"""
Notification dispatcher — sends pending notification events via ntfy.

RSS is pull-based so no dispatch is needed for it; events are simply
marked dispatched once ntfy is sent (or immediately if the user has no
ntfy configured but has an RSS token, so the feed can clean up old items).

Runs every 5 minutes on Celery Beat.
"""
import base64
import logging
from collections import defaultdict
from datetime import datetime, timedelta, timezone

import requests

from app.database import get_sync_db
from app.models.follow import Follow
from app.models.notification import NotificationEvent
from app.models.user import User
from app.workers.celery_app import celery_app

logger = logging.getLogger(__name__)

NTFY_TIMEOUT = 10

_EVENT_TITLES = {
    "new_document": "New Bill Text",
    "new_amendment": "Amendment Filed",
    "bill_updated": "Bill Updated",
    "weekly_digest": "Weekly Digest",
}

_EVENT_TAGS = {
    "new_document": "page_facing_up",
    "new_amendment": "memo",
    "bill_updated": "rotating_light",
}

# Milestone events are more urgent than LLM brief events
_EVENT_PRIORITY = {
    "bill_updated": "high",
    "new_document": "default",
    "new_amendment": "default",
}


_FILTER_DEFAULTS = {
    "new_document": False, "new_amendment": False, "vote": False,
    "presidential": False, "committee_report": False, "calendar": False,
    "procedural": False, "referral": False,
}


def _should_dispatch(event, prefs: dict, follow_mode: str = "neutral") -> bool:
    payload = event.payload or {}
    source = payload.get("source", "bill_follow")

    # Map event type directly for document events
    if event.event_type == "new_document":
        key = "new_document"
    elif event.event_type == "new_amendment":
        key = "new_amendment"
    else:
        # Use action_category if present (new events), fall back from milestone_tier (old events)
        key = payload.get("action_category")
        if not key:
            key = "referral" if payload.get("milestone_tier") == "referral" else "vote"

    all_filters = prefs.get("alert_filters")
    if all_filters is None:
        return True  # user hasn't configured filters yet — send everything

    if source in ("member_follow", "topic_follow"):
        source_filters = all_filters.get(source)
        if source_filters is None:
            return True  # section not configured — send everything
        if not source_filters.get("enabled", True):
            return False  # master toggle off
        # Per-entity mute checks
        if source == "member_follow":
            muted_ids = source_filters.get("muted_ids") or []
            if payload.get("matched_member_id") in muted_ids:
                return False
        if source == "topic_follow":
            muted_tags = source_filters.get("muted_tags") or []
            if payload.get("matched_topic") in muted_tags:
                return False
        return bool(source_filters.get(key, _FILTER_DEFAULTS.get(key, True)))

    # Bill follow — use follow mode filters (existing behaviour)
    mode_filters = all_filters.get(follow_mode) or {}
    return bool(mode_filters.get(key, _FILTER_DEFAULTS.get(key, True)))


def _in_quiet_hours(prefs: dict, now: datetime) -> bool:
    """Return True if the current local time falls within the user's quiet window.

    Quiet hours are stored as local-time hour integers. If the user has a stored
    IANA timezone name we convert ``now`` (UTC) to that zone before comparing.
    Falls back to UTC if the timezone is absent or unrecognised.
    """
    start = prefs.get("quiet_hours_start")
    end = prefs.get("quiet_hours_end")
    if start is None or end is None:
        return False

    tz_name = prefs.get("timezone")
    if tz_name:
        try:
            from zoneinfo import ZoneInfo
            h = now.astimezone(ZoneInfo(tz_name)).hour
        except Exception:
            h = now.hour  # unrecognised timezone — degrade gracefully to UTC
    else:
        h = now.hour

    if start <= end:
        return start <= h < end
    # Wraps midnight (e.g. 22 → 8)
    return h >= start or h < end


