const path = require('path');
const { VueLoaderPlugin } = require('vue-loader');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const webpack = require('webpack');
const dotenv = require('dotenv');
const fs = require('fs');

module.exports = (env, argv) => {
  // 默认为开发环境
  const mode = argv.mode || 'development';
  
  // 确定环境
  const nodeEnv = env?.testing ? 'testing' : mode;
  
  // 加载对应的环境变量文件
  const envFile = `.env.${nodeEnv}`;
  const defaultEnvFile = '.env';
  
  // 加载环境变量
  let envConfig = {};
  
  // 先尝试加载默认环境变量文件
  if (fs.existsSync(defaultEnvFile)) {
    envConfig = dotenv.parse(fs.readFileSync(defaultEnvFile));
  }
  
  // 再尝试加载特定环境的环境变量文件
  if (fs.existsSync(envFile)) {
    envConfig = { ...envConfig, ...dotenv.parse(fs.readFileSync(envFile)) };
  }
  
  // 将环境变量转换为 webpack 定义插件需要的格式
  const envKeys = Object.keys(envConfig).reduce((prev, next) => {
    prev[`process.env.${next}`] = JSON.stringify(envConfig[next]);
    return prev;
  }, {});
  
  // 确保 NODE_ENV 被正确设置
  envKeys['process.env.NODE_ENV'] = JSON.stringify(nodeEnv);
  
  console.log(`Building for ${nodeEnv} environment`);
  
  return {
    mode,
    entry: './src/main.js',
    output: {
      path: path.resolve(__dirname, 'dist'),
      filename: 'bundle.js',
      publicPath: '/'
    },
    module: {
      rules: [
        {
          test: /\.vue$/,
          loader: 'vue-loader'
        },
        {
          test: /\.js$/,
          loader: 'babel-loader',
          exclude: /node_modules/
        },
        {
          test: /\.css$/,
          use: ['style-loader', 'css-loader']
        },
        {
          test: /\.(png|jpg|gif|svg)$/,
          type: 'asset/resource'
        }
      ]
    },
    plugins: [
      new VueLoaderPlugin(),
      new HtmlWebpackPlugin({
        template: './public/index.html'
      }),
      new webpack.DefinePlugin(envKeys)
    ],
    resolve: {
      extensions: ['.js', '.vue', '.json'],
      alias: {
        '@': path.resolve(__dirname, 'src')
      }
    },
    devServer: {
      static: {
        directory: path.join(__dirname, 'public'),
      },
      historyApiFallback: true,
      port: 8080,
      hot: true
    }
  };
};