from sqlalchemy import create_engine, Table
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from typing import Optional, Dict
from dataclasses import dataclass
import json


@dataclass
class Database:
    engine: str
    name: str
    host: str
    user: str
    password: str
    options: Optional[Dict] = None

    def get_url(self):
        option_str = ""
        if self.options:
            opt = [name+'='+'+'.join(value.split())
                   for name, value in self.options.items()]
            option_str = "?"+"&".join(opt)
        return f"{self.engine}://{self.user}:{self.password}@{self.host}/{self.name}{option_str}"


data = {}

with open('settings', 'r') as settings:
    data_str = settings.read()
    data = json.loads(data_str)
db = Database(**data.get('database'))

SQL_ALCHEMY_DATABASE_URL_MSSQL = db.get_url()


engine = create_engine(
    SQL_ALCHEMY_DATABASE_URL_MSSQL, connect_args={"check_same_thread": False}
)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()


def get_table(tablename: str, dbname: str = None) -> Table:
    metadata = Base.metadata
    metadata.reflect(bind=engine)

    if dbname == None:
        dbname = db.name

    return Table(tablename, metadata, schema=dbname+'.dbo', autoload=True, autoload_with=engine)


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()