Case-sensitive filename changes

js/forum/src/utils/History.js

@@ -0,0 +1,98 @@
+/**
+ * The `History` class keeps track and manages a stack of routes that the user
+ * has navigated to in their session.
+ *
+ * An item can be pushed to the top of the stack using the `push` method. An
+ * item in the stack has a name and a URL. The name need not be unique; if it is
+ * the same as the item before it, that will be overwritten with the new URL. In
+ * this way, if a user visits a discussion, and then visits another discussion,
+ * popping the history stack will still take them back to the discussion list
+ * rather than the previous discussion.
+ */
+export default class History {
+  constructor() {
+    /**
+     * The stack of routes that have been navigated to.
+     *
+     * @type {Array}
+     * @protected
+     */
+    this.stack = [];
+
+    // Push the homepage as the first route, so that the user will always be
+    // able to click on the 'back' button to go home, regardless of which page
+    // they started on.
+    this.push('index', '/');
+  }
+
+  /**
+   * Get the item on the top of the stack.
+   *
+   * @return {Object}
+   * @protected
+   */
+  getTop() {
+    return this.stack[this.stack.length - 1];
+  }
+
+  /**
+   * Push an item to the top of the stack.
+   *
+   * @param {String} name The name of the route.
+   * @param {String} [url] The URL of the route. The current URL will be used if
+   *     not provided.
+   * @public
+   */
+  push(name, url = m.route()) {
+    // If we're pushing an item with the same name as second-to-top item in the
+    // stack, we will assume that the user has clicked the 'back' button in
+    // their browser. In this case, we don't want to push a new item, so we will
+    // pop off the top item, and then the second-to-top item will be overwritten
+    // below.
+    const secondTop = this.stack[this.stack.length - 2];
+    if (secondTop && secondTop.name === name) {
+      this.stack.pop();
+    }
+
+    // If we're pushing an item with the same name as the top item in the stack,
+    // then we'll overwrite it with the new URL.
+    const top = this.getTop();
+    if (top && top.name === name) {
+      top.url = url;
+    } else {
+      this.stack.push({name, url});
+    }
+  }
+
+  /**
+   * Check whether or not the history stack is able to be popped.
+   *
+   * @return {Boolean}
+   * @public
+   */
+  canGoBack() {
+    return this.stack.length > 1;
+  }
+
+  /**
+   * Go back to the previous route in the history stack.
+   *
+   * @public
+   */
+  back() {
+    this.stack.pop();
+
+    m.route(this.getTop().url);
+  }
+
+  /**
+   * Go to the first route in the history stack.
+   *
+   * @public
+   */
+  home() {
+    this.stack.splice(1);
+
+    m.route(this.stack[0].url);
+  }
+}