# scheduler/db_utils.py
from dotenv import load_dotenv
import os
from datetime import datetime
import logging
from sqlalchemy.orm import sessionmaker, joinedload
from sqlalchemy import create_engine, or_, and_, text
from models.models import Event, EventMedia, EventException, SystemSetting
from dateutil.rrule import rrulestr
from urllib.request import Request, urlopen
from datetime import timezone

# Load .env only in development to mirror server/database.py behavior
if os.getenv("ENV", "development") == "development":
    # Expect .env at workspace root
    load_dotenv('/workspace/.env')

# DB-URL aus Umgebungsvariable oder Fallback wie im Server
DB_URL = os.environ.get("DB_CONN")
if not DB_URL:
    DB_USER = os.environ.get("DB_USER", "infoscreen_admin")
    DB_PASSWORD = os.environ.get("DB_PASSWORD", "KqtpM7wmNd&mFKs")
    DB_HOST = os.environ.get("DB_HOST", "db")
    DB_NAME = os.environ.get("DB_NAME", "infoscreen_by_taa")
    DB_URL = f"mysql+pymysql://{DB_USER}:{DB_PASSWORD}@{DB_HOST}/{DB_NAME}"

print(f"[Scheduler] Using DB_URL: {DB_URL}")
engine = create_engine(DB_URL)
# Proactive connectivity check to surface errors early
try:
    with engine.connect() as conn:
        conn.execute(text("SELECT 1"))
    print("[Scheduler] DB connectivity OK")
except Exception as db_exc:
    print(f"[Scheduler] DB connectivity FAILED: {db_exc}")
Session = sessionmaker(bind=engine)

# Base URL from .env for file URLs
API_BASE_URL = os.environ.get("API_BASE_URL", "http://server:8000")

# Cache conversion decisions per media to avoid repeated lookups/logs within the scheduler lifetime
_media_conversion_cache = {}  # media_id -> pdf_url or None
_media_decision_logged = set()  # media_id(s) already logged


def get_active_events(start: datetime, end: datetime, group_id: int = None):
    session = Session()
    try:
        # Now this will work with the relationship defined
        query = session.query(Event).options(
            joinedload(Event.event_media)
        ).filter(Event.is_active == True)

        if start and end:
            # Include:
            # 1) Non-recurring events that overlap [start, end]
            # 2) Recurring events whose recurrence window intersects [start, end]
            #    We consider dtstart (Event.start) <= end and (recurrence_end is NULL or >= start)
            non_recurring_overlap = and_(
                Event.recurrence_rule == None,
                Event.start < end,
                Event.end > start,
            )
            recurring_window = and_(
                Event.recurrence_rule != None,
                Event.start <= end,
                or_(Event.recurrence_end == None, Event.recurrence_end >= start),
            )
            query = query.filter(or_(non_recurring_overlap, recurring_window))
        if group_id:
            query = query.filter(Event.group_id == group_id)

        # Log base event count before expansion
        try:
            base_count = query.count()
            # Additional diagnostics: split counts
            non_rec_q = session.query(Event.id).filter(Event.is_active == True)
            rec_q = session.query(Event.id).filter(Event.is_active == True)
            if start and end:
                non_rec_q = non_rec_q.filter(non_recurring_overlap)
                rec_q = rec_q.filter(recurring_window)
            if group_id:
                non_rec_q = non_rec_q.filter(Event.group_id == group_id)
                rec_q = rec_q.filter(Event.group_id == group_id)
            non_rec_count = non_rec_q.count()
            rec_count = rec_q.count()
            logging.debug(f"[Scheduler] Base events total={base_count} non_recurring_overlap={non_rec_count} recurring_window={rec_count}")
        except Exception:
            base_count = None
        events = query.all()
        logging.debug(f"[Scheduler] Base events fetched: {len(events)} (count={base_count})")
        if len(events) == 0:
            # Quick probe: are there any active events at all?
            try:
                any_active = session.query(Event).filter(Event.is_active == True).count()
                logging.info(f"[Scheduler] Active events in DB (any group, any time): {any_active}")
            except Exception as e:
                logging.warning(f"[Scheduler] Could not count active events: {e}")

        formatted_events = []
        for event in events:
            # If event has RRULE, expand into instances within [start, end]
            if event.recurrence_rule:
                try:
                    # Ensure dtstart is timezone-aware (UTC if naive)
                    dtstart = event.start
                    if dtstart.tzinfo is None:
                        dtstart = dtstart.replace(tzinfo=timezone.utc)
                    
                    r = rrulestr(event.recurrence_rule, dtstart=dtstart)
                    
