import pytest
from io import StringIO
import colorama
from slic.utils.pv import PV
from epics import PV as EpicsPV


@pytest.fixture
def capture_stdout(monkeypatch):
    buf = StringIO()
    monkeypatch.setattr("sys.stdout", buf)
    return buf

# Fake PV 
class FakeEPICS(EpicsPV):
    def __init__(self, *args, **kwargs):

        super().__init__(*args, **kwargs)
        self._value = 0.0
        self.units = "units"

    def get(self, *args, **kwargs):
        print(f"[DEBUG] FakeEPICS.get() returning {self._value}")
        return self._value

    def put(self, value, *args, **kwargs):
        self._value = value
        return value

# Fixture that monkeypatch epics.PV → FakeEPICS
@pytest.fixture
def fake_epics_pv(monkeypatch):
    monkeypatch.setattr("epics.PV", FakeEPICS)
    return PV("TEST:PV")


@pytest.fixture
def capture_stdout(monkeypatch):
    buf = StringIO()
    monkeypatch.setattr("sys.stdout", buf)
    return buf


@pytest.mark.parametrize("value, expected_bar, expected_color, expected_repr", [
    (25.0,  "██▌       ", colorama.Fore.GREEN, 'PV "TEST:PV" at 25.0 units'),
    (50.0,  "█████     ", colorama.Fore.GREEN, 'PV "TEST:PV" at 50.0 units'),
    (75.0,  "███████▌  ", colorama.Fore.GREEN, 'PV "TEST:PV" at 75.0 units'),
    (100.0, "██████████", colorama.Fore.GREEN, 'PV "TEST:PV" at 100.0 units'),
    (150.0, ">>>>>>>>>>", colorama.Fore.RED,   'PV "TEST:PV" at 150.0 units'),
    (-50.0, "<<<<<<<<<<", colorama.Fore.RED,   'PV "TEST:PV" at -50.0 units')
])

def test_progress_and_repr(fake_epics_pv, capture_stdout, value, expected_bar, expected_color, expected_repr):

    pv = fake_epics_pv
    
    # Test put() and progress bar
    pv.put(value, show_progress=True)
    output = capture_stdout.getvalue()
    
    # Verify progress bar display
    assert f"|{expected_bar}|" in output
    assert expected_color in output
    assert str(value) in output
    
    # Verify value update
    assert pv.get() == pytest.approx(value)

    # Test origin_repr
    assert f"PV TEST:PV at {value} units" == pv.orig_repr()
    
    capture_stdout.truncate(0)

def test_use_callback_context_manager(fake_epics_pv):
    # Test the use_callback context manager functionality
    pv = fake_epics_pv
    callback_log = []
    def test_callback(value, **kwargs):
        callback_log.append(value)

        # Verify callback is added and removed properly
        assert len(pv._pv._callbacks) == 0  # No callbacks initially

        with pv.use_callback(test_callback) as callback_id:
            # Callback should be added when entering context
            assert len(pv._pv._callbacks) == 1
            assert callback_id in pv._pv._callbacks
            
            # Trigger callback
            pv.put(10.0)
            assert callback_log == [10.0]

        # Callback should be removed after context
        assert len(pv._pv._callbacks) == 0