from tkinter import *

# Trial - Dynamic Label Updates
# Purpose: Learn how a single label can act as both an error display
#          AND a result display, by changing its text, colour and font.
#          This is how the answer_error label works in the Distance Converter.

class LabelTrial:

    def __init__(self):

        self.frame = Frame(padx=20, pady=20)
        self.frame.grid()

        Label(self.frame,
              text="Dynamic Label Trial",
              font=("Arial", "16", "bold")).grid(row=0)

        Label(self.frame,
              text="One label handles errors AND results - watch it change.",
              font=("Arial", "11"), fg="#666666",
              wraplength=300).grid(row=1, pady=5)

        self.entry = Entry(self.frame, font=("Arial", "14"), width=20)
        self.entry.grid(row=2, pady=10)

        # This is the shared answer/error label
        # Starts red (error state)
        self.answer_error = Label(self.frame,
                                  text="Please enter a number",
                                  font=("Arial", "13", "bold"),
                                  fg="#9C0000")
        self.answer_error.grid(row=3, pady=5)

        # Buttons that trigger different states
        btn_frame = Frame(self.frame)
        btn_frame.grid(row=4, pady=10)

        Button(btn_frame,
               text="Simulate Result",
               font=("Arial", "11", "bold"),
               bg="#004C99", fg="#FFFFFF", width=14,
               command=self.show_result).grid(row=0, column=0, padx=5)

        Button(btn_frame,
               text="Simulate Error",
               font=("Arial", "11", "bold"),
               bg="#9C0000", fg="#FFFFFF", width=14,
               command=self.show_error).grid(row=0, column=1, padx=5)

        Button(btn_frame,
               text="Simulate Success",
               font=("Arial", "11", "bold"),
               bg="#009900", fg="#FFFFFF", width=14,
               command=self.show_success).grid(row=1, column=0,
                                               padx=5, pady=5)

        Button(btn_frame,
               text="Reset",
               font=("Arial", "11", "bold"),
               bg="#666666", fg="#FFFFFF", width=14,
               command=self.reset).grid(row=1, column=1, padx=5, pady=5)

    def show_result(self):
        """Mimic a conversion result - blue, normal size"""
        text = self.entry.get() or "1.5"
        self.answer_error.config(
            text=f"{text} km = {float(text) * 1000 if text.replace('.','').isdigit() else '?'} m",
            fg="#004C99",
            font=("Arial", "13", "bold")
        )
        self.entry.config(bg="#FFFFFF")

    def show_error(self):
        """Mimic a validation error - red, entry goes pink"""
        self.answer_error.config(
            text="Please enter a valid positive number",
            fg="#9C0000",
            font=("Arial", "13", "bold")
        )
        self.entry.config(bg="#F4CCCC")
        self.entry.delete(0, END)

    def show_success(self):
        """Mimic an export success - green, larger font"""
        self.answer_error.config(
            text="Export successful! File saved.",
            fg="#009900",
            font=("Arial", "13", "bold")
        )
        self.entry.config(bg="#FFFFFF")

    def reset(self):
        """Return to the initial error state"""
        self.answer_error.config(
            text="Please enter a number",
            fg="#9C0000",
            font=("Arial", "13", "bold")
        )
        self.entry.config(bg="#FFFFFF")
        self.entry.delete(0, END)


# main routine
if __name__ == "__main__":
    root = Tk()
    root.title("Dynamic Label Trial")
    LabelTrial()
    root.mainloop()