import hashlib
import os
import math

class EntanglementSwapper:
    def __init__(self, num_relay_nodes, link_fidelity, swap_success_probability):
        self.num_relay_nodes = num_relay_nodes
        self.link_fidelity = link_fidelity
        self.swap_success_probability = swap_success_probability

    def simulate_relay_chain(self, distance_km):
        # Base fidelity degrades over distance and swaps
        end_to_end_fidelity = (self.link_fidelity ** self.num_relay_nodes) * self.swap_success_probability + 0.1
        return {
            "end_to_end_fidelity": end_to_end_fidelity,
            "one_way_latency_seconds": distance_km / 300_000,
        }

class OrbitalSatelliteNoiseModel:
    def __init__(self, orbit):
        self.orbit = orbit
        
    def compute_channel_model(self):
        models = {
            "LEO": {"altitude_km": 500, "atmospheric_error_rate": 0.05, "doppler_shift_ghz": 0.01, "beam_divergence_loss_db": 20, "background_noise_cps": 1000},
            "GEO": {"altitude_km": 35786, "atmospheric_error_rate": 0.08, "doppler_shift_ghz": 0.005, "beam_divergence_loss_db": 40, "background_noise_cps": 500},
            "LUNAR": {"altitude_km": 384400, "atmospheric_error_rate": 0.0, "doppler_shift_ghz": 0.05, "beam_divergence_loss_db": 60, "background_noise_cps": 100},
            "MARS": {"altitude_km": 225000000, "atmospheric_error_rate": 0.0, "doppler_shift_ghz": 1.5, "beam_divergence_loss_db": 120, "background_noise_cps": 10},
        }
        return models.get(self.orbit, models["LEO"])

class DeepSpaceRelay:
    def simulate_route(self, route_name):
        routes = {
            "Earth-LEO": {"distance_km": 500, "nodes": 1, "fid": 0.99},
            "Earth-Moon": {"distance_km": 384400, "nodes": 2, "fid": 0.97},
            "Earth-Mars": {"distance_km": 225000000, "nodes": 5, "fid": 0.95},
        }
        r = routes.get(route_name, routes["Earth-LEO"])
        swapper = EntanglementSwapper(r["nodes"], r["fid"], 0.8)
        sim = swapper.simulate_relay_chain(r["distance_km"])
        return {
            "entanglement_swapping": sim,
            "is_viable": sim["end_to_end_fidelity"] > 0.1
        }

class QKDTelemetryChannel:
    def __init__(self, probe_name, distance_km):
        self.probe_name = probe_name
        self.distance_km = distance_km
        self._shared_key = os.urandom(32)

    def negotiate_key(self, num_raw_bits):
        # Simulate QKD
        sifted = num_raw_bits // 2
        qber = 0.02
        return {
            "sifted_key_length": sifted,
            "qber": qber,
            "is_secure": qber < 0.11,
            "final_key_hex": self._shared_key.hex()
        }

    def encrypt_telemetry_frame(self, plaintext):
        plaintext_bytes = plaintext.encode("utf-8")
        key_stream = b""
        counter = 0
        while len(key_stream) < len(plaintext_bytes):
            key_stream += hashlib.sha256(self._shared_key + counter.to_bytes(4, "big")).digest()
            counter += 1
        ciphertext = bytes(p ^ k for p, k in zip(plaintext_bytes, key_stream))
        return {
            "ciphertext_hex": ciphertext.hex(),
            "security_level": "InformationTheoretic"
        }

    def decrypt_telemetry_frame(self, ciphertext_hex):
        ciphertext_bytes = bytes.fromhex(ciphertext_hex)
        key_stream = b""
        counter = 0
        while len(key_stream) < len(ciphertext_bytes):
            key_stream += hashlib.sha256(self._shared_key + counter.to_bytes(4, "big")).digest()
            counter += 1
        plaintext = bytes(c ^ k for c, k in zip(ciphertext_bytes, key_stream))
        return plaintext.decode("utf-8")

class EntanglementSensorNetwork:
    def __init__(self, num_sensors, baseline_sensitivity):
        self.num_sensors = num_sensors
        self.baseline_sensitivity = baseline_sensitivity

    def deploy_network(self, positions):
        return {
            "num_sensors": len(positions),
            "max_baseline_km": 100 * len(positions),
            "effective_aperture_km2": 100 * len(positions) ** 2
        }

    def simulate_measurement(self, signal_strength):
        sql = 1 / math.sqrt(self.num_sensors)
        hl = 1 / self.num_sensors
        return {
            "true_signal": signal_strength,
            "heisenberg_sensitivity": hl * self.baseline_sensitivity,
            "standard_quantum_limit": sql * self.baseline_sensitivity,
            "snr_heisenberg": signal_strength / (hl * self.baseline_sensitivity),
            "snr_classical": signal_strength / (sql * self.baseline_sensitivity),
            "quantum_advantage_factor": sql / hl,
            "entanglement_state": f"GHZ_{self.num_sensors}"
        }


# Re-export phase 31 production implementations.
from .space import (
    EntanglementSwapper,
    OrbitalSatelliteNoiseModel,
    DeepSpaceRelay,
    QKDTelemetryChannel,
    EntanglementSensorNetwork,
)
