import tkinter as tk # Creates a Tkinter window so the code runs in it's own window and not the Python shell.
import random # Randomises integers.

class MainWindow(tk.Frame):

    def __init__(self, master=None):
        # Master constructor (constucts the Tkinter window).
        super().__init__(master)
        self.grid(columnspan=2)
        # Calls the creation of all UI items used.
        self.create_widgets() # Calls the function.

    def create_widgets(self): # Window creation, all GUI related items defined here
        # Banner
        self.banner = tk.Label(self, text="WELCOME TO OUR BANKING SYSTEM") # Welcoming text.
        self.banner.grid(row=0, columnspan=2, padx=5, pady=10) # Location of the welcoming text (at the top of the window).
        # Buttons
        self.loginBtn = tk.Button(self, text="Login with existing account", command=self.loginForm) # Buttom that allows you to log in.
        self.loginBtn.grid(row=1, column=0, padx=5) # Location of the text. In this case it will be in row 1, column 1 (on the left).
        self.createBtn = tk.Button(self, text="Setup an account", command=self.registerForm) # Button that allows you to create a profile.
        self.createBtn.grid(row=1, column=1, padx=5) # Location of the text. In this case it will be in row 1, column 2 (on the right).
        self.quitBtn = tk.Button(self, text="QUIT", fg="red", command=root.destroy) # Quit button that quits the code. Also makes the letters red.
        self.quitBtn.grid(row=2, column=0, columnspan=2, pady=20) # Location of the text. In this case it will be in row 2 (in the middle).
        # User widgets for seting up an account.
        self.usernameLabel = tk.Label(self, text="Username:")
        self.usernameEntry = tk.Entry(self)
        self.passwordLabel = tk.Label(self, text="Password:")
        self.passwordEntry = tk.Entry(self, show="*")
        self.hiddenPhraseLabel = tk.Label(self, text="Hidden phrase:")
        self.hiddenPhraseEntry = tk.Entry(self)
        # User widgets for logging in with an existing one.
        self.doLoginBtn = tk.Button(self, text="Login", command=self.login)
        self.doRegisterBtn = tk.Button(self, text="Register", command=self.register)
        self.warningLabel = tk.Label(self, fg="red")
        self.confirmPhraseLabel = tk.Label(self, fg="blue")
        self.confirmPhraseBtn = tk.Button(self, text="Confirm phrase")

    def login(self): # Function for the loggin phase.
        self.clearWarnings() # Clears any previous warnings (if any)
        username = self.usernameEntry.get() # Gets input value from the username field.
        password = self.passwordEntry.get() # Gets input value from the password field.
        userData = self.findUserData(username) # Checks if the username and password exist
        if userData:
            # Checks if given password matches the stored password.
            if userData[1]==password:
                # Shows the hidden phrase challenge (last step of login).
                self.hiddenPhraseLabel.grid(row=5, column=0, padx=10) # Location of the text.
                self.hiddenPhraseEntry.grid(row=5, column=1, padx=10) # Location of the text.
                self.doLoginBtn.grid_forget()
                # Gets three random numbers or letters from the hidden phrase to complete login.
                challengeIndexes = self.getPhraseChallenge()
                challengeText = "Enter the characters number\n" + str(challengeIndexes[0]+1) # Makes you enter your first out of three number or letter.
                challengeText += ", " + str(challengeIndexes[1]+1) + " and " + str(challengeIndexes[2]+1) # Makes you enter your second out of three number or letter.
                challengeText += " from your hidden phrase.\n (comma separated)" # Makes you enter your third out of three number or letter.
                # Shows the hidden phrase challenge
                self.confirmPhraseLabel["text"]=challengeText # Shows the text
                self.confirmPhraseLabel.grid(row=8, column=0) # Location of the text.
                self.confirmPhraseBtn["command"] = lambda: self.confirmPhrase(userData[2], challengeIndexes)
                self.confirmPhraseBtn.grid(row=8, column=1) # Location of the text.
            else:
                # If the password doesn't match, a message saying that the password is incorrect will pop up.
                self.warningLabel["text"]="The password is incorrect" # The message saying that the password is incorrect.
                self.warningLabel.grid(row=7, columnspan=2) # Location of the text.
        else:
            #If the username is not recognised a message saying that the username was not found will pop up.
            self.warningLabel["text"]="Username not found" # The message saying that the username was not found.
            self.warningLabel.grid(row=7, columnspan=2) # Location of the text.

    def confirmPhrase(self, hiddenPhrase, indexes): # Function for the hidden phrase.
        # Gets the text from user input.
        confirmText = self.hiddenPhraseEntry.get()
        # Constructs how the user input should look using the random indexes.
        challengeText = hiddenPhrase[indexes[0]] + "," + hiddenPhrase[indexes[1]] + "," + hiddenPhrase[indexes[2]]
        if confirmText == challengeText:
            #If the texts match, complete login
            self.cleanWidgets()
            self.warningLabel["text"]="Login Successful!\nWelcome" # This text will appear if the login is completed successfully.
            self.warningLabel.grid(row=9, columnspan=2) # Location of the text.
        else:
            #If the text does not match, show an alert
            self.warningLabel["text"]="Hidden phrase challenge failed" # This text will appear if the login is not completed successfully.
            self.warningLabel.grid(row=9, columnspan=2) # Location of the text.

