"""Mattermost channel implementation using WebSocket + REST API."""

from __future__ import annotations

import asyncio
import json
import re
from pathlib import Path
from typing import Any, cast

import httpx
from pydantic import Field, model_validator

from nanobot.bus.events import OutboundMessage
from nanobot.bus.queue import MessageBus
from nanobot.channels.base import BaseChannel
from nanobot.config.paths import get_media_dir
from nanobot.config_base import Base
from nanobot.pairing import PAIRING_CODE_META_KEY, format_pairing_reply, generate_code, is_approved
from nanobot.utils.helpers import safe_filename, split_message

MATTERMOST_MAX_MESSAGE_LEN = 16383
MATTERMOST_WS_RECONNECT_BASE_DELAY = 1
MATTERMOST_WS_RECONNECT_MAX_DELAY = 30

_CHANNEL_TYPES = {
    "O": "public",
    "P": "private",
    "D": "dm",
    "G": "group",
}


class MattermostDMConfig(Base):
    """Mattermost DM policy configuration."""
    enabled: bool = True
    policy: str = "open"
    allow_from: list[str] = Field(default_factory=list)


class MattermostConfig(Base):
    """Mattermost channel configuration."""
    enabled: bool = False
    server_url: str = ""
    token: str = ""
    team_id: str = ""
    allow_from_match_mode: str = "id"
    allow_from: list[str] = Field(default_factory=list)
    group_policy: str = "mention"
    group_policy_in_thread: str = "open"
    group_allow_from: list[str] = Field(default_factory=list)
    reply_in_thread: bool = True
    include_thread_context: bool = True
    thread_context_limit: int = 20
    streaming: bool = True
    react_emoji: str = "eyes"
    done_emoji: str = "white_check_mark"
    send_progress: bool = True
    send_tool_hints: bool = True
    dm: MattermostDMConfig = Field(default_factory=MattermostDMConfig)

    @model_validator(mode="before")
    @classmethod
    def _inherit_thread_policy(cls, data: Any) -> Any:
        """Preserve the existing group policy unless a thread override is set."""
        if not isinstance(data, dict):
            return data
        raw = cast(dict[str, Any], data)
        if "groupPolicyInThread" in raw or "group_policy_in_thread" in raw:
            return raw
        values = dict(raw)
        values["group_policy_in_thread"] = values.get(
            "groupPolicy",
            values.get("group_policy", "mention"),
        )
        return values


def _server_url_to_ws_url(server_url: str) -> str:
    if server_url.startswith("https://"):
        return server_url.replace("https://", "wss://", 1) + "/api/v4/websocket"
    if server_url.startswith("http://"):
        return server_url.replace("http://", "ws://", 1) + "/api/v4/websocket"
    return server_url + "/api/v4/websocket"


class MattermostChannel(BaseChannel):
    """Mattermost channel using WebSocket + REST API."""

    name = "mattermost"
    display_name = "Mattermost"

    @classmethod
    def default_config(cls) -> dict[str, Any]:
        return MattermostConfig().model_dump(by_alias=True)

    def __init__(self, config: Any, bus: MessageBus):
        if isinstance(config, dict):
            config = MattermostConfig.model_validate(config)
        super().__init__(config, bus)
        self.config: MattermostConfig = config
        self._server_url = config.server_url.rstrip("/")
        self._ws_url = _server_url_to_ws_url(self._server_url)
        self._http_client: httpx.AsyncClient | None = None
        self._ws_task: asyncio.Task[None] | None = None
        self._self_id: str | None = None
        self._self_username: str | None = None
        self._usernames: dict[str, str] = {}
        self._user_emails: dict[str, str] = {}
        self._channel_types: dict[str, str] = {}
        self._channel_team_ids: dict[str, str] = {}
        self._stream_posts: dict[str, str] = {}
        self._stream_buffers: dict[str, str] = {}
        self._stream_last_content: dict[str, str] = {}
        self._stream_committed: dict[str, str] = {}
        self._stream_root_ids: dict[str, str] = {}
        self._thread_context_attempted: set[str] = set()