@celery_app.task(bind=True, name="app.workers.notification_dispatcher.dispatch_notifications")
def dispatch_notifications(self):
    """Fan out pending notification events to ntfy and mark dispatched."""
    db = get_sync_db()
    try:
        pending = (
            db.query(NotificationEvent)
            .filter(NotificationEvent.dispatched_at.is_(None))
            .order_by(NotificationEvent.created_at)
            .limit(200)
            .all()
        )

        sent = 0
        failed = 0
        held = 0
        now = datetime.now(timezone.utc)

        for event in pending:
            user = db.get(User, event.user_id)
            if not user:
                event.dispatched_at = now
                db.commit()
                continue

            # Look up follow mode for this (user, bill) pair
            follow = db.query(Follow).filter_by(
                user_id=event.user_id, follow_type="bill", follow_value=event.bill_id
            ).first()
            follow_mode = follow.follow_mode if follow else "neutral"

            prefs = user.notification_prefs or {}

            if not _should_dispatch(event, prefs, follow_mode):
                event.dispatched_at = now
                db.commit()
                continue
            ntfy_url = prefs.get("ntfy_topic_url", "").strip()
            ntfy_auth_method = prefs.get("ntfy_auth_method", "none")
            ntfy_token = prefs.get("ntfy_token", "").strip()
            ntfy_username = prefs.get("ntfy_username", "").strip()
            ntfy_password = prefs.get("ntfy_password", "").strip()
            ntfy_enabled = prefs.get("ntfy_enabled", False)
            rss_enabled = prefs.get("rss_enabled", False)
            digest_enabled = prefs.get("digest_enabled", False)

            ntfy_configured = ntfy_enabled and bool(ntfy_url)

            # Hold events when ntfy is configured but delivery should be deferred
            in_quiet = _in_quiet_hours(prefs, now) if ntfy_configured else False
            hold = ntfy_configured and (in_quiet or digest_enabled)

            if hold:
                held += 1
                continue  # Leave undispatched — digest task or next run after quiet hours

            if ntfy_configured:
                try:
                    _send_ntfy(
                        event, ntfy_url, ntfy_auth_method, ntfy_token,
                        ntfy_username, ntfy_password, follow_mode=follow_mode,
                    )
                    sent += 1
                except Exception as e:
                    logger.warning(f"ntfy dispatch failed for event {event.id}: {e}")
                    failed += 1

            email_enabled = prefs.get("email_enabled", False)
            email_address = prefs.get("email_address", "").strip()
            if email_enabled and email_address:
                try:
                    _send_email(event, email_address, unsubscribe_token=user.email_unsubscribe_token)
                    sent += 1
                except Exception as e:
                    logger.warning(f"email dispatch failed for event {event.id}: {e}")
                    failed += 1

            # Mark dispatched: channels were attempted, or user has no channels configured (RSS-only)
            event.dispatched_at = now
            db.commit()

        logger.info(
            f"dispatch_notifications: {sent} sent, {failed} failed, "
            f"{held} held (quiet hours/digest), {len(pending)} total pending"
        )
        return {"sent": sent, "failed": failed, "held": held, "total": len(pending)}
    finally:
        db.close()


@celery_app.task(bind=True, name="app.workers.notification_dispatcher.send_notification_digest")
def send_notification_digest(self):
    """
    Send a bundled ntfy digest for users with digest mode enabled.
    Runs daily; weekly-frequency users only receive on Mondays.
    """
    db = get_sync_db()
    try:
        now = datetime.now(timezone.utc)
        users = db.query(User).all()
        digest_users = [
            u for u in users
            if (u.notification_prefs or {}).get("digest_enabled", False)
            and (u.notification_prefs or {}).get("ntfy_enabled", False)
            and (u.notification_prefs or {}).get("ntfy_topic_url", "").strip()
        ]

        sent = 0
        for user in digest_users:
            prefs = user.notification_prefs or {}
            frequency = prefs.get("digest_frequency", "daily")

