import os
import logging
import asyncio
from pathlib import Path # For handling file paths robustly

from hydrogram import Client, filters
from hydrogram.types import Message
from hydrogram.errors import SessionPasswordNeeded, PhoneCodeInvalid, PhoneNumberInvalid, PasswordHashInvalid

# --- Configuration ---
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)

# Retrieve Session String from Hugging Face secrets
# MUST be set in your Hugging Face Space/Repo secrets settings as SESSION_STRING
SESSION_STRING = os.environ.get('SESSION_STRING')

# Path for storing the template content
DATA_DIR = Path("data")
TEMPLATE_FILE_PATH = DATA_DIR / "template_content.txt"

# Global variable to hold the loaded template content
current_template_content = None

# --- Helper Functions for Template Management ---
def ensure_data_dir_exists():
    """Ensures the data directory exists."""
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    logger.info(f"Data directory '{DATA_DIR}' ensured.")

async def load_template_from_file():
    """Loads template content from the persistent file."""
    global current_template_content
    ensure_data_dir_exists()
    if TEMPLATE_FILE_PATH.exists():
        try:
            with open(TEMPLATE_FILE_PATH, "r", encoding="utf-8") as f:
                current_template_content = f.read()
            logger.info(f"Template loaded successfully from {TEMPLATE_FILE_PATH}")
        except Exception as e:
            logger.error(f"Error loading template from {TEMPLATE_FILE_PATH}: {e}")
            current_template_content = None # Or a default error message
    else:
        logger.info(f"Template file {TEMPLATE_FILE_PATH} not found. No template loaded.")
        current_template_content = None

async def save_template_to_file(content: str):
    """Saves template content to the persistent file."""
    global current_template_content
    ensure_data_dir_exists()
    try:
        with open(TEMPLATE_FILE_PATH, "w", encoding="utf-8") as f:
            f.write(content)
        current_template_content = content
        logger.info(f"Template saved successfully to {TEMPLATE_FILE_PATH}")
        return True
    except Exception as e:
        logger.error(f"Error saving template to {TEMPLATE_FILE_PATH}: {e}")
        return False

# --- Initialization ---
if not SESSION_STRING:
    logger.error("SESSION_STRING environment variable not found. Please set it in Hugging Face secrets.")
    exit(1)

# Initialize the Hydrogram Client using the session string
# The name "user_session" is arbitrary when using a session_string,
# as the session is loaded directly from the string into memory.
logger.info("Initializing Hydrogram Client with session string...")
try:
    app = Client(
        name="user_session", # Name is a placeholder when session_string is used
        session_string=SESSION_STRING,
        # workdir="." # workdir is not strictly necessary for session file when session_string is used,
                      # but good if other client files are ever created.
                      # The template file path is handled separately.
    )
    logger.info("Hydrogram Client initialized.")
except Exception as e:
    logger.error(f"Failed to initialize Hydrogram Client: {type(e).__name__} - {e}")
    exit(1)


# --- Bot Event Handlers ---
@app.on_message(filters.command("start") & filters.private)
async def start_handler(client: Client, message: Message):
    """Handler for the /start command."""
    sender_name = message.from_user.first_name if message.from_user else "User"
    logger.info(f"Received /start command from {sender_name} (ID: {message.from_user.id})")

    welcome_text = f"Hello {sender_name}!\n"
    welcome_text += "I am ready to manage your template.\n"
    welcome_text += "Use /settemplate <your text> to set a new template.\n"
    welcome_text += "Use /gettemplate to view the current template."

    if current_template_content:
        welcome_text += "\n\nA template is currently set."
    else:
        welcome_text += "\n\nNo template is currently set."

    await message.reply_text(welcome_text)

@app.on_message(filters.command("settemplate") & filters.private)
async def set_template_handler(client: Client, message: Message):
    """Handler for the /settemplate command."""
    user_id = message.from_user.id
    logger.info(f"Received /settemplate command from User ID: {user_id}")

    if len(message.command) > 1:
        new_template = message.text.split(" ", 1)[1].strip() # Get content after "/settemplate "
        if new_template:
            if await save_template_to_file(new_template):
                await message.reply_text("✅ Template updated successfully!")
            else:
                await message.reply_text("❌ Failed to save the template. Please check the logs.")
        else:
            await message.reply_text("⚠️ Please provide content for the template. Usage: `/settemplate Your template text here`")
    else:
        await message.reply_text("ℹ️ Usage: `/settemplate Your template text here`")

@app.on_message(filters.command("gettemplate") & filters.private)
async def get_template_handler(client: Client, message: Message):
    """Handler for the /gettemplate command."""
    user_id = message.from_user.id
    logger.info(f"Received /gettemplate command from User ID: {user_id}")

    if current_template_content:
        response_text = f"📜 **Current Template:**\n\n{current_template_content}"
    else:
        response_text = "ℹ️ No template is currently set. Use `/settemplate <your text>` to set one."
    await message.reply_text(response_text)

# --- Main Execution ---
async def main():
    """Main function to load initial data and start the bot."""
    await load_template_from_file() # Load any existing template on startup

    logger.info("Attempting to connect and start the bot...")
    try:
        await app.start()
        me = await app.get_me()
        logger.info(f"Bot started successfully as {me.first_name} (ID: {me.id})")
        logger.info("Listening for messages...")
        await asyncio.Event().wait()  # Keep the bot running indefinitely
    except (SessionPasswordNeeded, PhoneCodeInvalid, PhoneNumberInvalid, PasswordHashInvalid) as e:
        logger.error(f"Authorization error: {type(e).__name__} - {e}. Your SESSION_STRING might be invalid or expired.")
    except ConnectionError as e:
        logger.error(f"Connection error: {e}. Check your network or Telegram's status.")
    except Exception as e:
        logger.error(f"An unexpected error occurred during bot startup or runtime: {type(e).__name__} - {e}", exc_info=True)
    finally:
        if app.is_connected:
            logger.info("Stopping the bot...")
            await app.stop()
            logger.info("Bot stopped.")
        else:
            logger.info("Bot was not connected or already stopped.")

if __name__ == '__main__':
    # Run the main function in the asyncio event loop
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        logger.info("Bot manually interrupted. Exiting...")
    except Exception as e:
        logger.critical(f"Critical error in main execution block: {e}", exc_info=True)