"""页面路由 — 首页、日期页、论文详情。"""

from datetime import date, datetime, timedelta
from zoneinfo import ZoneInfo

from fastapi import APIRouter, Depends, HTTPException, Request
from fastapi.responses import RedirectResponse
from fastapi.templating import Jinja2Templates
from sqlalchemy.orm import Session, joinedload

from app.config import settings
from app.database import get_db
from app.models import Paper

router = APIRouter()
templates = Jinja2Templates(directory="app/templates")


def _today() -> str:
    tz = ZoneInfo(settings.APP_TIMEZONE)
    return datetime.now(tz).strftime("%Y-%m-%d")


@router.get("/")
def index(request: Request):
    """重定向到 /day/{today}。"""
    return RedirectResponse(url=f"/day/{_today()}")


@router.get("/day/{date_str}")
def day_page(date_str: str, request: Request, db: Session = Depends(get_db)):
    """指定日期论文列表。"""
    try:
        target = date.fromisoformat(date_str)
    except ValueError:
        raise HTTPException(status_code=404, detail="Invalid date format")

    prev_day = (target - timedelta(days=1)).isoformat()
    next_day = (target + timedelta(days=1)).isoformat()
    today_str = _today()

    papers = (
        db.query(Paper)
        .filter(Paper.paper_date == date_str)
        .options(
            joinedload(Paper.authors),
            joinedload(Paper.tags),
            joinedload(Paper.summary_status),
            joinedload(Paper.bookmark),
        )
        .order_by(Paper.upvotes.desc())
        .all()
    )

    dates_raw = (
        db.query(Paper.paper_date)
        .distinct()
        .order_by(Paper.paper_date.desc())
        .limit(30)
        .all()
    )
    available_dates = [d[0].isoformat() if isinstance(d[0], date) else str(d[0]) for d in dates_raw]

    return templates.TemplateResponse(
        request, "index.html",
        {
            "papers": papers,
            "current_date": date_str,
            "prev_day": prev_day,
            "next_day": next_day,
            "today": today_str,
            "available_dates": available_dates,
            "page_title": f"{date_str} 论文列表",
        },
    )


@router.get("/paper/{arxiv_id}")
def paper_detail(arxiv_id: str, request: Request, db: Session = Depends(get_db)):
    """论文详情页。"""
    paper = (
        db.query(Paper)
        .filter(Paper.arxiv_id == arxiv_id)
        .options(
            joinedload(Paper.authors),
            joinedload(Paper.tags),
            joinedload(Paper.summary),
            joinedload(Paper.summary_status),
            joinedload(Paper.bookmark),
            joinedload(Paper.reading_status),
            joinedload(Paper.note),
        )
        .first()
    )
    if not paper:
        raise HTTPException(status_code=404, detail="Paper not found")

    summary_state = "none"
    if paper.summary_status:
        summary_state = paper.summary_status.status

    return templates.TemplateResponse(
        request, "detail.html",
        {
            "paper": paper,
            "summary_state": summary_state,
            "page_title": paper.title_zh or paper.title_en,
        },
    )