    # Checks if the user is in the file and returns the data in a list.
    def findUserData(self, username):
        try:
            users = open("users.txt", "r") # Opens the local file in reading mode.
            lines = users.readlines() # Reads all the lines of the text and puts them in a list.
            # Checks each line.
            for line in lines:
                # The user data is separated by ; so it splits the text and checks if the username matches the first field in the line
                data = line.split(";")
                if data[0]==username:
                    # If found, returns the data.
                    return data
            return None
        except FileNotFoundError:
            # If the file does not exist, nothing will register.
            return None

    # Generates 3 random positions from 0 to 9 to ask the user for the hidden phrase challenge.
    def getPhraseChallenge(self):
        # Creates an empty list
        indexes = []
        #3 times loop
        for i in range(1,4): # This line of code will determine how many letters or numbers of the hidden phrase the user must confirm with 1 being the least to 4 being the most.
            # If the number is already in the list, it will generate one that isn't.
            while num in indexes:
                num = random.randint(0,10)
            # Adds  the number to the list.
            indexes.append(num)
        return indexes # Returns the list

    def register(self): # Function for making an account.
        self.clearWarnings() # Clears any previous warnings (if any).
        username = self.usernameEntry.get() # Gets the username input fields.
        password = self.passwordEntry.get() # Gets the password input fields.
        hiddenPhrase = self.hiddenPhraseEntry.get() # Gets the hidden phrase input fields.
        if hiddenPhrase.isalnum() and len(hiddenPhrase) == 10: # Checks if the hidden phrase is 10 characters long and alphanumeric.
            # Checks that the username hasn't already been registered
            if not self.findUserData(username):
                # Opens the local file in append mode (to write new data at the end of the file)
                users = open("users.txt", "a+")
                # Creates the structure of the saved data (username;password;hiddenphrase)
                data = username + ";" + password + ";" + hiddenPhrase + "\n"
                # Writes the data to the file and closes it
                users.write(data)
                users.close()
                # Cleans the form and shows a confirmation message
                self.cleanWidgets()
                self.warningLabel["text"]="Account setup successful"
                self.warningLabel.grid(row=7, columnspan=2) # Location of the text.
            else:
                # Shows an alert for a duplicate username entry
                self.warningLabel["text"]="Username already exists"
                self.warningLabel.grid(row=7, columnspan=2) # Location of the text.
        else:
            # Shows an alert stating the hidden phrase constraints.
            self.warningLabel["text"]="The hidden phrase needs to be alphanumeric\n with no spaces and 10 characters long"
            self.warningLabel.grid(row=7, columnspan=2) # Location of the text.

    def registerForm(self):
        self.cleanWidgets()
        # Displays the username, password and hidden phrase input fields and labels for the register form.
        self.usernameLabel.grid(row=3, column=0, padx=10) # Location of the text.
        self.usernameEntry.grid(row=3, column=1, padx=10) # Location of the text.
        self.passwordLabel.grid(row=4, column=0, padx=10) # Location of the text.
        self.passwordEntry.grid(row=4, column=1, padx=10) # Location of the text.
        self.hiddenPhraseLabel.grid(row=5, column=0, padx=10) # Location of the text.
        self.hiddenPhraseEntry.grid(row=5, column=1, padx=10) # Location of the text.
        # Displays the register button
        self.doRegisterBtn.grid(row=6, columnspan=2, pady=10) # Location of the text.

    def loginForm(self):
        self.cleanWidgets()
        # Displays the username and password inut fields for the login form.
        self.usernameLabel.grid(row=3, column=0, padx=10) # Location of the text.
        self.usernameEntry.grid(row=3, column=1, padx=10) # Location of the text.
        self.passwordLabel.grid(row=4, column=0, padx=10) # Location of the text.
        self.passwordEntry.grid(row=4, column=1, padx=10) # Location of the text.
        # Displays the login button
        self.doLoginBtn.grid(row=6, columnspan=2, pady=10) # Location of the text.

    def cleanWidgets(self):
        # Hides all the login/register related items (if present).
        self.usernameLabel.grid_forget()
        self.usernameEntry.grid_forget()
        self.passwordLabel.grid_forget()
        self.passwordEntry.grid_forget()
        self.hiddenPhraseLabel.grid_forget()
        self.hiddenPhraseEntry.grid_forget()
        self.doRegisterBtn.grid_forget()
        self.doLoginBtn.grid_forget()
        self.warningLabel.grid_forget()
        self.confirmPhraseLabel.grid_forget()
        self.confirmPhraseBtn.grid_forget()

    def clearWarnings(self):
        # Hides all the warning/messages in the UI (if any).
        self.warningLabel.grid_forget()
        self.confirmPhraseLabel.grid_forget()
        self.confirmPhraseBtn.grid_forget

# Creates a root Frame from Tkinter.
root = tk.Tk()
# Sets the frame title.
root.title("WELCOME")
# Creates a new window with the root frame
app = MainWindow(master=root)
# Starts/displays the window.
app.mainloop()