import pytest
import smtplib
from unittest.mock import patch, MagicMock

import bmspy.ups as ups_mod
from bmspy.classes import BMSScalarField, BMSMultiField, BMSInfoField, UPS
from bmspy.ups import _get_field_value, handle_shutdown, handle_email


# ---------------------------------------------------------------------------
# Fixtures: reset module-level globals between tests
# ---------------------------------------------------------------------------

@pytest.fixture(autouse=True)
def _reset_globals():
    ups_mod.scheduled_shutdown = False
    ups_mod.critical_sent = False
    ups_mod.warning_sent = False
    ups_mod.alert_sent = False
    yield
    ups_mod.scheduled_shutdown = False
    ups_mod.critical_sent = False
    ups_mod.warning_sent = False
    ups_mod.alert_sent = False


# ---------------------------------------------------------------------------
# _get_field_value
# ---------------------------------------------------------------------------

class TestGetFieldValue:
    def _ups(self):
        return UPS.from_dict({
            "bms_current_amps": {
                "help": "Current",
                "raw_value": -2.5,
                "value": "-2.50",
                "units": "A",
            },
            "bms_capacity_charge_ratio": {
                "help": "Percent Charge",
                "raw_value": 0.75,
                "value": "0.75",
                "units": "%",
            },
            "bms_date": {
                "help": "Date",
                "info": "2023-01-15",
            },
            "bms_cells": {
                "help": "Cells",
                "label": "cell",
                "raw_values": {1: 3.6},
                "values": {1: "3.600"},
                "units": "V",
            },
        })

    def test_found_scalar_field(self):
        ups = self._ups()
        assert _get_field_value(ups, "bms_current_amps") == pytest.approx(-2.5)

    def test_found_charge_ratio(self):
        ups = self._ups()
        assert _get_field_value(ups, "bms_capacity_charge_ratio") == pytest.approx(0.75)

    def test_field_not_found_returns_none(self):
        ups = self._ups()
        assert _get_field_value(ups, "nonexistent_field") is None

    def test_info_field_returns_none(self):
        # BMSInfoField is not a scalar, should return None
        ups = self._ups()
        assert _get_field_value(ups, "bms_date") is None

    def test_multi_field_returns_none(self):
        # BMSMultiField is not a scalar, should return None
        ups = self._ups()
        assert _get_field_value(ups, "bms_cells") is None


# ---------------------------------------------------------------------------
# handle_shutdown
# ---------------------------------------------------------------------------

class TestHandleShutdown:
    def test_shutdown_calls_os_system(self):
        with patch("bmspy.ups.os.system") as mock_sys:
            handle_shutdown(action="shutdown", delay=5)
        mock_sys.assert_called_once_with("/sbin/shutdown 5")

    def test_shutdown_sets_scheduled_flag(self):
        with patch("bmspy.ups.os.system"):
            handle_shutdown(action="shutdown", delay=5)
        assert ups_mod.scheduled_shutdown is not False

    def test_shutdown_does_not_reschedule_if_already_scheduled(self):
        ups_mod.scheduled_shutdown = 9999999999.0
        with patch("bmspy.ups.os.system") as mock_sys:
            handle_shutdown(action="shutdown", delay=5)
        mock_sys.assert_not_called()

    def test_cancel_calls_os_system(self):
        with patch("bmspy.ups.os.system") as mock_sys:
            handle_shutdown(action="cancel")
        mock_sys.assert_called_once_with("/sbin/shutdown -c")

    def test_cancel_does_not_set_flag(self):
        with patch("bmspy.ups.os.system"):
            handle_shutdown(action="cancel")
        assert ups_mod.scheduled_shutdown is False


# ---------------------------------------------------------------------------
# handle_email
# ---------------------------------------------------------------------------

class TestHandleEmail:
    def _mock_smtp(self):
        mock_server = MagicMock()
        mock_smtp_class = MagicMock()
        mock_smtp_class.return_value.__enter__ = MagicMock(return_value=mock_server)
        mock_smtp_class.return_value.__exit__ = MagicMock(return_value=False)
        return mock_smtp_class, mock_server

    def test_basic_send(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class):
            handle_email(
                text="test message",
                level="Alert",
                recipient="user@example.com",
            )
        mock_server.sendmail.assert_called_once()

    def test_ssl_port_triggers_starttls(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class), \
             patch("bmspy.ups.ssl.create_default_context") as mock_ssl:
            handle_email(
                text="test",
                level="Alert",
                recipient="user@example.com",
                port=465,
            )
        mock_server.starttls.assert_called_once()

    def test_port_587_also_triggers_starttls(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class), \
             patch("bmspy.ups.ssl.create_default_context"):
            handle_email(
                text="test",
                level="Alert",
                recipient="user@example.com",
                port=587,
            )
        mock_server.starttls.assert_called_once()

    def test_no_ssl_no_starttls(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class):
            handle_email(
                text="test",
                level="Alert",
                recipient="user@example.com",
                port=25,
            )
        mock_server.starttls.assert_not_called()

