"""Mattermost gateway adapter.

Connects to a self-hosted (or cloud) Mattermost instance via its REST API
(v4) and WebSocket for real-time events.  No external Mattermost library
required — uses aiohttp which is already a Hermes dependency.

Environment variables:
    MATTERMOST_URL              Server URL (e.g. https://mm.example.com)
    MATTERMOST_TOKEN            Bot token or personal-access token
    MATTERMOST_ALLOWED_USERS    Comma-separated user IDs
    MATTERMOST_HOME_CHANNEL     Channel ID for cron/notification delivery
"""

from __future__ import annotations

import asyncio
import json
import logging
import os
import re
import time
from pathlib import Path
from typing import Any, Dict, List, Optional, Tuple

from gateway.config import Platform, PlatformConfig
from gateway.platforms.base import (
    BasePlatformAdapter,
    MessageEvent,
    MessageType,
    SendResult,
)

logger = logging.getLogger(__name__)

# Mattermost post size limit (server default is 16383, but 4000 is the
# practical limit for readable messages — matching OpenClaw's choice).
MAX_POST_LENGTH = 4000

# Channel type codes returned by the Mattermost API.
_CHANNEL_TYPE_MAP = {
    "D": "dm",
    "G": "group",
    "P": "group",   # private channel → treat as group
    "O": "channel",
}

# Reconnect parameters (exponential backoff).
_RECONNECT_BASE_DELAY = 2.0
_RECONNECT_MAX_DELAY = 60.0
_RECONNECT_JITTER = 0.2


def check_mattermost_requirements() -> bool:
    """Return True if the Mattermost adapter can be used."""
    token = os.getenv("MATTERMOST_TOKEN", "")
    url = os.getenv("MATTERMOST_URL", "")
    if not token:
        logger.debug("Mattermost: MATTERMOST_TOKEN not set")
        return False
    if not url:
        logger.warning("Mattermost: MATTERMOST_URL not set")
        return False
    try:
        import aiohttp  # noqa: F401
        return True
    except ImportError:
        logger.warning("Mattermost: aiohttp not installed")
        return False


class MattermostAdapter(BasePlatformAdapter):
    """Gateway adapter for Mattermost (self-hosted or cloud)."""

    def __init__(self, config: PlatformConfig):
        super().__init__(config, Platform.MATTERMOST)

        self._base_url: str = (
            config.extra.get("url", "")
            or os.getenv("MATTERMOST_URL", "")
        ).rstrip("/")
        self._token: str = config.token or os.getenv("MATTERMOST_TOKEN", "")

        self._bot_user_id: str = ""
        self._bot_username: str = ""

        # aiohttp session + websocket handle
        self._session: Any = None  # aiohttp.ClientSession
        self._ws: Any = None       # aiohttp.ClientWebSocketResponse
        self._ws_task: Optional[asyncio.Task] = None
        self._reconnect_task: Optional[asyncio.Task] = None
        self._closing = False

        # Reply mode: "thread" to nest replies, "off" for flat messages.
        self._reply_mode: str = (
            config.extra.get("reply_mode", "")
            or os.getenv("MATTERMOST_REPLY_MODE", "off")
        ).lower()

        # Dedup cache: post_id → timestamp (prevent reprocessing)
        self._seen_posts: Dict[str, float] = {}
        self._SEEN_MAX = 2000
        self._SEEN_TTL = 300  # 5 minutes

    # ------------------------------------------------------------------
    # HTTP helpers
    # ------------------------------------------------------------------

    def _headers(self) -> Dict[str, str]:
        return {
            "Authorization": f"Bearer {self._token}",
            "Content-Type": "application/json",
        }

    async def _api_get(self, path: str) -> Dict[str, Any]:
        """GET /api/v4/{path}."""
        import aiohttp
        url = f"{self._base_url}/api/v4/{path.lstrip('/')}"
        try:
            async with self._session.get(url, headers=self._headers()) as resp:
                if resp.status >= 400:
                    body = await resp.text()
                    logger.error("MM API GET %s → %s: %s", path, resp.status, body[:200])
                    return {}
                return await resp.json()
        except aiohttp.ClientError as exc:
            logger.error("MM API GET %s network error: %s", path, exc)
            return {}