                    # Ensure query bounds are timezone-aware
                    query_start = start if start.tzinfo else start.replace(tzinfo=timezone.utc)
                    query_end = end if end.tzinfo else end.replace(tzinfo=timezone.utc)

                    # Clamp by recurrence_end if present
                    if getattr(event, "recurrence_end", None):
                        rec_end = event.recurrence_end
                        if rec_end and rec_end.tzinfo is None:
                            rec_end = rec_end.replace(tzinfo=timezone.utc)
                        if rec_end and rec_end < query_end:
                            query_end = rec_end
                    
                    # iterate occurrences within range
                    # Use a lookback equal to the event's duration to catch occurrences that started
                    # before query_start but are still running within the window.
                    duration = (event.end - event.start) if (event.end and event.start) else None
                    lookback_start = query_start
                    if duration:
                        lookback_start = query_start - duration
                    occ_starts = r.between(lookback_start, query_end, inc=True)
                    for occ_start in occ_starts:
                        occ_end = (occ_start + duration) if duration else occ_start
                        # Apply exceptions
                        exc = session.query(EventException).filter(
                            EventException.event_id == event.id,
                            EventException.exception_date == occ_start.date()
                        ).first()
                        if exc:
                            if exc.is_skipped:
                                continue
                            if exc.override_start:
                                occ_start = exc.override_start
                            if exc.override_end:
                                occ_end = exc.override_end
                        # Filter out instances that do not overlap [start, end]
                        if not (occ_start < end and occ_end > start):
                            continue
                        inst = format_event_with_media(event)
                        # Apply overrides to title/description if provided
                        if exc and exc.override_title:
                            inst["title"] = exc.override_title
                        if exc and exc.override_description:
                            inst["description"] = exc.override_description
                        inst["start"] = occ_start.isoformat()
                        inst["end"] = occ_end.isoformat()
                        inst["occurrence_of_id"] = event.id
                        formatted_events.append(inst)
                except Exception as e:
                    # On parse error, fall back to single event formatting
                    logging.warning(f"Failed to parse recurrence rule for event {event.id}: {e}")
                    formatted_events.append(format_event_with_media(event))
            else:
                formatted_events.append(format_event_with_media(event))

        return formatted_events
    finally:
        session.close()


def get_system_setting_value(key: str, default: str | None = None) -> str | None:
    """Fetch a system setting value by key from DB.

    Returns the setting's string value or the provided default if missing.
    """
    session = Session()
    try:
        setting = session.query(SystemSetting).filter_by(key=key).first()
        return setting.value if setting else default
    except Exception as e:
        logging.debug(f"[Scheduler] Failed to read system setting '{key}': {e}")
        return default
    finally:
        session.close()


def format_event_with_media(event):
    """Transform Event + EventMedia into client-expected format"""
    event_dict = {
        "id": event.id,
        "title": event.title,
        "start": str(event.start),
        "end": str(event.end),
        "group_id": event.group_id,
        "event_type": event.event_type.value if event.event_type else None,
        # Carry recurrence metadata for consumers if needed
        "recurrence_rule": getattr(event, "recurrence_rule", None),
        "recurrence_end": (event.recurrence_end.isoformat() if getattr(event, "recurrence_end", None) else None),
    }

    # Now you can directly access event.event_media
    if event.event_media:
        media = event.event_media

        if event.event_type.value == "presentation":
            event_dict["presentation"] = {
                "type": "slideshow",
                "files": [],
                "slide_interval": event.slideshow_interval or 5000,
                "auto_advance": True,
                "page_progress": getattr(event, "page_progress", True),
                "auto_progress": getattr(event, "auto_progress", True)
            }

