feat: updated diagram to ER

Signed-off-by: Mateusz Urbanek <[email protected]>

Author: shanduur

Diff for: docs/projects/s3gw/s3gw.md

@@ -65,47 +65,47 @@ The relationships between these entities are depicted as follows:
 * Many authorizations can be associated with one bucket (`Many [Authorizations] to One [Bucket]`).
 
 ```mermaid
-classDiagram
-    class Users {
-        +uuid user_id: primary_key, autogenerated, unique
-        +string username: unique
-        +string password_hash
-        +timestamp created_at: autogenerated
+erDiagram
+    Users ||--o{ API_Keys: has
+    Users }o--o{ Buckets: owns
+    Buckets ||--o{ Objects: contains
+    API_Keys ||--o{ Authorisations: specifies
+    Authorisations }o--|| Buckets: specifies
+
+    Users {
+        uuid user_id
+        string username
+        string password_hash
+        timestamp created_at
     }
 
-    class API_Keys {
-        +int api_key_id: primary_key, autogenerated, unique
-        +uuid user_id: foreign_key[Users]
-        +string api_key_hash: unique
-        +timestamp created_at: autogenerated
+    Buckets {
+        int bucket_id
+        string bucket_name
+        timestamp created_at
     }
 
-    class Buckets {
-        +int bucket_id: primary_key, autogenerated, unique
-        +string bucket_name: unique
-        +timestamp created_at: autogenerated
+    API_Keys {
+        int api_key_id
+        uuid user_id
+        string api_key_hash
+        timestamp created_at
     }
 
-    class Objects {
-        +int object_id: primary_key, autogenerated, unique
-        +int bucket_id: foreign_key[Buckets]
-        +int object_version
-        +string object_key
-        +bytes object_data
-        +sha256 object_data_checksum
-        +timestamp created_at: autogenerated
+    Authorisations {
+        int auth_id
+        int api_key_id
+        int bucket_id
+        timestamp created_at
     }
 
-    class Authorisations {
-        +int auth_id: primary_key, autogenerated, unique
-        +int api_key_id: foreign_key[API_Keys]
-        +int bucket_id: foreign_key[Buckets]
-        +timestamp created_at: autogenerated
+    Objects {
+        int object_id
+        int bucket_id
+        int object_version
+        string object_key
+        bytes object_data
+        sha256 object_data_checksum
+        timestamp created_at
     }
-
-    Users "1" <--> "N" API_Keys : "One [User] to Many [API_Keys]"
-    Users "N" <--> "N" Buckets : "Many [Users] to Many [Buckets]"
-    Buckets "1" <--> "N" Objects : "One [Bucket] to Many [Objects]"
-    API_Keys "1" <--> "N" Authorisations : "One [API_Key] to Many [Authorizations]"
-    Authorisations "N" <--> "1" Buckets : "Many [Authorization] to One [Bucket]"
 ```