from datetime import datetime
from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.ext.asyncio import AsyncSession

from backend.database import get_db
from backend.schemas.post import PostResponse, PostDetailResponse
from backend.services import post_service
from backend.models.metric_snapshot import MetricSnapshot
from sqlalchemy import select

router = APIRouter(prefix="/posts", tags=["posts"])


@router.get("")
async def list_posts(
    subreddit_id: int | None = None,
    author: str | None = None,
    flair: str | None = None,
    sort_by: str = Query("created_utc", pattern="^(created_utc|score|num_comments)$"),
    sort_order: str = Query("desc", pattern="^(asc|desc)$"),
    since: datetime | None = None,
    until: datetime | None = None,
    page: int = Query(1, ge=1),
    per_page: int = Query(25, ge=1, le=100),
    db: AsyncSession = Depends(get_db),
):
    posts, total = await post_service.list_posts(
        db, subreddit_id, author, flair, sort_by, sort_order, since, until, page, per_page
    )
    return {
        "data": posts,
        "total": total,
        "page": page,
        "per_page": per_page,
        "pages": (total + per_page - 1) // per_page if per_page else 0,
    }


@router.get("/{post_id}")
async def get_post(post_id: int, db: AsyncSession = Depends(get_db)):
    post = await post_service.get_post(db, post_id)
    if not post:
        raise HTTPException(status_code=404, detail="Post not found")
    return post


@router.get("/{post_id}/snapshots")
async def get_post_snapshots(post_id: int, db: AsyncSession = Depends(get_db)):
    stmt = (
        select(MetricSnapshot)
        .where(MetricSnapshot.post_id == post_id)
        .order_by(MetricSnapshot.snapshot_at.asc())
    )
    result = await db.execute(stmt)
    snapshots = result.scalars().all()
    return [
        {
            "score": s.score,
            "num_comments": s.num_comments,
            "upvote_ratio": s.upvote_ratio,
            "snapshot_at": s.snapshot_at,
        }
        for s in snapshots
    ]