From 4b0921342bdea4056b9780f73b1095379ad36b54 Mon Sep 17 00:00:00 2001
From: Jason Reed <jcreed@gmail.com>
Date: Thu, 21 Mar 2024 15:18:32 -0400
Subject: [PATCH] Add support for getUrl FragmentAction

---
 src/encoding.ts |  8 +++++++-
 src/index.ts    | 13 ++++++++++---
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/encoding.ts b/src/encoding.ts
index 914f79d..5bb6f26 100644
--- a/src/encoding.ts
+++ b/src/encoding.ts
@@ -49,8 +49,14 @@ export async function encode(text: string): Promise<string> {
   return encodeWithJsonz({ t: 'setTextAndExec', text });
 }
 
-export type FragmentAction =
+export type UrlAction =
   | { t: 'setTextAndExec', text: string }
+
+export type FragmentAction =
+  | UrlAction
+  // fetch url, expected to be json-encoded UrlAction,
+  // and then we will do that.
+  | { t: 'getUrl', url: string }
   ;
 
 export async function decode(fragment: string): Promise<FragmentAction> {
diff --git a/src/index.ts b/src/index.ts
index ec4bb46..93c2aa1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,7 +1,7 @@
 import { syntaxHighlighting } from '@codemirror/language';
 import { Diagnostic, lintGutter, setDiagnostics } from '@codemirror/lint';
 import { EditorView, basicSetup } from "codemirror";
-import { FragmentAction, decode, encode } from "./encoding";
+import { FragmentAction, UrlAction, decode, encode } from "./encoding";
 import { twelfHighlightStyle, twelfLanguage } from './twelf-mode';
 import { TwelfStatus, TwelfError, TwelfExecStatus } from './twelf-worker-types';
 import { TwelfWorker, mkTwelfWorker } from './twelf-worker';
@@ -78,12 +78,19 @@ function initEditor(): EditorView {
 
 async function initTwelf(editor: EditorView) {
 
-  function resolveFragmentAction(action: FragmentAction): void {
+  async function resolveFragmentAction(action: FragmentAction): Promise<void> {
     switch (action.t) {
       case 'setTextAndExec': {
         setText(action.text);
         execCurrentBuffer();
       } break;
+      case 'getUrl': {
+        const urlAction = await (await fetch(action.url)).json() as UrlAction;
+        resolveFragmentAction(urlAction);
+      } break;
+      default: {
+        throw new Error(`Unknown FragmentAction: ${JSON.stringify(action)}`);
+      }
     }
   }
 
@@ -165,7 +172,7 @@ async function initTwelf(editor: EditorView) {
   };
 
   if (window.location.hash) {
-    resolveFragmentAction(await decode(window.location.hash.substring(1)));
+    await resolveFragmentAction(await decode(window.location.hash.substring(1)));
   }
   else {
     const savedElf = localStorage.getItem('savedElf');