Refactor compilation logic and fix webpack4 flow

Author: rvlb

lib/index.js

@@ -143,21 +143,31 @@ class BundleTrackerPlugin {
   }
   /**
    * Handle compile hook
-   * @param {Compiler} _compiler
    */
-  _handleCompile(_compiler) {
+  _handleCompile() {
     this.output = { status: 'compile', assets: {}, chunks: {} };
     this._writeOutput();
   }
 
-  _handleAssetEmitted(_compiler, assetName, stats) {
+  /**
+   * Hook to inject the webpack compilation object
+   */
+  _handleThisCompilation(compilation) {
+    this._compilation = compilation;
+  }
+
+  /**
+   * Hook to handle each compiled asset and set their
+   * info into the output object
+   */
+  _handleAssetEmitted(assetName) {
     const fileInfo = {
       name: assetName,
-      path: getAssetPath(stats.compilation, assetName),
+      path: getAssetPath(this._compilation, assetName),
     };
 
     if (this.options.integrity === true) {
-      fileInfo.integrity = this._computeIntegrity(getSource(stats.compilation, assetName));
+      fileInfo.integrity = this._computeIntegrity(getSource(this._compilation, assetName));
     }
 
     if (this.options.publicPath) {
@@ -173,20 +183,19 @@ class BundleTrackerPlugin {
     }
 
     // @ts-ignore: TS2339: Property 'assetsInfo' does not exist on type 'Compilation'.
-    if (stats.compilation.assetsInfo) {
+    if (this._compilation.assetsInfo) {
       // @ts-ignore: TS2339: Property 'assetsInfo' does not exist on type 'Compilation'.
-      fileInfo.sourceFilename = stats.compilation.assetsInfo.get(assetName).sourceFilename;
+      fileInfo.sourceFilename = this._compilation.assetsInfo.get(assetName).sourceFilename;
     }
 
     this.output.assets[assetName] = fileInfo;
   }
 
   /**
-   * Handle compile hook
-   * @param {Compiler} _compiler
+   * Handle done hook and write output file
    * @param {Stats} stats
    */
-  _handleDone(_compiler, stats) {
+  _handleDone(stats) {
     if (stats.hasErrors()) {
       const findError = compilation => {
         if (compilation.errors.length > 0) {
@@ -195,6 +204,7 @@ class BundleTrackerPlugin {
         return compilation.children.find(child => findError(child));
       };
       const error = findError(stats.compilation);
+      // @ts-ignore: TS2739
       this.output = {
         status: 'error',
         error: error?.name ?? 'unknown-error',
@@ -224,9 +234,12 @@ class BundleTrackerPlugin {
    */
   apply(compiler) {
     this._setParamsFromCompiler(compiler);
-    compiler.hooks.compile.tap(this.name, this._handleCompile.bind(this, compiler));
-    compiler.hooks.assetEmitted.tap(this.name, this._handleAssetEmitted.bind(this, compiler));
-    compiler.hooks.done.tap(this.name, this._handleDone.bind(this, compiler));
+    compiler.hooks.compile.tap(this.name, this._handleCompile.bind(this));
+    // The thisCompilation hook is required here because webpack4 does not properly
+    // inject the stats object with the compilation data into the assetEmitted hook
+    compiler.hooks.thisCompilation.tap(this.name, this._handleThisCompilation.bind(this));
+    compiler.hooks.assetEmitted.tap(this.name, this._handleAssetEmitted.bind(this));
+    compiler.hooks.done.tap(this.name, this._handleDone.bind(this));
   }
 }