import datetime

from sqlalchemy import and_, desc
from sqlalchemy.orm import Session

from backend.models import NewsItem, NewsTranslation

SUPPORTED_LANGUAGES = {"en", "ta", "ml"}


def create_news(
    db: Session,
    headline: str,
    summary: str,
    source_url: str | None = None,
    image_url: str | None = None,
    image_credit: str | None = None,
    published_at: datetime.datetime | None = None,
) -> NewsItem:
    item = NewsItem(
        headline=headline,
        summary=summary,
        source_url=source_url,
        image_url=image_url,
        image_credit=image_credit,
        published_at=published_at or datetime.datetime.utcnow(),
    )
    db.add(item)
    db.commit()
    db.refresh(item)
    return item


def get_recent_news(db: Session, limit: int = 10) -> list[NewsItem]:
    return (
        db.query(NewsItem)
        .filter(NewsItem.archived.is_(False))
        .order_by(desc(NewsItem.published_at))
        .limit(limit)
        .all()
    )


def get_latest_news(db: Session) -> NewsItem | None:
    return (
        db.query(NewsItem)
        .filter(NewsItem.archived.is_(False))
        .order_by(desc(NewsItem.published_at))
        .first()
    )


def create_translation(
    db: Session,
    news_item_id: int,
    language: str,
    headline: str,
    summary: str,
) -> NewsTranslation:
    translation = NewsTranslation(
        news_item_id=news_item_id,
        language=language,
        headline=headline,
        summary=summary,
    )
    db.add(translation)
    db.commit()
    db.refresh(translation)
    return translation


def get_translation(db: Session, news_item_id: int, language: str) -> NewsTranslation | None:
    return (
        db.query(NewsTranslation)
        .filter(
            and_(
                NewsTranslation.news_item_id == news_item_id,
                NewsTranslation.language == language,
            )
        )
        .first()
    )


def translation_exists(db: Session, news_item_id: int, language: str) -> bool:
    return get_translation(db, news_item_id, language) is not None


def get_translations_by_article(db: Session, news_item_id: int) -> list[NewsTranslation]:
    return (
        db.query(NewsTranslation)
        .filter(NewsTranslation.news_item_id == news_item_id)
        .order_by(NewsTranslation.language.asc())
        .all()
    )


def resolve_news_content(item: NewsItem, translation: NewsTranslation | None) -> tuple[str, str]:
    if translation is None:
        return item.headline, item.summary
    return translation.headline, translation.summary


def normalize_language(language: str | None) -> str:
    if not language:
        return "en"
    lower = language.lower()
    if lower not in SUPPORTED_LANGUAGES:
        return "en"
    return lower


def get_news_paginated(
    db: Session, cursor: int | None = None, limit: int = 10, exclude_id: int | None = None
) -> list[NewsItem]:
    query = db.query(NewsItem).filter(NewsItem.archived.is_(False))

    if exclude_id is not None:
        query = query.filter(NewsItem.id != exclude_id)

    if cursor is not None:
        query = query.filter(NewsItem.id < cursor)

    return query.order_by(desc(NewsItem.id)).limit(limit).all()


def headline_exists_within_24h(db: Session, headline: str) -> bool:
    cutoff = datetime.datetime.utcnow() - datetime.timedelta(hours=24)
    return (
        db.query(NewsItem)
        .filter(
            and_(
                NewsItem.headline == headline,
                NewsItem.created_at >= cutoff,
            )
        )
        .first()
        is not None
    )


def archive_old_news(db: Session, retention_days: int = 30) -> int:
    cutoff = datetime.datetime.utcnow() - datetime.timedelta(days=retention_days)
    count = (
        db.query(NewsItem)
        .filter(
            and_(
                NewsItem.created_at < cutoff,
                NewsItem.archived.is_(False),
            )
        )
        .update({"archived": True})
    )
    db.commit()
    return count


def delete_archived_news(db: Session, days_after_archive: int = 60) -> int:
    cutoff = datetime.datetime.utcnow() - datetime.timedelta(days=days_after_archive)
    count = (
        db.query(NewsItem)
        .filter(
            and_(
                NewsItem.archived.is_(True),
                NewsItem.created_at < cutoff,
            )
        )
        .delete()
    )
    db.commit()
    return count