    # Lifecycle ----------------------------------------------------------------

    async def start(self) -> None:
        if not self.config.server_url or not self.config.token:
            self.logger.error("serverUrl and token must be configured")
            return

        if self._http_client is None:
            self._http_client = httpx.AsyncClient(
                base_url=self._server_url,
                headers={"Authorization": f"Bearer {self.config.token}"},
                timeout=30.0,
            )

        try:
            resp = await self._http_client.get("/api/v4/users/me")
            resp.raise_for_status()
            me = cast(dict[str, Any], resp.json())
            self._self_id = me.get("id")
            self._self_username = me.get("username")
            self.logger.info("bot @{} connected", self._self_username)
        except Exception as e:
            self.logger.error("Failed to identify bot user: {}", e)
            await self._cleanup_http()
            return

        self._running = True
        self._ws_task = asyncio.create_task(self._ws_listen_loop())
        try:
            await self._ws_task
        finally:
            self._ws_task = None

    async def stop(self) -> None:
        self._running = False
        task = self._ws_task
        if task and task is not asyncio.current_task():
            task.cancel()
            try:
                await task
            except asyncio.CancelledError:
                pass
            self._ws_task = None
        await self._cleanup_http()

    async def _cleanup_http(self) -> None:
        if self._http_client:
            await self._http_client.aclose()
            self._http_client = None

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

    async def _ws_listen_loop(self) -> None:
        import websockets

        delay = MATTERMOST_WS_RECONNECT_BASE_DELAY
        while self._running:
            try:
                async with websockets.connect(
                    self._ws_url,
                    additional_headers={"Authorization": f"Bearer {self.config.token}"},
                    ping_interval=20,
                    ping_timeout=10,
                ) as ws:
                    self.logger.debug("websocket connected")
                    delay = MATTERMOST_WS_RECONNECT_BASE_DELAY
                    async for raw in ws:
                        await self._handle_ws_message(cast(dict[str, Any], json.loads(raw)))
            except asyncio.CancelledError:
                break
            except Exception as e:
                if not self._running:
                    break
                self.logger.warning("websocket error: {} (reconnect in {}s)", e, delay)
                await asyncio.sleep(delay)
                delay = min(delay * 2, MATTERMOST_WS_RECONNECT_MAX_DELAY)

    async def _handle_ws_message(self, msg: dict[str, Any]) -> None:
        event = msg.get("event", "")
        if event == "posted":
            await self._handle_posted_event(msg)
        elif event == "action":
            await self._handle_action_event(msg)
        elif event == "post_deleted":
            await self._handle_post_deleted_event(msg)

    # Event: posted ------------------------------------------------------------

    async def _handle_posted_event(self, msg: dict[str, Any]) -> None:
        data = cast(dict[str, Any], msg.get("data", {}))
        broadcast = cast(dict[str, Any], msg.get("broadcast", {}))

        raw_post = data.get("post", "{}")
        try:
            post = cast(
                dict[str, Any],
                json.loads(raw_post) if isinstance(raw_post, str) else raw_post,
            )
        except json.JSONDecodeError:
            self.logger.warning("failed to parse post json")
            return

        post_type = post.get("type")
        if isinstance(post_type, str) and post_type.startswith("system_"):
            return

        sender_id = post.get("user_id", "")
        channel_id = post.get("channel_id", "")
        message_text = post.get("message", "")
        root_id = post.get("root_id", "") or ""
        post_id = post.get("id", "")
        file_ids = cast(list[str], post.get("file_ids", []))

        if self._self_id and sender_id == self._self_id:
            return
        if not sender_id or not channel_id:
            return

        channel_type_code = data.get("channel_type", "")
        channel_type = _CHANNEL_TYPES.get(channel_type_code, "public")
        is_dm = channel_type == "dm"

        team_id = broadcast.get("team_id", "")
        if self.config.team_id and not is_dm:
            if not team_id:
                team_id = await self.resolve_channel_team_id(channel_id)
            if team_id != self.config.team_id:
                return

