// CRA 를 eject 해서 webpack.config.js 를 살펴본다.

// style files regexes
const cssRegex = /\.css$/;
const cssModuleRegex = /\.module\.css$/;
const sassRegex = /\.(scss|sass)$/;
const sassModuleRegex = /\.module\.(scss|sass)$/;

영역 하나당 어떤 style-loader 를 사용할지 결정한다.
// cssRegex = /\.css$/;
test: cssRegex,
exclude: cssModuleRegex,
// module.css 는 css 방식과 다르게 loader 를 사용한다는걸 알 수 있다.

// const sassRegex = /\.(scss|sass)$/;
test: sassRegex,  // sass or scss
exclude: sassModuleRegex, // module.sass or module.scss
// module.(scss|sass) 는 (sass|scss) 파일과는 다른 방식을 사용한다.

						// "postcss" loader applies autoprefixer to our CSS.
            // "css" loader resolves paths in CSS and adds assets as dependencies.
            // "style" loader turns CSS into JS modules that inject <style> tags.
            // In production, we use MiniCSSExtractPlugin to extract that CSS
            // to a file, but in development "style" loader enables hot editing
            // of CSS.
            // By default we support CSS Modules with the extension .module.css
            {
              test: cssRegex,
              exclude: cssModuleRegex,
              use: getStyleLoaders({
                importLoaders: 1,
                sourceMap: isEnvProduction
                  ? shouldUseSourceMap
                  : isEnvDevelopment,
              }),
              // Don't consider CSS imports dead code even if the
              // containing package claims to have no side effects.
              // Remove this when webpack adds a warning or an error for this.
              // See <https://github.com/webpack/webpack/issues/6571>
              sideEffects: true,
            },
            // Adds support for CSS Modules (<https://github.com/css-modules/css-modules>)
            // using the extension .module.css
            {
              test: cssModuleRegex,
              use: getStyleLoaders({
                importLoaders: 1,
                sourceMap: isEnvProduction
                  ? shouldUseSourceMap
                  : isEnvDevelopment,
                modules: {
                  getLocalIdent: getCSSModuleLocalIdent,
                },
              }),
            },
            // Opt-in support for SASS (using .scss or .sass extensions).
            // By default we support SASS Modules with the
            // extensions .module.scss or .module.sass
            {
              test: sassRegex,
              exclude: sassModuleRegex,
              use: getStyleLoaders(
                {
                  importLoaders: 3,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                },
                'sass-loader'
              ),
              // Don't consider CSS imports dead code even if the
              // containing package claims to have no side effects.
              // Remove this when webpack adds a warning or an error for this.
              // See <https://github.com/webpack/webpack/issues/6571>
              sideEffects: true,
            },
            // Adds support for CSS Modules, but using SASS
            // using the extension .module.scss or .module.sass
            {
              test: sassModuleRegex,
              use: getStyleLoaders(
                {
                  importLoaders: 3,
                  sourceMap: isEnvProduction
                    ? shouldUseSourceMap
                    : isEnvDevelopment,
                  modules: {
                    getLocalIdent: getCSSModuleLocalIdent,
                  },
                },
                'sass-loader'
              ),