import mariadb
import os

pool = None

def createConnectionPool():
    global pool

    try:
        user = os.environ["DB_USER"]
        password = os.environ["DB_PASS"]
        host = os.environ["DB_HOST"]
        database = os.environ["DB_NAME"]
    except KeyError as err:
        raise Exception("Database configuration variable {} not available".format(err))

    pool = mariadb.ConnectionPool(
        user = user,
        password = password,
        host = host,
        database = database,
        pool_name = 'hv-wep-app',
        pool_size = 5
    )

def getConnection():
    global pool
    return pool.get_connection()


def getMany(stmt, params, objName):
    try:
        dbh = getConnection()
        objs = []
        cur = dbh.cursor(dictionary=True)
        cur.execute(stmt, params)
        for obj in cur:
            objs.append(obj)
        return objs
    except Exception as err:
        return str(err), 500
    finally:
        dbh.close()


def getOne(stmt, params, objName):
    try:
        dbh = getConnection()
        cur = dbh.cursor(dictionary=True)
        cur.execute(stmt, params)
        obj = cur.next()
        if not obj:
            return "{} not found".format(objName), 404
        invObj = cur.next()
        if invObj:
            return "More than one {} by that id ({}, {})".format(objName, id, invObj), 500
        return obj
    except Exception as err:
        return str(err), 500
    finally:
        dbh.close()