from datetime import date
from typing import Optional
from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from ..database import get_db
from ..models.news import ProcessedNews

router = APIRouter()


def _serialize(n: ProcessedNews) -> dict:
    return {
        "id": n.id,
        "title_zh": n.title_zh,
        "summary": n.summary,
        "opinion": n.opinion,
        "keywords": n.keywords or [],
        "importance_score": n.importance_score,
        "importance_reason": n.importance_reason,
        "category": n.category,
        "is_featured": n.is_featured,
        "featured_rank": n.featured_rank,
        "source_name": n.source_name or "",
        "source_url": n.source_url or "",
        "published_at": n.published_at.isoformat() if n.published_at else None,
        "processed_at": n.processed_at.isoformat() if n.processed_at else None,
    }


@router.get("/featured")
async def get_featured(
    news_date: Optional[str] = Query(default=None, alias="date"),
    db: AsyncSession = Depends(get_db),
):
    target = date.fromisoformat(news_date) if news_date else date.today()
    stmt = (
        select(ProcessedNews)
        .where(ProcessedNews.is_featured == True)
        .where(func.date(ProcessedNews.processed_at) == target)
        .order_by(ProcessedNews.featured_rank)
    )
    result = await db.execute(stmt)
    items = result.scalars().all()
    return {"date": str(target), "items": [_serialize(n) for n in items]}


@router.get("")
async def get_news(
    news_date: Optional[str] = Query(default=None, alias="date"),
    category: Optional[str] = Query(default=None),
    page: int = Query(default=1, ge=1),
    page_size: int = Query(default=20, ge=1, le=100),
    db: AsyncSession = Depends(get_db),
):
    target = date.fromisoformat(news_date) if news_date else date.today()
    stmt = select(ProcessedNews).where(func.date(ProcessedNews.processed_at) == target)
    if category:
        stmt = stmt.where(ProcessedNews.category == category)

    count_stmt = select(func.count()).select_from(stmt.subquery())
    total = (await db.execute(count_stmt)).scalar_one()

    stmt = stmt.order_by(ProcessedNews.importance_score.desc()).offset((page - 1) * page_size).limit(page_size)
    result = await db.execute(stmt)
    items = result.scalars().all()

    return {"date": str(target), "total": total, "page": page, "items": [_serialize(n) for n in items]}


@router.get("/dates")
async def get_dates(db: AsyncSession = Depends(get_db)):
    stmt = select(
        func.date(ProcessedNews.processed_at).label("d"),
        func.count(ProcessedNews.id).label("cnt"),
    ).group_by("d").order_by(func.date(ProcessedNews.processed_at).desc()).limit(30)
    result = await db.execute(stmt)
    return [{"date": str(row.d), "count": row.cnt} for row in result]


@router.get("/{news_id}")
async def get_news_detail(news_id: int, db: AsyncSession = Depends(get_db)):
    stmt = select(ProcessedNews).where(ProcessedNews.id == news_id)
    result = await db.execute(stmt)
    news = result.scalar_one_or_none()
    if not news:
        raise HTTPException(status_code=404, detail="Not found")
    return _serialize(news)