"""The usage roll-up: payload shape, accumulation, pruning and sampling."""

from __future__ import annotations

import json
import tempfile
import unittest
from datetime import datetime, timedelta, timezone
from pathlib import Path

from webrestrict.telemetry import (
    MAX_DAYS,
    MAX_SAMPLE_SECONDS,
    TelemetryStore,
    UsageSampler,
    build_payload,
    day_key,
    to_entries,
)

NOW = datetime(2026, 10, 14, 20, 0, tzinfo=timezone.utc)


class PayloadTests(unittest.TestCase):
    def test_shape_matches_the_control_service(self):
        body = build_payload("2026-10-14", {"notepad.exe": 120, "steam.exe": 60})
        self.assertEqual(body["day"], "2026-10-14")
        self.assertEqual(body["apps"], [{"name": "notepad.exe", "seconds": 120}, {"name": "steam.exe", "seconds": 60}])
        # Windows cannot attribute domains cheaply; the gap is explicit, not guessed.
        self.assertEqual(body["domains"], [])

    def test_zero_and_blank_entries_are_dropped(self):
        self.assertEqual(to_entries({"": 10, "steam.exe": 0, "notepad.exe": 5}), [{"name": "notepad.exe", "seconds": 5}])

    def test_day_key_is_local(self):
        self.assertEqual(day_key(datetime(2026, 1, 2, 23, 59)), "2026-01-02")

    def test_an_aware_timestamp_is_converted_to_local_time(self):
        # The day boundary must be the child's midnight, not UTC's.
        offset = datetime.now().astimezone().utcoffset()
        utc = datetime(2026, 1, 2, 23, 30, tzinfo=timezone.utc)
        self.assertEqual(day_key(utc), (utc + offset).strftime("%Y-%m-%d"))


class StoreTests(unittest.TestCase):
    def setUp(self):
        self.tmp = tempfile.TemporaryDirectory()
        self.path = Path(self.tmp.name) / "telemetry.json"
        self.addCleanup(self.tmp.cleanup)

    def test_accumulates_and_persists(self):
        store = TelemetryStore(self.path)
        store.add_seconds("2026-10-14", {"notepad.exe": 60})
        store.add_seconds("2026-10-14", {"notepad.exe": 30, "steam.exe": 10})
        self.assertEqual(store.day("2026-10-14"), {"notepad.exe": 90, "steam.exe": 10})

        reloaded = TelemetryStore(self.path)
        self.assertEqual(reloaded.day("2026-10-14"), {"notepad.exe": 90, "steam.exe": 10})

    def test_ignores_non_positive_samples(self):
        store = TelemetryStore(self.path)
        store.add_seconds("2026-10-14", {"notepad.exe": 0, "steam.exe": -5})
        self.assertEqual(store.day("2026-10-14"), {})

    def test_prunes_to_the_most_recent_days(self):
        store = TelemetryStore(self.path)
        for day in range(1, MAX_DAYS + 5):
            store.add_seconds(f"2026-01-{day:02d}", {"notepad.exe": 1})
        self.assertEqual(len(store.days), MAX_DAYS)
        self.assertIn("2026-01-18", store.days)
        self.assertNotIn("2026-01-01", store.days)

    def test_an_unreadable_file_starts_empty(self):
        self.path.write_text("{not json", encoding="utf-8")
        store = TelemetryStore(self.path).load()
        self.assertEqual(store.days, {})

    def test_written_json_is_readable(self):
        store = TelemetryStore(self.path)
        store.add_seconds("2026-10-14", {"notepad.exe": 5})
        self.assertIn("days", json.loads(self.path.read_text(encoding="utf-8")))


class SamplerTests(unittest.TestCase):
    def setUp(self):
        self.tmp = tempfile.TemporaryDirectory()
        self.store = TelemetryStore(Path(self.tmp.name) / "telemetry.json")
        self.addCleanup(self.tmp.cleanup)

    def test_the_first_sample_only_starts_the_clock(self):
        sampler = UsageSampler(self.store)
        self.assertEqual(sampler.sample(["notepad.exe"], now=NOW, day="2026-10-14"), {})

    def test_credits_elapsed_seconds_to_each_visible_app(self):
        sampler = UsageSampler(self.store)
        sampler.sample(["notepad.exe"], now=NOW, day="2026-10-14")
        totals = sampler.sample(["notepad.exe", "steam.exe"], now=NOW + timedelta(seconds=60), day="2026-10-14")
        self.assertEqual(totals, {"notepad.exe": 60, "steam.exe": 60})

    def test_a_long_gap_is_capped(self):
        sampler = UsageSampler(self.store)
        sampler.sample(["notepad.exe"], now=NOW, day="2026-10-14")
        totals = sampler.sample(
            ["notepad.exe"], now=NOW + timedelta(hours=5), day="2026-10-14"
        )
        self.assertEqual(totals["notepad.exe"], int(MAX_SAMPLE_SECONDS))

    def test_no_visible_apps_adds_nothing(self):
        sampler = UsageSampler(self.store)
        sampler.sample([], now=NOW, day="2026-10-14")
        self.assertEqual(sampler.sample([], now=NOW + timedelta(seconds=60), day="2026-10-14"), {})


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