        if not await self._is_allowed(sender_id, channel_id, channel_type):
            if is_dm and self.config.dm.enabled:
                code = generate_code(self.name, str(sender_id))
                await self.send(
                    OutboundMessage(
                        channel=self.name,
                        chat_id=str(channel_id),
                        content=format_pairing_reply(code),
                        metadata={PAIRING_CODE_META_KEY: code},
                    )
                )
                self.logger.info(
                    "Sent pairing code {} to sender {} in chat {}",
                    code, sender_id, channel_id,
                )
            return

        if not is_dm:
            in_thread = bool(root_id)
            if not self._should_respond_in_channel(message_text, channel_id, in_thread=in_thread):
                return

        message_text = self._strip_bot_mention(message_text)

        thread_ts = root_id if root_id else None
        if self.config.reply_in_thread and not thread_ts and not is_dm:
            thread_ts = post_id
        session_key = f"mattermost:{channel_id}:{thread_ts}" if thread_ts else None

        try:
            await self._add_reaction(channel_id, post_id, self.config.react_emoji)
        except Exception:
            self.logger.debug("add reaction failed")

        media_paths: list[str] = []
        for fid in file_ids:
            path = await self._download_file(fid)
            if path:
                media_paths.append(path)

        content = message_text
        if root_id and self.config.include_thread_context:
            content = await self._with_thread_context(
                content, channel_id=channel_id, root_id=root_id,
            )

        mm_meta: dict[str, Any] = {
            "post_id": post_id,
            "root_id": root_id,
            "channel_type": channel_type,
        }
        if thread_ts:
            mm_meta["thread_ts"] = thread_ts

        await self._handle_message(
            sender_id=sender_id,
            chat_id=channel_id,
            content=content,
            media=media_paths,
            metadata={
                "mattermost": mm_meta,
                "message_id": post_id,
            },
            session_key=session_key,
            is_dm=is_dm,
        )

    # Event: action ------------------------------------------------------------

    async def _handle_action_event(self, msg: dict[str, Any]) -> None:
        data = cast(dict[str, Any], msg.get("data", {}))
        sender_id = data.get("user_id", "")
        channel_id = data.get("channel_id", "")
        context = cast(dict[str, Any], data.get("context", {}) or {})
        value = cast(str, context.get("selected_option", ""))

        if not sender_id or not channel_id or not value:
            return

        channel_type = await self.resolve_channel_type(channel_id)
        if self.config.team_id and channel_type != "dm":
            team_id = await self.resolve_channel_team_id(channel_id)
            if team_id != self.config.team_id:
                return
        if not await self._is_allowed(sender_id, channel_id, channel_type):
            return

        await self._handle_message(
            sender_id=sender_id,
            chat_id=channel_id,
            content=value,
            metadata={"mattermost": {"channel_type": channel_type, "is_action": True}},
        )

    # Event: post_deleted ------------------------------------------------------

    async def _handle_post_deleted_event(self, msg: dict[str, Any]) -> None:
        data = cast(dict[str, Any], msg.get("data", {}))
        raw_post = data.get("post", "{}")
        try:
            post = cast(
                dict[str, Any],
                json.loads(raw_post) if isinstance(raw_post, str) else raw_post,
            )
        except json.JSONDecodeError:
            return
        post_id = post.get("id", "")
        if not post_id:
            return
        to_remove = [sid for sid, pid in self._stream_posts.items() if pid == post_id]
        for sid in to_remove:
            self._stream_posts.pop(sid, None)
            self._stream_buffers.pop(sid, None)
            self._stream_last_content.pop(sid, None)
            self._stream_committed.pop(sid, None)

    # Permission / policy ------------------------------------------------------

    def is_allowed(self, sender_id: str) -> bool:
        return True

    async def _is_allowed(self, sender_id: str, chat_id: str, channel_type: str) -> bool:
        if channel_type == "dm":
            if not self.config.dm.enabled:
                return False
            if is_approved(self.name, str(sender_id)):
                return True
            if self.config.dm.policy == "allowlist":
                return await self._match_sender(sender_id, self.config.dm.allow_from)
            return True

        if self.config.group_policy == "allowlist":
            return chat_id in self.config.group_allow_from
        return True

    def _should_respond_in_channel(
        self, text: str, chat_id: str, *, in_thread: bool = False,
    ) -> bool:
        policy = (
            self.config.group_policy_in_thread if in_thread
            else self.config.group_policy
        )
        if policy == "open":
            return True
        if policy == "mention":
            return self._is_mentioned(text)
        if policy == "allowlist":
            return chat_id in self.config.group_allow_from
        return False