            # Avoid per-call media-type debug to reduce log noise

            # Decide file URL with caching to avoid repeated DB lookups/logs
            pdf_url = _media_conversion_cache.get(media.id, None)

            if pdf_url is None and getattr(media.media_type, 'value', str(media.media_type)) in ("ppt", "pptx", "odp"):
                from sqlalchemy.orm import scoped_session
                from models.models import Conversion, ConversionStatus
                session = scoped_session(Session)
                try:
                    conversion = session.query(Conversion).filter_by(
                        source_event_media_id=media.id,
                        target_format="pdf",
                        status=ConversionStatus.ready
                    ).order_by(Conversion.completed_at.desc()).first()
                    logging.debug(
                        f"[Scheduler] Conversion lookup for media_id={media.id}: found={bool(conversion)}, path={getattr(conversion, 'target_path', None) if conversion else None}")
                    if conversion and conversion.target_path:
                        pdf_url = f"{API_BASE_URL}/api/files/converted/{conversion.target_path}"
                finally:
                    session.remove()
                # Cache the decision (even if None) to avoid repeated lookups in the same run
                _media_conversion_cache[media.id] = pdf_url

            # Build file entry and log decision only once per media
            if pdf_url:
                filename = os.path.basename(pdf_url)
                event_dict["presentation"]["files"].append({
                    "name": filename,
                    "url": pdf_url,
                    "checksum": None,
                    "size": None
                })
                if media.id not in _media_decision_logged:
                    logging.debug(
                        f"[Scheduler] Using converted PDF for event_media_id={media.id}: {pdf_url}")
                    _media_decision_logged.add(media.id)
            elif media.file_path:
                filename = os.path.basename(media.file_path)
                event_dict["presentation"]["files"].append({
                    "name": filename,
                    "url": f"{API_BASE_URL}/api/files/{media.id}/{filename}",
                    "checksum": None,
                    "size": None
                })
                if media.id not in _media_decision_logged:
                    logging.debug(
                        f"[Scheduler] Using original file for event_media_id={media.id}: {filename}")
                    _media_decision_logged.add(media.id)

        # Handle website and webuntis events (both display a website)
        elif event.event_type.value in ("website", "webuntis"):
            event_dict["website"] = {
                "type": "browser",
                "url": media.url if media.url else None
            }
            if media.id not in _media_decision_logged:
                logging.debug(
                    f"[Scheduler] Using website URL for event_media_id={media.id} (type={event.event_type.value}): {media.url}")
                _media_decision_logged.add(media.id)

        # Handle video events
        elif event.event_type.value == "video":
            filename = os.path.basename(media.file_path) if media.file_path else "video"
            # Use streaming endpoint for better video playback support
            stream_url = f"{API_BASE_URL}/api/eventmedia/stream/{media.id}/{filename}"

            # Best-effort: probe the streaming endpoint for cheap metadata (HEAD request)
            mime_type = None
            size = None
            accept_ranges = False
            try:
                req = Request(stream_url, method='HEAD')
                with urlopen(req, timeout=2) as resp:
                    # getheader returns None if missing
                    mime_type = resp.getheader('Content-Type')
                    length = resp.getheader('Content-Length')
                    if length:
                        try:
                            size = int(length)
                        except Exception:
                            size = None
                    accept_ranges = (resp.getheader('Accept-Ranges') or '').lower() == 'bytes'
            except Exception as e:
                # Don't fail the scheduler for probe errors; log once per media
                if media.id not in _media_decision_logged:
                    logging.debug(f"[Scheduler] HEAD probe for media_id={media.id} failed: {e}")

            event_dict["video"] = {
                "type": "media",
                "url": stream_url,
                "autoplay": getattr(event, "autoplay", True),
                "loop": getattr(event, "loop", False),
                "volume": getattr(event, "volume", 0.8),
                # Best-effort metadata to help clients decide how to stream
                "mime_type": mime_type,
                "size": size,
                "accept_ranges": accept_ranges,
                # Optional richer info (may be null if not available): duration (seconds), resolution, bitrate
                "duration": None,
                "resolution": None,
                "bitrate": None,
                "qualities": [],
                "thumbnails": [],
                "checksum": None,
            }
            if media.id not in _media_decision_logged:
                logging.debug(
                    f"[Scheduler] Using video streaming URL for event_media_id={media.id}: {filename}")
                _media_decision_logged.add(media.id)

        # Add other event types (message, etc.) here as needed...

    return event_dict