"""Album watcher service - polls Immich and detects changes."""

from __future__ import annotations

import logging
from datetime import datetime, timezone
from typing import Any

import aiohttp
from sqlmodel import select
from sqlmodel.ext.asyncio.session import AsyncSession
from sqlalchemy.ext.asyncio import AsyncEngine

from immich_watcher_core.asset_utils import build_asset_detail, get_any_url
from immich_watcher_core.change_detector import detect_album_changes
from immich_watcher_core.immich_client import ImmichApiError, ImmichClient
from immich_watcher_core.models import AlbumChange, AlbumData

from ..database.engine import get_engine
from ..database.models import (
    AlbumState,
    AlbumTracker,
    EventLog,
    ImmichServer,
    NotificationTarget,
    TemplateConfig,
    TrackingConfig,
)
from .notifier import send_notification

_LOGGER = logging.getLogger(__name__)


async def check_tracker(tracker_id: int) -> dict[str, Any]:
    """Check a single tracker for album changes.

    Called by the scheduler (creates its own session).
    """
    engine = get_engine()
    async with AsyncSession(engine) as session:
        return await check_tracker_with_session(tracker_id, session)


async def check_tracker_with_session(
    tracker_id: int, session: AsyncSession
) -> dict[str, Any]:
    """Check a single tracker using a provided session.

    Called by API trigger (reuses route session) or by check_tracker.
    """
    tracker = await session.get(AlbumTracker, tracker_id)
    if not tracker or not tracker.enabled:
        return {"skipped": True, "reason": "disabled or not found"}

    server = await session.get(ImmichServer, tracker.server_id)
    if not server:
        return {"error": "Server not found"}

    # Eagerly read all needed data before entering aiohttp context
    # (SQLAlchemy async greenlet context doesn't survive across other async CMs)
    album_ids = list(tracker.album_ids)
    target_ids = list(tracker.target_ids)
    tracker_db_id = tracker_id
    server_url = server.url
    server_api_key = server.api_key

    results = []
    async with aiohttp.ClientSession() as http_session:
        client = ImmichClient(http_session, server_url, server_api_key)

        await client.get_server_config()
        users_cache = await client.get_users()

        for album_id in album_ids:
            result = await _check_album(
                session, http_session, client, tracker_db_id,
                album_id, users_cache, target_ids,
            )
            results.append(result)

    await session.commit()
    return {"albums_checked": len(album_ids), "results": results}


async def _check_album(
    session: AsyncSession,
    http_session: aiohttp.ClientSession,
    client: ImmichClient,
    tracker_id: int,
    album_id: str,
    users_cache: dict[str, str],
    target_ids: list[int],
) -> dict[str, Any]:
    """Check a single album for changes."""
    try:
        album = await client.get_album(album_id, users_cache)
    except ImmichApiError as err:
        _LOGGER.error("Failed to fetch album %s: %s", album_id, err)
        return {"album_id": album_id, "error": str(err)}

    if album is None:
        return {"album_id": album_id, "status": "not_found"}

    # Load previous state
    result = await session.exec(
        select(AlbumState).where(
            AlbumState.tracker_id == tracker_id,
            AlbumState.album_id == album_id,
        )
    )
    state = result.first()

    if state is None:
        # First check - save state, no change detection
        state = AlbumState(
            tracker_id=tracker_id,
            album_id=album_id,
            asset_ids=list(album.asset_ids),
            pending_asset_ids=[],
            last_updated=datetime.now(timezone.utc),
        )
        session.add(state)
        return {"album_id": album_id, "status": "initialized", "asset_count": album.asset_count}

    # Build previous AlbumData from persisted state for change detection
    previous_asset_ids = set(state.asset_ids)
    pending = set(state.pending_asset_ids)

    # Create a minimal previous AlbumData for comparison
    prev_album = AlbumData(
        id=album_id,
        name=album.name,  # Use current name (rename detection compares)
        asset_count=len(previous_asset_ids),
        photo_count=0,
        video_count=0,
        created_at=album.created_at,
        updated_at="",
        shared=album.shared,  # Use current (sharing detection compares)
        owner=album.owner,
        thumbnail_asset_id=None,
        asset_ids=previous_asset_ids,
    )

    # Detect changes
    change, updated_pending = detect_album_changes(prev_album, album, pending)

    # Update persisted state
    state.asset_ids = list(album.asset_ids)
    state.pending_asset_ids = list(updated_pending)
    state.last_updated = datetime.now(timezone.utc)
    session.add(state)

    if change is None:
        return {"album_id": album_id, "status": "no_changes"}

    # Log the event
    shared_links = await client.get_shared_links(album_id)
    event_data = _build_event_data(change, album, client.external_url, shared_links)

    event_log = EventLog(
        tracker_id=tracker_id,
        event_type=change.change_type,
        album_id=album_id,
        album_name=album.name,
        details={"added_count": change.added_count, "removed_count": change.removed_count},
    )
    session.add(event_log)

    # Send notifications to each target, filtered by its tracking config
    for target_id in target_ids:
        target = await session.get(NotificationTarget, target_id)
        if not target:
            continue

        # Check target's tracking config for event filtering
        tracking_config = None
        if target.tracking_config_id:
            tracking_config = await session.get(TrackingConfig, target.tracking_config_id)

        if tracking_config:
            # Filter by event type
            should_notify = False
            if change.change_type == "assets_added" and tracking_config.track_assets_added:
                should_notify = True
            elif change.change_type == "assets_removed" and tracking_config.track_assets_removed:
                should_notify = True
            elif change.change_type == "album_renamed" and tracking_config.track_album_renamed:
                should_notify = True
            elif change.change_type == "album_deleted" and tracking_config.track_album_deleted:
                should_notify = True
            elif change.change_type == "changed":
                should_notify = True  # "changed" = mixed, always notify
            if not should_notify:
                continue

        # Get target's template config
        template_config = None
        if target.template_config_id:
            template_config = await session.get(TemplateConfig, target.template_config_id)

        try:
            use_ai = target.config.get("ai_captions", False)
            await send_notification(target, event_data, template_config, use_ai_caption=use_ai)
        except Exception:
            _LOGGER.exception("Failed to send notification to target %d", target_id)

    return {
        "album_id": album_id,
        "status": "changed",
        "change_type": change.change_type,
        "added_count": change.added_count,
        "removed_count": change.removed_count,
    }


def _build_event_data(
    change: AlbumChange,
    album: AlbumData,
    external_url: str,
    shared_links: list,
) -> dict[str, Any]:
    """Build event data dict for template rendering and webhook payload."""
    added_details = []
    for asset in change.added_assets:
        if asset.is_processed:
            added_details.append(
                build_asset_detail(asset, external_url, shared_links, include_thumbnail=False)
            )

    album_url = get_any_url(external_url, shared_links)

    return {
        "album_id": change.album_id,
        "album_name": change.album_name,
        "album_url": album_url or "",
        "change_type": change.change_type,
        "added_count": change.added_count,
        "removed_count": change.removed_count,
        "added_assets": added_details,
        "removed_assets": change.removed_asset_ids,
        "people": list(album.people),
        "shared": album.shared,
        "old_name": change.old_name,
        "new_name": change.new_name,
        "old_shared": change.old_shared,
        "new_shared": change.new_shared,
    }