HomeInventory.py

#!/usr/bin/env python3

"""
HomeInventory.py

Author: Dr. Andreas Janzen, janzen@gmx.net
Date: 2020-08-03
"""

import sqlite3
import sys

from contextlib import contextmanager


DB = "HomeInventory.db"


def first_launch():
    """ Creates a new database on first launch """
    try:
        conn = sqlite3.connect(DB)
    except:
        sys.exit(f"Error: could not create database {DB}")


@contextmanager
def access_db():
    """ Generator to yield a DB cursor and close the connection afterwards """
    try:
        conn = sqlite3.connect(DB)
        cursor = conn.cursor()
        yield cursor
    finally:
        conn.commit()
        conn.close()


def scrub(text):
    """ Removes all non-alphanumeric characters from the input string """ 
    return "".join([chr for chr in text if chr.isalnum()])


def main_menu():
    menu = dict()

    menu["1"] = "Create new room"
    menu["2"] = "Create new inventory"
    menu["3"] = "Show inventory list"
    menu["4"] = "Show total value"
    menu["5"] = "Quit"

    while True:
        print("\n")
        for item, description in sorted(menu.items()):
            print(f"{item}) {description}")
        print()

        choice = scrub(input("Please chose an action > "))
        if choice == "1":
            create_room()
        elif choice == "2":
            create_inventory(select_room())
        elif choice == "3":
            show_inventory(select_room())
        elif choice == "4":
            show_value()
        elif choice == "5":
            sys.exit()
        else:
            print("\n=== Invalid input. Please try again! ===\n")


def room_list():
    rooms = list()
    with access_db() as cursor:
        cursor.execute("SELECT name from sqlite_master WHERE type='table'")
        for room in cursor:
            rooms.append(room[0])
    return rooms


def select_room():
    while True:
        print("\n")
        for room in room_list():
            print(room)
        selection = input("\nPlease select a room: ").lower()
        if selection not in room_list():
            print(f"Room does not exist: {selection}")
        else:
            return scrub(selection)


def create_room():
    name = input("\nWhat name would you like to give the room? > ")
    name = scrub(name)
    with access_db() as cursor:
        cursor.execute("CREATE TABLE '" + name.lower() + "' (Item TEXT, Value REAL)")
    print(f"\nA room with name '{name}' has been added to the database.\n")


def create_inventory(room):
    while True:
        item = scrub(input("Please specify item name > "))
        value = int(input("Please specify item value > "))
        with access_db() as cursor:
            cursor.execute("INSERT INTO '" + room + "' VALUES(?,?)", (item, value))

        cont = input("\nWould you like to add another item or (q)uit? > ")
        if cont.lower() == "q":
            break


def show_inventory(room):
    total_value = 0
    with access_db() as cursor:
        cursor.execute("SELECT * FROM '" + room + "'")
        print("\n")
        for item in cursor:
            print(f"{item[0]}, value: {item[1]}")
            total_value += item[1]
    print(f"\nTotal value of all items in room {room}: {total_value}")
    return total_value


def show_value():
    total_value = 0
    for room in room_list():
        total_value += show_inventory(room)
    print(f"\nTotal value of all rooms: {total_value}")


first_launch()
main_menu()