"""Tests for CalDAVSyncProvider — bidirectional Apple Calendar sync (U6).

The ``caldav`` library is not installed in the test environment, so we inject
a mock module into ``sys.modules`` before importing the provider. All CalDAV
interactions are mocked via the ``client_factory`` injection point.
"""

from __future__ import annotations

import asyncio
import json
import sys
from pathlib import Path
from typing import Any
from unittest.mock import MagicMock

import pytest

# caldav is not installed in the test env — inject a mock module so that
# `import caldav` in caldav_provider.py succeeds at import time.
if "caldav" not in sys.modules:  # pragma: no cover
    sys.modules["caldav"] = MagicMock()

from agentkit.calendar.db import (
    get_event_by_external_id,
    init_calendar_db,
    insert_event,
    list_events,
)
from agentkit.calendar.models import CalendarEvent, ExternalCalendarConfig
from agentkit.calendar.sync.caldav_provider import CalDAVSyncProvider

USER_ID = "user-1"


# ---------------------------------------------------------------------------
# ICS + Mock helpers
# ---------------------------------------------------------------------------


def make_ics(
    uid: str,
    summary: str,
    start: str = "20260701T100000Z",
    end: str = "20260701T110000Z",
    description: str = "",
    location: str = "",
    rrule: str | None = None,
    last_modified: str = "20260601T000000Z",
) -> bytes:
    """Build a minimal valid ICS bytes payload for a single VEVENT."""
    lines = [
        b"BEGIN:VCALENDAR",
        b"VERSION:2.0",
        b"PRODID:-//Test//Test//EN",
        b"BEGIN:VEVENT",
        f"UID:{uid}".encode(),
        f"SUMMARY:{summary}".encode(),
        f"DTSTART:{start}".encode(),
        f"DTEND:{end}".encode(),
    ]
    if description:
        lines.append(f"DESCRIPTION:{description}".encode())
    if location:
        lines.append(f"LOCATION:{location}".encode())
    if rrule:
        lines.append(f"RRULE:{rrule}".encode())
    if last_modified:
        lines.append(f"LAST-MODIFIED:{last_modified}".encode())
    lines.extend([b"END:VEVENT", b"END:VCALENDAR"])
    return b"\r\n".join(lines)


class MockCaldavEvent:
    """Mock caldav.Event — exposes .data returning ICS bytes."""

    def __init__(self, ics_data: bytes) -> None:
        self.data = ics_data


def make_mock_client(
    remote_events: list[bytes],
    saved_uid: str | None = None,
    raise_on_connect: Exception | None = None,
) -> tuple[Any, Any]:
    """Create a mock CalDAV client and its mock calendar.

    Returns ``(client, mock_calendar)``. ``mock_calendar`` is None when
    ``raise_on_connect`` is set (connection fails before calendar is reached).
    """
    client = MagicMock()
    if raise_on_connect is not None:
        client.principal.side_effect = raise_on_connect
        return client, None

    principal = MagicMock()
    calendar = MagicMock()
    calendar.date_search.return_value = [MockCaldavEvent(d) for d in remote_events]
    saved_ics = make_ics(saved_uid or "saved-uid", "Saved Event")
    calendar.save_event.return_value = MockCaldavEvent(saved_ics)
    principal.calendars.return_value = [calendar]
    client.principal.return_value = principal
    return client, calendar


def client_factory_from(client: Any) -> Any:
    """Wrap a mock client in a client_factory callable."""

    def factory(config: ExternalCalendarConfig) -> Any:
        return client

    return factory


def make_config(
    config_id: str = "config-1",
    user_id: str = USER_ID,
    provider: str = "caldav",
    last_sync: str | None = None,
) -> ExternalCalendarConfig:
    return ExternalCalendarConfig(
        id=config_id,
        user_id=user_id,
        provider=provider,
        credentials=json.dumps(
            {"url": "https://caldav.example.com", "username": "user", "password": "pass"}
        ),
        last_sync=last_sync,
    )


def make_local_event(
    event_id: str = "evt-1",
    title: str = "Local Event",
    external_id: str | None = None,
    last_modified: str = "2026-01-01T00:00:00+00:00",
    rrule: str | None = None,
) -> CalendarEvent:
    return CalendarEvent(
        id=event_id,
        user_id=USER_ID,
        title=title,
        start_time="2026-07-01T10:00:00+00:00",
        end_time="2026-07-01T11:00:00+00:00",
        external_id=external_id,
        external_provider="caldav" if external_id else None,
        last_modified=last_modified,
        created_at=last_modified,
        rrule=rrule,
    )


