Keymaps as a clean architecture [WIP]

src/content/InputDriver.ts

@@ -0,0 +1,80 @@
+import * as dom from '../shared/utils/dom';
+import * as keys from '../shared/utils/keys';
+
+const cancelKey = (e: KeyboardEvent): boolean => {
+  return e.key === 'Escape' || e.key === '[' && e.ctrlKey;
+};
+
+export default class InputDriver {
+  private pressed: {[key: string]: string} = {};
+
+  private onKeyListeners: ((key: keys.Key) => boolean)[] = [];
+
+  constructor(target: HTMLElement) {
+    this.pressed = {};
+    this.onKeyListeners = [];
+
+    target.addEventListener('keypress', this.onKeyPress.bind(this));
+    target.addEventListener('keydown', this.onKeyDown.bind(this));
+    target.addEventListener('keyup', this.onKeyUp.bind(this));
+  }
+
+  onKey(cb: (key: keys.Key) => boolean) {
+    this.onKeyListeners.push(cb);
+  }
+
+  private onKeyPress(e: KeyboardEvent) {
+    if (this.pressed[e.key] && this.pressed[e.key] !== 'keypress') {
+      return;
+    }
+    this.pressed[e.key] = 'keypress';
+    this.capture(e);
+  }
+
+  private onKeyDown(e: KeyboardEvent) {
+    if (this.pressed[e.key] && this.pressed[e.key] !== 'keydown') {
+      return;
+    }
+    this.pressed[e.key] = 'keydown';
+    this.capture(e);
+  }
+
+  private onKeyUp(e: KeyboardEvent) {
+    delete this.pressed[e.key];
+  }
+
+  // eslint-disable-next-line max-statements
+  private capture(e: KeyboardEvent) {
+    let target = e.target;
+    if (!(target instanceof HTMLElement)) {
+      return;
+    }
+    if (this.fromInput(target)) {
+      if (cancelKey(e) && target.blur) {
+        target.blur();
+      }
+      return;
+    }
+    if (['Shift', 'Control', 'Alt', 'OS'].includes(e.key)) {
+      // pressing only meta key is ignored
+      return;
+    }
+
+    let key = keys.fromKeyboardEvent(e);
+    for (let listener of this.onKeyListeners) {
+      let stop = listener(key);
+      if (stop) {
+        e.preventDefault();
+        e.stopPropagation();
+        break;
+      }
+    }
+  }
+
+  private fromInput(e: Element) {
+    return e instanceof HTMLInputElement ||
+      e instanceof HTMLTextAreaElement ||
+      e instanceof HTMLSelectElement ||
+      dom.isContentEditable(e);
+  }
+}