from fastapi import APIRouter, Depends
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, desc, asc
from datetime import datetime, timezone, timedelta
from app.database import get_db
from app.models.user import User
from app.models.scan import Scan
from app.utils.security import get_current_user

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

@router.get("/stats")
async def get_stats(user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
    now = datetime.now(timezone.utc)
    month_start = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
    
    # Total scans
    total_res = await db.execute(select(func.count(Scan.id)).where(Scan.user_id == user.id))
    total_scans = total_res.scalar() or 0
    
    # Average score
    avg_res = await db.execute(select(func.avg(Scan.score)).where(Scan.user_id == user.id))
    avg_score = round(avg_res.scalar() or 0, 1)
    
    # Monthly scans
    monthly_res = await db.execute(
        select(func.count(Scan.id)).where(Scan.user_id == user.id, Scan.scanned_at >= month_start)
    )
    monthly_scans = monthly_res.scalar() or 0
    
    # Top 10 best this month
    best_res = await db.execute(
        select(Scan).where(Scan.user_id == user.id, Scan.scanned_at >= month_start)
        .order_by(desc(Scan.score)).limit(10)
    )
    best = [{"id": s.id, "product_name": s.product_name, "brand": s.brand, "score": s.score, 
             "scanned_at": s.scanned_at.isoformat() if s.scanned_at else None} for s in best_res.scalars().all()]
    
    # Top 10 worst this month
    worst_res = await db.execute(
        select(Scan).where(Scan.user_id == user.id, Scan.scanned_at >= month_start)
        .order_by(asc(Scan.score)).limit(10)
    )
    worst = [{"id": s.id, "product_name": s.product_name, "brand": s.brand, "score": s.score,
              "scanned_at": s.scanned_at.isoformat() if s.scanned_at else None} for s in worst_res.scalars().all()]
    
    return {
        "total_scans": total_scans,
        "avg_score": avg_score,
        "monthly_scans": monthly_scans,
        "best": best,
        "worst": worst,
    }

@router.get("/stats/evolution")
async def get_evolution(user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
    now = datetime.now(timezone.utc)
    three_months_ago = now - timedelta(days=90)
    
    result = await db.execute(
        select(Scan.scanned_at, Scan.score)
        .where(Scan.user_id == user.id, Scan.scanned_at >= three_months_ago)
        .order_by(Scan.scanned_at)
    )
    scans = result.all()
    
    # Group by week
    weeks = {}
    for scanned_at, score in scans:
        # ISO week
        week_key = scanned_at.strftime("%Y-W%W")
        week_start = scanned_at - timedelta(days=scanned_at.weekday())
        if week_key not in weeks:
            weeks[week_key] = {"week": week_start.strftime("%d/%m"), "scores": [], "count": 0}
        weeks[week_key]["scores"].append(score)
        weeks[week_key]["count"] += 1
    
    evolution = []
    for key in sorted(weeks.keys()):
        w = weeks[key]
        evolution.append({
            "week": w["week"],
            "avg_score": round(sum(w["scores"]) / len(w["scores"]), 1),
            "count": w["count"],
        })
    
    return {"evolution": evolution}