fix(users): require otp verification before google signup

apps/users/services/google_oauth.py

@@ -173,6 +173,32 @@ def _build_claim_required_payload(
     }
 
 
+def _create_user_and_social_account_from_google_profile(*, mobile: str, profile: GoogleProfile) -> User:
+    user = User.objects.create_user(
+        mobile=mobile,
+        password=None,
+        first_name=profile.first_name,
+        last_name=profile.last_name,
+        email=profile.email,
+        is_verified=True,
+        is_active=True,
+    )
+    user.set_unusable_password()
+    user.save(update_fields=["password"])
+    sync_user_from_google_profile(user, profile)
+
+    UserSocialAccount.objects.create(
+        user=user,
+        provider=UserSocialAccount.ProviderType.GOOGLE,
+        provider_user_id=profile.provider_user_id,
+        email=profile.email,
+        email_verified=profile.email_verified,
+        avatar_url=profile.avatar_url,
+        is_active=True,
+    )
+    return user
+
+
 def _build_public_google_flow_payload(flow_payload: dict[str, Any]) -> dict[str, Any]:
     status = flow_payload.get("status")
     if status == "authenticated":
@@ -410,32 +436,62 @@ def complete_google_signup(flow: str, mobile: str) -> dict[str, Any]:
         update_google_flow(flow, claim_payload)
         return _build_public_google_flow_payload(claim_payload)
 
-    user = User.objects.create_user(
-        mobile=normalized_mobile,
-        password=None,
-        first_name=profile.first_name,
-        last_name=profile.last_name,
-        email=profile.email,
-        is_verified=False,
-        is_active=True,
-    )
-    user.set_unusable_password()
-    user.save(update_fields=["password"])
-    sync_user_from_google_profile(user, profile)
+    generate_and_send_otp(normalized_mobile, "register")
+    signup_payload = {
+        "status": "claim_required",
+        "google_profile": _profile_to_payload(profile),
+        "mobile": normalized_mobile,
+        "user_id": None,
+        "resolution": "new_account",
+        "email": profile.email,
+        "mobile_hint": None,
+        "detail": "Verify this mobile number to finish creating your account with Google.",
+    }
+    update_google_flow(flow, signup_payload)
+    return _build_public_google_flow_payload(signup_payload)
 
-    UserSocialAccount.objects.create(
-        user=user,
-        provider=UserSocialAccount.ProviderType.GOOGLE,
-        provider_user_id=profile.provider_user_id,
-        email=profile.email,
-        email_verified=profile.email_verified,
-        avatar_url=profile.avatar_url,
-        is_active=True,
+
+def _verify_otp_code(*, mobile: str, code: str) -> None:
+    from django_redis import get_redis_connection
+
+    redis_conn = get_redis_connection("default")
+    stored_code = redis_conn.get(f"verification_code:{mobile}")
+    if not stored_code or stored_code.decode("utf-8") != code:
+        raise ValidationError({"code": "Invalid or expired verification code."})
+    redis_conn.delete(f"verification_code:{mobile}")
+
+
+def _create_new_google_user_after_otp(*, mobile: str, profile: GoogleProfile) -> User:
+    existing_email_user = _find_user_by_email(profile.email)
+    if existing_email_user is not None:
+        raise GoogleOAuthFlowError(
+            "This Google email is already attached to an existing account.",
+            "google_email_already_claimed",
+            extra={"mobile_hint": mask_mobile(existing_email_user.mobile)},
         )
 
-    authenticated_payload = build_authenticated_flow_payload(user)
-    update_google_flow(flow, authenticated_payload)
-    return authenticated_payload
+    existing_mobile_user = User.objects.filter(mobile=mobile).first()
+    if existing_mobile_user is not None:
+        existing_mobile_email = normalize_email_identity(existing_mobile_user.email)
+        if existing_mobile_email:
+            raise GoogleOAuthFlowError(
+                "This mobile number already belongs to another account with a different email address.",
+                "google_mobile_belongs_to_other_email",
+            )
+        raise GoogleOAuthFlowError(
+            "This mobile number is no longer available for creating a new Google account.",
+            "google_flow_invalid_state",
+            status_code=409,
+        )
+
+    existing_link = find_social_account_for_profile(profile)
+    if existing_link is not None:
+        raise GoogleOAuthFlowError(
+            "This Google account is already attached to another user.",
+            "google_email_already_claimed",
+        )
+
+    return _create_user_and_social_account_from_google_profile(mobile=mobile, profile=profile)
 
 
 def send_google_claim_otp(flow: str) -> dict[str, Any]:
@@ -446,13 +502,13 @@ def send_google_claim_otp(flow: str) -> dict[str, Any]:
     if not isinstance(mobile, str) or not mobile:
         raise _invalid_flow_error("Claim mobile number is missing.")
 
-    generate_and_send_otp(mobile, "login")
+    resolution = flow_payload.get("resolution")
+    otp_mode = "register" if resolution == "new_account" else "login"
+    generate_and_send_otp(mobile, otp_mode)
     return {"detail": "Verification code sent successfully."}
 
 
 def verify_google_claim(flow: str, code: str) -> dict[str, Any]:
-    from django_redis import get_redis_connection
-
     flow_payload = get_google_flow_payload(flow)
     _ensure_flow_status(flow_payload, "claim_required")
 
@@ -462,18 +518,19 @@ def verify_google_claim(flow: str, code: str) -> dict[str, Any]:
 
     profile = _profile_from_flow(flow_payload)
     user_id = flow_payload.get("user_id")
+    resolution = flow_payload.get("resolution")
+    _verify_otp_code(mobile=mobile, code=code)
+
+    if resolution == "new_account":
+        user = _create_new_google_user_after_otp(mobile=mobile, profile=profile)
+        authenticated_payload = build_authenticated_flow_payload(user)
+        update_google_flow(flow, authenticated_payload)
+        return authenticated_payload
+
     user = User.objects.filter(id=user_id, mobile=mobile).first()
     if not user:
         raise _invalid_flow_error("Target account could not be found.")
 
-    redis_conn = get_redis_connection("default")
-    stored_code = redis_conn.get(f"verification_code:{mobile}")
-    if not stored_code or stored_code.decode("utf-8") != code:
-        raise ValidationError({"code": "Invalid or expired verification code."})
-
-    redis_conn.delete(f"verification_code:{mobile}")
-
-    resolution = flow_payload.get("resolution")
     user_email = normalize_email_identity(user.email)
 
     if resolution == "existing_email_claim" and user_email != profile.email: