import config as cfg
from catquery import *
import sqlite3

class DBHandler():
    def __init__(self,config):
        self.DB = cfg.DB_NAME
        self.init_db()
        return

    def init_db(self):
        self.commit(DB_SCHEMA)

    # this wrapper doesn't handle exception
    # catch them in the caller.
    # another remark: we don't expect much DB throughput
    # and it's not necessary to maintain a long-lived connection
    def commit(self, str, data=None):
        conn = sqlite3.connect(self.DB)
        cur = conn.cursor()
        if data == None:
            cur.execute(str)
        else:
            cur.execute(str,data)
        conn.commit()
        conn.close()

    # read-only access
    def query(self,str):
        conn = sqlite3.connect(self.DB)
        cur = conn.cursor()
        res = cur.execute(str).fetchall()
        conn.close()
        return res

    # the insert_event exception should be handled here
    # because this is used as a log, and should have no effect
    # on the programs even if it fails
    def insert_event(self, _type, remarks, correspond):
        try:
            self.commit(QUERY_INSERT_EVENT, (_type,remarks,correspond))
        except Exception as e:
            print("ERROR ","failed to insert event to the db, ignoring ",e)

    def count_interaction(self):
        try:
            res = self.query(QUERY_COUNT_INTERACTION)
            return dict(res)
        except:
            print("query failed")
        return None