"""
Notifications API — user notification settings and per-user RSS feed.
"""
import secrets
from xml.etree.ElementTree import Element, SubElement, tostring

from fastapi import APIRouter, Depends, HTTPException
from fastapi.responses import Response
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.dependencies import get_current_user
from app.database import get_db
from app.models.notification import NotificationEvent
from app.models.user import User
from app.schemas.schemas import NotificationSettingsResponse, NotificationSettingsUpdate

router = APIRouter()

_EVENT_LABELS = {
    "new_document": "New Bill Text",
    "new_amendment": "Amendment Filed",
    "bill_updated": "Bill Updated",
}


def _prefs_to_response(prefs: dict, rss_token: str | None) -> NotificationSettingsResponse:
    return NotificationSettingsResponse(
        ntfy_topic_url=prefs.get("ntfy_topic_url", ""),
        ntfy_auth_method=prefs.get("ntfy_auth_method", "none"),
        ntfy_token=prefs.get("ntfy_token", ""),
        ntfy_username=prefs.get("ntfy_username", ""),
        ntfy_password=prefs.get("ntfy_password", ""),
        ntfy_enabled=prefs.get("ntfy_enabled", False),
        rss_enabled=prefs.get("rss_enabled", False),
        rss_token=rss_token,
    )


@router.get("/settings", response_model=NotificationSettingsResponse)
async def get_notification_settings(
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    user = await db.get(User, current_user.id)
    # Auto-generate RSS token on first visit so the feed URL is always available
    if not user.rss_token:
        user.rss_token = secrets.token_urlsafe(32)
        await db.commit()
        await db.refresh(user)
    return _prefs_to_response(user.notification_prefs or {}, user.rss_token)


@router.put("/settings", response_model=NotificationSettingsResponse)
async def update_notification_settings(
    body: NotificationSettingsUpdate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    user = await db.get(User, current_user.id)
    prefs = dict(user.notification_prefs or {})

    if body.ntfy_topic_url is not None:
        prefs["ntfy_topic_url"] = body.ntfy_topic_url.strip()
    if body.ntfy_auth_method is not None:
        prefs["ntfy_auth_method"] = body.ntfy_auth_method
    if body.ntfy_token is not None:
        prefs["ntfy_token"] = body.ntfy_token.strip()
    if body.ntfy_username is not None:
        prefs["ntfy_username"] = body.ntfy_username.strip()
    if body.ntfy_password is not None:
        prefs["ntfy_password"] = body.ntfy_password.strip()
    if body.ntfy_enabled is not None:
        prefs["ntfy_enabled"] = body.ntfy_enabled
    if body.rss_enabled is not None:
        prefs["rss_enabled"] = body.rss_enabled

    user.notification_prefs = prefs

    if not user.rss_token:
        user.rss_token = secrets.token_urlsafe(32)

    await db.commit()
    await db.refresh(user)
    return _prefs_to_response(user.notification_prefs or {}, user.rss_token)


@router.post("/settings/rss-reset", response_model=NotificationSettingsResponse)
async def reset_rss_token(
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    """Regenerate the RSS token, invalidating the old feed URL."""
    user = await db.get(User, current_user.id)
    user.rss_token = secrets.token_urlsafe(32)
    await db.commit()
    await db.refresh(user)
    return _prefs_to_response(user.notification_prefs or {}, user.rss_token)


@router.get("/feed/{rss_token}.xml", include_in_schema=False)
async def rss_feed(rss_token: str, db: AsyncSession = Depends(get_db)):
    """Public tokenized RSS feed — no auth required."""
    result = await db.execute(select(User).where(User.rss_token == rss_token))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(status_code=404, detail="Feed not found")

    events_result = await db.execute(
        select(NotificationEvent)
        .where(NotificationEvent.user_id == user.id)
        .order_by(NotificationEvent.created_at.desc())
        .limit(50)
    )
    events = events_result.scalars().all()
    return Response(content=_build_rss(events), media_type="application/rss+xml")


def _build_rss(events: list) -> bytes:
    rss = Element("rss", version="2.0")
    channel = SubElement(rss, "channel")
    SubElement(channel, "title").text = "PocketVeto — Bill Alerts"
    SubElement(channel, "description").text = "Updates on your followed bills"
    SubElement(channel, "language").text = "en-us"

    for event in events:
        payload = event.payload or {}
        item = SubElement(channel, "item")
        label = _EVENT_LABELS.get(event.event_type, "Update")
        bill_label = payload.get("bill_label", event.bill_id.upper())
        SubElement(item, "title").text = f"{label}: {bill_label} — {payload.get('bill_title', '')}"
        SubElement(item, "description").text = payload.get("brief_summary", "")
        if payload.get("bill_url"):
            SubElement(item, "link").text = payload["bill_url"]
        SubElement(item, "pubDate").text = event.created_at.strftime("%a, %d %b %Y %H:%M:%S +0000")
        SubElement(item, "guid").text = str(event.id)

    return tostring(rss, encoding="unicode").encode("utf-8")