            # Weekly digests only fire on Mondays (weekday 0)
            if frequency == "weekly" and now.weekday() != 0:
                continue

            lookback_hours = 168 if frequency == "weekly" else 24
            cutoff = now - timedelta(hours=lookback_hours)

            events = (
                db.query(NotificationEvent)
                .filter_by(user_id=user.id)
                .filter(
                    NotificationEvent.dispatched_at.is_(None),
                    NotificationEvent.created_at > cutoff,
                )
                .order_by(NotificationEvent.created_at.desc())
                .all()
            )

            if not events:
                continue

            try:
                ntfy_url = prefs.get("ntfy_topic_url", "").strip()
                _send_digest_ntfy(events, ntfy_url, prefs)
                for event in events:
                    event.dispatched_at = now
                db.commit()
                sent += 1
            except Exception as e:
                logger.warning(f"Digest send failed for user {user.id}: {e}")

        logger.info(f"send_notification_digest: digests sent to {sent} users")
        return {"sent": sent}
    finally:
        db.close()


def _build_reason(payload: dict) -> str | None:
    source = payload.get("source", "bill_follow")
    mode_labels = {"pocket_veto": "Pocket Veto", "pocket_boost": "Pocket Boost", "neutral": "Following"}
    if source == "bill_follow":
        mode = payload.get("follow_mode", "neutral")
        return f"\U0001f4cc {mode_labels.get(mode, 'Following')} this bill"
    if source == "member_follow":
        name = payload.get("matched_member_name")
        return f"\U0001f464 You follow {name}" if name else "\U0001f464 Member you follow"
    if source == "topic_follow":
        topic = payload.get("matched_topic")
        return f"\U0001f3f7 You follow \"{topic}\"" if topic else "\U0001f3f7 Topic you follow"
    return None


def _send_email(
    event: NotificationEvent,
    email_address: str,
    unsubscribe_token: str | None = None,
) -> None:
    """Send a plain-text email notification via SMTP."""
    import smtplib
    from email.mime.multipart import MIMEMultipart
    from email.mime.text import MIMEText

    from app.config import settings as app_settings

    if not app_settings.SMTP_HOST or not email_address:
        return

    payload = event.payload or {}
    bill_label = payload.get("bill_label", event.bill_id.upper())
    bill_title = payload.get("bill_title", "")
    event_label = _EVENT_TITLES.get(event.event_type, "Bill Update")
    base_url = (app_settings.PUBLIC_URL or app_settings.LOCAL_URL).rstrip("/")

    subject = f"PocketVeto: {event_label} — {bill_label}"

    lines = [f"{event_label}: {bill_label}"]
    if bill_title:
        lines.append(bill_title)
    if payload.get("brief_summary"):
        lines.append("")
        lines.append(payload["brief_summary"][:500])
    reason = _build_reason(payload)
    if reason:
        lines.append("")
        lines.append(reason)
    if payload.get("bill_url"):
        lines.append("")
        lines.append(f"View bill: {payload['bill_url']}")

    unsubscribe_url = f"{base_url}/api/notifications/unsubscribe/{unsubscribe_token}" if unsubscribe_token else None
    if unsubscribe_url:
        lines.append("")
        lines.append(f"Unsubscribe from email alerts: {unsubscribe_url}")

    body = "\n".join(lines)

    from_addr = app_settings.SMTP_FROM or app_settings.SMTP_USER
    msg = MIMEMultipart()
    msg["Subject"] = subject
    msg["From"] = from_addr
    msg["To"] = email_address
    if unsubscribe_url:
        msg["List-Unsubscribe"] = f"<{unsubscribe_url}>"
        msg["List-Unsubscribe-Post"] = "List-Unsubscribe=One-Click"
    msg.attach(MIMEText(body, "plain", "utf-8"))

    with smtplib.SMTP(app_settings.SMTP_HOST, app_settings.SMTP_PORT, timeout=10) as s:
        if app_settings.SMTP_STARTTLS:
            s.starttls()
        if app_settings.SMTP_USER:
            s.login(app_settings.SMTP_USER, app_settings.SMTP_PASSWORD)
        s.sendmail(from_addr, [email_address], msg.as_string())


