/**
 * @license
 * Copyright 2022 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @fileoverview Lightweight conversion from tsc ouptut to Closure Compiler
 * compatible input.
 */
'use strict';

// eslint-disable-next-line no-undef
const fs = require('fs');

// eslint-disable-next-line no-undef
const DIR = process.argv[2];

// Number of files rewritten.
let fileCount = 0;

/**
 * Recursively spider the given directory and rewrite any JS files found.
 * @param {string} dir Directory path to start from.
 */
function spider(dir) {
 if (!dir.endsWith('/')) {
 dir += '/';
 }
 const entries = fs.readdirSync(dir, {withFileTypes: true});
 for (const entry of entries) {
 if (entry.isDirectory()) {
 spider(dir + entry.name + '/');
 } else if (entry.name.endsWith('.js')) {
 rewriteFile(dir + entry.name);
 }
 }
}

/**
 * Given a file, rewrite it if it contains problematic patterns.
 * @param {string} path Path of file to potentially rewrite.
 */
function rewriteFile(path) {
 const oldCode = fs.readFileSync(path, 'utf8');
 const newCode = rewriteEnum(oldCode);
 if (newCode !== oldCode) {
 fileCount++;
 fs.writeFileSync(path, newCode);
 }
}

/**
 * Unquote enum definitions in the given code string.
 * @param {string} code Original code generated by tsc.
 * @return {string} Rewritten code for Closure Compiler.
 */
function rewriteEnum(code) {
 // Find all enum definitions. They look like this:
 // (function (names) {
 // ...
 // })(names || (names = {}));
 const enumDefs =
 code.match(
 /\s+\(function \((\w+)\)\{\n[^}]*\}\)\(1円[^)]+1円 = \{\}\)\);/g,
 ) || [];
 for (const oldEnumDef of enumDefs) {
 // enumDef looks like a bunch of lines in one of these two formats:
 // ScopeType["BLOCK"] = "block";
 // KeyCodes[KeyCodes["TAB"] = 9] = "TAB";
 // We need to unquote them to look like one of these two formats:
 // ScopeType.BLOCK = "block";
 // KeyCodes[KeyCodes.TAB = 9] = "TAB";
 let newEnumDef = oldEnumDef.replace(/\["(\w+)"\]/g, '.1ドル');
 newEnumDef = newEnumDef.replace(') {', ') { // Converted by tsick.');
 code = code.replace(oldEnumDef, newEnumDef);
 }
 return code;
}

if (DIR) {
 spider(DIR);
 console.log(`Unquoted enums in ${fileCount} files.`);
} else {
 throw Error('No source directory specified');
}