bank.py

# ─── IMPORTS ────────────────────────────────────────────────────────────────────

import math
import json
import os
import random
from datetime import datetime
from os.path import exists


# ─── CONSTANTS ──────────────────────────────────────────────────────────────────


FILE_PATH = "bank.json"


# ─── DATABASE ───────────────────────────────────────────────────────────────────


def get_data():
    """
    Reads the bank information from the data file.
    """
    # assume none existent file as empty file
    if not exists(FILE_PATH):
        return {}
    f = open(FILE_PATH, "r")
    data = f.read()
    # convert string json to python object
    return json.loads(data)


def set_data(data):
    """
    Writes the bank information into the data file
    """
    f = open(FILE_PATH, "w")
    json_data = json.dumps(data)
    f.write(json_data)


def get_users_as_list():
    """
    This functions loads the user data and converts it
    from a dictionary to a list and then appends the
    account_number as a key from outside into the the
    data object.
    """
    result = []
    users = get_data()
    for user_account_number in users:
        user_data = users[user_account_number]
        user_data["account_number"] = user_account_number
        result.append(user_data)
    results_as_ll = list_to_linked_list(result)
    return results_as_ll


# ─── LINKED LIST ────────────────────────────────────────────────────────────────


class LinkedList:
    """
    A Linked List Node
    """

    def __init__(self, _value, _next):
        """
        Creates the node with a value and reference to
        the next object
        """
        self.value = _value
        self.next = _next

    def index(self, index):
        """
        Similar to A[i], this works as A.index(i)
        """
        if index == 0:
            return self.value
        else:
            if self.next == None:
                return None
            else:
                return self.next.index(index - 1)

    def set_index(self, index, value):
        """
        Similar to A[i] = value, this is A.set_index(i, value)
        """
        if index == 0:
            self.value = value
        else:
            self.next.set_index(index - 1, value)

    def size(self):
        """
        Similar to len(A), this is A.size()
        """
        if self.next == None:
            return 1
        else:
            return 1 + self.next.size()

    def append(self, x):
        """
        Appends a new node to the end of nodes
        """
        if self.next == None:
            self.next = LinkedList(x, None)
        else:
            self.next.append(x)


def list_to_linked_list(arr):
    """
    Converts a Python List to a LinkedList
    """
    n = None
    for i in range(len(arr) - 1, -1, -1):
        node = LinkedList(arr[i], n)
        n = node
    return n


# ─── HEAP SORT ──────────────────────────────────────────────────────────────────


def heap_sort(input_list, field):
    """
    A custom implementation of the heap sort function that
    also gets a field and then assumes the input_list contains
    data objects. So it sorts based on a common key on all those
    functions. This makes possible to sort users based on different
    aspects, like based on full name or phone number
    """
    range_start = int((input_list.size()-2)/2)
    for start in range(range_start, -1, -1):
        sift_down(input_list, field, start, input_list.size()-1)

    range_start = int(input_list.size()-1)
    for end_index in range(range_start, 0, -1):
        swap(input_list, end_index, 0)
        sift_down(input_list, field, 0, end_index - 1)
    return input_list


def swap(input_list, a, b):
    """
    Swaps two elements of a list with the python shorthand
    """
    a_value = input_list.index(a)
    b_value = input_list.index(b)
    input_list.set_index(a, b_value)
    input_list.set_index(b, a_value)


def sift_down(input_list, field, start_index, end_index):
    """
    The "Sift Down" function of the heap sort algorithm,
    customized to also include object fields.
    """
    root_index = start_index
    while True:
        child = root_index * 2 + 1
        if child > end_index:
            break
        if child + 1 <= end_index and input_list.index(child)[field] < input_list.index(child + 1)[field]:
            child += 1
        if input_list.index(root_index)[field] < input_list.index(child)[field]:
            swap(input_list, child, root_index)
            root_index = child
        else:
            break


