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

from __future__ import annotations

import asyncio
import re

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

from bao.bus.events import OutboundMessage
from bao.bus.queue import MessageBus
from bao.channels.base import BaseChannel
from bao.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


def _split_message(content: str, max_len: int = 4000) -> list[str]:
    """Split content into chunks within max_len, preferring line breaks."""
    if len(content) <= max_len:
        return [content]
    chunks: list[str] = []
    while content:
        if len(content) <= max_len:
            chunks.append(content)
            break
        cut = content[:max_len]
        pos = cut.rfind("\n")
        if pos == -1:
            pos = cut.rfind(" ")
        if pos == -1:
            pos = max_len
        chunks.append(content[:pos])
        content = content[pos:].lstrip()
    return chunks


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("session", "Switch conversation"),
        BotCommand("delete", "Delete current conversation"),
        BotCommand("stop", "Stop the current task"),
        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
        self._media_group_buffers: dict[str, list[dict[str, object]]] = {}
        self._media_group_tasks: dict[str, asyncio.Task] = {}

    async def start(self) -> None:
        """Start the Telegram bot with long polling."""
        token = self.config.token.get_secret_value()
        if not token:
            logger.error("❌ 未配置 / not configured: Telegram token")
            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(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()
        app = self._app
        app.add_error_handler(self._on_error)

        # Add command handlers
        app.add_handler(CommandHandler("start", self._on_start))
        app.add_handler(CommandHandler("new", self._forward_command))
        app.add_handler(CommandHandler("session", self._forward_command))
        app.add_handler(CommandHandler("delete", self._forward_command))
        app.add_handler(CommandHandler("stop", self._forward_command))
        app.add_handler(CommandHandler("help", self._on_help))

        # Add message handler for text, photos, voice, documents
        app.add_handler(
            MessageHandler(
                (
                    filters.TEXT
                    | filters.PHOTO
                    | filters.VOICE
                    | filters.AUDIO
                    | filters.Document.ALL
                )
                & ~filters.COMMAND,
                self._on_message,
            )
        )

        logger.info("📡 启动通道 / starting: Telegram polling")

        # Initialize and start polling
        await app.initialize()
        await app.start()

        # Get bot info and register command menu
        bot_info = await app.bot.get_me()
        logger.info("✅ 连接成功 / connected: @{}", bot_info.username)

        try:
            await app.bot.set_my_commands(self.BOT_COMMANDS)
            logger.debug("Telegram bot commands registered")
        except Exception as e:
            logger.warning("⚠️ 注册失败 / register failed: {}", e)

        # Start polling (this runs until stopped)
        await 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)

        flush_tasks = list(self._media_group_tasks.values())
        for task in flush_tasks:
            if not task.done():
                task.cancel()
        if flush_tasks:
            await asyncio.gather(*flush_tasks, return_exceptions=True)
        self._media_group_tasks.clear()
        self._media_group_buffers.clear()

        if self._app:
            app = self._app
            logger.info("📡 停止通道 / stopping: Telegram bot")
            await app.updater.stop()
            await app.stop()
            await app.shutdown()
            self._app = None

    @staticmethod
    def _get_media_type(path: str) -> str:
        """Guess media type from file extension."""
        ext = path.rsplit(".", 1)[-1].lower() if "." in path else ""
        if ext in ("jpg", "jpeg", "png", "gif", "webp"):
            return "photo"
        if ext == "ogg":
            return "voice"
        if ext in ("mp3", "m4a", "wav", "aac"):
            return "audio"
        return "document"

    async def send(self, msg: OutboundMessage) -> None:
        """Send a message through Telegram."""
        if not self._app:
            logger.warning("⚠️ 未运行 / not running: Telegram bot")
            return

        self._stop_typing(msg.chat_id)

        try:
            chat_id = int(msg.chat_id)
        except ValueError:
            logger.error("❌ 参数无效 / invalid chat_id: {}", msg.chat_id)
            return

        reply_params = None
        if self.config.reply_to_message:
            reply_to_raw = msg.reply_to or msg.metadata.get("message_id")
            reply_to_message_id = None
            if isinstance(reply_to_raw, int) and not isinstance(reply_to_raw, bool):
                reply_to_message_id = reply_to_raw
            elif isinstance(reply_to_raw, str):
                raw = reply_to_raw.strip()
                if raw.lstrip("-").isdigit():
                    reply_to_message_id = int(raw)
            if reply_to_message_id is not None:
                reply_params = ReplyParameters(
                    message_id=reply_to_message_id, allow_sending_without_reply=True
                )

        # Send media files
        for media_path in msg.media or []:
            try:
                media_type = self._get_media_type(media_path)
                sender = {
                    "photo": self._app.bot.send_photo,
                    "voice": self._app.bot.send_voice,
                    "audio": self._app.bot.send_audio,
                }.get(media_type, self._app.bot.send_document)
                param = (
                    "photo"
                    if media_type == "photo"
                    else media_type
                    if media_type in ("voice", "audio")
                    else "document"
                )
                with open(media_path, "rb") as f:
                    await sender(chat_id=chat_id, **{param: f}, reply_parameters=reply_params)
            except Exception as e:
                filename = media_path.rsplit("/", 1)[-1]
                logger.error("❌ 发送失败 / media failed: {}: {}", media_path, e)
                await self._app.bot.send_message(
                    chat_id=chat_id,
                    text=f"[Failed to send: {filename}]",
                    reply_parameters=reply_params,
                )