# ---------------------------------------------------------------------------
# Fixtures
# ---------------------------------------------------------------------------


@pytest.fixture
def calendar_db_path(tmp_path: Path) -> Path:
    path = tmp_path / "test_calendar.db"
    asyncio.run(init_calendar_db(path))
    return path


# ---------------------------------------------------------------------------
# Pull tests
# ---------------------------------------------------------------------------


async def test_caldav_provider_pull_creates_local_events(calendar_db_path: Path) -> None:
    """Mock returns 2 events → 2 local events created with external_id set."""
    ics1 = make_ics("uid-1", "Remote Event 1")
    ics2 = make_ics("uid-2", "Remote Event 2")
    client, _ = make_mock_client([ics1, ics2])
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    pulled = await provider.pull_changes(config)

    assert len(pulled) == 2
    events = await list_events(USER_ID, db_path=calendar_db_path)
    assert len(events) == 2
    titles = {e.title for e in events}
    assert titles == {"Remote Event 1", "Remote Event 2"}
    for event in events:
        assert event.external_id is not None
        assert event.external_provider == "caldav"


async def test_caldav_provider_pull_updates_existing_event(calendar_db_path: Path) -> None:
    """Local event exists (matched by external_id), remote is newer → local updated."""
    local = make_local_event(
        event_id="evt-1",
        title="Old Title",
        external_id="uid-1",
        last_modified="2026-01-01T00:00:00+00:00",
    )
    await insert_event(local, calendar_db_path)

    ics_remote = make_ics("uid-1", "Updated Title", last_modified="20260601T120000Z")
    client, _ = make_mock_client([ics_remote])
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    pulled = await provider.pull_changes(config)

    assert len(pulled) == 1
    updated = await get_event_by_external_id("uid-1", "caldav", USER_ID, calendar_db_path)
    assert updated is not None
    assert updated.title == "Updated Title"


# ---------------------------------------------------------------------------
# Push tests
# ---------------------------------------------------------------------------


async def test_caldav_provider_push_creates_remote_event(calendar_db_path: Path) -> None:
    """Local event with no external_id → push creates remote, external_id stored."""
    local = make_local_event(event_id="evt-1", title="New Local Event", external_id=None)
    await insert_event(local, calendar_db_path)

    client, _ = make_mock_client([], saved_uid="remote-uid-1")
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    events = await list_events(USER_ID, db_path=calendar_db_path)
    pushed = await provider.push_changes(config, events)

    assert len(pushed) == 1
    assert pushed[0].external_id == "remote-uid-1"
    assert pushed[0].external_provider == "caldav"
    db_event = await get_event_by_external_id("remote-uid-1", "caldav", USER_ID, calendar_db_path)
    assert db_event is not None


async def test_caldav_provider_push_updates_remote_event(calendar_db_path: Path) -> None:
    """Local event modified, has external_id → push updates remote."""
    local = make_local_event(
        event_id="evt-1",
        title="Updated Local Event",
        external_id="existing-uid",
        last_modified="2026-06-01T00:00:00+00:00",
    )
    await insert_event(local, calendar_db_path)

    client, mock_calendar = make_mock_client([], saved_uid="existing-uid")
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    events = await list_events(USER_ID, db_path=calendar_db_path)
    pushed = await provider.push_changes(config, events)

    assert len(pushed) == 1
    assert pushed[0].external_id == "existing-uid"
    # Verify save_event was called with ICS containing the existing UID
    saved_ics = mock_calendar.save_event.call_args[0][0]
    assert b"UID:existing-uid" in saved_ics