# ─── BINARY SEARCH ──────────────────────────────────────────────────────────────


def text_binary_search(input_list, field, query):
    """
    A custom binary search implementation that:
    (1) Assumes the input_list to have elements of type object
        and then sorts by a common key in all those objects name
        "field"
    (2) Make the text lowercase and trims the text in the fields
        so for example "foo bar" can match "FooBar"
    """
    low = 0
    high = input_list.size() - 1
    query = make_text_searchable(query)
    while low <= high:
        mid = math.floor((low + high) / 2)
        if make_text_searchable(input_list.index(mid)[field]) > query:
            high = mid - 1
        elif make_text_searchable(input_list.index(mid)[field]) < query:
            low = mid + 1
        else:
            return mid
    return -1


def make_text_searchable(text):
    """
    Make the text lowercase the text and removes spaces
    """
    return text.lower().replace(" ", "")


# ─── ACCOUNT NUMBER ─────────────────────────────────────────────────────────────


def generate_account_number():
    """
    Generates a new unique account number. The bank
    prefix number is 1717 2424, the 8 other digits are
    then generated randomly
    """
    prefix = "17172424"
    result = ""
    for _ in range(0, 8):
        random_number = random.randint(1, 9)
        result += str(random_number)

    return prefix + result


# ─── TRANSACTION ────────────────────────────────────────────────────────────────


def perform_transaction(sender_number, receiver_number, amount):
    """
    Given two account numbers and a transaction amount, this will move
    the money from the sender account to the recipient account.
    """
    users = get_data()

    if sender_number not in users:
        print("Did not found the account with number: " + sender_number)
        return

    if receiver_number not in users:
        print("Did not found the account with number: " + receiver_number)
        return

    if users[sender_number]["balance"] < amount:
        print("your account balance is not enough")
        return

    users[sender_number]["balance"] -= amount
    users[receiver_number]["balance"] += amount

    set_data(users)

    print("Transferred ", amount, "$ from account",
          users[sender_number]["full_name"], "to", users[receiver_number]["full_name"])


# ─── update information ──────────────────────────────────────────────────────────


def update_information(account_number):
    """
    Given an account number, this asks the user what to change and then
    changes the properties of that.
    """
    users = get_data()
    print_horizontal_line()
    print("► 1 ∙ Full Name ")
    print_horizontal_line()
    print("► 2 ∙ Gender ")
    print_horizontal_line()
    print("► 3 ∙ City ")
    print_horizontal_line()
    print("► 4 ∙ Phone Number ")
    print_horizontal_line()
    command = int(input("What to change? "))
    print_horizontal_line()
    if command == 1:
        new_name = input("New Full Name: ")
        users[account_number]["full_name"] = new_name
    if command == 2:
        new_gender = input("New Gender: ")
        users[account_number]["gender"] = new_gender
    if command == 3:
        new_city = input("New City: ")
        users[account_number]["city"] = new_city
    if command == 4:
        new_phone_number = input("New Phone Number: ")
        users[account_number]["phone_number"] = new_phone_number

    set_data(users)
    clean_terminal_screen()
    display_account_information_by_given_account_number(account_number)


# ─── CREATE A NEW USER ──────────────────────────────────────────────────────────


def create_new_user(full_name, balance, gender, city, phone_number):
    """
    Creates a new user with the given information
    """
    users = get_data()
    date = datetime.today().strftime('%Y-%m-%d')
    account_number = generate_account_number()
    users[account_number] = {
        "full_name": full_name,
        "gender": gender,
        "balance": balance,
        "account_creation_date": date,
        "city": city,
        "phone_number": phone_number
    }
    set_data(users)
    display_account_information_by_given_account_number(account_number)


# ─── SEARCH ACCOUNT ─────────────────────────────────────────────────────────────


def search_account(field, query):
    """
    Searches the "query" from the user data in the "field" fields
    """
    users = get_users_as_list()
    users = heap_sort(users, field)
    index = text_binary_search(users, field, query)
    if index == -1:
        print("──── Error ──────────────────────────────────")
        print("Found no one as", query)
    else:
        user = users.index(index)
        display_user_object(user, user["account_number"])


