build: Updating source maps when moving them

app/build/package.ts

@@ -0,0 +1,104 @@
+#!/usr/bin/env ts-node
+import fs from 'fs/promises';
+import path from 'path';
+
+// This script copies the build app from srcPath to targetPath, while updating all '*.js.map' references to the original TS source file
+const srcPath = `build/out/src`;
+const targetPath = `bin/`;
+
+// Moves a src directory to a target directory
+/**
+ * Recursively copies a directory (and its content) from dirSrc to dirTarget. 'js.map' file references will be updated
+ * @param dirSrc - Source directory
+ * @param dirTarget - Target directory
+ */
+async function copyDir(dirSrc: string, dirTarget: string) {
+    console.log(`Moving ${dirSrc} to ${dirTarget}`);
+    const srcStat = await fs.readdir(dirSrc, {withFileTypes: true});
+    for (const entry of srcStat) {
+        if (entry.isDirectory()) {
+            copyDir(path.join(entry.path, entry.name), path.join(dirTarget, entry.name));
+            continue;
+        }
+
+        if (entry.isFile()) {
+            await copyFile(path.join(entry.path, entry.name), path.join(dirTarget, entry.name));
+        }
+    }
+}
+
+/**
+ * Copies a file from fileSrc to fileTarget - src is validated to be a file and not a directory. Will maintain 'js.map' references to the original TS source file
+ * @param fileSrc - Src file
+ * @param fileTarget - Target file
+ */
+async function copyFile(fileSrc: string, fileTarget: string) {
+    // Making sure src file exists (we need the dirent anyway)
+    const srcFile = await (fs.stat(fileSrc)
+        .catch(() => undefined));
+    if (!srcFile) {
+        console.log(`Not moving file ${fileSrc}, because it does not exist`);
+        return;
+    }
+
+    // Making sure target dir exists, creating it otherwise
+    const fileTargetDir = path.dirname(fileTarget);
+    const targetDir = await (fs.stat(fileTargetDir)
+        .catch(() => undefined));
+    if (!targetDir) {
+        console.log(`Creating directory ${fileTargetDir}`);
+        await fs.mkdir(fileTargetDir, {recursive: true});
+    }
+
+    // Checking if target file exists and is newer than src file
+    const targetFile = await (fs.stat(fileTarget)
+        .catch(() => undefined));
+    if (targetFile && srcFile.mtimeMs < targetFile.mtimeMs) {
+        console.log(`Skipping ${fileSrc} as it is older than ${fileTarget}`);
+        return;
+    }
+
+    // Special treatment of 'js.map' files
+    if (fileSrc.endsWith(`js.map`)) {
+        await moveSrcMap(fileSrc, fileTarget);
+        return;
+    }
+
+    console.log(`Copying regular file ${fileSrc} to ${fileTarget}`);
+    await fs.copyFile(fileSrc, fileTarget);
+}
+
+/**
+ * Moves a source map file, while updating the source map's source reference to the original TS file
+ * @param fileSrc - Source map file
+ * @param fileTarget - Target file
+ */
+async function moveSrcMap(fileSrc: string, fileTarget: string) {
+    const fileSrcDirectory = path.dirname(fileSrc);
+    const fileTargetDirectory = path.dirname(fileTarget);
+
+    // Getting content
+    const srcMapContent = JSON.parse(await fs.readFile(fileSrc, {encoding: `utf-8`}));
+    if (srcMapContent.sources.length !== 1) {
+        console.warn(`Unexpected number of sources in ${fileSrc}, skipping file`);
+        return;
+    }
+
+    // Resolves the TS source file path based on the src map's 'sources' entry
+    const tsFileLocation = path.resolve(fileSrcDirectory, srcMapContent.sources[0]);
+
+    // Creates the relative path from the target file to the TS source file
+    const newReference = path.relative(fileTargetDirectory, tsFileLocation);
+
+    console.log(`Moving src map file ${fileSrc} to ${fileTarget}, while still pointing to ${srcMapContent.sources[0]}, by updating it to ${newReference}`);
+
+    // Making sure new reference is valid
+    if (path.resolve(fileTargetDirectory, newReference) !== tsFileLocation) {
+        throw new Error(`Target mismatch for ${fileSrc} -> ${fileTarget} -> ${newReference} -> ${tsFileLocation}`);
+    }
+
+    srcMapContent.sources = [newReference];
+    await fs.writeFile(fileTarget, JSON.stringify(srcMapContent), {encoding: `utf-8`});
+}
+
+await copyDir(srcPath, targetPath);

app/package.json

@@ -23,7 +23,7 @@
     "build:dev": "npm run build:schema && npm run build:typescript",
     "build": "npm run build:dev",
     "dist:clean": "rm -rf bin/ && mkdir -p bin/",
-    "dist:package": "cp -r ./build/out/src/* bin/ && cp ../README.md ../LICENSE .",
+    "dist:package": "npx ts-node-esm build/package.ts && cp ../README.md ../LICENSE .",
     "dist:sourcemap": "npx backtrace-js process bin/",
     "dist": "npm run dist:clean && npm run dist:package && npm run dist:sourcemap",
     "test": "NODE_NO_WARNINGS=1 NODE_OPTIONS='--experimental-vm-modules' npx jest --config jest.config.json",