    def test_with_credentials_calls_login(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class):
            handle_email(
                text="test",
                level="Alert",
                recipient="user@example.com",
                mailuser="user",
                mailpass="pass",
            )
        mock_server.login.assert_called_once_with("user", "pass")

    def test_without_credentials_no_login(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class):
            handle_email(
                text="test",
                level="Alert",
                recipient="user@example.com",
            )
        mock_server.login.assert_not_called()

    def test_recipient_without_at_gets_hostname_appended(self):
        mock_smtp_class, mock_server = self._mock_smtp()
        with patch("bmspy.ups.smtplib.SMTP", mock_smtp_class), \
             patch("bmspy.ups.socket.gethostname", return_value="myhost"):
            handle_email(
                text="test",
                level="Alert",
                recipient="root",
            )
        # sendmail recipient should be root@myhost
        args = mock_server.sendmail.call_args[0]
        assert args[1] == "root@myhost"


# ---------------------------------------------------------------------------
# ups main() - comprehensive loop testing
# ---------------------------------------------------------------------------

def _make_ups(current_amps: float, charge_ratio: float) -> UPS:
    """Build a UPS with bms_current_amps and bms_capacity_charge_ratio."""
    return UPS.from_dict({
        "bms_current_amps": {
            "help": "Current",
            "raw_value": current_amps,
            "value": str(current_amps),
            "units": "A",
        },
        "bms_capacity_charge_ratio": {
            "help": "Charge Ratio",
            "raw_value": charge_ratio,
            "value": str(charge_ratio),
            "units": "%",
        },
    })


class TestUpsMain:
    """Test ups.main() loop behavior by running a limited number of iterations."""

    def _run_main_with_data(self, data_sequence, argv=None, extra_patches=None):
        """Run main() with a sequence of UPS data, stopping when data runs out."""
        call_count = 0

        def _read_data(*args, **kwargs):
            nonlocal call_count
            if call_count >= len(data_sequence):
                raise StopIteration("done")
            result = data_sequence[call_count]
            call_count += 1
            return result

        patches = {
            "bmspy.ups.client.read_data": _read_data,
            "bmspy.ups.client.handle_registration": MagicMock(),
            "bmspy.ups.time.sleep": MagicMock(),
            "bmspy.ups.os.system": MagicMock(),
        }
        if extra_patches:
            patches.update(extra_patches)

        with patch("sys.argv", ["bmspy-ups"] + (argv or [])):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=_read_data), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.os.system"):
                    ups_mod.main()
        return call_count

    def _make_data(self, current_amps, charge_ratio):
        return {"testups": _make_ups(current_amps, charge_ratio)}

    def test_main_history_pruned_at_10(self):
        """History is pruned to max 10 items."""
        # Send 15 readings to ensure pruning happens
        data_seq = [self._make_data(0.0, 0.80)] * 15

        with patch("sys.argv", ["bmspy-ups"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()

    def test_main_runs_with_not_enough_history(self):
        """With < 4 readings, should print 'not enough readings' and continue."""
        data = [self._make_data(0.0, 0.95)] * 5
        self._run_main_with_data(data)

    def test_main_debug_2_prints_not_enough_readings(self, capsys):
        data = [self._make_data(0.0, 0.95)] * 5
        with patch("sys.argv", ["bmspy-ups", "-v", "-v"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data + [StopIteration]),\
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.os.system"):
                    ups_mod.main()

    def test_main_below_critical_threshold_triggers_shutdown(self):
        """When charge drops below critical threshold, shutdown should be triggered."""
        # Need 5+ readings (>3 in history) to trigger comparisons
        ups_mod.scheduled_shutdown = False
        ups_mod.critical_sent = False
        data_seq = []
        # Populate history with 5 readings all at 20% (below 30% critical)
        for _ in range(5):
            data_seq.append(self._make_data(0.0, 0.20))

        mock_shutdown = MagicMock()
        mock_email = MagicMock()
        with patch("sys.argv", ["bmspy-ups", "--critical", "30"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown", mock_shutdown), \
                     patch("bmspy.ups.handle_email", mock_email):
                    ups_mod.main()
        mock_shutdown.assert_called()

    def test_main_below_warning_threshold_sends_email(self):
        """When charge drops below warning threshold, email alert should be sent."""
        ups_mod.scheduled_shutdown = False
        ups_mod.warning_sent = False
        data_seq = []
        # 5 readings at 60% (below 75% warning, above 30% critical)
        for _ in range(5):
            data_seq.append(self._make_data(0.0, 0.60))

        mock_email = MagicMock()
        with patch("sys.argv", ["bmspy-ups", "--warning", "75", "--critical", "30"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email", mock_email):
                    ups_mod.main()
        mock_email.assert_called()

    def test_main_discharge_alert(self):
        """When current goes negative, discharge alert should be sent.

