feat: source map remapping for runtime stack trace displays

packages/core/inspector_modules.ts

@@ -6,3 +6,117 @@ import './debugger/webinspector-css';
 // require('./debugger/webinspector-network');
 // require('./debugger/webinspector-dom');
 // require('./debugger/webinspector-css');
+
+/**
+ * Source map remapping for stack traces for the runtime in-flight error displays
+ * Currently this is very slow. Need to find much faster way to remap stack traces.
+ * NOTE: This likely should not be in core because errors can happen on boot before core is fully loaded. Ideally the runtime should provide this in full but unsure.
+ */
+import { File, knownFolders } from './file-system';
+import { SourceMapConsumer } from 'source-map-js';
+
+// note: webpack config can by default use 'source-map' files with runtimes v9+
+// helps avoid having to decode the inline base64 source maps
+// currently same performance on inline vs file source maps so file source maps may just be cleaner
+const usingSourceMapFiles = true;
+let loadedSourceMaps: Map<string, any>;
+let consumerCache: Map<string, any>;
+
+function getConsumer(mapPath: string, sourceMap: any): SourceMapConsumer {
+	if (!consumerCache) {
+		consumerCache = new Map();
+	}
+	let c = consumerCache.get(mapPath);
+	if (!c) {
+		// parse once
+		c = new SourceMapConsumer(sourceMap);
+		consumerCache.set(mapPath, c);
+	}
+	return c;
+}
+
+function loadAndExtractMap(mapPath: string) {
+	// check cache first
+	if (!loadedSourceMaps) {
+		loadedSourceMaps = new Map();
+	}
+	let mapText = loadedSourceMaps.get(mapPath);
+	// Note: not sure if separate source map files or inline is better
+	// need to test build times one way or other with webpack, vite and rspack
+	// but this handles either way
+	if (mapText) {
+		return mapText; // already loaded
+	} else {
+		if (File.exists(mapPath)) {
+			const contents = File.fromPath(mapPath).readTextSync();
+			if (usingSourceMapFiles) {
+				mapText = contents;
+			} else {
+				// parse out the inline base64
+				const match = contents.match(/\/\/[#@] sourceMappingURL=data:application\/json[^,]+,(.+)$/);
+				const base64 = match[1];
+				const binary = atob(base64);
+				// this is the raw text of the source map
+				// seems to work without doing the decodeURIComponent trick
+				mapText = binary;
+				// // escape each char code into %XX and let decodeURIComponent build the UTF-8 string
+				// mapText = decodeURIComponent(
+				//   binary
+				//     .split('')
+				//     .map(c => '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2))
+				//     .join('')
+				// );
+			}
+		} else {
+			// no source maps
+			return { source: null, line: 0, column: 0 };
+		}
+	}
+	loadedSourceMaps.set(mapPath, mapText); // cache it
+	return mapText;
+}
+
+function remapFrame(file: string, line: number, column: number) {
+	/**
+	 * webpack config can use source map files or inline.
+	 * To use source map files, run with `--env.sourceMap=source-map`.
+	 * @nativescript/webpack 5.1 enables `source-map` files by default when using runtimes v9+.
+	 */
+
+	const appPath = knownFolders.currentApp().path;
+	let sourceMapFileExt = '';
+	if (usingSourceMapFiles) {
+		sourceMapFileExt = '.map';
+	}
+	const mapPath = `${appPath}/${file.replace('file:///app/', '')}${sourceMapFileExt}`;
+
+	// 3) hand it to the consumer
+	const sourceMap = loadAndExtractMap(mapPath);
+	const consumer = getConsumer(mapPath, sourceMap);
+	return consumer.originalPositionFor({ line, column });
+}
+
+function remapStack(raw: string): string {
+	const lines = raw.split('\n');
+	const out = lines.map((line) => {
+		const m = /\((.+):(\d+):(\d+)\)/.exec(line);
+		if (!m) return line;
+		const [_, file, l, c] = m;
+		const orig = remapFrame(file, +l, +c);
+		if (!orig.source) return line;
+		return line.replace(/\(.+\)/, `(${orig.source}:${orig.line}:${orig.column})`);
+	});
+	return out.join('\n');
+}
+
+/**
+ * Added in 9.0 runtimes.
+ * Allows the runtime to remap stack traces before displaying them in the in-flight error screens.
+ */
+(global as any).__ns_remapStack = (rawStack: string) => {
+	console.log('Remapping stack trace...');
+	return remapStack(rawStack);
+};
+/**
+ * End of source map remapping for stack traces
+ */