# ——— MERGE ACCOUNTS —————————————————————————————————————————————————————————————
        

def merge_accounts(account_numbers_to_merge):
    """
    Merges the balance in each of the accounts keeping the first account, and then deleting the rest.
    Checks that all the information is the same expect for the balance. If any information is different,
    the user gets an error message.
    """
    users = get_data()
    first_account_number = account_numbers_to_merge[0]
    first_user_object = users[first_account_number]
    full_name = first_user_object["full_name"]
    account_creation_date = first_user_object["account_creation_date"]
    gender =  first_user_object["gender"]
    city = first_user_object["city"]
    phone_number = first_user_object["phone_number"]

    merge = True
    total_balance = 0
    for i in range(len(account_numbers_to_merge)):
        total_balance += float(users[account_numbers_to_merge[i]]["balance"])
        if users[account_numbers_to_merge[i]]["full_name"] != full_name:
            merge = False
            break
        if users[account_numbers_to_merge[i]]["account_creation_date"] != account_creation_date:
            merge = False
            break
        if users[account_numbers_to_merge[i]]["gender"] != gender:
            merge = False
            break
        if users[account_numbers_to_merge[i]]["city"] != city:
            merge = False
            break
        if users[account_numbers_to_merge[i]]["phone_number"] != phone_number:
            merge = False
            break

    if merge:
        for i in range(len(account_numbers_to_merge)):
            if i != 0:
                delete_account(account_numbers_to_merge[i])
        users[first_account_number]["balance"] = str(total_balance)
        set_data(users)
        print("Accounts successfully merged under account number " + first_account_number)
        display_user_object(first_user_object, first_account_number)
    else:
        print("──── Error ──────────────────────────────────")
        print("Could not merge accounts: Account information does not match for all accounts.")


# ─── DELETE AN ACCOUNT ──────────────────────────────────────────────────────────


def delete_account(account_number):
    """
    Deletes an account if exists, otherwise displays an error
    """
    users = get_data()
    if account_number not in users:
        print("Did not found the account with number: " + account_number)
        return
    del users[account_number]
    set_data(users)
    print("Account number", account_number, "removed.")


# ─── INTERFACE TOOLS ────────────────────────────────────────────────────────────


def clean_terminal_screen():
    """
    Cleans the terminal screen by performing a system
    clear command. Cls on windows and Clear on UNIX ones.
    """
    os.system('cls' if os.name == 'nt' else 'clear')


def print_horizontal_line():
    """
    A pretty decorative horizontal line.
    """
    print("─────────────────────────────────────────────")


# ─── DISPLAY USER OBJECT ────────────────────────────────────────────────────────


def display_account_information_by_given_account_number(account_number):
    """
    Displays the information about a given account number
    """
    users = get_data()
    user = users[account_number]
    display_user_object(user, account_number)


def display_user_object(user_object, account_number):
    """
    Displays a single user object. The account_number is taken
    separately since there can be either a list input or a dictionary
    input. In a list input the account_number is within the user object
    and in the dictionary form the account_number is the key mapped
    to the dictionary
    """
    print_horizontal_line()
    print("Full name:      ", user_object["full_name"])
    print("Account number: ", account_number)
    print("Created at:     ", user_object["account_creation_date"])
    print("Balance:        ", user_object["balance"])
    print("Gender:         ", user_object["gender"])
    print("City:           ", user_object["city"])
    print("Phone:          ", user_object["phone_number"])


def display_all_accounts_sorted_by(field):
    """
    Displays all the users one after the other, sorted by a given field
    """
    users = get_users_as_list()
    users = heap_sort(users, field)
    clean_terminal_screen()
    for i in range(0, users.size()):
        user = users.index(i)
        display_user_object(user, user["account_number"])


def beatify_field_name(field):
    if field == "full_name":
        return "Full Name"
    if field == "account_creation_date":
        return "Account Creation Data"
    if field == "city":
        return "City"
    if field == "gender":
        return "Gender"
    if field == "phone_number":
        return "Phone Number"
    return "Unknown"


def ask_user_what_field_to_sort_the_display_by():
    """
    Shows a menu so that the user cas pick a field to sort the data by.
    """
    print("Sorting by:")
    print_horizontal_line()
    print("► 1 ∙ Full Name ")
    print_horizontal_line()
    print("► 2 ∙ Gender ")
    print_horizontal_line()
    print("► 3 ∙ City ")
    print_horizontal_line()
    print("► 4 ∙ Phone Number ")
    print_horizontal_line()
    print("► 5 ∙ Account Creating Date ")
    print_horizontal_line()
    print("► 6 ∙ Account Number ")
    print()
    command = input("Your option: ")
    if command == "1":
        return "full_name"
    if command == "2":
        return "gender"
    if command == "3":
        return "city"
    if command == "4":
        return "phone_number"
    if command == "5":
        return "account_creation_date"
    if command == "6":
        return "account_number"
    return "full_name"


# ─── DISPLAY MENU ───────────────────────────────────────────────────────────────

def display_menu():
    """
    Displays the welcome menu and asks the user for a
    command to perform (which then performs).

