From 1f58816a4bdc44cefe807ae28b13dd0ad38af462 Mon Sep 17 00:00:00 2001
From: Gleb Kochergin <k-g-a@users.noreply.github.com>
Date: Mon, 5 Jul 2021 18:48:47 +0500
Subject: [PATCH] WIP

---
 index.js     | 94 ++++++++++++++++++++++++++++++++++++++++------------
 package.json |  2 +-
 2 files changed, 74 insertions(+), 22 deletions(-)

diff --git a/index.js b/index.js
index dbb0344..54d1995 100644
--- a/index.js
+++ b/index.js
@@ -1,39 +1,91 @@
+const fs = require("fs");
+const path = require("path");
+
+function findMainPackageJson(entryPath, packageName) {
+  entryPath = entryPath.replace(/\//g, path.sep);
+  let directoryName = path.dirname(entryPath);
+  while (directoryName && !directoryName.endsWith(packageName)) {
+    const parentDirectoryName = path.resolve(directoryName, "..");
+    if (parentDirectoryName === directoryName) {
+      break;
+    }
+    directoryName = parentDirectoryName;
+  }
+
+  const suspect = path.resolve(directoryName, "package.json");
+  if (fs.existsSync(suspect)) {
+    return JSON.parse(fs.readFileSync(suspect).toString());
+  }
+
+  return null;
+}
+
 module.exports = (request, options) => {
-  let pkgName = "";
+  let packageName = "";
   let submoduleName = "";
 
   // NOTE: jest-sequencer is a special prefixed jest request
-  if (
+  const isNodeModuleRequest =
     !request.startsWith(".") &&
     !request.startsWith("/") &&
-    !request.startsWith("jest-sequencer")
-  ) {
+    !request.startsWith("jest-sequencer");
+
+  if (isNodeModuleRequest) {
     const pkgPathParts = request.split("/");
     if (request.startsWith("@") && pkgPathParts.length > 2) {
-      pkgName = pkgPathParts.slice(0, 2).join("/");
+      packageName = pkgPathParts.slice(0, 2).join("/");
       submoduleName = `./${pkgPathParts.slice(2).join("/")}`;
     } else if (!request.startsWith("@") && pkgPathParts.length > 1) {
-      pkgName = pkgPathParts[0];
+      packageName = pkgPathParts[0];
       submoduleName = `./${pkgPathParts.slice(1).join("/")}`;
     }
   }
 
-  const submoduleHasExtension = /\.\w+$/.test(submoduleName);
-  if (pkgName && submoduleName && !submoduleHasExtension) {
-    let pkg;
+  const extension = path.extname(submoduleName);
+  if (packageName && submoduleName && !extension) {
+    let packageJson = undefined;
+
     try {
-      pkg = require(`${pkgName}/package.json`);
-    } catch (e) {
-      console.log(`Error while trying to get ${pkgName}'s package.json:`);
-      console.error(e);
+      packageJson = require(`${packageName}/package.json`);
+    } catch (requireError) {
+      if (requireError.code === "ERR_PACKAGE_PATH_NOT_EXPORTED") {
+        // modules's package.json does not provide the "./package.json" path at it's "exports" field
+        // try to resolve manually
+        try {
+          const requestPath = require.resolve(packageName);
+          packageJson =
+            requestPath && findMainPackageJson(requestPath, packageName);
+        } catch (resolveError) {
+          if (resolveError.code === "ERR_PACKAGE_PATH_NOT_EXPORTED") {
+            console.warn(
+              `Could not retrieve package.json neither through require (package.json itself is not within "exports" field), nor through require.resolve (package.json does not specify "main" field) - falling back to default resolver logic`
+            );
+          } else {
+            console.log(
+              `Unexpected error while performing require.resolve(${packageName}):`
+            );
+            console.error(resolveError);
+            return null;
+          }
+        }
+      } else {
+        console.log(`Unexpected error while requiring ${packageName}:`);
+        console.error(requireError);
+        return null;
+      }
     }
 
-    if (
-      pkg &&
-      pkg.exports &&
-      Object.keys(pkg.exports).every((k) => k.startsWith("."))
-    ) {
-      const exportValue = pkg.exports[submoduleName];
+    if (!packageJson) {
+      console.error(`Failed to find package.json for ${packageName}`);
+    }
+
+    const hasExports = packageJson && packageJson.exports;
+    const isEntryPointsExports =
+      hasExports &&
+      Object.keys(packageJson.exports).every((k) => k.startsWith("."));
+
+    if (hasExports && isEntryPointsExports) {
+      const exportValue = packageJson.exports[submoduleName];
 
       let targetFilePath;
       if (typeof exportValue === "string") {
@@ -45,13 +97,13 @@ module.exports = (request, options) => {
           targetFilePath = exportValue.require;
         }
 
-        if (!targetFilePath && pkg.type !== "module") {
+        if (!targetFilePath && packageJson.type !== "module") {
           targetFilePath = exportValue.default;
         }
       }
 
       if (targetFilePath) {
-        const target = targetFilePath.replace("./", `${pkgName}/`);
+        const target = targetFilePath.replace("./", `${packageName}/`);
         return options.defaultResolver(target, options);
       }
     }
diff --git a/package.json b/package.json
index e0cecaf..f8ecc4d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "jest-node-exports-resolver",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "Jest resolver to handle node's 'exports' package entry points.",
   "main": "index.js",
   "repository": "https://github.com/k-g-a/jest-node-exports-resolver.git",