    _bot_mention_re: re.Pattern[str] | None = None

    def _is_mentioned(self, text: str) -> bool:
        if not self._self_username:
            return False
        if self._bot_mention_re is None:
            pat = r"(?<![@\w])@" + re.escape(self._self_username) + r"(?![@\w])"
            self._bot_mention_re = re.compile(pat)
        return bool(self._bot_mention_re.search(text))

    def _strip_bot_mention(self, text: str) -> str:
        if not text or not self._self_username:
            return text
        return re.sub(rf"@{re.escape(self._self_username)}\s*", "", text).strip()

    async def _match_sender(self, sender_id: str, allow_list: list[str]) -> bool:
        if not allow_list:
            return False
        if "*" in allow_list:
            return True
        mode = self.config.allow_from_match_mode
        if mode == "id":
            return sender_id in allow_list
        if mode == "username":
            username = await self._resolve_username(sender_id)
            return username in allow_list if username else False
        if mode == "email":
            email = await self._resolve_email(sender_id)
            return email in allow_list if email else False
        return False

    async def _resolve_username(self, user_id: str) -> str | None:
        if user_id in self._usernames:
            return self._usernames[user_id]
        try:
            user = await self._api_get(f"/api/v4/users/{user_id}")
            self._usernames[user_id] = user.get("username", "")
            return self._usernames[user_id]
        except Exception as e:
            self.logger.warning("failed to resolve username for {}: {}", user_id, e)
            return None

    async def _resolve_email(self, user_id: str) -> str | None:
        if user_id in self._user_emails:
            return self._user_emails[user_id]
        try:
            user = await self._api_get(f"/api/v4/users/{user_id}")
            self._user_emails[user_id] = user.get("email", "").lower()
            return self._user_emails[user_id]
        except Exception as e:
            self.logger.warning("failed to resolve email for {}: {}", user_id, e)
            return None

    # Thread context -----------------------------------------------------------

    async def _with_thread_context(self, text: str, *, channel_id: str, root_id: str) -> str:
        key = f"{channel_id}:{root_id}"
        if key in self._thread_context_attempted:
            return text
        self._thread_context_attempted.add(key)

        try:
            data = await self._api_get(
                f"/api/v4/posts/{root_id}/thread?perPage={max(1, self.config.thread_context_limit)}",
            )
        except Exception as e:
            self.logger.warning("thread context unavailable for {}: {}", key, e)
            return text

        posts = cast(dict[str, dict[str, Any]], data.get("posts", {}))
        order = cast(list[str], data.get("order", []))
        if not order:
            return text

        lines: list[str] = []
        for pid in order:
            post = posts.get(pid, {})
            if post.get("id") == root_id:
                continue
            if post.get("user_id") == self._self_id:
                label = "bot"
            else:
                label = f"<{post.get('user_id', 'unknown')}>"
            msg_text = (post.get("message", "") or "").strip()
            if not msg_text:
                continue
            if len(msg_text) > 500:
                msg_text = msg_text[:500] + "\u2026"
            lines.append(f"- {label}: {msg_text}")

        if not lines:
            return text
        return "Mattermost thread context before this mention:\n" + "\n".join(lines) + f"\n\nCurrent message:\n{text}"

    # Send ---------------------------------------------------------------------

    async def send(self, msg: OutboundMessage) -> None:
        if not self._http_client:
            self.logger.warning("client not initialized")
            return

        try:
            chat_id = msg.chat_id
            meta = msg.metadata or {}
            mm_meta = cast(dict[str, Any], meta.get("mattermost", {}) or {})
            root_id = cast(
                str | None,
                mm_meta.get("root_id") or mm_meta.get("thread_ts") or meta.get("root_id"),
            )

            file_ids: list[str] = []
            for media_path in msg.media or []:
                try:
                    fid = await self._upload_file(chat_id, media_path)
                    if fid:
                        file_ids.append(fid)
                except Exception:
                    self.logger.exception("Failed to upload file {}", media_path)

