From c35bda352f308b527532464d10635c61ab254144 Mon Sep 17 00:00:00 2001
From: th0r <grunin.ya@ya.ru>
Date: Thu, 5 Nov 2020 19:12:57 +0300
Subject: [PATCH] Properly parse Webpack 5 entry modules

---
 src/analyzer.js   | 55 ++++++++++++++++++++++++++++++++++++++++-------
 src/parseUtils.js | 48 ++++++++++++++++++++++++++++++-----------
 2 files changed, 83 insertions(+), 20 deletions(-)

diff --git a/src/analyzer.js b/src/analyzer.js
index e7a84aa5..39bc24a2 100644
--- a/src/analyzer.js
+++ b/src/analyzer.js
@@ -76,7 +76,7 @@ function getViewerData(bundleStats, bundleDir, opts) {
         continue;
       }
 
-      bundlesSources[statAsset.name] = bundleInfo.src;
+      bundlesSources[statAsset.name] = _.pick(bundleInfo, 'src', 'runtimeSrc');
       _.assign(parsedModules, bundleInfo.modules);
     }
 
@@ -94,19 +94,48 @@ function getViewerData(bundleStats, bundleDir, opts) {
     const asset = result[statAsset.name] = _.pick(statAsset, 'size');
 
     if (bundlesSources && _.has(bundlesSources, statAsset.name)) {
-      asset.parsedSize = Buffer.byteLength(bundlesSources[statAsset.name]);
-      asset.gzipSize = gzipSize.sync(bundlesSources[statAsset.name]);
+      asset.parsedSize = Buffer.byteLength(bundlesSources[statAsset.name].src);
+      asset.gzipSize = gzipSize.sync(bundlesSources[statAsset.name].src);
     }
 
     // Picking modules from current bundle script
-    asset.modules = _(modules)
-      .filter(statModule => assetHasModule(statAsset, statModule))
-      .each(statModule => {
-        if (parsedModules) {
+    const assetModules = modules.filter(statModule => assetHasModule(statAsset, statModule));
+
+    // Adding parsed sources
+    if (parsedModules) {
+      const unparsedEntryModules = [];
+
+      for (const statModule of assetModules) {
+        if (parsedModules[statModule.id]) {
           statModule.parsedSrc = parsedModules[statModule.id];
+        } else if (isEntryModule(statModule)) {
+          unparsedEntryModules.push(statModule);
         }
-      });
+      }
+
+      // Webpack 5 changed bundle format and now entry modules are concatenated and located at the end on the it.
+      // Because of this they basically become a concatenated module, for which we can't even precisely determine its
+      // parsed source as it's located in the same scope as all Webpack runtime helpers.
+      if (unparsedEntryModules.length) {
+        if (unparsedEntryModules.length === 1) {
+          // So if there is only one entry we consider its parsed source to be all the bundle code excluding code
+          // from parsed modules.
+          unparsedEntryModules[0].parsedSrc = bundlesSources[statAsset.name].runtimeSrc;
+        } else {
+          // If there are multiple entry points we move all of them under synthetic concatenated module.
+          _.pullAll(assetModules, unparsedEntryModules);
+          assetModules.unshift({
+            identifier: './entry modules',
+            name: './entry modules',
+            modules: unparsedEntryModules,
+            size: unparsedEntryModules.reduce((totalSize, module) => totalSize + module.size, 0),
+            parsedSrc: bundlesSources[statAsset.name].runtimeSrc
+          });
+        }
+      }
+    }
 
+    asset.modules = assetModules;
     asset.tree = createModulesTree(asset.modules);
   }, {});
 
@@ -148,6 +177,8 @@ function getBundleModules(bundleStats) {
     .compact()
     .flatten()
     .uniqBy('id')
+    // Filtering out Webpack's runtime modules as they don't have ids and can't be parsed (introduced in Webpack 5)
+    .reject(isRuntimeModule)
     .value();
 }
 
@@ -158,6 +189,14 @@ function assetHasModule(statAsset, statModule) {
   );
 }
 
+function isEntryModule(statModule) {
+  return statModule.depth === 0;
+}
+
+function isRuntimeModule(statModule) {
+  return statModule.moduleType === 'runtime';
+}
+
 function createModulesTree(modules) {
   const root = new Folder('.');
 
diff --git a/src/parseUtils.js b/src/parseUtils.js
index 1d775ae3..bce9878c 100644
--- a/src/parseUtils.js
+++ b/src/parseUtils.js
@@ -45,17 +45,19 @@ function parseBundle(bundlePath) {
             // ...nor parameters
             fn.callee.params.length === 0
           ) {
-            // Modules are stored in the very first variable as hash
-            const {body} = fn.callee.body;
-
-            if (
-              body.length &&
-              body[0].type === 'VariableDeclaration' &&
-              body[0].declarations.length &&
-              body[0].declarations[0].type === 'VariableDeclarator' &&
-              body[0].declarations[0].init.type === 'ObjectExpression'
-            ) {
-              state.locations = getModulesLocations(body[0].declarations[0].init);
+            // Modules are stored in the very first variable declaration as hash
+            const firstVariableDeclaration = fn.callee.body.body.find(node => node.type === 'VariableDeclaration');
+
+            if (firstVariableDeclaration) {
+              for (const declaration of firstVariableDeclaration.declarations) {
+                if (declaration.init) {
+                  state.locations = getModulesLocations(declaration.init);
+
+                  if (state.locations) {
+                    break;
+                  }
+                }
+              }
             }
           }
         }
@@ -66,6 +68,7 @@ function parseBundle(bundlePath) {
 
         state.expressionStatementDepth--;
       },
+
       AssignmentExpression(node, state) {
         if (state.locations) return;
 
@@ -82,6 +85,7 @@ function parseBundle(bundlePath) {
           state.locations = getModulesLocations(right);
         }
       },
+
       CallExpression(node, state, c) {
         if (state.locations) return;
 
@@ -147,11 +151,31 @@ function parseBundle(bundlePath) {
   }
 
   return {
+    modules,
     src: content,
-    modules
+    runtimeSrc: getBundleRuntime(content, walkState.locations)
   };
 }
 
+/**
+ * Returns bundle source except modules
+ */
+function getBundleRuntime(content, modulesLocations) {
+  const sortedLocations = _(modulesLocations)
+    .values()
+    .sortBy('start');
+
+  let result = '';
+  let lastIndex = 0;
+
+  for (const {start, end} of sortedLocations) {
+    result += content.slice(lastIndex, start);
+    lastIndex = end;
+  }
+
+  return result + content.slice(lastIndex, content.length);
+}
+
 function isIIFE(node) {
   return (
     node.type === 'ExpressionStatement' &&