import tkinter as tk
from tkinter import scrolledtext, messagebox, filedialog, ttk
import markdown
from fpdf import FPDF
from typing import Optional

# It's better to manage this path from the main application later,
# but for now, we keep it simple.
HELP_MARKDOWN_FILE = "help.md"

class HelpWindow(tk.Toplevel):
    """
    A Toplevel window that displays help content from a Markdown file.
    
    The window provides options to export the content to HTML or PDF.
    """

    def __init__(self, master: tk.Tk):
        """
        Initializes the help window.

        Args:
            master: The parent tk.Tk window.
        """
        super().__init__(master)
        self.title("Radalyze - Help")
        self.geometry("800x600")

        self._help_content: Optional[str] = None

        self._create_widgets()
        self._load_and_display_help()
        self._center_window()

    def _create_widgets(self) -> None:
        """Creates and arranges the widgets in the window."""
        # --- Toolbar ---
        toolbar_frame = ttk.Frame(self)
        toolbar_frame.pack(side=tk.TOP, fill=tk.X, padx=5, pady=5)
        
        export_html_button = ttk.Button(
            toolbar_frame, text="Export to HTML", command=self._export_to_html
        )
        export_html_button.pack(side=tk.LEFT, padx=5)

        export_pdf_button = ttk.Button(
            toolbar_frame, text="Export to PDF", command=self._export_to_pdf
        )
        export_pdf_button.pack(side=tk.LEFT, padx=5)

        # --- Text Area ---
        self._text_widget = scrolledtext.ScrolledText(self, wrap=tk.WORD, padx=5)
        self._text_widget.pack(expand=True, fill="both")
        self._text_widget.config(state=tk.DISABLED)  # Make it read-only

    def _load_and_display_help(self) -> None:
        """Loads the content from the Markdown file and displays it."""
        try:
            with open(HELP_MARKDOWN_FILE, "r", encoding="utf-8") as f:
                self._help_content = f.read()
            
            self._text_widget.config(state=tk.NORMAL)
            self._text_widget.delete("1.0", tk.END)
            self._text_widget.insert(tk.INSERT, self._help_content)
            self._text_widget.config(state=tk.DISABLED)
            
        except FileNotFoundError:
            self._show_error(f"Help file not found: '{HELP_MARKDOWN_FILE}'")
        except Exception as e:
            self._show_error(f"An error occurred while reading the help file: {e}")

    def _export_to_html(self) -> None:
        """Exports the help content to an HTML file."""
        if not self._help_content:
            self._show_error("Help content is not loaded. Cannot export.")
            return
            
        save_path = filedialog.asksaveasfilename(
            title="Save Help as HTML",
            defaultextension=".html",
            filetypes=[("HTML files", "*.html"), ("All files", "*.*")]
        )
        if not save_path:
            return # User cancelled

        try:
            html_content = markdown.markdown(self._help_content)
            with open(save_path, "w", encoding="utf-8") as f:
                f.write(html_content)
            messagebox.showinfo(
                "Export Successful", f"Help content successfully saved to:\n{save_path}", parent=self
            )
        except Exception as e:
            self._show_error(f"Failed to export to HTML: {e}")

    def _export_to_pdf(self) -> None:
        """Exports the help content to a PDF file."""
        if not self._help_content:
            self._show_error("Help content is not loaded. Cannot export.")
            return
    
        save_path = filedialog.asksaveasfilename(
            title="Save Help as PDF",
            defaultextension=".pdf",
            filetypes=[("PDF files", "*.pdf"), ("All files", "*.*")]
        )
        if not save_path:
            return # User cancelled
            
        try:
            pdf = self._create_pdf_from_markdown(self._help_content)
            pdf.output(save_path)
            messagebox.showinfo(
                "Export Successful", f"Help content successfully saved to:\n{save_path}", parent=self
            )
        except Exception as e:
            self._show_error(f"Failed to export to PDF: {e}")

    @staticmethod
    def _create_pdf_from_markdown(markdown_text: str) -> FPDF:
        """
        Creates an FPDF object from a Markdown string.
        
        This is a basic parser and handles headings (#) and list items (*).
        """
        pdf = FPDF()
        pdf.add_page()
        pdf.set_font("Arial", size=12)

        for line in markdown_text.split('\n'):
            line = line.strip()
            if line.startswith('#'):
                level = line.find(' ')
                text = line[level:].strip()
                size = max(12, 20 - 2 * level)
                pdf.set_font("Arial", 'B', size=size)
                pdf.multi_cell(0, 10, text, 0, 'L')
                pdf.set_font("Arial", size=12)
            elif line.startswith('*'):
                text = line[1:].strip()
                pdf.set_x(15)
                pdf.multi_cell(0, 5, f"• {text}")
                pdf.set_x(10)
            else:
                pdf.multi_cell(0, 5, line)
            
            if not line: # Add a small space for empty lines
                pdf.ln(5)
                
        return pdf

    def _center_window(self) -> None:
        """Centers the window on the screen."""
        self.update_idletasks()
        screen_width = self.winfo_screenwidth()
        screen_height = self.winfo_screenheight()
        window_width = self.winfo_width()
        window_height = self.winfo_height()
        pos_x = (screen_width // 2) - (window_width // 2)
        pos_y = (screen_height // 2) - (window_height // 2)
        self.geometry(f"+{pos_x}+{pos_y}")

    def _show_error(self, message: str) -> None:
        """Convenience method to show an error message box."""
        messagebox.showerror("Help Window Error", message, parent=self)