import sqlite3

class db:
    def __init__(self, dbfile):
        # final variable
        self.dbfile = dbfile
        try:
            open(dbfile)
        except FileNotFoundError:
            self.setup()
    def exec(cmd):
        con = sqlite3.connect(self.dbfile)
        cur = con.cursor
        cur.execute(cmd)
        con.commit()
        con.close()

def setup(dbfile):
    '''
    Necessary when the database does not exist and the tables must be
    created for the first time, otherwise not needed to be run.
    '''
    con = sqlite3.connect(dbfile)
    cur = con.cursor()
    cur.execute(
            '''
    CREATE TABLE temperature (
        date        text not null, 
        time        integer not null, 
        temperature            real,
        target           real,
        PRIMARY KEY (date, time)
    );
            '''
            )
    cur.execute(
            '''
    CREATE TABLE weather (
        date        text not null,
        temperature real,
        wind        real,
        PRIMARY KEY (date),
        FOREIGN KEY (date) REFERENCES temperature(date)
    );
            '''
            )
    cur.execute(
            '''
    CREATE TABLE schedule (
        day        text not null, 
        time        integer not null, 
        temperature real,
        PRIMARY KEY (day, time)
            '''
    );
    cur.execute(
            '''
    CREATE TABLE history (
        date        text not null,
        time        integer not null, 
        heating_on  integer,
        PRIMARY KEY (day, time),
        FOREIGN KEY (date) REFERENCES temperature(date),
        FOREIGN KEY (time) REFERENCES temperature(time)
            '''
    );
    con.commit()
    con.close()
    pass
    def export_csv(self):
        return 0