1 files changed, 69 insertions, 9 deletions

diff --git a/src/db/logic/db_access.erl b/src/db/logic/db_access.erl
index 1591ead..0a18edb 100644
--- a/src/db/logic/db_access.erl
+++ b/src/db/logic/db_access.erl
@@ -11,7 +11,10 @@
 (
    [
       read/3,
-      insert/5,
+      remove/3,
+      reserve/3,
+      insert_at/5,
+      insert/4,
       query/1
    ]
 ).
@@ -25,18 +28,28 @@ query_transaction (Query) ->
    ID = shr_db_query:get_entry_id(Query),
    [Item] = mnesia:read(DB, ID),
    {ok, UpdatedItem} = shr_db_query:apply_to(Query, Item),
-   % FIXME: handle return value, mnesia:write -> (transaction abort | ok).
-   % FIXME: is this an atomic OP? Is the lock freed afterwards?
+
    mnesia:write(DB, UpdatedItem, sticky_write),
+
+   ok.
+
+-spec add_new_item (atom(), shr_db_item:type()) -> 'ok'.
+add_new_item (DB, Item) ->
+   ID = shr_db_item:get_id(Item),
+   [] = mnesia:read(DB, ID),
+
+   mnesia:write(DB, Item, sticky_write),
+
    ok.
 
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 -spec read
    (
       atom(),
-      any(),
+      binary(),
       shr_db_user:user()
    )
    -> ({'aborted', any()} | {'atomic', ({'ok', any()} | 'not_found')}).
@@ -47,7 +60,7 @@ read (DB, ID, Cred) ->
          true =
             shr_db_user:can_access
             (
-               shr_db_item:get_write_permission(Item),
+               shr_db_item:get_read_permission(Item),
                Cred
             ),
          {'atomic', {ok, shr_db_item:get_value(Item)}};
@@ -55,18 +68,65 @@ read (DB, ID, Cred) ->
       Other -> {'aborted', Other}
    end.
 
--spec insert
+-spec insert_at
    (
       atom(),
-      any(),
+      binary(),
       shr_db_user:permission(),
       shr_db_user:permission(),
       any())
    -> ({'aborted', any()} | {'atomic', 'ok'}).
-insert (DB, ID, ReadPerm, WritePerm, Value) ->
+insert_at (DB, ID, ReadPerm, WritePerm, Value) ->
    Item = shr_db_item:new(ID, ReadPerm, WritePerm, Value),
-   mnesia:transaction(fun mnesia:write/3, [DB, Item, sticky_write]).
+   mnesia:transaction(fun add_new_item/2, [DB, Item]).
+
+-spec insert
+   (
+      atom(),
+      shr_db_user:permission(),
+      shr_db_user:permission(),
+      any())
+   -> ({'aborted', any()} | {'atomic', {'ok', binary()}}).
+insert (DB, ReadPerm, WritePerm, Value) ->
+   ID = <<"?">>, %% TODO: gen new ID.
+   case insert_at(DB, ID, ReadPerm, WritePerm, Value) of
+      {'atomic', 'ok'} -> {'atomic', {'ok', ID}};
+      {aborted, Val} -> {aborted, Val}
+   end.
 
 -spec query (shr_db_query:type()) -> ({'aborted', any()} | {'atomic', 'ok'}).
 query (Query) ->
    mnesia:transaction(fun query_transaction/1, [Query]).
+
+-spec reserve
+   (
+      atom(),
+      binary(),
+      shr_db_user:user()
+   )
+   -> ({'aborted', any()} | {'atomic', 'ok'}).
+reserve (DB, ID, Cred) ->
+   insert_at
+   (
+      DB,
+      ID,
+      [Cred],
+      [Cred],
+      {
+         reserved,
+         <<"?">> %% TODO: timestamp
+      }
+   ).
+
+-spec remove
+   (
+      atom(),
+      binary(),
+      shr_db_user:user()
+   )
+   -> ({'aborted', any()} | {'atomic', ({'ok', any()} | 'not_found')}).
+remove (_DB, _ID, _Cred) ->
+   %% TODO: unimplemented
+   %% Don't forget to checkt that Cred has write access before removing the
+   %% value.
+   {'aborted', 'unimplemented'}.