Implement slightly hacky plugin to convert CJS to AMD modules

.vite/lib/content-scripts.js

@@ -4,6 +4,7 @@ import path from "path";
 import fs from "fs";
 import { SwapDefinedVariablesPlugin } from "../plugins/swap-defined-variables.js";
 import { ScssViteReadEnvVariableFunctionPlugin } from "../plugins/scss-read-env-variable-function.js";
+import { ConvertCjsToAmd } from "../plugins/convert-cjs-to-amd.js";
 
 /**
  * Create the result base file name for the file.
@@ -208,6 +209,7 @@ export async function buildScriptsAndStyles(buildOptions) {
       alias: aliasesSettings,
     },
     plugins: [
+      ConvertCjsToAmd(),
       wrapScriptIntoIIFE(),
       collectDependenciesForManifestBuilding((fileName, dependencies) => {
         pathsReplacementByOutputPath

.vite/plugins/convert-cjs-to-amd.js

@@ -0,0 +1,170 @@
+/**
+ * # CJS → AMD module format converter.
+ *
+ * Incredibly scary and potentially unstable way to bring back AMD modules on Vite 8+. Converts require() calls into
+ * list of dependencies and forms define() function with module name, dependencies and exports.
+ *
+ * @return {import('vite').Plugin}
+ */
+export function ConvertCjsToAmd() {
+  const requireAssignmentsRegExp = /(?:const\s*|,\s*)(?<variable>[a-z0-9_$]+)\s*=\s*require\((?<path>['"][^'"]+['"])\)/iy;
+  const inlineRequireRegExp = /require\((?<path>['"][^'"]+['"])\)\.(?<variable>[a-z0-9_$]+)/gi
+  const exportsDefinitionRegExp = /Object.defineProperty\(exports,['"](?<export_variable>[^'"]+)['"],{enumerable:!\d,get:function\(\){return\s*(?<assigned_variable>[^};]+)}}\)(?<separator>[,;])/gi;
+  const exportVariablePrefix = "$";
+  const exportVariableCollisionsRegExp = /\$[a-z_$]+/g;
+  const amdExportsModule = '"exports"';
+
+  /**
+   * Clears the name of the module to be fit with what we had before.
+   * @param {string} path Path to normalize.
+   * @returns {string} Normalized path.
+   */
+  function normalizeDependencyName(path) {
+    return path.replace(/\.js(['"])$/, "$1");
+  }
+
+  /**
+   * Deduce the potentially unused variable from the current code. Uses special rarely encountered prefix.
+   * @param {string} code Code to parse the used symbols from. Ideally, code should be passed here before any
+   * replacements.
+   * @param {Set<string>} usedSymbols Set of symbols which were already used or found in code.
+   * @returns {string} Not-yet used variable which is likely safe to use.
+   */
+  function findUnusedSpecialVariable(code, usedSymbols) {
+    // Run complete scan of the source code first, to find any potential collisions.
+    if (!usedSymbols.size) {
+      let match;
+
+      exportVariableCollisionsRegExp.lastIndex = 0;
+
+      while (match = exportVariableCollisionsRegExp.exec(code)) {
+        usedSymbols.add(match[0]);
+      }
+    }
+
+    if (!usedSymbols.size || !usedSymbols.has(exportVariablePrefix)) {
+      usedSymbols.add(exportVariablePrefix);
+      return exportVariablePrefix;
+    }
+
+    let count = 0;
+    let resultVariable;
+
+    do {
+      resultVariable = exportVariablePrefix + count.toString(36);
+    } while (count++ < 1000 && usedSymbols.has(resultVariable));
+
+    if (usedSymbols.has(resultVariable)) {
+      throw new Error('Failed to convert CJS to AMD: Failed to find non-colliding variable after 100 tries!');
+    }
+
+    usedSymbols.add(resultVariable);
+    return resultVariable;
+  }
+
+  /**
+   * Main function doing the conversion of one chunk.
+   * @param {import('rolldown').OutputChunk} chunk
+   */
+  function convertChunkToAmd(chunk) {
+    /** @type {string} */
+    let chunkCode = chunk.code;
+    let lastRequireIndex = 0;
+    /**
+     * Saved per-chunk set of used symbols. This set is reused for multiple calls to not parse code multiple times.
+     * @type {Set<string>}
+     */
+    const chunkUsedSymbols = new Set();
+
+    /** @type {Record<string, string>} */
+    let dependenciesVarsToPaths = {};
+
+    // region Extracting `const x = require()` calls from the start of the source code...
+
+    do {
+      requireAssignmentsRegExp.lastIndex = lastRequireIndex;
+      const result = requireAssignmentsRegExp.exec(chunkCode);
+
+      if (!result) {
+        break;
+      }
+
+      dependenciesVarsToPaths[result.groups.variable] = normalizeDependencyName(result.groups.path);
+      lastRequireIndex += result["0"].length;
+    } while (true);
+
+    if (lastRequireIndex > 0) {
+      const characterAfterRequires = chunkCode[lastRequireIndex];
+
+      if (characterAfterRequires !== ';') {
+        throw new Error("Failed to convert CJS to AMD: reached last require() assignment, but list didn't stop.");
+      }
+    }
+
+    // endregion
+
+    // region Finding and replacing inlined `require().x` calls...
+
+    chunkCode = chunkCode.replaceAll(inlineRequireRegExp, (match, dependencyPath, variable) => {
+      const dependencyVariable = findUnusedSpecialVariable(chunkCode, chunkUsedSymbols);
+      dependenciesVarsToPaths[dependencyVariable] = dependencyPath;
+      return `${dependencyVariable}.${variable}`;
+    });
+
+    // endregion
+
+    // region Finding and replacing all exports with AMD exports...
+
+    /** @type {string|undefined} */
+    let chunkExportsVariable;
+
+    exportsDefinitionRegExp.lastIndex = 0;
+
+    chunkCode = chunkCode.replaceAll(exportsDefinitionRegExp, (substring, exportVariable, assignedVariable, separator) => {
+      chunkExportsVariable ??= findUnusedSpecialVariable(chunkCode, chunkUsedSymbols);
+
+      if (!(chunkExportsVariable in dependenciesVarsToPaths)) {
+        dependenciesVarsToPaths = {
+          [chunkExportsVariable]: amdExportsModule,
+          ...dependenciesVarsToPaths,
+        };
+      }
+
+      return `${chunkExportsVariable}.${exportVariable}=${assignedVariable}${separator}`;
+    });
+
+    // endregion
+
+    const normalizedModuleName = normalizeDependencyName(`"${chunk.fileName}"`);
+    const dependenciesVariables = Object.keys(dependenciesVarsToPaths).join(',');
+    const dependenciesPaths = Object.values(dependenciesVarsToPaths).join(',');
+
+    if (lastRequireIndex > 0) {
+      chunkCode = chunkCode.substring(lastRequireIndex + 1);
+    }
+
+    chunk.code = `define(${normalizedModuleName},[${dependenciesPaths}],function(${dependenciesVariables}){${chunkCode}})`;
+  }
+
+  return {
+    name: "koloml:covert-cjs-to-amd",
+    apply: "build",
+    enforce: "pre",
+
+    /**
+     * @param _
+     * @param {Record<string, (import('rolldown').OutputBundle|import('rolldown').OutputChunk)>} bundle
+     */
+    generateBundle(_, bundle) {
+      for (const chunkId in bundle) {
+        const chunkOrAsset = bundle[chunkId];
+
+        if (chunkOrAsset.type === 'asset') {
+          continue;
+        }
+
+        convertChunkToAmd(chunkOrAsset);
+      }
+    }
+  }
+}