            if msg.content or file_ids:
                text = msg.content or " "
                chunks = split_message(text, MATTERMOST_MAX_MESSAGE_LEN)
                for i, chunk in enumerate(chunks):
                    await self._create_post(
                        chat_id, chunk,
                        root_id=root_id if self.config.reply_in_thread else None,
                        file_ids=(file_ids if i == 0 else None) or None,
                    )

            if not meta.get("_progress") and meta.get("message_id"):
                try:
                    await self._remove_reaction(meta["message_id"], self.config.react_emoji)
                except Exception:
                    self.logger.debug("remove reaction failed")
                if self.config.done_emoji:
                    try:
                        await self._add_reaction(chat_id, meta["message_id"], self.config.done_emoji)
                    except Exception:
                        self.logger.debug("done reaction failed")

        except Exception:
            self.logger.exception("Error sending message")
            raise

    # Streaming -----------------------------------------------------------------

    async def send_delta(
        self,
        chat_id: str,
        delta: str,
        metadata: dict[str, Any] | None = None,
        *,
        stream_id: str | None = None,
        stream_end: bool = False,
        resuming: bool = False,
        merge_next: bool = False,
    ) -> None:
        if not self._http_client:
            return

        meta = metadata or {}
        stream_id = cast(str, stream_id or meta.get("_stream_id") or chat_id)
        stream_end = stream_end or bool(meta.get("_stream_end"))
        resuming = resuming or bool(meta.get("_resuming"))

        if stream_end:
            committed = self._stream_committed.get(stream_id, "")
            buf = self._stream_buffers.get(stream_id, "")
            final = committed or buf
            if delta:
                final += delta

            if resuming:
                if merge_next:
                    self._stream_buffers[stream_id] = final
                    self._stream_committed[stream_id] = final
                else:
                    self._clear_stream_state(stream_id)
                return

            if final and not meta.get("_progress"):
                mm_meta = (
                    cast(dict[str, Any], meta.get("mattermost", {}) or {})
                    if isinstance(meta.get("mattermost"), dict)
                    else {}
                )
                root_id = cast(str | None, (
                    mm_meta.get("root_id")
                    or mm_meta.get("thread_ts")
                    or meta.get("root_id")
                    or self._stream_root_ids.get(stream_id)
                ))
                chunks = split_message(final, MATTERMOST_MAX_MESSAGE_LEN)
                first_post_id: str | None = None
                try:
                    for chunk in chunks:
                        post = await self._create_post(
                            chat_id, chunk,
                            root_id=root_id if self.config.reply_in_thread else None,
                        )
                        if first_post_id is None:
                            first_post_id = post.get("id")
                except Exception:
                    self.logger.exception("stream final post failed")
                    raise

                if meta.get("message_id"):
                    try:
                        await self._remove_reaction(meta["message_id"], self.config.react_emoji)
                    except Exception:
                        self.logger.debug("remove reaction failed")
                if first_post_id and self.config.done_emoji:
                    try:
                        await self._add_reaction(chat_id, first_post_id, self.config.done_emoji)
                    except Exception:
                        self.logger.debug("done reaction failed")

            self._clear_stream_state(stream_id)
            return

        if not delta.strip():
            return

        mm_meta = (
            cast(dict[str, Any], meta.get("mattermost", {}) or {})
            if isinstance(meta.get("mattermost"), dict)
            else {}
        )
        root_id = cast(
            str | None,
            mm_meta.get("root_id") or mm_meta.get("thread_ts") or meta.get("root_id"),
        )
        if root_id:
            self._stream_root_ids[stream_id] = root_id
        committed = self._stream_committed.get(stream_id, "")
        buf = committed + delta
        self._stream_buffers[stream_id] = buf
        self._stream_committed[stream_id] = buf
        return

    def _clear_stream_state(self, stream_id: str) -> None:
        self._stream_root_ids.pop(stream_id, None)
        self._stream_posts.pop(stream_id, None)
        self._stream_buffers.pop(stream_id, None)
        self._stream_last_content.pop(stream_id, None)
        self._stream_committed.pop(stream_id, None)

