"""
Login Dialog - Modal dialog for user authentication
"""
import tkinter as tk
from tkinter import ttk, messagebox
from typing import Optional, Tuple


class LoginDialog:
    """
    Modal login dialog that captures user credentials

    Usage:
        login_dialog = LoginDialog(parent)
        credentials = login_dialog.get_credentials()
        if credentials:
            username, password = credentials
            # Proceed with authentication
    """

    def __init__(self, parent):
        """
        Initialize the login dialog

        Args:
            parent: The parent Tkinter window
        """
        self.parent = parent
        self.result = None  # Will hold (username, password) or None
        self.dialog = None

        # Create dialog as modal
        self._create_dialog()
        self.parent.wait_window(self.dialog)

    def _create_dialog(self):
        """Create the login dialog UI"""
        self.dialog = tk.Toplevel(self.parent)
        self.dialog.title("ERP 自动化工具 - 登录")
        self.dialog.geometry("400x250")
        self.dialog.resizable(False, False)

        # Center the dialog on parent
        self.dialog.transient(self.parent)
        self.dialog.grab_set()

        # Calculate position to center on parent
        self.parent.update_idletasks()
        parent_x = self.parent.winfo_x()
        parent_y = self.parent.winfo_y()
        parent_width = self.parent.winfo_width()
        parent_height = self.parent.winfo_height()

        dialog_width = 400
        dialog_height = 250
        x = parent_x + (parent_width - dialog_width) // 2
        y = parent_y + (parent_height - dialog_height) // 2
        self.dialog.geometry(f"{dialog_width}x{dialog_height}+{x}+{y}")

        # Create UI elements
        self._create_widgets()

        # Bind Enter key to login button
        self.dialog.bind('<Return>', lambda e: self._on_login())

        # Focus on username entry
        self.username_entry.focus_set()

    def _create_widgets(self):
        """Create the dialog widgets"""
        # Main frame with padding
        main_frame = ttk.Frame(self.dialog, padding="20")
        main_frame.pack(fill=tk.BOTH, expand=True)

        # Title
        title_label = ttk.Label(
            main_frame,
            text="请登录",
            font=('', 16, 'bold')
        )
        title_label.pack(pady=(0, 20))

        # Username field
        username_frame = ttk.Frame(main_frame)
        username_frame.pack(fill=tk.X, pady=5)

        ttk.Label(username_frame, text="用户名:", width=10).pack(side=tk.LEFT)
        self.username_entry = ttk.Entry(username_frame)
        self.username_entry.pack(side=tk.LEFT, fill=tk.X, expand=True)

        # Password field
        password_frame = ttk.Frame(main_frame)
        password_frame.pack(fill=tk.X, pady=5)

        ttk.Label(password_frame, text="密码:", width=10).pack(side=tk.LEFT)
        self.password_entry = ttk.Entry(password_frame, show="*")
        self.password_entry.pack(side=tk.LEFT, fill=tk.X, expand=True)

        # Buttons frame
        button_frame = ttk.Frame(main_frame)
        button_frame.pack(pady=(20, 0))

        # Login button
        login_btn = ttk.Button(
            button_frame,
            text="登录",
            command=self._on_login,
            width=10
        )
        login_btn.pack(side=tk.LEFT, padx=5)

        # Cancel button
        cancel_btn = ttk.Button(
            button_frame,
            text="取消",
            command=self._on_cancel,
            width=10
        )
        cancel_btn.pack(side=tk.LEFT, padx=5)

        # Version info
        version_label = ttk.Label(
            main_frame,
            text="v1.0",
            font=('', 8),
            foreground='gray'
        )
        version_label.pack(side=tk.BOTTOM, pady=10)

    def _on_login(self):
        """Handle login button click"""
        username = self.username_entry.get().strip()
        password = self.password_entry.get().strip()

        if not username:
            messagebox.showwarning("输入错误", "请输入用户名")
            self.username_entry.focus_set()
            return

        if not password:
            messagebox.showwarning("输入错误", "请输入密码")
            self.password_entry.focus_set()
            return

        # Return credentials for validation
        self.result = (username, password)
        self.dialog.destroy()

    def _on_cancel(self):
        """Handle cancel button click"""
        self.result = None
        self.dialog.destroy()

    def get_credentials(self) -> Optional[Tuple[str, str]]:
        """
        Get the entered credentials

        Returns:
            Tuple of (username, password) if user clicked Login,
            None if user clicked Cancel or closed the dialog
        """
        return self.result