fix: simplify how relative path to compatLayer is calculated

Author: danielcondemarin

lib/getCompatLayerCode.js

@@ -13,27 +13,32 @@ const lambdaHandlerWithCompatLayer = `
   };
 `;
 
-const fixCompatLayerPath = p => {
-  // path.relative doesn't check if is a file or dir
-  // this makes sure the path is actually correct
-  // https://stackoverflow.com/questions/31023972/node-path-relative-returns-incorrect-path
-  if (p.startsWith("../compatLayer")) {
-    return p.replace(path.normalize("../"), path.normalize("./"));
+const relativePathToCompatLayerFile = jsHandlerPath => {
+  const pathSegments = jsHandlerPath.split(path.sep);
+  let relativePathToCompatLayer = "";
+
+  if (pathSegments.length > 2) {
+    // this is a nested page in the build directory. e.g. sls-next-build/categories/uno/dos.js
+    // compatLayer is in sls-next-build/compatLayer.js
+    const stepsUp = pathSegments.length - 2;
+
+    for (let index = 0; index < stepsUp; index++) {
+      relativePathToCompatLayer += "../";
+    }
   } else {
-    return p.replace(path.normalize("../"), "");
+    relativePathToCompatLayer = "./";
   }
+
+  relativePathToCompatLayer += "compatLayer";
+  return relativePathToCompatLayer;
 };
 
 module.exports = jsHandlerPath => {
   const basename = path.basename(jsHandlerPath, ".js");
-  const [rootDir] = jsHandlerPath.split(path.sep);
-  const pathToCompatLayer = path.resolve(path.join(rootDir, "compatLayer"));
-  let relativePathToCompatLayer = path.relative(
-    jsHandlerPath,
-    pathToCompatLayer
-  );
 
-  relativePathToCompatLayer = fixCompatLayerPath(relativePathToCompatLayer);
+  const relativePathToCompatLayer = relativePathToCompatLayerFile(
+    jsHandlerPath
+  );
 
   return lambdaHandlerWithCompatLayer
     .replace(PAGE_BUNDLE_PATH, `./${basename}.original.js`)