from __future__ import annotations

from datetime import datetime, timezone
from io import StringIO
from pathlib import Path
from tempfile import TemporaryDirectory

from django.core.management import call_command
from django.test import TestCase

from pobsync.util import write_yaml_atomic
from pobsync_backend.models import GlobalConfig, HostConfig, SnapshotRecord
from pobsync_backend.snapshot_discovery import discover_snapshots, parse_snapshot_datetime


class SnapshotDiscoveryTests(TestCase):
    def test_parse_snapshot_datetime_prefers_metadata(self) -> None:
        parsed = parse_snapshot_datetime(
            "20260519-021500Z__ABCDEFGH",
            {"started_at": "2026-05-20T03:16:00Z"},
            "started_at",
        )

        self.assertEqual(parsed, datetime(2026, 5, 20, 3, 16, tzinfo=timezone.utc))

    def test_parse_snapshot_datetime_falls_back_to_dirname(self) -> None:
        parsed = parse_snapshot_datetime("20260519-021500Z__ABCDEFGH", {}, "started_at")

        self.assertEqual(parsed, datetime(2026, 5, 19, 2, 15, tzinfo=timezone.utc))

    def test_discovery_upserts_snapshot_records_idempotently(self) -> None:
        with TemporaryDirectory() as tmp:
            backup_root = Path(tmp) / "backups"
            GlobalConfig.objects.create(name="default", backup_root=str(backup_root))
            host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
            snapshot_dir = backup_root / host.host / "scheduled" / "20260519-021500Z__ABCDEFGH"
            meta_dir = snapshot_dir / "meta"
            meta_dir.mkdir(parents=True)
            write_yaml_atomic(
                meta_dir / "meta.yaml",
                {
                    "status": "success",
                    "started_at": "2026-05-19T02:15:00Z",
                    "ended_at": "2026-05-19T02:16:00Z",
                },
            )

            first = discover_snapshots(host=host)
            second = discover_snapshots(host=host)

        self.assertEqual(first["created"], 1)
        self.assertEqual(first["updated"], 0)
        self.assertEqual(second["created"], 0)
        self.assertEqual(second["updated"], 1)
        self.assertEqual(SnapshotRecord.objects.count(), 1)
        record = SnapshotRecord.objects.get()
        self.assertEqual(record.status, "success")
        self.assertEqual(record.kind, "scheduled")
        self.assertEqual(record.started_at, datetime(2026, 5, 19, 2, 15, tzinfo=timezone.utc))

    def test_command_discovers_snapshots_for_host(self) -> None:
        with TemporaryDirectory() as tmp:
            backup_root = Path(tmp) / "backups"
            GlobalConfig.objects.create(name="default", backup_root=str(backup_root))
            host = HostConfig.objects.create(host="web-01", address="web-01.example.test")
            snapshot_dir = backup_root / host.host / ".incomplete" / "20260519-021500Z__ABCDEFGH"
            (snapshot_dir / "meta").mkdir(parents=True)

            call_command("discover_pobsync_snapshots", host=host.host, kind="incomplete", stdout=StringIO())

        self.assertEqual(SnapshotRecord.objects.count(), 1)
        self.assertEqual(SnapshotRecord.objects.get().kind, "incomplete")