"""Tests performance of quantum Shannon decomposition.
"""

import sys
import time

from scipy.stats import unitary_group

import cirq


if not sys.warnoptions:
    import warnings
    warnings.simplefilter("ignore")


def main():
    measurements = []
    n_qubits = 7
    for i in range(10):
        print(f'Iteration {i}')
        U = unitary_group.rvs(2**n_qubits)
        qubits = [cirq.NamedQubit(f'q{i}') for i in range(n_qubits)]
        start_time = time.time()
        circuit = cirq.Circuit(cirq.quantum_shannon_decomposition(qubits, U))
        elapsed_time = time.time() - start_time
        print(f'Time taken: {elapsed_time:.2f} seconds')

        # Run cirq transpiler
        start_time = time.time()
        circuit = cirq.optimize_for_target_gateset(circuit, gateset=cirq.CZTargetGateset(preserve_moment_structure=False), max_num_passes=None)
        elapsed_time = time.time() - start_time
        measurements.append(elapsed_time)
        print(f'Cirq depth for {n_qubits} qubits (with transpiler): {len(circuit)} ({elapsed_time:.2f} sec)')

    print(f'Average time taken: {sum(measurements) / len(measurements):.2f} seconds')


if __name__ == '__main__':
    main()