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

from __future__ import annotations

import asyncio
import re
import time
import unicodedata

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 asedclaw.bus.events import OutboundMessage
from asedclaw.bus.queue import MessageBus
from asedclaw.channels.base import BaseChannel
from asedclaw.config.paths import get_media_dir
from asedclaw.config.schema import TelegramConfig
from asedclaw.utils.helpers import split_message

TELEGRAM_MAX_MESSAGE_LEN = 4000  # Telegram message character limit


def _strip_md(s: str) -> str:
    """Strip markdown inline formatting from text."""
    s = re.sub(r'\*\*(.+?)\*\*', r'\1', s)
    s = re.sub(r'__(.+?)__', r'\1', s)
    s = re.sub(r'~~(.+?)~~', r'\1', s)
    s = re.sub(r'`([^`]+)`', r'\1', s)
    return s.strip()


def _render_table_box(table_lines: list[str]) -> str:
    """Convert markdown pipe-table to compact aligned text for <pre> display."""

    def dw(s: str) -> int:
        return sum(2 if unicodedata.east_asian_width(c) in ('W', 'F') else 1 for c in s)

    rows: list[list[str]] = []
    has_sep = False
    for line in table_lines:
        cells = [_strip_md(c) for c in line.strip().strip('|').split('|')]
        if all(re.match(r'^:?-+:?$', c) for c in cells if c):
            has_sep = True
            continue
        rows.append(cells)
    if not rows or not has_sep:
        return '\n'.join(table_lines)

    ncols = max(len(r) for r in rows)
    for r in rows:
        r.extend([''] * (ncols - len(r)))
    widths = [max(dw(r[c]) for r in rows) for c in range(ncols)]

    def dr(cells: list[str]) -> str:
        return '  '.join(f'{c}{" " * (w - dw(c))}' for c, w in zip(cells, widths))

    out = [dr(rows[0])]
    out.append('  '.join('─' * w for w in widths))
    for row in rows[1:]:
        out.append(dr(row))
    return '\n'.join(out)


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)

    # 1.5. Convert markdown tables to box-drawing (reuse code_block placeholders)
    lines = text.split('\n')
    rebuilt: list[str] = []
    li = 0
    while li < len(lines):
        if re.match(r'^\s*\|.+\|', lines[li]):
            tbl: list[str] = []
            while li < len(lines) and re.match(r'^\s*\|.+\|', lines[li]):
                tbl.append(lines[li])
                li += 1
            box = _render_table_box(tbl)
            if box != '\n'.join(tbl):
                code_blocks.append(box)
                rebuilt.append(f"\x00CB{len(code_blocks) - 1}\x00")
            else:
                rebuilt.extend(tbl)
        else:
            rebuilt.append(lines[li])
            li += 1
    text = '\n'.join(rebuilt)

    # 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("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, dict] = {}
        self._media_group_tasks: dict[str, asyncio.Task] = {}
        self._message_threads: dict[tuple[str, int], int] = {}

    def is_allowed(self, sender_id: str) -> bool:
        """Preserve Telegram's legacy id|username allowlist matching."""
        if super().is_allowed(sender_id):
            return True

        allow_list = getattr(self.config, "allow_from", [])
        if not allow_list or "*" in allow_list:
            return False

        sender_str = str(sender_id)
        if sender_str.count("|") != 1:
            return False

        sid, username = sender_str.split("|", 1)
        if not sid.isdigit() or not username:
            return False

        return sid in allow_list or username in allow_list

    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,
            proxy=self.config.proxy if self.config.proxy else None,
        )
        builder = Application.builder().token(self.config.token).request(req).get_updates_request(req)
        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("stop", self._forward_command))
        self._app.add_handler(CommandHandler("help", self._on_help))

