"""Telegram channel implementation using python-telegram-bot."""

from __future__ import annotations

import asyncio
import re
from loguru import logger
from telegram import BotCommand, Update
from telegram.ext import Application, CommandHandler, MessageHandler, filters, ContextTypes
from telegram.request import HTTPXRequest

from miu_bot.bus.events import OutboundMessage
from miu_bot.bus.queue import MessageBus
from miu_bot.channels.base import BaseChannel
from miu_bot.config.schema import TelegramConfig


def _markdown_to_telegram_html(text: str) -> str:
    """
    Convert markdown to Telegram-safe HTML.
    """
    if not text:
        return ""
    
    # 1. Extract and protect code blocks (preserve content from other processing)
    code_blocks: list[str] = []
    def save_code_block(m: re.Match) -> str:
        code_blocks.append(m.group(1))
        return f"\x00CB{len(code_blocks) - 1}\x00"
    
    text = re.sub(r'```[\w]*\n?([\s\S]*?)```', save_code_block, text)
    
    # 2. Extract and protect inline code
    inline_codes: list[str] = []
    def save_inline_code(m: re.Match) -> str:
        inline_codes.append(m.group(1))
        return f"\x00IC{len(inline_codes) - 1}\x00"
    
    text = re.sub(r'`([^`]+)`', save_inline_code, text)
    
    # 3. Headers # Title -> just the title text
    text = re.sub(r'^#{1,6}\s+(.+)$', r'\1', text, flags=re.MULTILINE)
    
    # 4. Blockquotes > text -> just the text (before HTML escaping)
    text = re.sub(r'^>\s*(.*)$', r'\1', text, flags=re.MULTILINE)
    
    # 5. Escape HTML special characters
    text = text.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
    
    # 6. Links [text](url) - must be before bold/italic to handle nested cases
    text = re.sub(r'\[([^\]]+)\]\(([^)]+)\)', r'<a href="\2">\1</a>', text)
    
    # 7. Bold **text** or __text__
    text = re.sub(r'\*\*(.+?)\*\*', r'<b>\1</b>', text)
    text = re.sub(r'__(.+?)__', r'<b>\1</b>', text)
    
    # 8. Italic _text_ (avoid matching inside words like some_var_name)
    text = re.sub(r'(?<![a-zA-Z0-9])_([^_]+)_(?![a-zA-Z0-9])', r'<i>\1</i>', text)
    
    # 9. Strikethrough ~~text~~
    text = re.sub(r'~~(.+?)~~', r'<s>\1</s>', text)
    
    # 10. Bullet lists - item -> • item
    text = re.sub(r'^[-*]\s+', '• ', text, flags=re.MULTILINE)
    
    # 11. Restore inline code with HTML tags
    for i, code in enumerate(inline_codes):
        # Escape HTML in code content
        escaped = code.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
        text = text.replace(f"\x00IC{i}\x00", f"<code>{escaped}</code>")
    
    # 12. Restore code blocks with HTML tags
    for i, code in enumerate(code_blocks):
        # Escape HTML in code content
        escaped = code.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
        text = text.replace(f"\x00CB{i}\x00", f"<pre><code>{escaped}</code></pre>")
    
    return text


class TelegramChannel(BaseChannel):
    """
    Telegram channel using long polling.
    
    Simple and reliable - no webhook/public IP needed.
    """
    
    name = "telegram"
    
    # Commands registered with Telegram's command menu
    BOT_COMMANDS = [
        BotCommand("start", "Start the bot"),
        BotCommand("new", "Start a new conversation"),
        BotCommand("help", "Show available commands"),
    ]
    
    def __init__(
        self,
        config: TelegramConfig,
        bus: MessageBus,
        groq_api_key: str = "",
    ):
        super().__init__(config, bus)
        self.config: TelegramConfig = config
        self.groq_api_key = groq_api_key
        self._app: Application | None = None
        self._chat_ids: dict[str, int] = {}  # Map sender_id to chat_id for replies
        self._typing_tasks: dict[str, asyncio.Task] = {}  # chat_id -> typing loop task
    
    async def start(self) -> None:
        """Start the Telegram bot with long polling."""
        if not self.config.token:
            logger.error("Telegram bot token not configured")
            return
        
        self._running = True
        
        # Build the application with larger connection pool to avoid pool-timeout on long runs
        req = HTTPXRequest(connection_pool_size=16, pool_timeout=5.0, connect_timeout=30.0, read_timeout=30.0)
        builder = Application.builder().token(self.config.token).request(req).get_updates_request(req)
        if self.config.proxy:
            builder = builder.proxy(self.config.proxy).get_updates_proxy(self.config.proxy)
        self._app = builder.build()
        self._app.add_error_handler(self._on_error)
        
