implement the favourites feature-set in the db package (#143).

src/db.lisp

@@ -78,7 +78,10 @@
             #:get-files-for-account
             #:update-file
             ;; FAVOURITE
-            ;; nothing implemented yet.
+            #:create-favourite
+            #:delete-favourite
+            #:get-favourite-recipes
+            #:is-favourite?
             ;; UNSORTED
             #:delete-row-entry
             #:entry-exists?))
@@ -597,7 +600,42 @@ entries from the database for with the `ACCOUNT-ID'."
 
 ;; FAVOURITE
 ;; =============================================================================
-;; Nothing implemented yet...
+
+(defun create-favourite (account-id recipe-id)
+  "Adds an entry to the favourite table in the database."
+  (with-connection (db)
+    (mito:create-dao 'models:favourite
+                     :account-id account-id
+                     :recipe-id recipe-id)))
+
+(defun delete-favourite (account-id recipe-id)
+  "Deletes the row in 'favourite' table with `ACCOUNT-ID' & `RECIPE-ID'."
+  (with-connection (db)
+    (mito:delete-by-values 'models:favourite
+                           :account-id account-id
+                           :recipe-id recipe-id)))
+
+(defun get-favourite-recipes (account-id &key limit reverse)
+  "Returns a list of 'favourite' entries for `ACCOUNT-ID' from DB.
+Use `LIMIT' to specify the maximum number of entries you would like returned
+from the database."
+  (with-connection (db)
+    (let ((fav-ids
+            (mapcar (lambda (x) (append (models::favourite-recipe-id x)))
+                    (mito:select-dao 'models:favourite
+                      (sxql:where (:= :account-id account-id))))))
+      (when fav-ids
+        (mito:select-dao 'models:recipe
+          (sxql:where (:in :recipe-id fav-ids))
+          (when reverse (sxql:order-by (:desc :created-at)))
+          (when limit (sxql:limit limit)))))))
+
+(defun is-favourite? (account-id recipe-id)
+  "Checks to see if 'favourite' entry matching `ACCOUNT-ID' & `RECIPE-ID' exists."
+  (with-connection (db)
+    (mito:find-dao 'models:favourite
+                   :account-id account-id
+                   :recipe-id recipe-id)))
 
 #| UNSORTED
 ================================================================================