# chat/consumers.py
import json

from channels.db import database_sync_to_async
from channels.generic.websocket import AsyncWebsocketConsumer
from django.utils import timezone

from .models import Chat, ChatReadStatus, Message


class ChatConsumer(AsyncWebsocketConsumer):

    # -- CONNECT --

    async def connect(self):
        self.chat_id = self.scope["url_route"]["kwargs"]["chat_id"]
        self.chat_name = f"chat_{self.chat_id}"
        user = self.scope["user"]

        if not user.is_authenticated:
            await self.close(code=4401)
            return

        is_member = await _is_chat_member(self.chat_id, user)
        if not is_member:
            await self.close(code=4403)
            return

        await self.channel_layer.group_add(self.chat_name, self.channel_name)
        await self.accept()

    # -- DISCONNECT --

    async def disconnect(self, close_code):
        await self.channel_layer.group_discard(self.chat_name, self.channel_name)

    # -- RECEIVE --

    async def receive(self, text_data):
        data = json.loads(text_data)
        user = self.scope["user"]
        msg_type = data.get("type")

        if msg_type == "new_chat_message":
            message = await _create_message(
                chat_id=self.chat_id,
                sender=user,
                content=data["message"],
            )
            await self.channel_layer.group_send(self.chat_name, {
                "type": "chat.message",
                "message_id": message.id,
                "message": message.content,
                "sender_id": user.id,
                "sender": user.username,
                "sender_avatar": user.avatar.url if user.avatar else None,
            })

        elif msg_type == "new_reply_chat_message":
            message = await _create_message(
                chat_id=self.chat_id,
                sender=user,
                content=data["message"],
                reply_to_id=data.get("reply_to_id"),
            )
            await self.channel_layer.group_send(self.chat_name, {
                "type": "reply.chat.message",
                "message_id": message.id,
                "message": message.content,
                "reply_to_id": data.get("reply_to_id"),
                "sender_id": user.id,
                "sender": user.username,
                "sender_avatar": user.avatar.url if user.avatar else None,
            })

        elif msg_type == "reaction":
            action, reaction = await _toggle_reaction(
                message_id=data["message_id"],
                user=user,
                emoji=data["emoji"],
            )
            await self.channel_layer.group_send(self.chat_name, {
                "type": "message.reaction",
                "message_id": data["message_id"],
                "emoji": data["emoji"],
                "user": user.username,
                "action": action,  # 'added' | 'removed' | 'switched'
            })

        elif msg_type == "typing":
            await self.channel_layer.group_send(self.chat_name, {
                "type": "typing.status",
                "user": user.username,
                "is_typing": data.get("is_typing", True),
            })

        elif msg_type == "stop_typing":
            await self.channel_layer.group_send(self.chat_name, {
                "type": "stop.typing",
                "user": user.username,
            })

        elif msg_type == "mark_read":
            await _mark_read(chat_id=self.chat_id, user=user)
            await self.channel_layer.group_send(self.chat_name, {
                "type": "read.status",
                "user": user.username,
                "chat_id": int(self.chat_id),
            })

        else:
            await self.send(text_data=json.dumps({"error": "Unsupported message type."}))

    # -- GROUP EVENT HANDLERS --
    # These are called by the channel layer when another part of the system
    # (consumer or view) calls group_send.

    async def chat_message(self, event):
        await self.send(text_data=json.dumps({
            "type": "new_chat_message",
            "message_id": event["message_id"],
            "message": event["message"],
            "sender_id": event["sender_id"],
            "sender": event["sender"],
            "sender_avatar": event["sender_avatar"],
        }))

    async def reply_chat_message(self, event):
        await self.send(text_data=json.dumps({
            "type": "new_reply_chat_message",
            "message_id": event["message_id"],
            "message": event["message"],
            "reply_to_id": event["reply_to_id"],
            "sender_id": event["sender_id"],
            "sender": event["sender"],
            "sender_avatar": event["sender_avatar"],
        }))

    async def edit_message(self, event):
        await self.send(text_data=json.dumps({
            "type": "edit_chat_message",
            "message_id": event["message_id"],
            "content": event["content"],
            "is_edited": event.get("is_edited", True),
        }))

    async def delete_message(self, event):
        await self.send(text_data=json.dumps({
            "type": "delete_chat_message",
            "message_id": event["message_id"],
        }))

    async def message_reaction(self, event):
        await self.send(text_data=json.dumps({
            "type": "reaction",
            "message_id": event["message_id"],
            "emoji": event["emoji"],
            "user": event["user"],
            "action": event["action"],
        }))

    async def typing_status(self, event):
        await self.send(text_data=json.dumps({
            "type": "typing",
            "user": event["user"],
            "is_typing": event["is_typing"],
        }))

    async def stop_typing(self, event):
        await self.send(text_data=json.dumps({
            "type": "stop_typing",
            "user": event["user"],
        }))

    async def read_status(self, event):
        await self.send(text_data=json.dumps({
            "type": "read_status",
            "user": event["user"],
            "chat_id": event["chat_id"],
        }))


# ---------------------------------------------------------------------------
# DB helpers (run in thread pool via database_sync_to_async)
# ---------------------------------------------------------------------------

@database_sync_to_async
def _is_chat_member(chat_id, user):
    from django.db.models import Q
    return Chat.objects.filter(Q(pk=chat_id), Q(members=user) | Q(owner=user)).exists()


@database_sync_to_async
def _create_message(chat_id, sender, content, reply_to_id=None):
    return Message.objects.create(
        chat_id=chat_id,
        sender=sender,
        content=content,
        reply_to_id=reply_to_id,
    )


@database_sync_to_async
def _toggle_reaction(message_id, user, emoji):
    message = Message.objects.get(pk=message_id)
    return message.toggle_reaction(user, emoji)


@database_sync_to_async
def _mark_read(chat_id, user):
    ChatReadStatus.objects.update_or_create(
        user=user,
        chat_id=chat_id,
        defaults={"last_read_at": timezone.now()},
    )