feat(invites): add group/channel invite links and join by token

app/chats/service.py

@@ -1,3 +1,5 @@
+import secrets
+
 from fastapi import HTTPException, status
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -8,12 +10,15 @@ from app.chats.schemas import (
     ChatCreateRequest,
     ChatDeleteRequest,
     ChatDiscoverRead,
+    ChatJoinByInviteRequest,
     ChatNotificationSettingsRead,
     ChatNotificationSettingsUpdate,
+    ChatInviteLinkRead,
     ChatPinMessageRequest,
     ChatRead,
     ChatTitleUpdateRequest,
 )
+from app.config.settings import settings
 from app.messages.repository import (
     delete_messages_in_chat,
     get_hidden_message,
@@ -517,3 +522,42 @@ async def set_chat_pinned_for_user(
     await db.commit()
     await db.refresh(chat)
     return chat
+
+
+async def create_chat_invite_link_for_user(
+    db: AsyncSession,
+    *,
+    chat_id: int,
+    user_id: int,
+) -> ChatInviteLinkRead:
+    chat, membership = await _get_chat_and_membership(db, chat_id=chat_id, user_id=user_id)
+    _ensure_group_or_channel(chat.type)
+    _ensure_manage_permission(membership.role)
+    token = secrets.token_urlsafe(18)
+    await repository.create_chat_invite_link(db, chat_id=chat_id, creator_user_id=user_id, token=token)
+    await db.commit()
+    invite_url = f"{settings.frontend_base_url.rstrip('/')}/join?token={token}"
+    return ChatInviteLinkRead(chat_id=chat_id, token=token, invite_url=invite_url)
+
+
+async def join_chat_by_invite_for_user(
+    db: AsyncSession,
+    *,
+    user_id: int,
+    payload: ChatJoinByInviteRequest,
+) -> Chat:
+    link = await repository.get_active_chat_invite_by_token(db, token=payload.token.strip())
+    if not link:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Invite link not found")
+    chat = await repository.get_chat_by_id(db, link.chat_id)
+    if not chat:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Chat not found")
+    if chat.type not in {ChatType.GROUP, ChatType.CHANNEL}:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Invite link is not valid for this chat")
+    membership = await repository.get_chat_member(db, chat_id=chat.id, user_id=user_id)
+    if membership:
+        return chat
+    await repository.add_chat_member(db, chat_id=chat.id, user_id=user_id, role=ChatMemberRole.MEMBER)
+    await db.commit()
+    await db.refresh(chat)
+    return chat