From 02b08d421548a90daca1c9303576144887c29e39 Mon Sep 17 00:00:00 2001
From: amille44420 <adrien.mille.aer@gmail.com>
Date: Fri, 28 Feb 2020 20:55:15 +0800
Subject: [PATCH] feat: add custom webpack plugin WebpackPackagePlugin

---
 helpers/WebpackPackagePlugin.js | 93 +++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 helpers/WebpackPackagePlugin.js

diff --git a/helpers/WebpackPackagePlugin.js b/helpers/WebpackPackagePlugin.js
new file mode 100644
index 0000000..54cf861
--- /dev/null
+++ b/helpers/WebpackPackagePlugin.js
@@ -0,0 +1,93 @@
+const fs = require('fs');
+const { builtinModules } = require('module');
+const path = require('path');
+
+const pluginName = 'WebpackPackagePlugin';
+
+const getParentIdentifier = identifier => {
+    if (identifier[0] === '@') {
+        return identifier
+            .split('/')
+            .slice(0, 2)
+            .join('/');
+    }
+
+    return identifier.split('/')[0];
+};
+
+const defaultOptions = {
+    additionalModules: [],
+    packageJson: null,
+    packageContent: {},
+};
+
+class WebpackPackagePlugin {
+    constructor(options) {
+        this.options = { ...defaultOptions, ...options };
+
+        const { packageJson } = this.options;
+
+        if (!packageJson) {
+            throw new Error('packageJson file must be provided.');
+        }
+
+        if (fs.existsSync(packageJson)) {
+            throw new Error(`${packageJson} file not found.`);
+        }
+
+        // eslint-disable-next-line import/no-dynamic-require, global-require
+        this.package = require(packageJson);
+    }
+
+    apply(compiler) {
+        const outputFolder = compiler.options.output.path;
+        const outputFile = path.resolve(outputFolder, 'package.json');
+        const outputName = path.relative(outputFolder, outputFile);
+
+        compiler.hooks.emit.tap(pluginName, compilation => {
+            const dependencies = {};
+
+            const addDependency = module => {
+                // avoid core package
+                if (!builtinModules.includes(module)) {
+                    // look for a match
+                    const target = this.package.dependencies[module];
+
+                    if (!target) {
+                        // we fail if the dependencies is not added in the package.json
+                        throw new Error(`the module ${module} is not listed in dependencies`);
+                    }
+
+                    // add the dependency
+                    dependencies[module] = target;
+                }
+            };
+
+            compilation.modules.forEach(({ request, external }) => {
+                // we only look for external modules
+                if (external && !request.startsWith('./')) {
+                    // get the main module identifier and try to add i
+                    addDependency(getParentIdentifier(request));
+                }
+            });
+
+            // add additional dependencies
+            this.options.additionalModules.forEach(addDependency);
+
+            // write the new package.json
+            const output = JSON.stringify({
+                ...this.options.packageContent,
+                dependencies,
+            });
+
+            // add it through webpack assets
+            // eslint-disable-next-line no-param-reassign
+            compilation.assets[outputName] = {
+                source: () => output,
+                size: () => output.length,
+            };
+        });
+    }
+}
+
+module.exports = WebpackPackagePlugin;