"""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.error import Conflict
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 = "",
        bot_name: str = "",
    ):
        super().__init__(config, bus, bot_name=bot_name)
        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."""
        if isinstance(context.error, Conflict):
            # Transient during rolling deploys — old and new pods both poll briefly.
            # Self-heals once the old pod terminates.
            logger.warning("Telegram polling conflict (concurrent getUpdates) — transient during deploys")
            return
        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, "")