        # 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("Telegram bot @{} connected", bot_info.username)

        try:
            await self._app.bot.set_my_commands(self.BOT_COMMANDS)
            logger.debug("Telegram bot commands registered")
        except Exception as e:
            logger.warning("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)

        for task in self._media_group_tasks.values():
            task.cancel()
        self._media_group_tasks.clear()
        self._media_group_buffers.clear()

        if self._app:
            logger.info("Stopping Telegram bot...")
            await self._app.updater.stop()
            await self._app.stop()
            await self._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("Telegram bot not running")
            return

        # Only stop typing indicator for final responses
        if not msg.metadata.get("_progress", False):
            self._stop_typing(msg.chat_id)

        try:
            chat_id = int(msg.chat_id)
        except ValueError:
            logger.error("Invalid chat_id: {}", msg.chat_id)
            return
        reply_to_message_id = msg.metadata.get("message_id")
        message_thread_id = msg.metadata.get("message_thread_id")
        if message_thread_id is None and reply_to_message_id is not None:
            message_thread_id = self._message_threads.get((msg.chat_id, reply_to_message_id))
        thread_kwargs = {}
        if message_thread_id is not None:
            thread_kwargs["message_thread_id"] = message_thread_id

        reply_params = None
        if self.config.reply_to_message:
            if reply_to_message_id:
                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,
                        **thread_kwargs,
                    )
            except Exception as e:
                filename = media_path.rsplit("/", 1)[-1]
                logger.error("Failed to send media {}: {}", media_path, e)
                await self._app.bot.send_message(
                    chat_id=chat_id,
                    text=f"[Failed to send: {filename}]",
                    reply_parameters=reply_params,
                    **thread_kwargs,
                )

        # Send text content
        if msg.content and msg.content != "[empty message]":
            is_progress = msg.metadata.get("_progress", False)

            for chunk in split_message(msg.content, TELEGRAM_MAX_MESSAGE_LEN):
                # Final response: simulate streaming via draft, then persist
                if not is_progress:
                    await self._send_with_streaming(chat_id, chunk, reply_params, thread_kwargs)
                else:
                    await self._send_text(chat_id, chunk, reply_params, thread_kwargs)

    async def _send_text(
        self,
        chat_id: int,
        text: str,
        reply_params=None,
        thread_kwargs: dict | None = None,
    ) -> None:
        """Send a plain text message with HTML fallback."""
        try:
            html = _markdown_to_telegram_html(text)
            await self._app.bot.send_message(
                chat_id=chat_id, text=html, parse_mode="HTML",
                reply_parameters=reply_params,
                **(thread_kwargs or {}),
            )
        except Exception as e:
            logger.warning("HTML parse failed, falling back to plain text: {}", e)
            try:
                await self._app.bot.send_message(
                    chat_id=chat_id,
                    text=text,
                    reply_parameters=reply_params,
                    **(thread_kwargs or {}),
                )
            except Exception as e2:
                logger.error("Error sending Telegram message: {}", e2)

    async def _send_with_streaming(
        self,
        chat_id: int,
        text: str,
        reply_params=None,
        thread_kwargs: dict | None = None,
    ) -> None:
        """Simulate streaming via send_message_draft, then persist with send_message."""
        draft_id = int(time.time() * 1000) % (2**31)
        try:
            step = max(len(text) // 8, 40)
            for i in range(step, len(text), step):
                await self._app.bot.send_message_draft(
                    chat_id=chat_id, draft_id=draft_id, text=text[:i],
                )
                await asyncio.sleep(0.04)
            await self._app.bot.send_message_draft(
                chat_id=chat_id, draft_id=draft_id, text=text,
            )
            await asyncio.sleep(0.15)
        except Exception:
            pass
        await self._send_text(chat_id, text, reply_params, thread_kwargs)

    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 asedclaw.\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(
            "🐈 asedclaw commands:\n"
            "/new — Start a new conversation\n"
            "/stop — Stop the current task\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

