refactor: tidy structure of source files

Fixes #79

src/protocol/search/sort.ts

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2019 StApps
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+import {SCMap} from '../../general/map';
+import {SCThingsField} from '../../meta';
+import {SCDistanceSort} from './sorts/distance';
+import {SCDucetSort} from './sorts/ducet';
+import {SCPriceSort} from './sorts/price';
+
+/**
+ * Abstract sort instruction
+ */
+export interface SCSearchAbstractSort<T extends SCSearchAbstractSortArguments> {
+  /**
+   * Map of arguments for the sort instruction
+   */
+  arguments: T;
+
+  /**
+   * Direction of the sort instruction: `asc`ending or `desc`ending.
+   */
+  order: 'asc' | 'desc';
+
+  /**
+   * Type of the sort instruction
+   */
+  type: SCSearchSortType;
+}
+
+/**
+ * Map of arguments for the sort instruction
+ */
+export interface SCSearchAbstractSortArguments extends SCMap<unknown> {
+  /**
+   * Field to sort by
+   */
+  field: SCThingsField;
+}
+
+/**
+ * Type of a sort instruction
+ */
+export type SCSearchSortType = 'distance' | 'price' | 'ducet';
+
+/**
+ * A sort instruction
+ */
+export type SCSearchSort = SCDistanceSort | SCPriceSort | SCDucetSort;