from __future__ import annotations

import unittest

from PythonModels.components.amesim_pneumatic import (
    HELIUM_PNEUMATIC_GAS,
    AmesimPneumaticOrifice,
    AmesimPneumaticVolume,
    AmesimVariablePneumaticVolume,
    cm3_to_m3,
    compressible_orifice_mass_flow,
    diameter_mm_to_area_m2,
    kg_to_g,
    liters_to_m3,
    m3_to_cm3,
    mm2_to_m2,
)


class AmesimPneumaticComponentsTest(unittest.TestCase):
    def test_unit_conversions(self) -> None:
        self.assertAlmostEqual(liters_to_m3(15.0), 0.015)
        self.assertAlmostEqual(m3_to_cm3(0.015), 15000.0)
        self.assertAlmostEqual(cm3_to_m3(15000.0), 0.015)
        self.assertAlmostEqual(kg_to_g(1.25), 1250.0)
        self.assertAlmostEqual(mm2_to_m2(78.5), 78.5e-6)
        self.assertAlmostEqual(diameter_mm_to_area_m2(10.0), 7.853981633974483e-5)

    def test_volume_initial_state_matches_requested_pressure_temperature(self) -> None:
        volume = AmesimPneumaticVolume.from_liters(
            name="pn_general_chamber",
            volume_liters=57.0,
            p0=15.3e6,
            T0=293.15,
        )
        props = volume.properties()

        self.assertAlmostEqual(props.p, 15.3e6, delta=15.3e6 * 1.0e-12)
        self.assertAlmostEqual(props.T, 293.15)
        self.assertGreater(props.rho, 20.0)
        self.assertLess(props.rho, 30.0)

    def test_volume_reports_amesim_style_observables(self) -> None:
        volume = AmesimPneumaticVolume.from_liters(
            name="pn_general_chamber",
            volume_liters=57.0,
            p0=15.3e6,
            T0=293.15,
        )

        self.assertAlmostEqual(volume.volume_cm3(), 57000.0)
        self.assertAlmostEqual(
            volume.pressure_gauge_pa(reference_pressure_pa=101_300.0),
            15198700.0,
        )
        self.assertGreater(volume.gas_mass_g(), 1300.0)

    def test_volume_balances_two_connections_with_stream_enthalpy(self) -> None:
        volume = AmesimPneumaticVolume.from_liters(
            name="pn_general_chamber",
            volume_liters=57.0,
            p0=15.3e6,
            T0=293.15,
        )
        internal_h = volume.properties().h

        derivative = volume.derivatives_from_two_connections(
            port_a_m_flow=0.2,
            connected_h_a=internal_h + 1000.0,
            port_b_m_flow=-0.1,
            connected_h_b=internal_h - 1000.0,
            internal_h=internal_h,
        )

        self.assertAlmostEqual(derivative.m, 0.1)
        self.assertAlmostEqual(
            derivative.U,
            0.2 * (internal_h + 1000.0) - 0.1 * internal_h,
        )
        self.assertAlmostEqual(volume.port_a.p, volume.port_b.p)

    def test_variable_volume_tracks_external_volume(self) -> None:
        volume = AmesimVariablePneumaticVolume.from_liters(
            name="pn_c1_8",
            dead_volume_liters=15.0,
            p0=100000.0,
            T0=293.15,
        )

        self.assertAlmostEqual(volume.volume_cm3(), 15000.0)
        volume.set_external_volume_m3(cm3_to_m3(34242.54636512914))
        self.assertAlmostEqual(volume.volume_cm3(), 49242.54636512914)

    def test_orifice_returns_signed_mass_flow(self) -> None:
        orifice = AmesimPneumaticOrifice.from_mm2(
            name="pn_orifice_18",
            area_mm2=78.5,
            flow_coefficient=0.9,
        )

        forward = orifice.mass_flow(15.3e6, 1.0e6, 293.15)
        reverse = orifice.mass_flow(1.0e6, 15.3e6, 293.15)

        self.assertGreater(forward, 0.0)
        self.assertAlmostEqual(reverse, -forward)
        self.assertEqual(orifice.mass_flow(1.0e6, 1.0e6, 293.15), 0.0)

    def test_choked_flow_is_independent_of_lower_downstream_pressure(self) -> None:
        base = compressible_orifice_mass_flow(
            upstream_pressure=15.3e6,
            downstream_pressure=1.0e6,
            upstream_temperature=293.15,
            area=78.5e-6,
            flow_coefficient=0.9,
            gas=HELIUM_PNEUMATIC_GAS,
        )
        lower_back_pressure = compressible_orifice_mass_flow(
            upstream_pressure=15.3e6,
            downstream_pressure=0.1e6,
            upstream_temperature=293.15,
            area=78.5e-6,
            flow_coefficient=0.9,
            gas=HELIUM_PNEUMATIC_GAS,
        )

        self.assertGreater(base, 0.0)
        self.assertAlmostEqual(lower_back_pressure, base)

    def test_subcritical_flow_decreases_as_back_pressure_rises(self) -> None:
        low_back_pressure = compressible_orifice_mass_flow(
            upstream_pressure=1.0e6,
            downstream_pressure=0.6e6,
            upstream_temperature=293.15,
            area=78.5e-6,
            flow_coefficient=0.9,
        )
        high_back_pressure = compressible_orifice_mass_flow(
            upstream_pressure=1.0e6,
            downstream_pressure=0.9e6,
            upstream_temperature=293.15,
            area=78.5e-6,
            flow_coefficient=0.9,
        )

        self.assertGreater(low_back_pressure, high_back_pressure)
        self.assertGreater(high_back_pressure, 0.0)


if __name__ == "__main__":
    unittest.main()