    async def _api_post(
        self, path: str, payload: Dict[str, Any]
    ) -> Dict[str, Any]:
        """POST /api/v4/{path} with JSON body."""
        import aiohttp
        url = f"{self._base_url}/api/v4/{path.lstrip('/')}"
        try:
            async with self._session.post(
                url, headers=self._headers(), json=payload
            ) as resp:
                if resp.status >= 400:
                    body = await resp.text()
                    logger.error("MM API POST %s → %s: %s", path, resp.status, body[:200])
                    return {}
                return await resp.json()
        except aiohttp.ClientError as exc:
            logger.error("MM API POST %s network error: %s", path, exc)
            return {}

    async def _api_put(
        self, path: str, payload: Dict[str, Any]
    ) -> Dict[str, Any]:
        """PUT /api/v4/{path} with JSON body."""
        import aiohttp
        url = f"{self._base_url}/api/v4/{path.lstrip('/')}"
        try:
            async with self._session.put(
                url, headers=self._headers(), json=payload
            ) as resp:
                if resp.status >= 400:
                    body = await resp.text()
                    logger.error("MM API PUT %s → %s: %s", path, resp.status, body[:200])
                    return {}
                return await resp.json()
        except aiohttp.ClientError as exc:
            logger.error("MM API PUT %s network error: %s", path, exc)
            return {}

    async def _upload_file(
        self, channel_id: str, file_data: bytes, filename: str, content_type: str = "application/octet-stream"
    ) -> Optional[str]:
        """Upload a file and return its file ID, or None on failure."""
        import aiohttp

        url = f"{self._base_url}/api/v4/files"
        form = aiohttp.FormData()
        form.add_field("channel_id", channel_id)
        form.add_field(
            "files",
            file_data,
            filename=filename,
            content_type=content_type,
        )
        headers = {"Authorization": f"Bearer {self._token}"}
        async with self._session.post(url, headers=headers, data=form) as resp:
            if resp.status >= 400:
                body = await resp.text()
                logger.error("MM file upload → %s: %s", resp.status, body[:200])
                return None
            data = await resp.json()
            infos = data.get("file_infos", [])
            return infos[0]["id"] if infos else None

    # ------------------------------------------------------------------
    # Required overrides
    # ------------------------------------------------------------------

    async def connect(self) -> bool:
        """Connect to Mattermost and start the WebSocket listener."""
        import aiohttp

        if not self._base_url or not self._token:
            logger.error("Mattermost: URL or token not configured")
            return False

        self._session = aiohttp.ClientSession()
        self._closing = False

        # Verify credentials and fetch bot identity.
        me = await self._api_get("users/me")
        if not me or "id" not in me:
            logger.error("Mattermost: failed to authenticate — check MATTERMOST_TOKEN and MATTERMOST_URL")
            await self._session.close()
            return False

        self._bot_user_id = me["id"]
        self._bot_username = me.get("username", "")
        logger.info(
            "Mattermost: authenticated as @%s (%s) on %s",
            self._bot_username,
            self._bot_user_id,
            self._base_url,
        )

        # Start WebSocket in background.
        self._ws_task = asyncio.create_task(self._ws_loop())
        self._mark_connected()
        return True

    async def disconnect(self) -> None:
        """Disconnect from Mattermost."""
        self._closing = True

        if self._ws_task and not self._ws_task.done():
            self._ws_task.cancel()
            try:
                await self._ws_task
            except (asyncio.CancelledError, Exception):
                pass

        if self._reconnect_task and not self._reconnect_task.done():
            self._reconnect_task.cancel()

        if self._ws:
            await self._ws.close()
            self._ws = None

        if self._session and not self._session.closed:
            await self._session.close()

        logger.info("Mattermost: disconnected")

    async def send(
        self,
        chat_id: str,
        content: str,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Send a message (or multiple chunks) to a channel."""
        if not content:
            return SendResult(success=True)

