import tkinter as tk
from tkinter import filedialog, messagebox
from typing import Optional, Dict, Any

class DataFileSelectorDialog(tk.Toplevel):
    """
    A modal dialog window for selecting a data file and its type.
    
    This dialog prompts the user to browse for a file and specify whether
    it contains a "Vector" or a "Matrix".
    """

    def __init__(self, master: tk.Tk, initial_dir: str):
        """
        Initializes the dialog.

        Args:
            master: The parent tk.Tk window.
            initial_dir: The initial directory for the file browser.
        """
        super().__init__(master)
        self.title("Select Data File")
        self.transient(master)  # Keep dialog on top of the main window
        self.grab_set()         # Make the dialog modal

        # --- Internal state ---
        self._file_path = tk.StringVar()
        self._data_type = tk.StringVar(value="Vector") # Default selection
        self._initial_dir = initial_dir
        self.result: Optional[Dict[str, Any]] = None

        self._create_widgets()
        self._center_window()

        # This call blocks until the window is destroyed
        self.wait_window(self)

    def _create_widgets(self) -> None:
        """Creates and arranges the widgets in the dialog."""
        main_frame = tk.Frame(self, padx=15, pady=15)
        main_frame.pack(expand=True, fill=tk.BOTH)

        # --- File Path Selection ---
        file_frame = tk.Frame(main_frame)
        file_frame.pack(fill=tk.X, pady=(0, 10))
        
        lbl_file = tk.Label(file_frame, text="File Path:")
        lbl_file.pack(side=tk.LEFT, padx=(0, 5))
        
        entry_file = tk.Entry(file_frame, textvariable=self._file_path, width=40)
        entry_file.pack(side=tk.LEFT, fill=tk.X, expand=True)
        
        btn_browse = tk.Button(file_frame, text="Browse...", command=self._browse_file)
        btn_browse.pack(side=tk.LEFT, padx=(5, 0))

        # --- Data Type Selection ---
        type_frame = tk.LabelFrame(main_frame, text="Data Type", padx=10, pady=10)
        type_frame.pack(fill=tk.X, pady=5)
        
        rb_vector = tk.Radiobutton(
            type_frame, text="Vector (Single Column)", variable=self._data_type, value="Vector"
        )
        rb_vector.pack(anchor=tk.W)
        
        rb_matrix = tk.Radiobutton(
            type_frame, text="Matrix (Header + Data)", variable=self._data_type, value="Matrix"
        )
        rb_matrix.pack(anchor=tk.W)

        # --- Action Buttons ---
        button_frame = tk.Frame(main_frame)
        button_frame.pack(fill=tk.X, pady=(15, 0))
        
        btn_load = tk.Button(button_frame, text="Load", command=self._load_data)
        btn_load.pack(side=tk.RIGHT)
        
        btn_cancel = tk.Button(button_frame, text="Cancel", command=self._cancel)
        btn_cancel.pack(side=tk.RIGHT, padx=(0, 10))

    def _center_window(self) -> None:
        """Centers the dialog on the screen."""
        self.update_idletasks() # Ensure window size is calculated
        
        # Get screen and window dimensions
        screen_width = self.winfo_screenwidth()
        screen_height = self.winfo_screenheight()
        window_width = self.winfo_width()
        window_height = self.winfo_height()

        # Calculate position
        pos_x = (screen_width // 2) - (window_width // 2)
        pos_y = (screen_height // 2) - (window_height // 2)

        self.geometry(f"{window_width}x{window_height}+{pos_x}+{pos_y}")
        self.resizable(False, False)

    def _browse_file(self) -> None:
        """Opens the system's file browser dialog."""
        filename = filedialog.askopenfilename(
            initialdir=self._initial_dir,
            title="Select a CSV data file",
            filetypes=(("CSV files", "*.csv"), ("All files", "*.*"))
        )
        if filename:
            self._file_path.set(filename)

    def _load_data(self) -> None:
        """Validates the inputs and sets the result."""
        file_path = self._file_path.get()
        if not file_path:
            messagebox.showwarning("Input Missing", "Please select a file path.", parent=self)
            return

        self.result = {
            "file_path": file_path, 
            "data_type": self._data_type.get()
        }
        self.destroy()

    def _cancel(self) -> None:
        """Closes the dialog without setting a result."""
        self.result = None
        self.destroy()