    This also acts as the UI and receives the information
    regarding of the respective functions.
    """
    clean_terminal_screen()

    print()

    print("  ┌────────────────┐  ╭───────────────────────╮           ")
    print("  │  ╭┼┼╮          │  │ ▶︎ 1 • Create Account  │           ")
    print("  │  ╰┼┼╮          │  ├───────────────────────┴─────╮     ")
    print("  │  ╰┼┼╯          │  │ ▶︎ 2 • Perform Transaction   │     ")
    print("  │                │  ├────────────────────────────┬╯     ")
    print("  │  D R A G O N   │  │ ▶︎ 3 • Update Account Info  │      ")
    print("  │  B A N K       │  ├───────────────────────┬────╯      ")
    print("  │                │  │ ▶︎ 4 • Merge Accounts  │           ")
    print("  │                │  ├──────────────────────┬╯           ")
    print("  │                │  │ ▶︎ 5 • Delete Account │            ")
    print("  │                │  ├──────────────────────┴────╮       ")
    print("  │                │  │ ▶︎ 6 • Search Account Info │       ")
    print("  │                │  ├───────────────────────────┴╮      ")
    print("  │ ║│┃┃║║│┃║│║┃│  │  │ ▶︎ 7 • View Customer's List │      ")
    print("  │ ║│┃┃║║│┃║│║┃│  │  ├────────────────────┬───────╯      ")
    print("  │                │  │ ▶︎ 8 • Exit System  │              ")
    print("  └────────────────┘  ╰────────────────────╯              ")

    user_choice = int(input("\n  ☞ Enter your command: "))

    clean_terminal_screen()

    if user_choice == 1:
        print("── Creating a new user ──────────────────────")
        user_name = input("Full Name: ")
        balance = float(input("Balance: "))
        gender = input("Gender: ")
        city = input("City of Residence: ")
        phone_number = input("Phone Number: ")
        create_new_user(user_name, balance, gender, city, phone_number)

    if user_choice == 2:
        print("── Requesting Transaction ───────────────────")
        sender = input("Sender's Account Number:    ")
        receiver = input("Recipient's Account Number: ")
        amount = float(input("Transaction Amount: "))
        perform_transaction(sender, receiver, amount)

    if user_choice == 3:
        print("── Changing Account Information ─────────────")
        account_number = input("Account Number To Change: ")
        update_information(account_number)

    if user_choice == 4:
        print("── Merging Accounts ──────────────────────")
        number_of_accounts = int(input("Number of accounts to merge: "))
        if number_of_accounts <= 1:
            print("──── Error ──────────────────────────────────")
            print("Must merge two or more accounts")
        else:
            account_numbers_to_merge = []
            for i in range(number_of_accounts):
                account_number = input("Account " + str((i+1)) + ": Account number to merge: ")
                account_numbers_to_merge.append(account_number)
            merge_accounts(account_numbers_to_merge)

    if user_choice == 5:
        print("── Deleting an Account ──────────────────────")
        account_number = input("Account number to delete: ")
        delete_account(account_number)

    if user_choice == 6:
        print("── Search Account ───────────────────────────")
        query = input("Searching for: ")
        clean_terminal_screen()
        search_account("full_name", query)

    if user_choice == 7:
        print("── Displaying all Accounts ──────────────────")
        field = ask_user_what_field_to_sort_the_display_by()
        display_all_accounts_sorted_by(field)

        print("\n\nSorted by user", beatify_field_name(field))

    if user_choice == 8:
        quit()

    print()
    print_horizontal_line()
    input("PRESS ENTER TO CONTINUE ")
    print()


# ─── MAIN ───────────────────────────────────────────────────────────────────────


while True:
    display_menu()


# ────────────────────────────────────────────────────────────────────────────────