        formatted = self.format_message(content)
        chunks = self.truncate_message(formatted, MAX_POST_LENGTH)

        last_id = None
        for chunk in chunks:
            payload: Dict[str, Any] = {
                "channel_id": chat_id,
                "message": chunk,
            }
            # Thread support: reply_to is the root post ID.
            if reply_to and self._reply_mode == "thread":
                payload["root_id"] = reply_to

            data = await self._api_post("posts", payload)
            if not data or "id" not in data:
                return SendResult(success=False, error="Failed to create post")
            last_id = data["id"]

        return SendResult(success=True, message_id=last_id)

    async def get_chat_info(self, chat_id: str) -> Dict[str, Any]:
        """Return channel name and type."""
        data = await self._api_get(f"channels/{chat_id}")
        if not data:
            return {"name": chat_id, "type": "channel"}

        ch_type = _CHANNEL_TYPE_MAP.get(data.get("type", "O"), "channel")
        display_name = data.get("display_name") or data.get("name") or chat_id
        return {"name": display_name, "type": ch_type}

    # ------------------------------------------------------------------
    # Optional overrides
    # ------------------------------------------------------------------

    async def send_typing(
        self, chat_id: str, metadata: Optional[Dict[str, Any]] = None
    ) -> None:
        """Send a typing indicator."""
        await self._api_post(
            f"users/{self._bot_user_id}/typing",
            {"channel_id": chat_id},
        )

    async def edit_message(
        self, chat_id: str, message_id: str, content: str
    ) -> SendResult:
        """Edit an existing post."""
        formatted = self.format_message(content)
        data = await self._api_put(
            f"posts/{message_id}/patch",
            {"message": formatted},
        )
        if not data or "id" not in data:
            return SendResult(success=False, error="Failed to edit post")
        return SendResult(success=True, message_id=data["id"])

    async def send_image(
        self,
        chat_id: str,
        image_url: str,
        caption: Optional[str] = None,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Download an image and upload it as a file attachment."""
        return await self._send_url_as_file(
            chat_id, image_url, caption, reply_to, "image"
        )

    async def send_image_file(
        self,
        chat_id: str,
        image_path: str,
        caption: Optional[str] = None,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Upload a local image file."""
        return await self._send_local_file(
            chat_id, image_path, caption, reply_to
        )

    async def send_document(
        self,
        chat_id: str,
        file_path: str,
        caption: Optional[str] = None,
        file_name: Optional[str] = None,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Upload a local file as a document."""
        return await self._send_local_file(
            chat_id, file_path, caption, reply_to, file_name
        )

    async def send_voice(
        self,
        chat_id: str,
        audio_path: str,
        caption: Optional[str] = None,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Upload an audio file."""
        return await self._send_local_file(
            chat_id, audio_path, caption, reply_to
        )

    async def send_video(
        self,
        chat_id: str,
        video_path: str,
        caption: Optional[str] = None,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Upload a video file."""
        return await self._send_local_file(
            chat_id, video_path, caption, reply_to
        )

    def format_message(self, content: str) -> str:
        """Mattermost uses standard Markdown — mostly pass through.

        Strip image markdown into plain links (files are uploaded separately).
        """
        # Convert ![alt](url) to just the URL — Mattermost renders
        # image URLs as inline previews automatically.
        content = re.sub(r"!\[([^\]]*)\]\(([^)]+)\)", r"\2", content)
        return content

    # ------------------------------------------------------------------
    # File helpers
    # ------------------------------------------------------------------

    async def _send_url_as_file(
        self,
        chat_id: str,
        url: str,
        caption: Optional[str],
        reply_to: Optional[str],
        kind: str = "file",
    ) -> SendResult:
        """Download a URL and upload it as a file attachment."""
        import aiohttp
        try:
            async with self._session.get(url, timeout=aiohttp.ClientTimeout(total=30)) as resp:
                if resp.status >= 400:
                    # Fall back to sending the URL as text.
                    return await self.send(chat_id, f"{caption or ''}\n{url}".strip(), reply_to)
                file_data = await resp.read()
                ct = resp.content_type or "application/octet-stream"
                # Derive filename from URL.
                fname = url.rsplit("/", 1)[-1].split("?")[0] or f"{kind}.png"
        except Exception as exc:
            logger.warning("Mattermost: failed to download %s: %s", url, exc)
            return await self.send(chat_id, f"{caption or ''}\n{url}".strip(), reply_to)