# ---------------------------------------------------------------------------
# Conflict tests
# ---------------------------------------------------------------------------


async def test_caldav_conflict_last_write_wins(calendar_db_path: Path) -> None:
    """Both sides modified, local is newer → local wins, local not updated."""
    local = make_local_event(
        event_id="evt-1",
        title="Local Updated",
        external_id="uid-1",
        last_modified="2026-06-15T00:00:00+00:00",
    )
    await insert_event(local, calendar_db_path)

    ics_remote = make_ics("uid-1", "Remote Older", last_modified="20260601T000000Z")
    client, _ = make_mock_client([ics_remote])
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    pulled = await provider.pull_changes(config)

    # Local wins → no update, pulled is empty
    assert len(pulled) == 0
    db_event = await get_event_by_external_id("uid-1", "caldav", USER_ID, calendar_db_path)
    assert db_event is not None
    assert db_event.title == "Local Updated"


async def test_caldav_conflict_sends_ws_notification(calendar_db_path: Path) -> None:
    """Conflict detected → WS callback called with calendar_sync_conflict type (G4)."""
    notifications: list[tuple[str, dict[str, Any]]] = []

    async def notify(event_type: str, payload: dict[str, Any]) -> None:
        notifications.append((event_type, payload))

    local = make_local_event(
        event_id="evt-1",
        title="Local Updated",
        external_id="uid-1",
        last_modified="2026-06-15T00:00:00+00:00",
    )
    await insert_event(local, calendar_db_path)

    ics_remote = make_ics("uid-1", "Remote Older", last_modified="20260601T000000Z")
    client, _ = make_mock_client([ics_remote])
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path,
        client_factory=client_factory_from(client),
        notify_callback=notify,
    )
    config = make_config()

    await provider.pull_changes(config)

    assert len(notifications) == 1
    event_type, payload = notifications[0]
    assert event_type == "calendar_sync_conflict"
    assert payload["event_id"] == "evt-1"
    assert payload["winner"] == "local"


# ---------------------------------------------------------------------------
# RRULE roundtrip test
# ---------------------------------------------------------------------------


async def test_caldav_rrule_roundtrip(calendar_db_path: Path) -> None:
    """Event with RRULE synced → RRULE preserved in both pull and push."""
    rrule = "FREQ=WEEKLY;BYDAY=MO;COUNT=4"
    ics_remote = make_ics("uid-rrule", "Weekly Meeting", rrule=rrule)
    client, _ = make_mock_client([ics_remote])
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    # Pull: verify RRULE preserved
    pulled = await provider.pull_changes(config)
    assert len(pulled) == 1
    assert pulled[0].rrule is not None
    assert "FREQ=WEEKLY" in pulled[0].rrule
    assert "BYDAY=MO" in pulled[0].rrule
    assert "COUNT=4" in pulled[0].rrule

    # Push: verify RRULE in ICS sent to remote
    events = await list_events(USER_ID, db_path=calendar_db_path)
    client2, mock_calendar2 = make_mock_client([], saved_uid="uid-rrule")
    provider2 = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client2)
    )
    await provider2.push_changes(config, events)

    saved_ics = mock_calendar2.save_event.call_args[0][0]
    assert b"RRULE:FREQ=WEEKLY" in saved_ics
    assert b"BYDAY=MO" in saved_ics
    assert b"COUNT=4" in saved_ics


# ---------------------------------------------------------------------------
# test_connection tests
# ---------------------------------------------------------------------------


async def test_caldav_test_connection_success(calendar_db_path: Path) -> None:
    """Mock returns calendars → test_connection() returns (True, "")."""
    client, _ = make_mock_client([])
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    ok, msg = await provider.test_connection(config)
    assert ok is True
    assert msg == ""


async def test_caldav_test_connection_failure(calendar_db_path: Path) -> None:
    """Mock raises → test_connection() returns (False, error_msg)."""
    client, _ = make_mock_client([], raise_on_connect=ConnectionError("Auth failed"))
    provider = CalDAVSyncProvider(
        db_path=calendar_db_path, client_factory=client_factory_from(client)
    )
    config = make_config()

    ok, msg = await provider.test_connection(config)
    assert ok is False
    assert "Auth failed" in msg