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

app/chats/models.py

@@ -93,3 +93,17 @@ class ChatUserSetting(Base):
         onupdate=func.now(),
         nullable=False,
     )
+
+
+class ChatInviteLink(Base):
+    __tablename__ = "chat_invite_links"
+    __table_args__ = (
+        UniqueConstraint("token", name="uq_chat_invite_links_token"),
+    )
+
+    id: Mapped[int] = mapped_column(primary_key=True, index=True)
+    chat_id: Mapped[int] = mapped_column(ForeignKey("chats.id", ondelete="CASCADE"), nullable=False, index=True)
+    creator_user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
+    token: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
+    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, server_default="true")
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)

app/chats/repository.py

@@ -2,7 +2,7 @@ from sqlalchemy import Select, String, func, or_, select
 from sqlalchemy.orm import aliased
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.chats.models import Chat, ChatMember, ChatMemberRole, ChatNotificationSetting, ChatType, ChatUserSetting
+from app.chats.models import Chat, ChatInviteLink, ChatMember, ChatMemberRole, ChatNotificationSetting, ChatType, ChatUserSetting
 from app.messages.models import Message, MessageHidden, MessageReceipt
 
 
@@ -320,3 +320,25 @@ async def upsert_chat_pinned_setting(
     db.add(setting)
     await db.flush()
     return setting
+
+
+async def create_chat_invite_link(
+    db: AsyncSession,
+    *,
+    chat_id: int,
+    creator_user_id: int,
+    token: str,
+) -> ChatInviteLink:
+    link = ChatInviteLink(chat_id=chat_id, creator_user_id=creator_user_id, token=token, is_active=True)
+    db.add(link)
+    await db.flush()
+    return link
+
+
+async def get_active_chat_invite_by_token(db: AsyncSession, *, token: str) -> ChatInviteLink | None:
+    result = await db.execute(
+        select(ChatInviteLink)
+        .where(ChatInviteLink.token == token, ChatInviteLink.is_active.is_(True))
+        .limit(1)
+    )
+    return result.scalar_one_or_none()

app/chats/router.py

@@ -7,6 +7,8 @@ from app.chats.schemas import (
     ChatDetailRead,
     ChatDiscoverRead,
     ChatDeleteRequest,
+    ChatInviteLinkRead,
+    ChatJoinByInviteRequest,
     ChatMemberAddRequest,
     ChatMemberRead,
     ChatMemberRoleUpdateRequest,
@@ -19,6 +21,7 @@ from app.chats.schemas import (
 from app.chats.service import (
     add_chat_member_for_user,
     create_chat_for_user,
+    create_chat_invite_link_for_user,
     clear_chat_for_user,
     delete_chat_for_user,
     discover_public_chats_for_user,
@@ -27,6 +30,7 @@ from app.chats.service import (
     get_chat_notification_settings_for_user,
     get_chats_for_user,
     join_public_chat_for_user,
+    join_chat_by_invite_for_user,
     leave_chat_for_user,
     pin_chat_message_for_user,
     remove_chat_member_for_user,
@@ -278,3 +282,22 @@ async def unpin_chat(
 ) -> ChatRead:
     chat = await set_chat_pinned_for_user(db, chat_id=chat_id, user_id=current_user.id, pinned=False)
     return await serialize_chat_for_user(db, user_id=current_user.id, chat=chat)
+
+
+@router.post("/{chat_id}/invite-link", response_model=ChatInviteLinkRead)
+async def create_invite_link(
+    chat_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> ChatInviteLinkRead:
+    return await create_chat_invite_link_for_user(db, chat_id=chat_id, user_id=current_user.id)
+
+
+@router.post("/join-by-invite", response_model=ChatRead)
+async def join_by_invite(
+    payload: ChatJoinByInviteRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> ChatRead:
+    chat = await join_chat_by_invite_for_user(db, user_id=current_user.id, payload=payload)
+    return await serialize_chat_for_user(db, user_id=current_user.id, chat=chat)

app/chats/schemas.py

@@ -87,3 +87,13 @@ class ChatNotificationSettingsRead(BaseModel):
 
 class ChatNotificationSettingsUpdate(BaseModel):
     muted: bool
+
+
+class ChatInviteLinkRead(BaseModel):
+    chat_id: int
+    token: str
+    invite_url: str
+
+
+class ChatJoinByInviteRequest(BaseModel):
+    token: str = Field(min_length=8, max_length=64)

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

app/database/models.py

@@ -1,5 +1,5 @@
 from app.auth.models import EmailVerificationToken, PasswordResetToken
-from app.chats.models import Chat, ChatMember, ChatUserSetting
+from app.chats.models import Chat, ChatInviteLink, ChatMember, ChatUserSetting
 from app.email.models import EmailLog
 from app.media.models import Attachment
 from app.messages.models import Message, MessageHidden, MessageIdempotencyKey, MessageReaction, MessageReceipt
@@ -9,6 +9,7 @@ from app.users.models import User
 __all__ = [
     "Attachment",
     "Chat",
+    "ChatInviteLink",
     "ChatMember",
     "ChatUserSetting",
     "EmailLog",