    @staticmethod
    def _derive_topic_session_key(message) -> str | None:
        """Derive topic-scoped session key for non-private Telegram chats."""
        message_thread_id = getattr(message, "message_thread_id", None)
        if message.chat.type == "private" or message_thread_id is None:
            return None
        return f"telegram:{message.chat_id}:topic:{message_thread_id}"

    @staticmethod
    def _build_message_metadata(message, user) -> dict:
        """Build common Telegram inbound metadata payload."""
        return {
            "message_id": message.message_id,
            "user_id": user.id,
            "username": user.username,
            "first_name": user.first_name,
            "is_group": message.chat.type != "private",
            "message_thread_id": getattr(message, "message_thread_id", None),
            "is_forum": bool(getattr(message.chat, "is_forum", False)),
        }

    def _remember_thread_context(self, message) -> None:
        """Cache topic thread id by chat/message id for follow-up replies."""
        message_thread_id = getattr(message, "message_thread_id", None)
        if message_thread_id is None:
            return
        key = (str(message.chat_id), message.message_id)
        self._message_threads[key] = message_thread_id
        if len(self._message_threads) > 1000:
            self._message_threads.pop(next(iter(self._message_threads)))

    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
        message = update.message
        user = update.effective_user
        self._remember_thread_context(message)
        await self._handle_message(
            sender_id=self._sender_id(user),
            chat_id=str(message.chat_id),
            content=message.text,
            metadata=self._build_message_metadata(message, user),
            session_key=self._derive_topic_session_key(message),
        )

    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)
        self._remember_thread_context(message)

        # 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),
                    getattr(media_file, 'file_name', None),
                )
                media_dir = get_media_dir("telegram")

                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 asedclaw.providers.transcription import GroqTranscriptionProvider
                    transcriber = GroqTranscriptionProvider(api_key=self.groq_api_key)
                    transcription = await transcriber.transcribe(file_path)
                    if transcription:
                        logger.info("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("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("Telegram message from {}: {}...", sender_id, content[:50])

        str_chat_id = str(chat_id)
        metadata = self._build_message_metadata(message, user)
        session_key = self._derive_topic_session_key(message)

        # Telegram media groups: buffer briefly, forward as one aggregated turn.
        if media_group_id := getattr(message, "media_group_id", None):
            key = f"{str_chat_id}:{media_group_id}"
            if key not in self._media_group_buffers:
                self._media_group_buffers[key] = {
                    "sender_id": sender_id, "chat_id": str_chat_id,
                    "contents": [], "media": [],
                    "metadata": metadata,
                    "session_key": session_key,
                }
                self._start_typing(str_chat_id)
            buf = self._media_group_buffers[key]
            if content and content != "[empty message]":
                buf["contents"].append(content)
            buf["media"].extend(media_paths)
            if key not in self._media_group_tasks:
                self._media_group_tasks[key] = asyncio.create_task(self._flush_media_group(key))
            return

        # 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=metadata,
            session_key=session_key,
        )

    async def _flush_media_group(self, key: str) -> None:
        """Wait briefly, then forward buffered media-group as one turn."""
        try:
            await asyncio.sleep(0.6)
            if not (buf := self._media_group_buffers.pop(key, None)):
                return
            content = "\n".join(buf["contents"]) or "[empty message]"
            await self._handle_message(
                sender_id=buf["sender_id"], chat_id=buf["chat_id"],
                content=content, media=list(dict.fromkeys(buf["media"])),
                metadata=buf["metadata"],
                session_key=buf.get("session_key"),
            )
        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("Telegram error: {}", context.error)

    def _get_extension(
        self,
        media_type: str,
        mime_type: str | None,
        filename: str | None = None,
    ) -> str:
        """Get file extension based on media type or original filename."""
        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": ""}
        if ext := type_map.get(media_type, ""):
            return ext

        if filename:
            from pathlib import Path

            return "".join(Path(filename).suffixes)

        return ""