        file_id = await self._upload_file(chat_id, file_data, fname, ct)
        if not file_id:
            return await self.send(chat_id, f"{caption or ''}\n{url}".strip(), reply_to)

        payload: Dict[str, Any] = {
            "channel_id": chat_id,
            "message": caption or "",
            "file_ids": [file_id],
        }
        if reply_to and self._reply_mode == "thread":
            payload["root_id"] = reply_to

        data = await self._api_post("posts", payload)
        if not data or "id" not in data:
            return SendResult(success=False, error="Failed to post with file")
        return SendResult(success=True, message_id=data["id"])

    async def _send_local_file(
        self,
        chat_id: str,
        file_path: str,
        caption: Optional[str],
        reply_to: Optional[str],
        file_name: Optional[str] = None,
    ) -> SendResult:
        """Upload a local file and attach it to a post."""
        import mimetypes

        p = Path(file_path)
        if not p.exists():
            return await self.send(
                chat_id, f"{caption or ''}\n(file not found: {file_path})", reply_to
            )

        fname = file_name or p.name
        ct = mimetypes.guess_type(fname)[0] or "application/octet-stream"
        file_data = p.read_bytes()

        file_id = await self._upload_file(chat_id, file_data, fname, ct)
        if not file_id:
            return SendResult(success=False, error="File upload failed")

        payload: Dict[str, Any] = {
            "channel_id": chat_id,
            "message": caption or "",
            "file_ids": [file_id],
        }
        if reply_to and self._reply_mode == "thread":
            payload["root_id"] = reply_to

        data = await self._api_post("posts", payload)
        if not data or "id" not in data:
            return SendResult(success=False, error="Failed to post with file")
        return SendResult(success=True, message_id=data["id"])

    # ------------------------------------------------------------------
    # WebSocket
    # ------------------------------------------------------------------

    async def _ws_loop(self) -> None:
        """Connect to the WebSocket and listen for events, reconnecting on failure."""
        delay = _RECONNECT_BASE_DELAY
        while not self._closing:
            try:
                await self._ws_connect_and_listen()
                # Clean disconnect — reset delay.
                delay = _RECONNECT_BASE_DELAY
            except asyncio.CancelledError:
                return
            except Exception as exc:
                if self._closing:
                    return
                logger.warning("Mattermost WS error: %s — reconnecting in %.0fs", exc, delay)

            if self._closing:
                return

            # Exponential backoff with jitter.
            import random
            jitter = delay * _RECONNECT_JITTER * random.random()
            await asyncio.sleep(delay + jitter)
            delay = min(delay * 2, _RECONNECT_MAX_DELAY)

    async def _ws_connect_and_listen(self) -> None:
        """Single WebSocket session: connect, authenticate, process events."""
        # Build WS URL: https:// → wss://, http:// → ws://
        ws_url = re.sub(r"^http", "ws", self._base_url) + "/api/v4/websocket"
        logger.info("Mattermost: connecting to %s", ws_url)

        self._ws = await self._session.ws_connect(ws_url, heartbeat=30.0)

        # Authenticate via the WebSocket.
        auth_msg = {
            "seq": 1,
            "action": "authentication_challenge",
            "data": {"token": self._token},
        }
        await self._ws.send_json(auth_msg)
        logger.info("Mattermost: WebSocket connected and authenticated")

        async for raw_msg in self._ws:
            if self._closing:
                return

            if raw_msg.type in (
                raw_msg.type.TEXT,
                raw_msg.type.BINARY,
            ):
                try:
                    event = json.loads(raw_msg.data)
                except (json.JSONDecodeError, TypeError):
                    continue
                await self._handle_ws_event(event)
            elif raw_msg.type in (
                raw_msg.type.ERROR,
                raw_msg.type.CLOSE,
                raw_msg.type.CLOSING,
                raw_msg.type.CLOSED,
            ):
                logger.info("Mattermost: WebSocket closed (%s)", raw_msg.type)
                break

    async def _handle_ws_event(self, event: Dict[str, Any]) -> None:
        """Process a single WebSocket event."""
        event_type = event.get("event")
        if event_type != "posted":
            return

        data = event.get("data", {})
        raw_post_str = data.get("post")
        if not raw_post_str:
            return

        try:
            post = json.loads(raw_post_str)
        except (json.JSONDecodeError, TypeError):
            return

