from typing import List, Union
from fastapi import APIRouter, Depends, Query
from sqlmodel import Session, select, desc
from database import get_session
from models import Review, Attendance, GroupPost, User
from schemas import ReviewRead, AttendanceRead, GroupPostRead
from datetime import datetime

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

# We need a unified schema for the feed
from pydantic import BaseModel

class FeedItem(BaseModel):
    type: str # review, attendance, post
    timestamp: datetime
    data: Union[ReviewRead, AttendanceRead, GroupPostRead, dict]
    user: dict # Basic user info

@router.get("/", response_model=List[FeedItem])
def get_global_feed(
    limit: int = 20,
    session: Session = Depends(get_session)
):
    # Fetch latest reviews
    reviews = session.exec(
        select(Review).order_by(desc(Review.created_at)).limit(limit)
    ).all()
    
    # Fetch latest attendance
    attendance = session.exec(
        select(Attendance).order_by(desc(Attendance.created_at)).limit(limit)
    ).all()
    
    # Fetch latest group posts
    posts = session.exec(
        select(GroupPost).order_by(desc(GroupPost.created_at)).limit(limit)
    ).all()
    
    feed_items = []
    
    for r in reviews:
        user = session.get(User, r.user_id)
        user_data = {"id": 0, "username": "Deleted User", "avatar": None}
        if user:
            user_data = {
                "id": user.id, 
                "username": user.email.split("@")[0] if user.email else "User", 
                "avatar": user.avatar
            }
        
        feed_items.append(FeedItem(
            type="review",
            timestamp=r.created_at or datetime.utcnow(),
            data=r,
            user=user_data
        ))
        
    for a in attendance:
        user = session.get(User, a.user_id)
        user_data = {"id": 0, "username": "Deleted User", "avatar": None}
        if user:
            user_data = {
                "id": user.id, 
                "username": user.email.split("@")[0] if user.email else "User", 
                "avatar": user.avatar
            }

        feed_items.append(FeedItem(
            type="attendance",
            timestamp=a.created_at,
            data=a,
            user=user_data
        ))
        
    for p in posts:
        user = session.get(User, p.user_id)
        user_data = {"id": 0, "username": "Deleted User", "avatar": None}
        if user:
            user_data = {
                "id": user.id, 
                "username": user.email.split("@")[0] if user.email else "User", 
                "avatar": user.avatar
            }

        feed_items.append(FeedItem(
            type="post",
            timestamp=p.created_at,
            data=p,
            user=user_data
        ))
        
    # Sort by timestamp desc
    feed_items.sort(key=lambda x: x.timestamp, reverse=True)
    
    return feed_items[:limit]