Milestone 3

backend/app/services/invitations.py

@@ -0,0 +1,188 @@
+"""Invitation flow: admin issues a one-shot URL token, invitee accepts.
+
+The raw token is shown to the admin once (returned by `create_invitation`)
+and never persisted — only its SHA-256 lives in the DB. Pre-assigned groups
+are attached at creation and applied at acceptance.
+"""
+
+from __future__ import annotations
+
+import uuid
+from dataclasses import dataclass
+from datetime import datetime, timedelta, timezone
+from typing import Iterable
+
+from sqlalchemy import select
+
+from app.core.security import (
+    generate_opaque_token,
+    hash_opaque_token,
+    hash_password,
+)
+from app.db.session import session_scope
+from app.models.auth import Group, Invitation, InvitationGroup, User, UserGroup
+
+INVITATION_TTL = timedelta(days=7)
+
+
+class InvitationError(Exception):
+    pass
+
+
+class InvitationExpired(InvitationError):
+    pass
+
+
+class InvitationConsumed(InvitationError):
+    pass
+
+
+class InvitationRevoked(InvitationError):
+    pass
+
+
+@dataclass
+class InvitationCreated:
+    invitation_id: uuid.UUID
+    raw_token: str
+    expires_at: datetime
+
+
+@dataclass
+class InvitationPreview:
+    email_hint: str | None
+    expires_at: datetime
+    groups: list[str]
+    is_valid: bool
+    reason: str | None
+
+
+def _now() -> datetime:
+    return datetime.now(tz=timezone.utc)
+
+
+def create_invitation(
+    *,
+    created_by_user_id: uuid.UUID,
+    email_hint: str | None,
+    group_ids: Iterable[uuid.UUID] = (),
+    ttl: timedelta = INVITATION_TTL,
+) -> InvitationCreated:
+    raw = generate_opaque_token()
+    expires_at = _now() + ttl
+    with session_scope() as s:
+        inv = Invitation(
+            token_hash=hash_opaque_token(raw),
+            email_hint=email_hint.strip().lower() if email_hint else None,
+            created_by_user_id=created_by_user_id,
+            expires_at=expires_at,
+        )
+        s.add(inv)
+        s.flush()
+        for gid in group_ids:
+            s.add(InvitationGroup(invitation_id=inv.id, group_id=gid))
+        return InvitationCreated(
+            invitation_id=inv.id,
+            raw_token=raw,
+            expires_at=expires_at,
+        )
+
+
+def _load_by_token(s, raw_token: str) -> Invitation | None:
+    return s.scalar(
+        select(Invitation).where(Invitation.token_hash == hash_opaque_token(raw_token))
+    )
+
+
+def preview(raw_token: str) -> InvitationPreview:
+    with session_scope() as s:
+        inv = _load_by_token(s, raw_token)
+        if inv is None:
+            return InvitationPreview(None, _now(), [], False, "not_found")
+        groups = [g.name for g in inv.pre_assigned_groups]
+        if inv.revoked_at is not None:
+            return InvitationPreview(inv.email_hint, inv.expires_at, groups, False, "revoked")
+        if inv.consumed_at is not None:
+            return InvitationPreview(inv.email_hint, inv.expires_at, groups, False, "consumed")
+        if inv.expires_at <= _now():
+            return InvitationPreview(inv.email_hint, inv.expires_at, groups, False, "expired")
+        return InvitationPreview(inv.email_hint, inv.expires_at, groups, True, None)
+
+
+def accept(raw_token: str, *, email: str, password: str, display_name: str | None) -> uuid.UUID:
+    """Create the user, attach pre-assigned groups, mark invitation consumed."""
+    if len(password) < 8:
+        raise ValueError("password must be at least 8 characters")
+
+    email_norm = email.strip().lower()
+    with session_scope() as s:
+        inv = _load_by_token(s, raw_token)
+        if inv is None:
+            raise InvitationError("invitation not found")
+        if inv.revoked_at is not None:
+            raise InvitationRevoked("invitation revoked")
+        if inv.consumed_at is not None:
+            raise InvitationConsumed("invitation already consumed")
+        if inv.expires_at <= _now():
+            raise InvitationExpired("invitation expired")
+
+        # Email must not be already in use among active users.
+        existing = s.scalar(
+            select(User).where(User.email == email_norm, User.deleted_at.is_(None))
+        )
+        if existing is not None:
+            raise ValueError("email already in use")
+
+        user = User(
+            email=email_norm,
+            display_name=(display_name or "").strip() or None,
+            password_hash=hash_password(password),
+        )
+        s.add(user)
+        s.flush()
+
+        for grp in inv.pre_assigned_groups:
+            s.add(UserGroup(user_id=user.id, group_id=grp.id))
+
+        inv.consumed_at = _now()
+        inv.consumed_by_user_id = user.id
+        return user.id
+
+
+def revoke(invitation_id: uuid.UUID) -> bool:
+    with session_scope() as s:
+        inv = s.get(Invitation, invitation_id)
+        if inv is None:
+            return False
+        if inv.revoked_at is not None or inv.consumed_at is not None:
+            return False
+        inv.revoked_at = _now()
+        return True
+
+
+def list_active(*, limit: int = 100) -> list[Invitation]:
+    with session_scope() as s:
+        rows = s.scalars(
+            select(Invitation)
+            .where(
+                Invitation.consumed_at.is_(None),
+                Invitation.revoked_at.is_(None),
+                Invitation.expires_at > _now(),
+            )
+            .order_by(Invitation.created_at.desc())
+            .limit(limit)
+        ).all()
+        # detach so caller can read after session closes
+        for r in rows:
+            s.expunge(r)
+            for g in r.pre_assigned_groups:
+                s.expunge(g)
+        return list(rows)
+
+
+def find_group_id_by_name(name: str) -> uuid.UUID | None:
+    with session_scope() as s:
+        gid = s.scalar(
+            select(Group.id).where(Group.name == name, Group.deleted_at.is_(None))
+        )
+        return gid