        Discharge alert requires: current < 0 AND h1 < 0 AND h2 >= 0.
        After 5 reads with seq [+1, -1, +1, +1, -1]:
          h=[+1,-1,+1,+1,-1], current=-1, h1=-1, h2=+1 → triggers alert.
        """
        ups_mod.alert_sent = False
        data_seq = [
            self._make_data(1.0, 0.90),   # r1: +1
            self._make_data(-1.0, 0.89),  # r2: -1 (will be h1)
            self._make_data(1.0, 0.90),   # r3: +1 (will be h2)
            self._make_data(1.0, 0.90),   # r4: +1
            self._make_data(-1.0, 0.88),  # r5: -1 (current) → alert!
        ]

        mock_email = MagicMock()
        with patch("sys.argv", ["bmspy-ups"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email", mock_email):
                    ups_mod.main()
        mock_email.assert_called()

    def test_main_power_regained_alert(self):
        """When current goes from negative to positive, recovery alert sent.

        Recovery requires: current >= 0 AND h1 >= 0 AND h2 < 0.
        After 5 reads with seq [-1, +1, -1, +1, +1]:
          h=[-1,+1,-1,+1,+1], current=+1, h1=+1, h2=-1 → recovery!
        """
        ups_mod.alert_sent = True
        ups_mod.scheduled_shutdown = False
        data_seq = [
            self._make_data(-1.0, 0.80),  # r1: -1
            self._make_data(1.0, 0.81),   # r2: +1 (will be h1)
            self._make_data(-1.0, 0.79),  # r3: -1 (will be h2)
            self._make_data(1.0, 0.81),   # r4: +1
            self._make_data(1.0, 0.82),   # r5: +1 (current) → recovery!
        ]

        mock_email = MagicMock()
        mock_shutdown = MagicMock()
        with patch("sys.argv", ["bmspy-ups"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown", mock_shutdown), \
                     patch("bmspy.ups.handle_email", mock_email):
                    ups_mod.main()
        mock_email.assert_called()

    def test_main_not_enough_history_debug_2(self, capsys):
        """With debug=2 and < 4 readings, prints 'not enough readings'."""
        data_seq = [self._make_data(0.0, 0.95)] * 5
        with patch("sys.argv", ["bmspy-ups", "-v", "-v"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()
        captured = capsys.readouterr()
        assert "not enough readings" in captured.out.lower()

    def test_main_below_warning_debug_1(self, capsys):
        """With debug=1, warning message is printed."""
        ups_mod.warning_sent = False
        data_seq = [self._make_data(0.0, 0.60)] * 5
        with patch("sys.argv", ["bmspy-ups", "-v", "--warning", "75", "--critical", "30"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()
        captured = capsys.readouterr()
        assert "warning" in captured.out.lower()

    def test_main_discharge_alert_debug_1(self, capsys):
        """With debug=1, discharge alert message is printed."""
        ups_mod.alert_sent = False
        data_seq = [
            self._make_data(1.0, 0.90),
            self._make_data(-1.0, 0.89),
            self._make_data(1.0, 0.90),
            self._make_data(1.0, 0.90),
            self._make_data(-1.0, 0.88),
        ]
        with patch("sys.argv", ["bmspy-ups", "-v"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()
        captured = capsys.readouterr()
        assert "discharging" in captured.out.lower()

    def test_main_power_regained_debug_1(self, capsys):
        """With debug=1, power regained message is printed."""
        ups_mod.alert_sent = True
        data_seq = [
            self._make_data(-1.0, 0.80),
            self._make_data(1.0, 0.81),
            self._make_data(-1.0, 0.79),
            self._make_data(1.0, 0.81),
            self._make_data(1.0, 0.82),
        ]
        with patch("sys.argv", ["bmspy-ups", "-v"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()
        captured = capsys.readouterr()
        assert "power regained" in captured.out.lower()

    def test_main_debug_2_prints_current_and_capacity(self, capsys):
        """With debug=2, current and capacity are printed."""
        data_seq = [self._make_data(1.0, 0.80)] * 5
        with patch("sys.argv", ["bmspy-ups", "-v", "-v"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()
        captured = capsys.readouterr()
        assert "current" in captured.out.lower() or "capacity" in captured.out.lower()

    def test_main_debug_1_prints_thresholds(self, capsys):
        """With debug=1 and below threshold, threshold messages are printed."""
        ups_mod.critical_sent = False
        data_seq = [self._make_data(0.0, 0.20)] * 5
        with patch("sys.argv", ["bmspy-ups", "-v", "--critical", "30"]):
            with pytest.raises(StopIteration):
                with patch("bmspy.ups.client.read_data", side_effect=data_seq + [StopIteration("done")]), \
                     patch("bmspy.ups.client.handle_registration"), \
                     patch("bmspy.ups.time.sleep"), \
                     patch("bmspy.ups.handle_shutdown"), \
                     patch("bmspy.ups.handle_email"):
                    ups_mod.main()
        captured = capsys.readouterr()
        assert "critical" in captured.out.lower() or "threshold" in captured.out.lower()