% Small surface-code prototype tests.

for q = 1:9
    e = zeros(1,9);
    e(q) = 1;
    s = surface3_x_syndrome(e);
    ehat = decode_surface3_x_matching(s);
    assert(isequal(surface3_x_syndrome(xor(e, ehat)), [0 0 0 0]));
    assert(~surface3_logical_failure(xor(e, ehat)));
end

for q = 1:9
    e = zeros(1,9);
    e(q) = 1;
    s = surface3_z_syndrome(e);
    ehat = decode_surface3_z_matching(s);
    assert(isequal(surface3_z_syndrome(xor(e, ehat)), [0 0 0 0]));
    assert(~surface3_logical_failure(xor(e, ehat)));
end

for q = 1:9
    labels = repmat('I', 1, 9);

    labels(q) = 'X';
    x_error = (labels == 'X') | (labels == 'Y');
    z_error = (labels == 'Z') | (labels == 'Y');
    assert(~surface3_logical_failure(xor(x_error, decode_surface3_x_matching(surface3_x_syndrome(x_error)))));
    assert(~surface3_logical_failure(xor(z_error, decode_surface3_z_matching(surface3_z_syndrome(z_error)))));

    labels(q) = 'Y';
    x_error = (labels == 'X') | (labels == 'Y');
    z_error = (labels == 'Z') | (labels == 'Y');
    assert(~surface3_logical_failure(xor(x_error, decode_surface3_x_matching(surface3_x_syndrome(x_error)))));
    assert(~surface3_logical_failure(xor(z_error, decode_surface3_z_matching(surface3_z_syndrome(z_error)))));

    labels(q) = 'Z';
    x_error = (labels == 'X') | (labels == 'Y');
    z_error = (labels == 'Z') | (labels == 'Y');
    assert(~surface3_logical_failure(xor(x_error, decode_surface3_x_matching(surface3_x_syndrome(x_error)))));
    assert(~surface3_logical_failure(xor(z_error, decode_surface3_z_matching(surface3_z_syndrome(z_error)))));
end

out = simulate_surface3_pauli_once(0);
assert(out.success);
assert(isequal(out.error, repmat('I', 1, 9)));

history = [1 0 1 0; 1 1 1 0; 0 0 1 1];
assert(isequal(surface3_majority_syndrome(history), [1 0 1 0]));
assert(isequal(syndrome_detector_history(history), ...
                [1 0 1 0; 0 1 0 0; 1 1 0 1]));

assert(isequal(noisy_syndrome_surface3([1 0 1 0], 0), [1 0 1 0]));

for q = 1:9
    e = zeros(1,9);
    e(q) = 1;

    [~, s_hat_x, history_x, residual_x] = recover_surface3_x_noisy_syndrome(e, 0, 3);
    assert(isequal(history_x, repmat(surface3_x_syndrome(e), 3, 1)));
    assert(isequal(s_hat_x, surface3_x_syndrome(e)));
    assert(~surface3_logical_failure(residual_x));

    out_x = simulate_surface3_x_noisy_syndrome_once(0, 0, 3);
    assert(isequal(out_x.detector_history, syndrome_detector_history(out_x.syndrome_history)));

    [~, s_hat_z, history_z, residual_z] = recover_surface3_z_noisy_syndrome(e, 0, 3);
    assert(isequal(history_z, repmat(surface3_z_syndrome(e), 3, 1)));
    assert(isequal(s_hat_z, surface3_z_syndrome(e)));
    assert(~surface3_logical_failure(residual_z));

    out_z = simulate_surface3_z_noisy_syndrome_once(0, 0, 3);
    assert(isequal(out_z.detector_history, syndrome_detector_history(out_z.syndrome_history)));
end

schedule = surface3_measurement_schedule();
assert(isequal(schedule.data_qubits, 1:9));
assert(isequal(schedule.z_ancillas, 10:13));
assert(isequal(schedule.x_ancillas, 14:17));
assert(numel(schedule.z_checks) == 4);
assert(numel(schedule.x_checks) == 4);

out = simulate_surface3_circuit_level_once(0, 0, 0, 3);
assert(out.success);
assert(isequal(out.x_error, zeros(1, 9)));
assert(isequal(out.z_error, zeros(1, 9)));
assert(isequal(out.x_syndrome_history, zeros(3, 4)));
assert(isequal(out.z_syndrome_history, zeros(3, 4)));
assert(isequal(out.x_detector_history, zeros(3, 4)));
assert(isequal(out.z_detector_history, zeros(3, 4)));
assert(numel(out.hook_events) == 0);

rand('seed', 11);
out = simulate_surface3_circuit_level_once(0, 0, 1, 1);
assert(numel(out.hook_events) > 0);
assert(numel(out.x_error) == 9);
assert(numel(out.z_error) == 9);
assert(size(out.x_syndrome_history, 1) == 1);
assert(size(out.z_syndrome_history, 2) == 4);