import tkinter as tk
from tkinter import messagebox

def on_click(event):
    text = event.widget.cget("text")
    if text == "=":
        calculate_result()
    elif text == "C":
         clear_entry()
    else:
        entry_var.set(entry_var.get() + text)

def calculate_result(event=None):
    try:
        result = eval(str(entry.get()))
        result = round(float(result), 2)  # Format to 2 decimal places
        entry_var.set(f"{result:.2f}")
    except Exception as e:
        messagebox.showerror("Error", f"Invalid Expression: {e}")

def clear_entry(event=None):
    entry_var.set("")
    return "break"  # Prevents default behavior of inserting 'c' or 'C'

# Main window
root = tk.Tk()
root.title("Bobs Calc")
root.geometry("215x250")

entry_var = tk.StringVar()
entry = tk.Entry(root, textvariable=entry_var, font="Arial 20")
entry.pack(fill=tk.BOTH, ipadx=8, pady=10, padx=10)
entry.focus_set()  # Set focus to the entry widget
entry.bind("<Return>", calculate_result)  # Bind Enter key to calculate_result
entry.bind("<KP_Enter>", calculate_result)  # Bind NumPad Enter key
entry.bind("<c>", clear_entry)  # Bind 'c' key to clear_entry
entry.bind("<C>", clear_entry)  # Bind 'C' key to clear_entry

button_frame = tk.Frame(root)
button_frame.pack()

buttons = [
    ["7", "8", "9", "/"],
    ["4", "5", "6", "*"],
    ["1", "2", "3", "-"],
    ["C", "0", "=", "+"]
]

for row in buttons:
    row_frame = tk.Frame(button_frame)
    row_frame.pack(expand=True, fill="both")
    for btn_text in row:
        btn = tk.Button(row_frame, text=btn_text, font="Arial 18", relief=tk.RAISED)
        btn.pack(side=tk.LEFT, expand=True, fill="both")
        btn.bind("<Button-1>", on_click)

root.mainloop()