import os, json, sqlite3
from datetime import datetime, timedelta
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer
from huggingface_hub import HfApi

SECRET_KEY = os.environ.get("JWT_SECRET", "dev-secret-change-me")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 7  # 7天

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
security = HTTPBearer()

DB_PATH = "/tmp/users.db"
BUCKET_ID = os.environ.get("HF_BUCKET_ID", "your-username/learning-platform-data")

def init_db():
    conn = sqlite3.connect(DB_PATH)
    conn.execute("""
        CREATE TABLE IF NOT EXISTS users (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            username TEXT UNIQUE NOT NULL,
            password_hash TEXT NOT NULL,
            email TEXT,
            created_at TEXT
        )
    """)
    conn.commit()
    conn.close()
    # 尝试从 Buckets 恢复用户数据库
    _restore_db_from_bucket()

def _restore_db_from_bucket():
    try:
        from huggingface_hub import hf_hub_download
        path = hf_hub_download(
            repo_id=BUCKET_ID.replace("/", "_"),  # Buckets 访问方式
            filename="users.db",
            repo_type="bucket"
        )
        import shutil
        shutil.copy(path, DB_PATH)
    except Exception:
        pass  # 首次运行没有备份

def _backup_db_to_bucket():
    try:
        from huggingface_hub import upload_file
        upload_file(
            path_or_fileobj=DB_PATH,
            path_in_repo="users.db",
            repo_id=BUCKET_ID.replace("/", "_"),
            repo_type="bucket"
        )
    except Exception:
        pass

def hash_password(password: str) -> str:
    return pwd_context.hash(password)

def verify_password(plain: str, hashed: str) -> bool:
    return pwd_context.verify(plain, hashed)

def create_access_token(data: dict):
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)

def get_current_user(credentials=Depends(security)):
    token = credentials.credentials
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise HTTPException(status_code=401, detail="Invalid token")
        return username
    except JWTError:
        raise HTTPException(status_code=401, detail="Invalid token")