import os
import urllib.parse
from dotenv import load_dotenv

load_dotenv()

def quote(value):
    return urllib.parse.quote_plus(value)

class Config:
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    DEBUG = False
    TESTING = False

    DB_BACKEND = os.getenv('DB_BACKEND', 'sqlite').lower()
    DB_WINDOWS_AUTH = os.getenv('DB_WINDOWS_AUTH', 'false').strip().lower() in ['true', '1', 'yes']

    DB_USER = os.getenv('DB_USER', '')
    DB_PASSWORD = os.getenv('DB_PASSWORD', '')
    DB_HOST = os.getenv('DB_HOST', 'localhost')
    DB_PORT = os.getenv('DB_PORT', '')
    DB_NAME = os.getenv('DB_NAME', 'app.db')  # default file for sqlite

    SQLALCHEMY_DATABASE_URI = None  # <-- initialize properly

    if DB_BACKEND == 'mssql':
        driver = os.getenv('DB_DRIVER', 'ODBC Driver 17 for SQL Server')
        quoted_driver = quote(driver)

        if DB_WINDOWS_AUTH:
            SQLALCHEMY_DATABASE_URI = (
                f"mssql+pyodbc://@{DB_HOST}/{DB_NAME}?driver={quoted_driver}&Trusted_Connection=yes"
            )
        else:
            SQLALCHEMY_DATABASE_URI = (
                f"mssql+pyodbc://{quote(DB_USER)}:{quote(DB_PASSWORD)}@{DB_HOST}:{DB_PORT}/{DB_NAME}"
                f"?driver={quoted_driver}"
            )

    elif DB_BACKEND == 'postgres':
        SQLALCHEMY_DATABASE_URI = (
            f"postgresql://{quote(DB_USER)}:{quote(DB_PASSWORD)}@{DB_HOST}:{DB_PORT or '5432'}/{DB_NAME}"
        )

    elif DB_BACKEND in ['mariadb', 'mysql']:
        SQLALCHEMY_DATABASE_URI = (
            f"mysql+pymysql://{quote(DB_USER)}:{quote(DB_PASSWORD)}@{DB_HOST}:{DB_PORT or '3306'}/{DB_NAME}"
        )

    elif DB_BACKEND == 'sqlite':
        if DB_NAME == ':memory:':
            SQLALCHEMY_DATABASE_URI = 'sqlite:///:memory:'
        else:
            SQLALCHEMY_DATABASE_URI = f"sqlite:///{DB_NAME}"

    else:
        raise ValueError(
            f"Unsupported DB_BACKEND: {DB_BACKEND}. "
            "Supported backends: mssql, postgres, mariadb, mysql, sqlite."
        )