const std::array<uint8_t, 32>& constraints,
    const std::array<uint8_t, 32>& metric,
    uint32_t priority,
    uint32_t quantized_entropy
) {
    // 1. Initialize Circom Witness Calculator
    auto* ctx = new Circom_CalcWit();

    // 2. Load Inputs into ALGORITHM_ENGINE circuit
    FrElement val;
    Fr_fromBin(&val, target_space.data());
    ctx->setSignal("targetSpaceHash", val);
    
    Fr_fromBin(&val, constraints.data());
    ctx->setSignal("constraintsHash", val);
    
    Fr_fromBin(&val, metric.data());
    ctx->setSignal("successMetricHash", val);
    
    FrElement prio, ent;
    Fr_from32(&prio, priority);
    Fr_from32(&ent, quantized_entropy);
    ctx->setSignal("priority", prio);
    ctx->setSignal("entropyEstimate", ent);

    // 3. Compute Witness (Throws if constraints violated)
    ctx->generate();

    // 4. Pipe to Rapidsnark for CUDA Proving
    // Assumes proving key 'engine_final.zkey' is available
    auto proof_data = rapidsnark::groth16_prove_cuda(ctx->getWitness(), "engine_final.zkey");

    // 5. Construct result
    ZkProof result;
    result.pi_a = proof_data.pi_a;
    result.pi_b = proof_data.pi_b;
    result.pi_c = proof_data.pi_c;
    
    // Public signals: [resultHash, priority] (snarkjs order)
    result.public_signals.resize(32 + 4);
    // resultHash will be filled after Poseidon hash computation
    // For now, use mock
    result.public_signals[0..32].copy_from_slice(&target_space); // placeholder
    std::memcpy(&result.public_signals[32], &priority, 4);

    // 6. Compute commitment hashes
    // resultHash = Poseidon(targetSpace, constraints, metric, priority, entropy)
    // In real implementation: extract from witness or recompute
    std::vector<uint8_t> result_input;
    result_input.insert(result_input.end(), target_space.begin(), target_space.end());
    result_input.insert(result_input.end(), constraints.begin(), constraints.end());
    result_input.insert(result_input.end(), metric.begin(), metric.end());
    result_input.insert(result_input.end(), reinterpret_cast<const uint8_t*>(&priority), 
                        reinterpret_cast<const uint8_t*>(&priority) + 4);
    result_input.insert(result_input.end(), reinterpret_cast<const uint8_t*>(&quantized_entropy),
                        reinterpret_cast<const uint8_t*>(&quantized_entropy) + 4);
    
    result.result_hash = blake3_hash(result_input);
    
    // proofHash = hash of proof components
    std::vector<uint8_t> proof_input;
    proof_input.insert(proof_input.end(), result.pi_a.begin(), result.pi_a.end());
    proof_input.insert(proof_input.end(), result.pi_b.begin(), result.pi_b.end());
    proof_input.insert(proof_input.end(), result.pi_c.begin(), result.pi_c.end());
    result.proof_hash = blake3_hash(proof_input);

    // Update public signals with actual resultHash
    std::memcpy(result.public_signals.data(), result.result_hash.data(), 32);

    delete ctx;
    return result;
}

} // namespace algorithm_engine