from tkinter import *


class Calculator:

    def __init__(self, master):
        print("test")
        master.title("Random Generator")
        master.geometry("420x210")
        #Top Frame
        self.random_ch = ''
        self.entered_number = 0
        first_frame = Frame(root, bg='gainsboro', width=450, height=50, pady=3)
        first_frame.grid(row=0, sticky="ew")

        self.gen_btn = Button(first_frame, text="Generate", width="8", anchor="w",
                              command=lambda: self.update("add"))
        self.gen_btn.grid(row=2, column=1)

        self.input_reset_btn = Button(first_frame, text="Reset", width="6", anchor="w",
                                      command=lambda: self.update("reset"))
        self.input_reset_btn.grid(row=2, column=2)

        vcmd = (master.register(self.on_validate))
        self.input_box = Entry(first_frame, validate="key", width=3, validatecommand=(vcmd, "%P"))
        self.input_box.grid(row=1, column=1)

        self.input_length = Label(first_frame, text="Enter a number", bg='gainsboro')
        self.input_length.grid(row=1, column=0)

        #Second Frame
        second_frame = Frame(root, width=450, height=50, pady=3)
        second_frame.grid(row=1, sticky="ew")

        self.text_display = Text(second_frame, height=1, width=30)
        self.text_display.grid(row=3, column=0)

        #Third Frame
        third_frame = Frame(root, width=450, bg='gainsboro', height=50, pady=3)
        third_frame.grid(row=2, sticky="ew")

        self.quit_btn = Button(third_frame, text="Quit", width="8", command=lambda root=root:quit(root))
        self.quit_btn.grid(row=1, column=2)

        self.copy_btn = Button(third_frame, text="Copy", width="8", command=lambda root=root:self.copy_to_clipboard())
        self.copy_btn.grid(row=1, column=3)

    def on_validate(self, new_text):
        if not new_text:
            self.entered_number = 0

        try:
            self.entered_number = int(new_text)
            return True
        except ValueError:
            return False

    def update(self, method):
        import random
        import string
        if method == "add":
            self.text_display.delete('1.0', END)
            self.random_ch = ''.join([random.choice(string.ascii_letters + string.digits + string.punctuation)\
                                for n in range(self.entered_number)])
        elif method == "reset":

            self.random_ch = ''
            self.text_display.delete('1.0', END)
            self.input_box.delete(0, END)
        else:
            self.random_ch = ''
        self.text_display.insert(END, self.random_ch)

    def copy_to_clipboard(self):
        root.clipboard_clear()
        text = self.random_ch
        root.clipboard_append(text)


if __name__ == "__main__":
    root = Tk()
    my_gui = Calculator(root)
    root.mainloop()