"""Search contraction path and save."""
import time, os, pickle
from qibotn.parallel import parallel_path_search
from qibotn.observables import build_random_circuit
import qibo, quimb as qu

from mpi4py import MPI

NQUBITS, NLAYERS, WORKERS = 20, 10, 96

comm = MPI.COMM_WORLD
rank, size = comm.Get_rank(), comm.Get_size()
method = 'mpi' if size > 1 else 'processpool'

circuit = build_random_circuit(NQUBITS, NLAYERS)
qibo.set_backend("qibotn", platform="quimb")
backend = qibo.get_backend()
backend.configure_tn_simulation(ansatz="tn")
qc = backend._qibo_circuit_to_quimb(circuit, backend.circuit_ansatz)
tn = qc.local_expectation(qu.pauli('x') & qu.pauli('z'), (0, 1), rehearse='tn')

if rank == 0:
    print(f"Searching {NQUBITS}q {NLAYERS}l, method={method}, ranks={size}, workers/rank={WORKERS}...")
t0 = time.time()
tree = parallel_path_search(tn, tn.outer_inds(), method=method,
    total_repeats=1024, max_time=300, n_workers=WORKERS,trial_timeout=60)
t_search = time.time() - t0

if rank == 0:
    os.makedirs('data', exist_ok=True)
    path = f"data/tree_q{NQUBITS}_l{NLAYERS}.pkl"
    with open(path, 'wb') as f:
        pickle.dump(tree, f)
    print(f"Search: {t_search:.2f}s  Peak: {tree.max_size() * 16 / 1e9:.2f} GB  Saved: {path}")