        # Send text content
        if msg.content and msg.content != "[empty message]":
            for chunk in _split_message(msg.content):
                try:
                    html = _markdown_to_telegram_html(chunk)
                    await self._app.bot.send_message(
                        chat_id=chat_id, text=html, parse_mode="HTML", reply_parameters=reply_params
                    )
                except Exception as e:
                    logger.warning("⚠️ 解析失败 / parse failed: {}", e)
                    try:
                        await self._app.bot.send_message(
                            chat_id=chat_id, text=chunk, reply_parameters=reply_params
                        )
                    except Exception as e2:
                        logger.error("❌ 发送失败 / send failed: {}", 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 Bao.\n\n"
            "Send me a message and I'll respond!\n"
            "Type /help to see available commands."
        )

    async def _on_help(self, update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
        """Handle /help command, bypassing ACL so all users can access it."""
        if not update.message:
            return
        await update.message.reply_text(
            "🐈 Bao commands:\n"
            "/new — Start a new conversation\n"
            "/stop — Stop the current task\n"
            "/session — Switch between conversations\n"
            "/delete — Delete current conversation\n"
            "/model — Switch model\n"
            "/help — Show available commands"
        )

    @staticmethod
    def _sender_id(user) -> str:
        """Build sender_id with username for allowlist matching."""
        sid = str(user.id)
        return f"{sid}|{user.username}" if user.username else sid

    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=self._sender_id(update.effective_user),
            chat_id=str(update.message.chat_id),
            content=update.message.text or "",
        )

    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
        sender_id = self._sender_id(user)

        if not self.is_allowed(sender_id):
            logger.warning(
                "⚠️ 访问拒绝 / access denied: sender={} channel=telegram",
                sender_id,
            )
            return

        # 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)
                media_kind = media_type or "file"
                ext = self._get_extension(media_kind, getattr(media_file, "mime_type", None))

                # Save to workspace/media/
                from pathlib import Path

                media_dir = Path.home() / ".bao" / "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 bao.providers.transcription import GroqTranscriptionProvider

                    transcriber = GroqTranscriptionProvider(api_key=self.groq_api_key)
                    transcription = await transcriber.transcribe(file_path)
                    if transcription:
                        logger.info(
                            "🎙️ 转写完成 / 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("Downloaded {} to {}", media_type, file_path)
            except Exception as e:
                logger.error("❌ 下载失败 / download failed: {}", e)
                content_parts.append(f"[{media_type}: download failed]")

        content = "\n".join(content_parts) if content_parts else "[empty message]"

        logger.debug("Telegram message from {}: {}...", sender_id, content[:50])

        str_chat_id = str(chat_id)

        # Start typing indicator before processing
        self._start_typing(str_chat_id)

        metadata = {
            "message_id": message.message_id,
            "user_id": user.id,
            "username": user.username,
            "first_name": user.first_name,
            "is_group": message.chat.type != "private",
        }

        media_group_id = getattr(message, "media_group_id", None)
        if media_group_id:
            key = f"{str_chat_id}:{media_group_id}"
            self._media_group_buffers.setdefault(key, []).append(
                {
                    "sender_id": sender_id,
                    "chat_id": str_chat_id,
                    "content": content,
                    "media": media_paths,
                    "metadata": metadata,
                }
            )
            if key not in self._media_group_tasks or self._media_group_tasks[key].done():
                self._media_group_tasks[key] = asyncio.create_task(self._flush_media_group(key))
            return

        # Forward to the message bus
        await self._handle_message(
            sender_id=sender_id,
            chat_id=str_chat_id,
            content=content,
            media=media_paths,
            metadata=metadata,
        )

    async def _flush_media_group(self, key: str) -> None:
        try:
            await asyncio.sleep(0.6)
            items = self._media_group_buffers.pop(key, [])
            if not items:
                return

            sender_id = str(items[-1]["sender_id"])
            chat_id = str(items[-1]["chat_id"])
            metadata_obj = items[-1].get("metadata", {})
            metadata = metadata_obj if isinstance(metadata_obj, dict) else {}

            contents = [str(it.get("content", "")).strip() for it in items]
            merged_content = "\n".join(c for c in contents if c and c != "[empty message]")
            if not merged_content:
                merged_content = "[empty message]"

            merged_media: list[str] = []
            for it in items:
                media_obj = it.get("media", [])
                if isinstance(media_obj, list):
                    for media_path in media_obj:
                        if isinstance(media_path, str):
                            merged_media.append(media_path)
            merged_media = list(dict.fromkeys(merged_media))

            await self._handle_message(
                sender_id=sender_id,
                chat_id=chat_id,
                content=merged_content,
                media=merged_media,
                metadata=metadata,
            )
        except asyncio.CancelledError:
            self._media_group_buffers.pop(key, None)
            raise
        except Exception as e:
            logger.error("❌ 媒体组处理失败 / media-group flush failed: {}", e)
        finally:
            self._media_group_tasks.pop(key, None)

    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("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("❌ 处理异常 / handler 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, "")
