from __future__ import annotations

import unittest
from datetime import datetime, timedelta, timezone

from cold_display_guard import BatchEngine, EngineSettings, Observation


UTC = timezone.utc


def obs(ts: datetime, counts: dict[str, int], trash: bool | int = False) -> Observation:
    return Observation.from_dict(
        {
            "ts": ts.isoformat(),
            "zone_counts": counts,
            "trash_deposit": trash,
        }
    )


class BatchEngineTests(unittest.TestCase):
    def setUp(self) -> None:
        self.settings = EngineSettings(
            camera_id="test_cam",
            max_dwell_seconds=10,
            trash_confirmation_seconds=5,
            zone_ids=("r1c1", "r1c2"),
        )
        self.engine = BatchEngine(self.settings)
        self.t0 = datetime(2026, 4, 27, 10, 0, tzinfo=UTC)

    def test_starts_batch_when_zone_becomes_occupied(self) -> None:
        events = self.engine.process(obs(self.t0, {"r1c1": 3}))

        self.assertEqual([event["event"] for event in events], ["batch_started"])
        self.assertEqual(events[0]["zone_id"], "r1c1")
        self.assertEqual(events[0]["current_count"], 3)

    def test_consumes_batch_when_removed_before_threshold(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 2}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=9), {"r1c1": 0}))

        self.assertEqual([event["event"] for event in events], ["batch_consumed"])
        self.assertEqual(events[0]["dwell_seconds"], 9)

    def test_over_threshold_removal_waits_for_disposal_confirmation(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 2}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=10), {"r1c1": 0}))

        self.assertEqual([event["event"] for event in events], ["batch_pending_disposal"])
        self.assertEqual(events[0]["dwell_seconds"], 10)
        self.assertIn("disposal_deadline", events[0])

    def test_trash_deposit_confirms_pending_disposal(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 2}))
        self.engine.process(obs(self.t0 + timedelta(seconds=11), {"r1c1": 0}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=12), {"r1c1": 0}, trash=True))

        self.assertEqual([event["event"] for event in events], ["batch_discarded"])

    def test_missing_trash_deposit_raises_violation_after_deadline(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 2}))
        self.engine.process(obs(self.t0 + timedelta(seconds=11), {"r1c1": 0}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=17), {"r1c1": 0}))

        self.assertEqual([event["event"] for event in events], ["missing_disposal_violation"])
        self.assertEqual(events[0]["violation_reasons"], ["missing_disposal"])

    def test_adding_food_before_zone_clears_raises_mixed_batch_violation(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 2}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=1), {"r1c1": 3}))

        self.assertEqual([event["event"] for event in events], ["mixed_batch_violation"])
        self.assertEqual(events[0]["reason"], "food_added_before_zone_cleared")

    def test_count_decrease_keeps_same_batch_active(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 3}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=1), {"r1c1": 1}))

        self.assertEqual([event["event"] for event in events], ["batch_count_changed"])
        self.assertEqual(events[0]["previous_count"], 3)
        self.assertEqual(events[0]["current_count"], 1)

    def test_overdue_food_reappearing_before_disposal_raises_violation(self) -> None:
        self.engine.process(obs(self.t0, {"r1c1": 2}))
        self.engine.process(obs(self.t0 + timedelta(seconds=11), {"r1c1": 0}))
        events = self.engine.process(obs(self.t0 + timedelta(seconds=12), {"r1c2": 1}))

        self.assertEqual(
            [event["event"] for event in events],
            ["overdue_return_violation", "batch_started"],
        )
        self.assertEqual(events[0]["appeared_zones"], ["r1c2"])


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