        # Add command handlers
        self._app.add_handler(CommandHandler("start", self._on_start))
        self._app.add_handler(CommandHandler("new", self._forward_command))
        self._app.add_handler(CommandHandler("help", self._forward_command))
        
        # Add message handler for text, photos, voice, documents
        self._app.add_handler(
            MessageHandler(
                (filters.TEXT | filters.PHOTO | filters.VOICE | filters.AUDIO | filters.Document.ALL) 
                & ~filters.COMMAND, 
                self._on_message
            )
        )
        
        logger.info("Starting Telegram bot (polling mode)...")
        
        # Initialize and start polling
        await self._app.initialize()
        await self._app.start()
        
        # Get bot info and register command menu
        bot_info = await self._app.bot.get_me()
        logger.info(f"Telegram bot @{bot_info.username} connected")
        
        try:
            await self._app.bot.set_my_commands(self.BOT_COMMANDS)
            logger.debug("Telegram bot commands registered")
        except Exception as e:
            logger.warning(f"Failed to register bot commands: {e}")
        
        # Start polling (this runs until stopped)
        await self._app.updater.start_polling(
            allowed_updates=["message"],
            drop_pending_updates=True  # Ignore old messages on startup
        )
        
        # Keep running until stopped
        while self._running:
            await asyncio.sleep(1)
    
    async def stop(self) -> None:
        """Stop the Telegram bot."""
        self._running = False
        
        # Cancel all typing indicators
        for chat_id in list(self._typing_tasks):
            self._stop_typing(chat_id)
        
        if self._app:
            logger.info("Stopping Telegram bot...")
            await self._app.updater.stop()
            await self._app.stop()
            await self._app.shutdown()
            self._app = None
    
    async def send(self, msg: OutboundMessage) -> None:
        """Send a message through Telegram."""
        if not self._app:
            logger.warning("Telegram bot not running")
            return
        
        # Stop typing indicator for this chat
        self._stop_typing(msg.chat_id)
        
        try:
            chat_id = int(msg.chat_id)
        except ValueError:
            logger.error(f"Invalid chat_id: {msg.chat_id}")
            return

        # Telegram max message length is 4096 characters; split if needed
        max_len = 4096
        content = msg.content
        chunks = [content[i:i + max_len] for i in range(0, len(content), max_len)]

        for chunk in chunks:
            try:
                html_content = _markdown_to_telegram_html(chunk)
                await self._app.bot.send_message(
                    chat_id=chat_id,
                    text=html_content,
                    parse_mode="HTML"
                )
            except Exception:
                # Fallback to plain text if HTML parsing fails
                try:
                    await self._app.bot.send_message(
                        chat_id=chat_id,
                        text=chunk
                    )
                except Exception as e2:
                    logger.error(f"Error sending Telegram message: {e2}")
    
    async def _on_start(self, update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
        """Handle /start command."""
        if not update.message or not update.effective_user:
            return
        
        user = update.effective_user
        await update.message.reply_text(
            f"👋 Hi {user.first_name}! I'm miu_bot.\n\n"
            "Send me a message and I'll respond!\n"
            "Type /help to see available commands."
        )
    
    async def _forward_command(self, update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
        """Forward slash commands to the bus for unified handling in AgentLoop."""
        if not update.message or not update.effective_user:
            return
        await self._handle_message(
            sender_id=str(update.effective_user.id),
            chat_id=str(update.message.chat_id),
            content=update.message.text,
        )
    
    async def _on_message(self, update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
        """Handle incoming messages (text, photos, voice, documents)."""
        if not update.message or not update.effective_user:
            return
        
        message = update.message
        user = update.effective_user
        chat_id = message.chat_id
        
        # Use stable numeric ID, but keep username for allowlist compatibility
        sender_id = str(user.id)
        if user.username:
            sender_id = f"{sender_id}|{user.username}"
        
