db.py

""" """


# Tuple functions

def append(tup, elem): return tup + (elem,)


def ainit(length, func):
    return reduce(append, map(func, range(length)), ())


def amake(length, elem):
    return ainit(length, lambda _: elem)


# DB related functions

def nobody(): return {"name": "", "phone_number": (0, 0, 0, 0)}


def make(max_num):
    return dict(
        number_of_contacts=0,
        contacts=amake(max_num, nobody()))


def search(db, contact):
    def aux(idx):
        if idx >= db["number_of_contacts"]:
            return (False, db, contact)
        elif db["contacts"][idx]["name"] == contact["name"]:
            return (True, db, contact)
        else:
            return aux(idx + 1)

    return aux(0)


def insert(db, contact):
    if db["number_of_contacts"] >= len(db["contacts"]):
        return (False, db, nobody())
    else:
        (status, db, _) = search(db, contact)
        if status:
            return (False, db, contact)
        else:
            def cells(i):
                if i == db["number_of_contacts"]:
                    return contact
                else:
                    db["contacts"][i]

            db_ = dict(
                number_of_contacts=db["number_of_contacts"] + 1,
                contacts=ainit(len(db["contacts"]), cells))

            return (True, db_, contact)


def delete(db, contact):
    (status, db, contact) = search(db, contact)
    if not status:
        return (False, db, contact)
    else:
        def cells(i):
            if db["contacts"][i]["name"] == contact["name"]:
                return nobody()
            else:
                return db["contacts"][i]

        db_ = dict(
            number_of_contacts=db["number_of_contacts"] - 1,
            contacts=ainit(len(db["contacts"]), cells))

        return (True, db_, contact)


def engine(db, query):
    code, contact = query
    if code == 0:
        return insert(db, contact)
    elif code == 1:
        return delete(db, contact)
    elif code == 2:
        return search(db, contact)
    else:
        return (False, db, nobody())