from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from app.database import get_db
from app.models.user import User
from app.models.lesson import Lesson, UserLesson
from app.utils.auth import get_current_user
from app.services.gamification import check_achievements

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

@router.get("")
async def list_lessons(user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
    lessons = (await db.execute(select(Lesson).order_by(Lesson.order_num))).scalars().all()
    completed = (await db.execute(
        select(UserLesson.lesson_id).where(UserLesson.user_id == user.id)
    )).scalars().all()
    completed_ids = set(completed)
    return [
        {"id": str(l.id), "title": l.title, "category": l.category, "difficulty": l.difficulty,
         "duration_min": l.duration_min, "content": l.content, "is_premium": l.is_premium,
         "completed": l.id in completed_ids}
        for l in lessons
    ]

@router.post("/{lesson_id}/complete")
async def complete_lesson(lesson_id: str, user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
    lesson = (await db.execute(select(Lesson).where(Lesson.id == lesson_id))).scalar_one_or_none()
    if not lesson:
        raise HTTPException(404, "Lesson not found")
    existing = (await db.execute(
        select(UserLesson).where(UserLesson.user_id == user.id, UserLesson.lesson_id == lesson_id)
    )).scalar_one_or_none()
    if existing:
        return {"status": "already_completed"}
    ul = UserLesson(user_id=user.id, lesson_id=lesson_id)
    db.add(ul)
    user.total_points = (user.total_points or 0) + 10
    await db.commit()
    await check_achievements(user.id, db)
    return {"status": "completed", "points_earned": 10}