moderation: add chat bans for groups/channels with web actions

app/chats/models.py

@@ -108,3 +108,14 @@ class ChatInviteLink(Base):
     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)
+
+
+class ChatBan(Base):
+    __tablename__ = "chat_bans"
+    __table_args__ = (UniqueConstraint("chat_id", "user_id", name="uq_chat_bans_chat_user"),)
+
+    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)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
+    banned_by_user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=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, ChatInviteLink, ChatMember, ChatMemberRole, ChatNotificationSetting, ChatType, ChatUserSetting
+from app.chats.models import Chat, ChatBan, ChatInviteLink, ChatMember, ChatMemberRole, ChatNotificationSetting, ChatType, ChatUserSetting
 from app.messages.models import Message, MessageHidden, MessageReceipt
 
 
@@ -401,3 +401,31 @@ async def get_active_chat_invite_by_token(db: AsyncSession, *, token: str) -> Ch
         .limit(1)
     )
     return result.scalar_one_or_none()
+
+
+async def get_chat_ban(db: AsyncSession, *, chat_id: int, user_id: int) -> ChatBan | None:
+    result = await db.execute(select(ChatBan).where(ChatBan.chat_id == chat_id, ChatBan.user_id == user_id))
+    return result.scalar_one_or_none()
+
+
+async def is_user_banned_in_chat(db: AsyncSession, *, chat_id: int, user_id: int) -> bool:
+    result = await db.execute(select(ChatBan.id).where(ChatBan.chat_id == chat_id, ChatBan.user_id == user_id).limit(1))
+    return result.scalar_one_or_none() is not None
+
+
+async def upsert_chat_ban(db: AsyncSession, *, chat_id: int, user_id: int, banned_by_user_id: int) -> ChatBan:
+    existing = await get_chat_ban(db, chat_id=chat_id, user_id=user_id)
+    if existing:
+        existing.banned_by_user_id = banned_by_user_id
+        await db.flush()
+        return existing
+    ban = ChatBan(chat_id=chat_id, user_id=user_id, banned_by_user_id=banned_by_user_id)
+    db.add(ban)
+    await db.flush()
+    return ban
+
+
+async def remove_chat_ban(db: AsyncSession, *, chat_id: int, user_id: int) -> None:
+    ban = await get_chat_ban(db, chat_id=chat_id, user_id=user_id)
+    if ban:
+        await db.delete(ban)

app/chats/router.py

@@ -21,6 +21,7 @@ from app.chats.schemas import (
 )
 from app.chats.service import (
     add_chat_member_for_user,
+    ban_chat_member_for_user,
     create_chat_for_user,
     create_chat_invite_link_for_user,
     clear_chat_for_user,
@@ -39,6 +40,7 @@ from app.chats.service import (
     serialize_chats_for_user,
     set_chat_archived_for_user,
     set_chat_pinned_for_user,
+    unban_chat_member_for_user,
     update_chat_member_role_for_user,
     update_chat_notification_settings_for_user,
     update_chat_profile_for_user,
@@ -207,6 +209,29 @@ async def remove_chat_member(
     await realtime_gateway.publish_chat_updated(chat_id=chat_id)
 
 
+@router.post("/{chat_id}/bans/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def ban_chat_member(
+    chat_id: int,
+    user_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> None:
+    await ban_chat_member_for_user(db, chat_id=chat_id, actor_user_id=current_user.id, target_user_id=user_id)
+    realtime_gateway.remove_chat_subscription(chat_id=chat_id, user_id=user_id)
+    await realtime_gateway.publish_chat_updated(chat_id=chat_id)
+
+
+@router.delete("/{chat_id}/bans/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def unban_chat_member(
+    chat_id: int,
+    user_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> None:
+    await unban_chat_member_for_user(db, chat_id=chat_id, actor_user_id=current_user.id, target_user_id=user_id)
+    await realtime_gateway.publish_chat_updated(chat_id=chat_id)
+
+
 @router.post("/{chat_id}/leave", status_code=status.HTTP_204_NO_CONTENT)
 async def leave_chat(
     chat_id: int,

app/chats/service.py

@@ -350,6 +350,8 @@ async def add_chat_member_for_user(
     chat, membership = await _get_chat_and_membership(db, chat_id=chat_id, user_id=actor_user_id)
     _ensure_group_or_channel(chat.type)
     _ensure_manage_permission(membership.role)
+    if await repository.is_user_banned_in_chat(db, chat_id=chat_id, user_id=target_user_id):
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="User is banned from this chat")
     if target_user_id == actor_user_id:
         raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="User is already in chat")
     target_user = await get_user_by_id(db, target_user_id)
@@ -427,6 +429,45 @@ async def remove_chat_member_for_user(
     await db.commit()
 
 
+async def ban_chat_member_for_user(
+    db: AsyncSession,
+    *,
+    chat_id: int,
+    actor_user_id: int,
+    target_user_id: int,
+) -> None:
+    chat, actor_membership = await _get_chat_and_membership(db, chat_id=chat_id, user_id=actor_user_id)
+    _ensure_group_or_channel(chat.type)
+    if actor_membership.role not in {ChatMemberRole.OWNER, ChatMemberRole.ADMIN}:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Insufficient permissions")
+    if target_user_id == actor_user_id:
+        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="Cannot ban yourself")
+    target_membership = await repository.get_chat_member(db, chat_id=chat_id, user_id=target_user_id)
+    if target_membership:
+        if target_membership.role == ChatMemberRole.OWNER:
+            raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="Owner cannot be banned")
+        if actor_membership.role == ChatMemberRole.ADMIN and target_membership.role != ChatMemberRole.MEMBER:
+            raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin can ban only members")
+        await repository.delete_chat_member(db, target_membership)
+    await repository.upsert_chat_ban(db, chat_id=chat_id, user_id=target_user_id, banned_by_user_id=actor_user_id)
+    await db.commit()
+
+
+async def unban_chat_member_for_user(
+    db: AsyncSession,
+    *,
+    chat_id: int,
+    actor_user_id: int,
+    target_user_id: int,
+) -> None:
+    chat, actor_membership = await _get_chat_and_membership(db, chat_id=chat_id, user_id=actor_user_id)
+    _ensure_group_or_channel(chat.type)
+    if actor_membership.role not in {ChatMemberRole.OWNER, ChatMemberRole.ADMIN}:
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Insufficient permissions")
+    await repository.remove_chat_ban(db, chat_id=chat_id, user_id=target_user_id)
+    await db.commit()
+
+
 async def leave_chat_for_user(db: AsyncSession, *, chat_id: int, user_id: int) -> None:
     chat, membership = await _get_chat_and_membership(db, chat_id=chat_id, user_id=user_id)
     _ensure_group_or_channel(chat.type)
@@ -514,6 +555,8 @@ async def join_public_chat_for_user(db: AsyncSession, *, chat_id: int, user_id:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Chat not found")
     if not chat.is_public or chat.type not in {ChatType.GROUP, ChatType.CHANNEL}:
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Chat is not joinable")
+    if await repository.is_user_banned_in_chat(db, chat_id=chat_id, user_id=user_id):
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="You are banned from this chat")
     membership = await repository.get_chat_member(db, chat_id=chat_id, user_id=user_id)
     if membership:
         return chat
@@ -650,6 +693,8 @@ async def join_chat_by_invite_for_user(
         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")
+    if await repository.is_user_banned_in_chat(db, chat_id=chat.id, user_id=user_id):
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="You are banned from this chat")
     membership = await repository.get_chat_member(db, chat_id=chat.id, user_id=user_id)
     if membership:
         return chat