        # Ignore own messages.
        if post.get("user_id") == self._bot_user_id:
            return

        # Ignore system posts.
        if post.get("type"):
            return

        post_id = post.get("id", "")

        # Dedup.
        self._prune_seen()
        if post_id in self._seen_posts:
            return
        self._seen_posts[post_id] = time.time()

        # Build message event.
        channel_id = post.get("channel_id", "")
        channel_type_raw = data.get("channel_type", "O")
        chat_type = _CHANNEL_TYPE_MAP.get(channel_type_raw, "channel")

        # For DMs, user_id is sufficient.  For channels, check for @mention.
        message_text = post.get("message", "")

        # Resolve sender info.
        sender_id = post.get("user_id", "")
        sender_name = data.get("sender_name", "").lstrip("@") or sender_id

        # Thread support: if the post is in a thread, use root_id.
        thread_id = post.get("root_id") or None

        # Determine message type.
        file_ids = post.get("file_ids") or []
        msg_type = MessageType.TEXT
        if message_text.startswith("/"):
            msg_type = MessageType.COMMAND

        # Download file attachments immediately (URLs require auth headers
        # that downstream tools won't have).
        media_urls: List[str] = []
        media_types: List[str] = []
        for fid in file_ids:
            try:
                file_info = await self._api_get(f"files/{fid}/info")
                fname = file_info.get("name", f"file_{fid}")
                ext = Path(fname).suffix or ""
                mime = file_info.get("mime_type", "application/octet-stream")

                import aiohttp
                dl_url = f"{self._base_url}/api/v4/files/{fid}"
                async with self._session.get(
                    dl_url,
                    headers={"Authorization": f"Bearer {self._token}"},
                    timeout=aiohttp.ClientTimeout(total=30),
                ) as resp:
                    if resp.status < 400:
                        file_data = await resp.read()
                        from gateway.platforms.base import cache_image_from_bytes, cache_document_from_bytes
                        if mime.startswith("image/"):
                            local_path = cache_image_from_bytes(file_data, ext or ".png")
                            media_urls.append(local_path)
                            media_types.append(mime)
                        elif mime.startswith("audio/"):
                            from gateway.platforms.base import cache_audio_from_bytes
                            local_path = cache_audio_from_bytes(file_data, ext or ".ogg")
                            media_urls.append(local_path)
                            media_types.append(mime)
                        else:
                            local_path = cache_document_from_bytes(file_data, fname)
                            media_urls.append(local_path)
                            media_types.append(mime)
                    else:
                        logger.warning("Mattermost: failed to download file %s: HTTP %s", fid, resp.status)
            except Exception as exc:
                logger.warning("Mattermost: error downloading file %s: %s", fid, exc)

        source = self.build_source(
            chat_id=channel_id,
            chat_type=chat_type,
            user_id=sender_id,
            user_name=sender_name,
            thread_id=thread_id,
        )

        msg_event = MessageEvent(
            text=message_text,
            message_type=msg_type,
            source=source,
            raw_message=post,
            message_id=post_id,
            media_urls=media_urls if media_urls else None,
            media_types=media_types if media_types else None,
        )

        await self.handle_message(msg_event)

    def _prune_seen(self) -> None:
        """Remove expired entries from the dedup cache."""
        if len(self._seen_posts) < self._SEEN_MAX:
            return
        now = time.time()
        self._seen_posts = {
            pid: ts
            for pid, ts in self._seen_posts.items()
            if now - ts < self._SEEN_TTL
        }