def _send_ntfy(
    event: NotificationEvent,
    topic_url: str,
    auth_method: str = "none",
    token: str = "",
    username: str = "",
    password: str = "",
    follow_mode: str = "neutral",
) -> None:
    payload = event.payload or {}
    bill_label = payload.get("bill_label", event.bill_id.upper())
    bill_title = payload.get("bill_title", "")
    event_label = _EVENT_TITLES.get(event.event_type, "Bill Update")

    title = f"{event_label}: {bill_label}"

    lines = [bill_title] if bill_title else []
    if payload.get("brief_summary"):
        lines.append("")
        lines.append(payload["brief_summary"][:300])
    reason = _build_reason(payload)
    if reason:
        lines.append("")
        lines.append(reason)
    message = "\n".join(lines) or bill_label

    headers = {
        "Title": title,
        "Priority": _EVENT_PRIORITY.get(event.event_type, "default"),
        "Tags": _EVENT_TAGS.get(event.event_type, "bell"),
    }
    if payload.get("bill_url"):
        headers["Click"] = payload["bill_url"]

    if follow_mode == "pocket_boost":
        headers["Actions"] = (
            f"view, View Bill, {payload.get('bill_url', '')}; "
            "view, Find Your Rep, https://www.house.gov/representatives/find-your-representative"
        )

    if auth_method == "token" and token:
        headers["Authorization"] = f"Bearer {token}"
    elif auth_method == "basic" and username:
        creds = base64.b64encode(f"{username}:{password}".encode()).decode()
        headers["Authorization"] = f"Basic {creds}"

    resp = requests.post(topic_url, data=message.encode("utf-8"), headers=headers, timeout=NTFY_TIMEOUT)
    resp.raise_for_status()


@celery_app.task(bind=True, name="app.workers.notification_dispatcher.send_weekly_digest")
def send_weekly_digest(self):
    """
    Proactive week-in-review summary for followed bills.

    Runs every Monday at 8:30 AM UTC. Queries bills followed by each user
    for any activity in the past 7 days and dispatches a low-noise summary
    via ntfy and/or creates a NotificationEvent for the RSS feed.

    Unlike send_notification_digest (which bundles queued events), this task
    generates a fresh summary independent of the notification event queue.
    """
    from app.config import settings as app_settings
    from app.models.bill import Bill

    db = get_sync_db()
    try:
        now = datetime.now(timezone.utc)
        cutoff = now - timedelta(days=7)
        base_url = (app_settings.PUBLIC_URL or app_settings.LOCAL_URL).rstrip("/")

        users = db.query(User).all()
        ntfy_sent = 0
        rss_created = 0

        for user in users:
            prefs = user.notification_prefs or {}
            ntfy_enabled = prefs.get("ntfy_enabled", False)
            ntfy_url = prefs.get("ntfy_topic_url", "").strip()
            rss_enabled = prefs.get("rss_enabled", False)
            ntfy_configured = ntfy_enabled and bool(ntfy_url)

            if not ntfy_configured and not rss_enabled:
                continue

            bill_follows = db.query(Follow).filter_by(
                user_id=user.id, follow_type="bill"
            ).all()
            if not bill_follows:
                continue

            bill_ids = [f.follow_value for f in bill_follows]

            active_bills = (
                db.query(Bill)
                .filter(
                    Bill.bill_id.in_(bill_ids),
                    Bill.updated_at >= cutoff,
                )
                .order_by(Bill.updated_at.desc())
                .limit(20)
                .all()
            )

            if not active_bills:
                continue

            count = len(active_bills)
            anchor = active_bills[0]

            summary_lines = []
            for bill in active_bills[:10]:
                lbl = _format_bill_label(bill)
                action = (bill.latest_action_text or "")[:80]
                summary_lines.append(f"• {lbl}: {action}" if action else f"• {lbl}")
            if count > 10:
                summary_lines.append(f"  …and {count - 10} more")
            summary = "\n".join(summary_lines)

