From cb91a897367d02d2cd28da9cf59705aa8a2622fd Mon Sep 17 00:00:00 2001
From: "Joshua A. Horton" <joshua_horton@sil.org>
Date: Wed, 8 Feb 2023 09:26:13 +0700
Subject: [PATCH] feat(common/web): basic classes for DOM-based keyboard
 loading

---
 common/web/keyboard-processor/src/index.ts    |  2 +
 .../src/keyboards/domKeyboardLoader.ts        | 59 +++++++++++++++++++
 .../src/keyboards/domKeyboardSandbox.ts       | 35 +++++++++++
 .../src/keyboards/nodeKeyboardLoader.ts       |  2 -
 4 files changed, 96 insertions(+), 2 deletions(-)
 create mode 100644 common/web/keyboard-processor/src/keyboards/domKeyboardLoader.ts
 create mode 100644 common/web/keyboard-processor/src/keyboards/domKeyboardSandbox.ts

diff --git a/common/web/keyboard-processor/src/index.ts b/common/web/keyboard-processor/src/index.ts
index 4187d7f366..b420a1a930 100644
--- a/common/web/keyboard-processor/src/index.ts
+++ b/common/web/keyboard-processor/src/index.ts
@@ -1,5 +1,7 @@
 export * from "./keyboards/activeLayout.js";
 export * from "./keyboards/defaultLayouts.js";
+export { default as DOMKeyboardLoader } from "./keyboards/domKeyboardLoader.js";
+export { default as DOMKeyboardSandbox } from "./keyboards/domKeyboardSandbox.js";
 export { default as Keyboard } from "./keyboards/keyboard.js";
 export * from "./keyboards/keyboard.js";
 export { KeyboardHarness, KeyboardKeymanGlobal, MinimalCodesInterface, MinimalKeymanGlobal } from "./keyboards/keyboardHarness.js";
diff --git a/common/web/keyboard-processor/src/keyboards/domKeyboardLoader.ts b/common/web/keyboard-processor/src/keyboards/domKeyboardLoader.ts
new file mode 100644
index 0000000000..98d2ed193d
--- /dev/null
+++ b/common/web/keyboard-processor/src/keyboards/domKeyboardLoader.ts
@@ -0,0 +1,59 @@
+// Enables DOM types, but just for this one module.
+
+///<reference lib="dom" />
+
+import { KeyboardHarness, MinimalKeymanGlobal } from './keyboardHarness.js';
+
+import Keyboard from './keyboard.js';
+import KeyboardLoaderBase from './keyboardLoaderBase.js';
+
+import { ManagedPromise } from '@keymanapp/web-utils';
+
+export default class DOMKeyboardLoader extends KeyboardLoaderBase {
+  public readonly element: HTMLIFrameElement;
+
+  constructor()
+  constructor(harness: KeyboardHarness);
+  constructor(harness?: KeyboardHarness) {
+    if(harness && harness._jsGlobal != window) {
+      // Copy the String typing over; preserve string extensions!
+      harness._jsGlobal['String'] = window['String'];
+    }
+
+    if(!harness) {
+      super(new KeyboardHarness(window, MinimalKeymanGlobal));
+    } else {
+      super(harness);
+    }
+  }
+
+  protected loadKeyboardInternal(uri: string): Promise<Keyboard> {
+    const promise = new ManagedPromise<Keyboard>();
+
+    try {
+      const document = this.harness._jsGlobal.document;
+      const script = document.createElement('script');
+      document.head.appendChild(script);
+      script.onerror = promise.reject;
+      script.onload = () => {
+        if(this.harness.activeKeyboard) {
+          promise.resolve(this.harness.activeKeyboard);
+        } else {
+          promise.reject();
+        }
+      }
+
+      promise.finally(() => {
+        // https://stackoverflow.com/a/37393041 - totally safe.
+        script.remove();
+      });
+
+      // Now that EVERYTHING ELSE is ready, establish the link to the keyboard's script.
+      script.src = uri;
+    } catch (err) {
+      return Promise.reject(err);
+    }
+
+    return Promise.resolve(this.harness.activeKeyboard);
+  }
+}
\ No newline at end of file
diff --git a/common/web/keyboard-processor/src/keyboards/domKeyboardSandbox.ts b/common/web/keyboard-processor/src/keyboards/domKeyboardSandbox.ts
new file mode 100644
index 0000000000..7e098621b1
--- /dev/null
+++ b/common/web/keyboard-processor/src/keyboards/domKeyboardSandbox.ts
@@ -0,0 +1,35 @@
+// Enables DOM types, but just for this one module.
+///<reference lib="dom" />
+
+import { ManagedPromise } from "@keymanapp/web-utils";
+
+export default class DOMKeyboardSandbox {
+  public readonly sandboxHost: HTMLIFrameElement;
+  public sandbox(): Window {
+    return this.sandboxHost.contentWindow;
+  }
+
+  private constructor() {
+    const host = this.sandboxHost = document.createElement('iframe');
+    host.style.display = 'none';
+    host.style.width = '0px';
+    host.style.height = '0px';
+    host.tabIndex = -1;
+    host.title = "Sandboxed keyboard loader";
+    host.hidden = true;
+  }
+
+  public static buildSandbox(): Promise<DOMKeyboardSandbox> {
+    // Promise:  because the iframe's document isn't instantly ready.
+    const promise = new ManagedPromise<DOMKeyboardSandbox>();
+    const instance = new DOMKeyboardSandbox();
+
+    instance.sandboxHost.onload = () => promise.resolve(instance);
+    instance.sandboxHost.onerror = () => promise.reject();
+
+    // Need to insert the sandbox into the DOM before it can load or error!
+    window.document.appendChild(instance.sandboxHost);
+
+    return promise.corePromise;
+  }
+}
\ No newline at end of file
diff --git a/common/web/keyboard-processor/src/keyboards/nodeKeyboardLoader.ts b/common/web/keyboard-processor/src/keyboards/nodeKeyboardLoader.ts
index f84eb4be63..e90636cc99 100644
--- a/common/web/keyboard-processor/src/keyboards/nodeKeyboardLoader.ts
+++ b/common/web/keyboard-processor/src/keyboards/nodeKeyboardLoader.ts
@@ -1,5 +1,3 @@
-// TODO:  export from ../index.ts as well!
-
 import { KeyboardHarness, MinimalKeymanGlobal } from './keyboardHarness.js';
 
 import Keyboard from './keyboard.js';