Refactor handling of environment variables (#2303)

* Refactor environment variables

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

src/utils/test-modes.js

@@ -0,0 +1,44 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+/**
+ * This file is intentionally a js and not a ts file because it is used in `next.config.js`
+ */
+
+/**
+ * Checks if the given string is a positive answer (yes, true or 1).
+ *
+ * @param {string} value The value to check
+ * @return {boolean} {@code true} if the value describes a positive answer string
+ */
+const isPositiveAnswer = (value) => {
+  const lowerValue = value.toLowerCase()
+  return lowerValue === 'yes' || lowerValue === '1' || lowerValue === 'true'
+}
+
+/**
+ * Defines if the current runtime is built in e2e test mode.
+ * @type boolean
+ */
+const isTestMode = !!process.env.NEXT_PUBLIC_TEST_MODE && isPositiveAnswer(process.env.NEXT_PUBLIC_TEST_MODE)
+
+/**
+ * Defines if the current runtime should use the mocked backend.
+ * @type boolean
+ */
+const isMockMode = !!process.env.NEXT_PUBLIC_USE_MOCK_API && isPositiveAnswer(process.env.NEXT_PUBLIC_USE_MOCK_API)
+
+/**
+ * Defines if the current runtime was built in development mode.
+ * @type boolean
+ */
+const isDevMode = process.env.NODE_ENV === 'development'
+
+module.exports = {
+  isTestMode,
+  isMockMode,
+  isDevMode
+}