            # Mark dispatched_at immediately so dispatch_notifications skips this event;
            # it still appears in the RSS feed since that endpoint reads all events.
            event = NotificationEvent(
                user_id=user.id,
                bill_id=anchor.bill_id,
                event_type="weekly_digest",
                dispatched_at=now,
                payload={
                    "bill_label": "Weekly Digest",
                    "bill_title": f"{count} followed bill{'s' if count != 1 else ''} had activity this week",
                    "brief_summary": summary,
                    "bill_count": count,
                    "bill_url": f"{base_url}/bills/{anchor.bill_id}",
                },
            )
            db.add(event)
            rss_created += 1

            if ntfy_configured:
                try:
                    _send_weekly_digest_ntfy(count, summary, ntfy_url, prefs)
                    ntfy_sent += 1
                except Exception as e:
                    logger.warning(f"Weekly digest ntfy failed for user {user.id}: {e}")

        db.commit()
        logger.info(f"send_weekly_digest: {ntfy_sent} ntfy sent, {rss_created} events created")
        return {"ntfy_sent": ntfy_sent, "rss_created": rss_created}
    finally:
        db.close()


def _format_bill_label(bill) -> str:
    _TYPE_MAP = {
        "hr": "H.R.", "s": "S.", "hjres": "H.J.Res.", "sjres": "S.J.Res.",
        "hconres": "H.Con.Res.", "sconres": "S.Con.Res.", "hres": "H.Res.", "sres": "S.Res.",
    }
    prefix = _TYPE_MAP.get(bill.bill_type.lower(), bill.bill_type.upper())
    return f"{prefix} {bill.bill_number}"


def _send_weekly_digest_ntfy(count: int, summary: str, ntfy_url: str, prefs: dict) -> None:
    auth_method = prefs.get("ntfy_auth_method", "none")
    ntfy_token = prefs.get("ntfy_token", "").strip()
    ntfy_username = prefs.get("ntfy_username", "").strip()
    ntfy_password = prefs.get("ntfy_password", "").strip()

    headers = {
        "Title": f"PocketVeto Weekly — {count} bill{'s' if count != 1 else ''} updated",
        "Priority": "low",
        "Tags": "newspaper,calendar",
    }
    if auth_method == "token" and ntfy_token:
        headers["Authorization"] = f"Bearer {ntfy_token}"
    elif auth_method == "basic" and ntfy_username:
        creds = base64.b64encode(f"{ntfy_username}:{ntfy_password}".encode()).decode()
        headers["Authorization"] = f"Basic {creds}"

    resp = requests.post(ntfy_url, data=summary.encode("utf-8"), headers=headers, timeout=NTFY_TIMEOUT)
    resp.raise_for_status()


def _send_digest_ntfy(events: list, ntfy_url: str, prefs: dict) -> None:
    auth_method = prefs.get("ntfy_auth_method", "none")
    ntfy_token = prefs.get("ntfy_token", "").strip()
    ntfy_username = prefs.get("ntfy_username", "").strip()
    ntfy_password = prefs.get("ntfy_password", "").strip()

    headers = {
        "Title": f"PocketVeto Digest — {len(events)} update{'s' if len(events) != 1 else ''}",
        "Priority": "default",
        "Tags": "newspaper",
    }

    if auth_method == "token" and ntfy_token:
        headers["Authorization"] = f"Bearer {ntfy_token}"
    elif auth_method == "basic" and ntfy_username:
        creds = base64.b64encode(f"{ntfy_username}:{ntfy_password}".encode()).decode()
        headers["Authorization"] = f"Basic {creds}"

    # Group by bill, show up to 10
    by_bill: dict = defaultdict(list)
    for event in events:
        by_bill[event.bill_id].append(event)

    lines = []
    for bill_id, bill_events in list(by_bill.items())[:10]:
        payload = bill_events[0].payload or {}
        bill_label = payload.get("bill_label", bill_id.upper())
        event_labels = list({_EVENT_TITLES.get(e.event_type, "Update") for e in bill_events})
        lines.append(f"• {bill_label}: {', '.join(event_labels)}")

    if len(by_bill) > 10:
        lines.append(f"  …and {len(by_bill) - 10} more bills")

    message = "\n".join(lines)
    resp = requests.post(ntfy_url, data=message.encode("utf-8"), headers=headers, timeout=NTFY_TIMEOUT)
    resp.raise_for_status()