#!/usr/bin/env python3
"""
P3Q Quantum Simulator Backend
Classical simulation of OpenQASM circuits for P4 interlock testing.
NOT a quantum computer - pure classical simulation for verification.
"""

import numpy as np
from typing import Dict, List, Tuple, Optional
from dataclasses import dataclass
from enum import IntEnum


class QSimCommandType(IntEnum):
    KEYGEN_256      = 0x01
    NONCE_128       = 0x02
    GROVER_AES4     = 0x03
    AMP_EST_LEAKAGE = 0x04


class QSimStatus(IntEnum):
    SUCCESS = 0x00
    TIMEOUT = 0x01
    ERROR   = 0x02
    UNSUPPORTED = 0xFF


@dataclass
class QSimCommand:
    cmd_type: QSimCommandType
    qubits: int
    shots: int
    params: bytes
    event_id: int


@dataclass
class QSimResponse:
    event_id: int
    status: QSimStatus
    data: bytes
    shots_completed: int


class P3QSimulator:
    """Classical simulator for P3Q quantum circuits."""

    def __init__(self, seed: Optional[int] = None):
        self.rng = np.random.default_rng(seed)
        self.max_qubits = 32

    def execute(self, cmd: QSimCommand) -> QSimResponse:
        if cmd.qubits > self.max_qubits:
            return QSimResponse(cmd.event_id, QSimStatus.ERROR, b'', 0)

        if cmd.cmd_type == QSimCommandType.KEYGEN_256:
            return self._sim_keygen(cmd)
        elif cmd.cmd_type == QSimCommandType.NONCE_128:
            return self._sim_nonce(cmd)
        elif cmd.cmd_type == QSimCommandType.GROVER_AES4:
            return self._sim_grover_aes4(cmd)
        elif cmd.cmd_type == QSimCommandType.AMP_EST_LEAKAGE:
            return self._sim_amp_est(cmd)
        else:
            return QSimResponse(cmd.event_id, QSimStatus.UNSUPPORTED, b'', 0)

    def _sim_keygen(self, cmd: QSimCommand) -> QSimResponse:
        key_bytes = self.rng.bytes(32)
        return QSimResponse(cmd.event_id, QSimStatus.SUCCESS, key_bytes, 1)

    def _sim_nonce(self, cmd: QSimCommand) -> QSimResponse:
        nonce_bytes = self.rng.bytes(16)
        return QSimResponse(cmd.event_id, QSimStatus.SUCCESS, nonce_bytes, 1)

    def _sim_grover_aes4(self, cmd: QSimCommand) -> QSimResponse:
        if len(cmd.params) < 32:
            return QSimResponse(cmd.event_id, QSimStatus.ERROR, b'', 0)

        results = bytearray()
        for _ in range(min(cmd.shots, 100)):
            key = self.rng.bytes(16)
            results.extend(key)

        return QSimResponse(cmd.event_id, QSimStatus.SUCCESS, bytes(results), len(results)//16)

    def _sim_amp_est(self, cmd: QSimCommand) -> QSimResponse:
        m = min(cmd.qubits - 256, 10)
        phase = self.rng.integers(0, 2**m)
        phase_bytes = phase.to_bytes(4, 'big')
        return QSimResponse(cmd.event_id, QSimStatus.SUCCESS, phase_bytes, cmd.shots)


def test_p4_interlock():
    """Test classical-quantum handshake with simulated P4 events."""
    sim = P3QSimulator(seed=42)

    cmd = QSimCommand(
        cmd_type=QSimCommandType.KEYGEN_256,
        qubits=256, shots=1, params=b'', event_id=0x00000001
    )
    rsp = sim.execute(cmd)
    assert rsp.status == QSimStatus.SUCCESS
    assert len(rsp.data) == 32
    print(f"KeyGen: {rsp.data.hex()}")

    cmd = QSimCommand(
        cmd_type=QSimCommandType.NONCE_128,
        qubits=128, shots=1, params=b'', event_id=0x00000002
    )
    rsp = sim.execute(cmd)
    assert rsp.status == QSimStatus.SUCCESS
    assert len(rsp.data) == 16
    print(f"Nonce: {rsp.data.hex()}")

    pt = bytes.fromhex("00112233445566778899aabbccddeeff")
    ct = bytes.fromhex("69c4e0d86a7b0430d8cdb78070b4c55a")
    cmd = QSimCommand(
        cmd_type=QSimCommandType.GROVER_AES4,
        qubits=512, shots=10, params=pt + ct, event_id=0x00000003
    )
    rsp = sim.execute(cmd)
    assert rsp.status == QSimStatus.SUCCESS
    print(f"Grover shots: {rsp.shots_completed}")

    print("All P4 interlock tests passed.")


if __name__ == "__main__":
    test_p4_interlock()