//
// Copyright (c) 2026 BEL ESPRIT D ACCORD TRUST HOLDINGS INC
// All rights reserved.

// BlackHoleEngine/Quantinuum.qs
// Hardware-specific: Quantinuum H1/H2 (all-to-all, native ZZ)
namespace BlackHoleEngine.Quantinuum {
    open Microsoft.Quantum.Intrinsic;
    open Microsoft.Quantum.Canon;
    open BlackHoleEngine.Primitives;

    operation QuantinuumXX(q1 : Qubit, q2 : Qubit, theta : Double) : Unit is Adj + Ctl {
        within {
            H(q1); H(q2);
        } apply {
            Exp([PauliZ, PauliZ], theta, [q1, q2]);
        }
    }

    operation QuantinuumHaydenPreskill(
        qubits : Qubit[],
        scrambleTime : Double,
        couplings : Double[][],
        fields : Double[]
    ) : Unit is Adj + Ctl {
        let n = Length(qubits);
        let dt = scrambleTime / 5.0;
        let steps = 5;

        for _ in 1..steps {
            for i in 0..n-1 {
                Rz(2.0 * fields[i] * dt, qubits[i]);
            }

            for layer in GetXXLayers(n, couplings) {
                for (i, j) in layer {
                    let J = couplings[i][j];
                    if (AbsD(J) > 1e-10) {
                        QuantinuumXX(qubits[i], qubits[j], 2.0 * J * dt);
                    }
                }
            }
        }
    }

    operation QuantinuumLindbladStep(
        ancilla : Qubit,
        qubits : Qubit[],
        viol : ViolatingAssignment,
        gamma_dt : Double
    ) : Unit {
        let sqrt_gamma = Sqrt(gamma_dt);
        let theta = 2.0 * Arcsin(sqrt_gamma);

        Ry(theta, ancilla);

        let (va, vb, vc) = viol;
        if (va) { X(qubits[0]); }
        if (vb) { X(qubits[1]); }
        if (vc) { X(qubits[2]); }

        // Quantinuum has high-fidelity CCZ
        CCZ(ancilla, qubits[0], qubits[1]);
        CCZ(ancilla, qubits[0], qubits[2]);
        CCZ(ancilla, qubits[1], qubits[2]);

        if (va) { X(qubits[0]); }
        if (vb) { X(qubits[1]); }
        if (vc) { X(qubits[2]); }

        let outcome = M(ancilla);
        Reset(ancilla);
    }
}