    # API helpers ---------------------------------------------------------------

    def _require_http_client(self) -> httpx.AsyncClient:
        if self._http_client is None:
            raise RuntimeError("Mattermost client is not started")
        return self._http_client

    async def _api_get(self, path: str) -> dict[str, Any]:
        resp = await self._require_http_client().get(path)
        resp.raise_for_status()
        return cast(dict[str, Any], resp.json())

    async def _api_post(self, path: str, json_data: dict[str, Any]) -> dict[str, Any]:
        resp = await self._require_http_client().post(path, json=json_data)
        resp.raise_for_status()
        return cast(dict[str, Any], resp.json())

    async def _create_post(
        self,
        channel_id: str,
        message: str,
        *,
        root_id: str | None = None,
        file_ids: list[str] | None = None,
    ) -> dict[str, Any]:
        body: dict[str, Any] = {
            "channel_id": channel_id,
            "message": message,
        }
        if root_id:
            body["root_id"] = root_id
        if file_ids:
            body["file_ids"] = file_ids
        return await self._api_post("/api/v4/posts", body)

    async def _upload_file(self, channel_id: str, file_path: str) -> str | None:
        path = Path(file_path)
        if not path.exists():
            self.logger.warning("file not found: {}", file_path)
            return None

        try:
            files = {"files": (path.name, path.read_bytes())}
            resp = await self._require_http_client().post(
                "/api/v4/files",
                data={"channel_id": channel_id},
                files=files,
            )
            resp.raise_for_status()
            data = cast(dict[str, Any], resp.json())
            infos = cast(list[dict[str, Any]], data.get("file_infos", []))
            if infos:
                return infos[0].get("id")
        except Exception as e:
            self.logger.warning("file upload failed for {}: {}", file_path, e)
        return None

    async def _download_file(self, file_id: str) -> str | None:
        try:
            client = self._require_http_client()
            info_resp = await client.get(f"/api/v4/files/{file_id}/info")
            info_resp.raise_for_status()
            info = cast(dict[str, Any], info_resp.json())
            name = Path(info.get("name", file_id)).name
            out = Path(get_media_dir("mattermost")) / safe_filename(f"{file_id}_{name}")
            out.parent.mkdir(parents=True, exist_ok=True)

            dl = await client.get(f"/api/v4/files/{file_id}")
            dl.raise_for_status()
            out.write_bytes(dl.content)
            return str(out)
        except Exception as e:
            self.logger.warning("file download failed for {}: {}", file_id, e)
            return None

    async def _add_reaction(self, channel_id: str, post_id: str, emoji: str) -> None:
        if not self._self_id or not emoji:
            return
        await self._api_post("/api/v4/reactions", {
            "user_id": self._self_id,
            "post_id": post_id,
            "emoji_name": emoji,
        })

    async def _remove_reaction(self, post_id: str, emoji: str) -> None:
        if not self._self_id or not emoji:
            return
        resp = await self._require_http_client().delete(
            f"/api/v4/users/{self._self_id}/posts/{post_id}/reactions/{emoji}",
        )
        if resp.status_code >= 400:
            self.logger.debug("remove reaction failed: {} {}", resp.status_code, resp.text)

    async def resolve_channel_type(self, channel_id: str) -> str:
        if channel_id in self._channel_types:
            return self._channel_types[channel_id]
        try:
            data = await self._api_get(f"/api/v4/channels/{channel_id}")
            ctype = _CHANNEL_TYPES.get(data.get("type", ""), "public")
            self._channel_types[channel_id] = ctype
            if "team_id" in data:
                self._channel_team_ids[channel_id] = data.get("team_id", "") or ""
            return ctype
        except Exception:
            return "public"

    async def resolve_channel_team_id(self, channel_id: str) -> str:
        if channel_id in self._channel_team_ids:
            return self._channel_team_ids[channel_id]
        try:
            data = await self._api_get(f"/api/v4/channels/{channel_id}")
            team_id = data.get("team_id", "") or ""
            self._channel_team_ids[channel_id] = team_id
            if "type" in data:
                self._channel_types[channel_id] = _CHANNEL_TYPES.get(data.get("type", ""), "public")
            return team_id
        except Exception:
            return ""