From c294f6fa425c47bb33581077848634a1143cedc0 Mon Sep 17 00:00:00 2001
From: Frederick Muriuki Muriithi
Date: Tue, 16 May 2023 14:01:12 +0300
Subject: auth: View a collection by its ID.

---
 gn3/auth/authorisation/users/collections/models.py | 18 ++++++++++++++++++
 gn3/auth/authorisation/users/collections/views.py  | 21 ++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/gn3/auth/authorisation/users/collections/models.py b/gn3/auth/authorisation/users/collections/models.py
index 46dfb53..a0c3ebf 100644
--- a/gn3/auth/authorisation/users/collections/models.py
+++ b/gn3/auth/authorisation/users/collections/models.py
@@ -6,6 +6,8 @@ from datetime import datetime
 from redis import Redis
 from email_validator import validate_email, EmailNotValidError
 
+from gn3.auth.authorisation.errors import InvalidData, NotFoundError
+
 from ..models import User
 
 class CollectionJSONEncoder(json.JSONEncoder):
@@ -127,3 +129,19 @@ def create_collection(rconn: Redis, user: User, name: str, traits: tuple) -> dic
         "num_members": len(traits),
         "members": traits
     })
+
+def get_collection(rconn: Redis, user: User, collection_id: UUID) -> dict:
+    """Retrieve the collection with ID `collection_id`."""
+    colls = tuple(coll for coll in user_collections(rconn, user)
+                  if coll["id"] == collection_id)
+    if len(colls) == 0:
+        raise NotFoundError(
+            f"Could not find a collection with ID `{collection_id}` for user "
+            f"with ID `{user.user_id}`")
+    if len(colls) > 1:
+        err = InvalidData(
+            "More than one collection was found having the ID "
+            f"`{collection_id}` for user with ID `{user.user_id}`.")
+        err.error_code = 513
+        raise err
+    return colls[0]
diff --git a/gn3/auth/authorisation/users/collections/views.py b/gn3/auth/authorisation/users/collections/views.py
index cd9458e..8ec6b46 100644
--- a/gn3/auth/authorisation/users/collections/views.py
+++ b/gn3/auth/authorisation/users/collections/views.py
@@ -12,7 +12,7 @@ from gn3.auth.authorisation.errors import NotFoundError
 from gn3.auth.authentication.users import User, user_by_id
 from gn3.auth.authentication.oauth2.resource_server import require_oauth
 
-from .models import user_collections, create_collection
+from .models import get_collection, user_collections, create_collection
 
 collections = Blueprint("collections", __name__)
 
@@ -71,3 +71,22 @@ def new_user_collection() -> Response:
                 redisconn, name, traits))
         return jsonify(__new_collection_as_anonymous_user__(
             redisconn, name, traits))
+
+@collections.route("/<uuid:collection_id>/view", methods=["POST"])
+@require_json
+def view_collection(collection_id: UUID) -> Response:
+    """View a particular collection"""
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        if bool(request.headers.get("Authorization")):
+            with require_oauth.acquire("profile user") as token:
+                return jsonify(get_collection(redisconn,
+                                              token.user,
+                                              collection_id))
+        return jsonify(get_collection(
+            redisconn,
+            User(
+                UUID(request.json.get("anon_id")),#type: ignore[union-attr]
+                "anon@ymous.user",
+                "Anonymous User"),
+            collection_id))
-- 
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