import pymysql
import json

class MaDbHelper:
    def __init__(self, config):
        self.mysqlConn = pymysql.connect(host=config["MYSQL_HOST"],
                                    user=config["MYSQL_USER"],
                                    passwd=config["MYSQL_PASSWORD"],
                                    db=config["MYSQL_DATABASE"],
                                    port=config["MYSQL_PORT"])

        self.mysqlCur = self.mysqlConn.cursor()
        self._initDb()

    def _initDb(self):
        """
        Generates required tables
        """

        query = """
        CREATE TABLE IF NOT EXISTS vmq_auth_acl
        (
        mountpoint VARCHAR(10) NOT NULL,
        client_id VARCHAR(128) NOT NULL,
        username VARCHAR(128) NOT NULL,
        password VARCHAR(128),
        publish_acl TEXT,
        subscribe_acl TEXT,
        CONSTRAINT vmq_auth_acl_primary_key PRIMARY KEY (mountpoint, client_id, username)
        )
        """

        self.mysqlCur.execute(
            query
        )

        self.mysqlConn.commit()

    def addUser(self, username, password, publishAclPatterns, subscribeAclPatterns):

        if self.userExists(username):
            return False

        query = "INSERT INTO `vmq_auth_acl` (`mountpoint`, `client_id`, `username`, `password`, `publish_acl`, `subscribe_acl`) VALUES (%s, %s, %s, PASSWORD(%s), %s, %s);"

        self.mysqlCur.execute(
            query, 
            (
                "",
                username, 
                username, 
                password, 
                self._convertAclPatternList(publishAclPatterns), 
                self._convertAclPatternList(subscribeAclPatterns)
            )
        )

        self.mysqlConn.commit()

        return True

    def userExists(self, username):
        query = "SELECT username FROM `vmq_auth_acl` WHERE username=%s"

        self.mysqlCur.execute(
            query,
            (username)
        )

        result = self.mysqlCur.fetchone()
        return result is not None

    
    def updateUser(self, username, password, publishAclPatterns, subscribeAclPatterns):
        if self.userExists(username):
            return self._updateUser(username, password, publishAclPatterns, subscribeAclPatterns)
        else:
            return False

    def getAllUsers(self):
        query = "SELECT username FROM `vmq_auth_acl`;"

        self.mysqlCur.execute(
            query
        )

        users = []
        for user in self.mysqlCur:
            users.append(user[0])

        return users

    def _updateUser(self, username, password, publishAclPatterns, subscribeAclPatterns):

        query = """
        UPDATE `vmq_auth_acl` 
        SET `password`=PASSWORD(%s), `publish_acl`=%s, `subscribe_acl`=%s
        WHERE `username`=%s;
        """

        self.mysqlCur.execute(
            query, 
            (
                password, 
                self._convertAclPatternList(publishAclPatterns), 
                self._convertAclPatternList(subscribeAclPatterns),
                username
            )
        )

        self.mysqlConn.commit()

    def _convertAclPatternList(self, patternList):
        patternMapLabda = lambda pattern: {"pattern": pattern}
        patternList = list(map(patternMapLabda, patternList))
        return json.dumps(patternList)