"""This module asserts correct runtime behaviour of the pyrate.act.pid module."""

# Test environment
from unittest import TestCase

# Mathematics
from numpy import array
from numpy import eye
from numpy.linalg import eig
from numpy import vstack

# Package under test
from pyrate.act.control import AntiWindupLqr


class TestAntiWindupLqr(TestCase):

    """Test for correct runtime behaviour in pyrate.act.control.anti_windup_lqr."""

    # In this context, we reproduce a common controller notation
    # pylint: disable=invalid-name

    def setUp(self) -> None:
        """Setup the LQR specification for testing."""

        # Model specification
        self.A = array([[0, 1], [0, 0]])
        self.B = array([0, 1])[:, None]
        self.C = array([1, 0])[None, :]
        self.max_control = array([1.0])
        self.dt = 0.5

        # Time discrete model
        self.Ad = self.dt * eye(2)
        self.Bd = self.B + self.A @ self.B * self.dt

        # Cost matrix specification
        self.Q = eye(3)
        self.R = array([[1.0]])

        # State and target
        # Target is already reached in this example
        self.wrong_state = vstack([1.0, 0.0])
        self.state_small_negative = vstack([-0.001, 0.0])
        self.state = vstack([0.0, 0.0])
        self.desired = vstack([0.0])
        self.desired1 = vstack([1.0])

    def test_lqr_design(self) -> None:
        """Assert stable controller dynamics"""

        # Initialize controller
        lqr = AntiWindupLqr(
            self.A, self.B, self.C, self.Q, self.R, self.max_control, self.dt, keep_trace=True
        )
        # check continous time eigen_values
        eigen_values, _ = eig(lqr.A - lqr.B @ lqr.K)
        assert all(ev.real < 0 for ev in eigen_values), "instable controller"

    def test_anti_windup(self) -> None:
        """Assert control signal in allowed range, LQR responsive by limited integral part."""

        # Initialize controller
        lqr = AntiWindupLqr(
            self.A, self.B, self.C, self.Q, self.R, self.max_control, self.dt, keep_trace=True
        )

        # Execute a few control steps
        for _ in range(10):
            control_signal = lqr.control(desired=self.desired, state=self.wrong_state)
            assert abs(control_signal) <= self.max_control, "control limits are not applied"

        assert control_signal == -self.max_control, f"control limits not reached {control_signal}"

        # test stationary summed error
        summed_error = lqr.summed_error
        control_signal = lqr.control(desired=self.desired, state=self.wrong_state)
        assert abs(lqr.summed_error - summed_error) < 1e-6, "summed error changes in saturation"

        # test reactiveness
        control_signal_back = lqr.control(desired=self.desired, state=self.state_small_negative)
        assert abs(control_signal_back) < self.max_control, "anti wind up is not working"

    def test_process_tracking(self) -> None:
        """Assert useful controller behavior and that a pandas.DataFrame with process data is created."""

        # Initialize controller
        lqr = AntiWindupLqr(
            self.A, self.B, self.C, self.Q, self.R, self.max_control, self.dt, keep_trace=True
        )

        # Check zero control
        control_signal = lqr.control(desired=self.desired, state=self.state)
        assert control_signal == 0, "Control signal not zero when desired value 0 reached"
        control_signal = lqr.control(desired=self.desired1, state=self.wrong_state)
        assert control_signal == 0, "Control signal not zero when desired value 0 reached"
        lqr.reset()

        # Execute a few control steps
        state = self.wrong_state.copy()
        initial_error = abs(self.C @ state - self.desired)
        for _ in range(10):
            control_signal = lqr.control(desired=self.desired, state=state)
            state = self.Ad.dot(state) + self.Bd.dot(control_signal)
            error = abs(self.C @ state - self.desired)
            assert error < initial_error or error == 0, "Error exceeds initial - instable controller?"

        # Assert correct process tracing with LQR controller
        assert lqr.process is not None, "LQR did not keep trace of process"
        assert len(lqr.process.index) == 10, "LQR has not traced enough steps"

        # Reset controller
        lqr.reset()

        # Assert correct reset to initial state
        assert lqr.summed_error == 0.0, "Integral did not reset summed error properly"
        assert len(lqr.process.index) == 0, "LQR has not dropped process trace properly"