Fixing a few time machine bugs

pxteditor/history.ts

@@ -311,8 +311,7 @@ namespace pxt.workspace {
         }
 
         // If no source changed, we can bail at this point
-        const diffed = diffScriptText(previousText, toWrite, currentTime, diff);
-        if (!diffed) {
+        if (scriptEquals(previousText, toWrite)) {
             toWrite[pxt.HISTORY_FILE] = JSON.stringify(history);
             return;
         }
@@ -340,7 +339,11 @@ namespace pxt.workspace {
             }
         }
         else {
-            history.entries.push(diffed);
+            const diffed = diffScriptText(previousText, toWrite, currentTime, diff);
+
+            if (diffed) {
+                history.entries.push(diffed);
+            }
         }
 
         // Finally, update the snapshots. These are failsafes in case something
@@ -379,4 +382,18 @@ namespace pxt.workspace {
             text: pxt.workspace.createSnapshot(text)
         };
     }
+
+    function scriptEquals(a: ScriptText, b: ScriptText) {
+        const aKeys = Object.keys(a);
+        const bKeys = Object.keys(b);
+
+        if (aKeys.length !== bKeys.length) return false;
+
+        for (const key of aKeys) {
+            if (bKeys.indexOf(key) === -1) return false;
+            if (a[key] !== b[key]) return false;
+        }
+
+        return true;
+    }
 }

theme/timeMachine.less

@@ -138,6 +138,7 @@
 
         .time-machine-back-button {
             flex-grow: 1;
+            flex-shrink: 0;
         }
     }
 

webapp/src/dialogs.tsx

@@ -860,7 +860,7 @@ export function isDontShowDownloadDialogFlagSet() {
 }
 
 export async function showTurnBackTimeDialogAsync(header: pxt.workspace.Header, reloadHeader: () => void) {
-    const text = await workspace.getTextAsync(header.id);
+    const text = await workspace.getTextAsync(header.id, true);
     let history: pxt.workspace.HistoryFile;
 
     if (text?.[pxt.HISTORY_FILE]) {

webapp/src/workspace.ts

@@ -281,24 +281,29 @@ export function initAsync() {
         })
 }
 
-export function getTextAsync(id: string): Promise<ScriptText> {
-    return maybeSyncHeadersAsync()
-        .then(() => {
-            let e = lookup(id)
-            if (!e)
-                return Promise.resolve(null as ScriptText)
-            if (e.text)
-                return Promise.resolve(e.text)
-            return headerQ.enqueue(id, () => impl.getAsync(e.header)
-                .then(resp => {
-                    if (!e.text) {
-                        // otherwise we were beaten to it
-                        e.text = fixupFileNames(resp.text);
-                    }
-                    e.version = resp.version;
-                    return e.text
-                }))
-        })
+export async function getTextAsync(id: string, getSavedText = false): Promise<ScriptText> {
+    await maybeSyncHeadersAsync();
+
+    const e = lookup(id);
+    if (!e) return null;
+
+    if (e.text && !getSavedText) {
+        return e.text;
+    }
+
+    return headerQ.enqueue(id, async () => {
+        const resp = await impl.getAsync(e.header);
+        const fixedText = fixupFileNames(resp.text);
+
+        if (getSavedText) {
+            return fixedText;
+        }
+        else if (!e.text) {
+            e.text = fixedText;
+        }
+        e.version = resp.version;
+        return e.text
+    });
 }
 
 export interface ScriptMeta {
@@ -578,14 +583,18 @@ export async function saveAsync(h: Header, text?: ScriptText, fromCloudSync?: bo
         await fixupVersionAsync(e);
         let ver: any;
 
-        const toWrite = text ? e.text : null;
+        let toWrite = text ? e.text : null;
 
         if (pxt.appTarget.appTheme.timeMachine) {
             try {
-                if (toWrite) {
-                    const previous = await impl.getAsync(h);
+                const previous = await impl.getAsync(h);
+
+                if (previous) {
+                    if (!toWrite && previous.header.pubVersions?.length !== h.pubVersions?.length) {
+                        toWrite = { ...previous.text };
+                    }
 
-                    if (previous) {
+                    if (toWrite) {
                         pxt.workspace.updateHistory(previous.text, toWrite, Date.now(), h.pubVersions || [], diffText, patchText);
                     }
                 }