Webpack Configuration

/**
 * Main plugin function that configures webpack for TypeScript compilation
 * Adds TypeScript loaders, optimizations, and type checking to webpack configuration
 * @param api - Vue CLI service API instance with chainWebpack access
 * @param projectOptions - Project configuration options including parallel settings
 */
function plugin(api, projectOptions): void;

// Applied automatically by Vue CLI when plugin is installed
// Manual usage (not typical):
const tsPlugin = require('@vue/cli-plugin-typescript');
// In vue.config.js
module.exports = {
  configureWebpack: config => {
    // Plugin is applied automatically via Vue CLI plugin system
  }
};

/**
 * Webpack configuration modifications applied by the plugin
 * These are applied automatically when the plugin is loaded
 */

// Entry point modification (if no pages config)
config.entry('app').clear().add('./src/main.ts');

// Extension resolution
config.resolve.extensions.prepend('.ts').prepend('.tsx');

// Loader configuration
config.module.rule('ts').test(/\.ts$/);
config.module.rule('tsx').test(/\.tsx$/);

/**
 * Loader configuration function used internally
 * @param loaderConfig - Configuration object for a specific loader
 * @param loaderConfig.name - Loader identifier
 * @param loaderConfig.loader - Loader module path
 * @param loaderConfig.options - Loader-specific options
 */
function addLoader({ name, loader, options }): void;

/**
 * Cache configuration automatically applied when cache-loader is available
 * Caches TypeScript compilation results in node_modules/.cache/ts-loader
 */
const cacheConfig = {
  'ts-loader': 'ts-loader package version',
  'typescript': 'typescript package version', 
  modern: 'modern build flag'
};

/**
 * Thread loader configuration applied when parallel option is enabled
 * @param projectOptions.parallel - Boolean or number for thread count
 */
const threadConfig = {
  workers: typeof projectOptions.parallel === 'number' 
    ? projectOptions.parallel 
    : undefined
};

/**
 * TypeScript loader configuration applied to both .ts and .tsx files
 */
const tsLoaderOptions = {
  transpileOnly: true,           // Skip type checking for performance
  appendTsSuffixTo: ['\\.vue$'], // Handle Vue SFC TypeScript blocks
  happyPackMode: boolean         // Enable when using thread-loader
};

const tsxLoaderOptions = {
  // Same as tsLoaderOptions but with:
  appendTsxSuffixTo: ['\\.vue$'] // Handle Vue SFC TSX blocks
};

/**
 * Fork TypeScript checker plugin configuration
 * Provides type checking without blocking webpack compilation
 */
const forkTsCheckerConfig = {
  typescript: {
    extensions: {
      vue: {
        enabled: true,
        compiler: string // Path to Vue compiler (vue/compiler-sfc or vue-template-compiler)
      }
    },
    diagnosticOptions: {
      semantic: true,
      syntactic: boolean // Based on useThreads setting
    }
  }
};

/**
 * Vue compiler path resolution for different Vue versions
 * Automatically detects and configures appropriate compiler
 */
let vueCompilerPath: string;

// Vue 2.7+ detection
try {
  vueCompilerPath = require.resolve('vue/compiler-sfc');
} catch (e) {
  // Vue 2.6 and lower fallback
  vueCompilerPath = require.resolve('vue-template-compiler');
}

/**
 * Environment and project-specific configuration
 */
const environmentConfig = {
  useThreads: boolean,           // process.env.NODE_ENV === 'production' && !!projectOptions.parallel
  modernBuild: boolean,          // process.env.VUE_CLI_MODERN_BUILD
  isTestEnvironment: boolean     // process.env.VUE_CLI_TEST
};