Localization added, but not implemented yet.

src/database.rb

@@ -50,19 +50,23 @@ class Database
         @conn.exec(sql_wallet)
         @conn.exec(sql_ledger)
         @conn.exec(sql_index)
+
+        begin
+            @conn.exec("ALTER TABLE wallets ADD COLUMN IF NOT EXISTS locale VARCHAR(5) DEFAULT 'en'")
+        rescue PG::Error => e
+            puts "Migration note: #{e.message}"
+        end
+
         puts "Database tables have been initialized."
     end
 
-    # We pass the user_id
     def get_currency(user_id)
-        # 1. Run the query using parameters ($1) to prevent SQL injection
+        # Run the query using parameters ($1) to prevent SQL injection
         result = @conn.exec_params("SELECT amount FROM wallets WHERE user_id = $1", [user_id])
 
-        # 2. Check if the user exists
         if result.num_tuples.zero?
             return 0 # User has no money/row yet
         else
-        # 3. Return the value (don't print it)
             return result[0]['amount'].to_i
         end
     end
@@ -106,4 +110,23 @@ class Database
             net: row['net_change'].to_i
         }
     end
+
+    def get_language(user_id)
+        result = @conn.exec("SELECT locale FROM wallets WHERE user_id = $1", [user_id])
+
+        return nil if result.num_tuples.zero?
+
+        return result[0]['locale']
+    end
+
+    def set_language(user_id, locale)
+        sql = <<~SQL
+            INSERT INTO wallets(user_id, amount, locale)
+            VALUES ($1, 0, $2)
+            ON CONFLICT (user_id)
+            DO UPDATE SET locale = $2
+        SQL
+
+        @conn.exec(sql, [user_id, locale])
+    end
 end