        # Store chat_id for replies
        self._chat_ids[sender_id] = chat_id
        
        # Build content from text and/or media
        content_parts = []
        media_paths = []
        
        # Text content
        if message.text:
            content_parts.append(message.text)
        if message.caption:
            content_parts.append(message.caption)
        
        # Handle media files
        media_file = None
        media_type = None
        
        if message.photo:
            media_file = message.photo[-1]  # Largest photo
            media_type = "image"
        elif message.voice:
            media_file = message.voice
            media_type = "voice"
        elif message.audio:
            media_file = message.audio
            media_type = "audio"
        elif message.document:
            media_file = message.document
            media_type = "file"
        
        # Download media if present
        if media_file and self._app:
            try:
                file = await self._app.bot.get_file(media_file.file_id)
                ext = self._get_extension(media_type, getattr(media_file, 'mime_type', None))
                
                # Save to workspace/media/
                from pathlib import Path
                media_dir = Path.home() / ".miu-bot" / "media"
                media_dir.mkdir(parents=True, exist_ok=True)
                
                file_path = media_dir / f"{media_file.file_id[:16]}{ext}"
                await file.download_to_drive(str(file_path))
                
                media_paths.append(str(file_path))
                
                # Handle voice transcription
                if media_type == "voice" or media_type == "audio":
                    from miu_bot.providers.transcription import GroqTranscriptionProvider
                    transcriber = GroqTranscriptionProvider(api_key=self.groq_api_key)
                    transcription = await transcriber.transcribe(file_path)
                    if transcription:
                        logger.info(f"Transcribed {media_type}: {transcription[:50]}...")
                        content_parts.append(f"[transcription: {transcription}]")
                    else:
                        content_parts.append(f"[{media_type}: {file_path}]")
                else:
                    content_parts.append(f"[{media_type}: {file_path}]")
                    
                logger.debug(f"Downloaded {media_type} to {file_path}")
            except Exception as e:
                logger.error(f"Failed to download media: {e}")
                content_parts.append(f"[{media_type}: download failed]")
        
        content = "\n".join(content_parts) if content_parts else "[empty message]"
        
        logger.debug(f"Telegram message from {sender_id}: {content[:50]}...")
        
        str_chat_id = str(chat_id)
        
        # Start typing indicator before processing
        self._start_typing(str_chat_id)
        
        # Forward to the message bus
        await self._handle_message(
            sender_id=sender_id,
            chat_id=str_chat_id,
            content=content,
            media=media_paths,
            metadata={
                "message_id": message.message_id,
                "user_id": user.id,
                "username": user.username,
                "first_name": user.first_name,
                "is_group": message.chat.type != "private"
            }
        )
    
    def _start_typing(self, chat_id: str) -> None:
        """Start sending 'typing...' indicator for a chat."""
        # Cancel any existing typing task for this chat
        self._stop_typing(chat_id)
        self._typing_tasks[chat_id] = asyncio.create_task(self._typing_loop(chat_id))
    
    def _stop_typing(self, chat_id: str) -> None:
        """Stop the typing indicator for a chat."""
        task = self._typing_tasks.pop(chat_id, None)
        if task and not task.done():
            task.cancel()
    
    async def _typing_loop(self, chat_id: str) -> None:
        """Repeatedly send 'typing' action until cancelled."""
        try:
            while self._app:
                await self._app.bot.send_chat_action(chat_id=int(chat_id), action="typing")
                await asyncio.sleep(4)
        except asyncio.CancelledError:
            pass
        except Exception as e:
            logger.debug(f"Typing indicator stopped for {chat_id}: {e}")
    
    async def _on_error(self, update: object, context: ContextTypes.DEFAULT_TYPE) -> None:
        """Log polling / handler errors instead of silently swallowing them."""
        logger.error(f"Telegram error: {context.error}")

    def _get_extension(self, media_type: str, mime_type: str | None) -> str:
        """Get file extension based on media type."""
        if mime_type:
            ext_map = {
                "image/jpeg": ".jpg", "image/png": ".png", "image/gif": ".gif",
                "audio/ogg": ".ogg", "audio/mpeg": ".mp3", "audio/mp4": ".m4a",
            }
            if mime_type in ext_map:
                return ext_map[mime_type]
        
        type_map = {"image": ".jpg", "voice": ".ogg", "audio": ".mp3", "file": ""}
        return type_map.get(media_type, "")
