const fs = require('fs');
const path = require('path');
const glob = require('glob');

// 递归地构建嵌套结构
function buildNestedStructure(filePaths) {
  const root = [];

  filePaths.forEach((filePath) => {
    const parts = filePath.split('/').slice(2, -1); // 去掉 'src/pages' 'meta.json'

    let current = root;

    parts.forEach((part, index) => {
      const find = current.find((item) => item._path === part);
      if (find) {
        current = find;
      } else {
        current.push({
          _path: part,
          _children: [],
        });
        current = current[current.length - 1];
      }

      if (index === parts.length - 1) {
        const content = fs.readFileSync(filePath, 'utf-8');
        Object.assign(current, JSON.parse(content), {
          _fullpath: parts.join('/'),
        });
      }
      current = current._children;
    });
  });

  return root;
}

// 自定义插件：用于生成 meta.js 文件
class GenerateMetaPlugin {
  apply(compiler) {
    compiler.hooks.emit.tapAsync(
      'GenerateMetaPlugin',
      (compilation, callback) => {
        const metaFiles = glob.sync('src/pages/**/meta.json');

        const metaInfo = buildNestedStructure(metaFiles);

        const output = `export const metaInfo = ${JSON.stringify(metaInfo, null, 2)};`;

        const outputPath = path.resolve(__dirname, '../src/meta.js');

        if (fs.existsSync(outputPath)) {
          const existingContent = fs.readFileSync(outputPath, 'utf8');
          if (existingContent === output) {
            // 文件已存在且内容相同，跳过文件生成
            return callback();
          }
        }

        fs.writeFileSync(outputPath, output, 'utf-8');

        console.log('meta.js has been generated successfully!');
        callback();
      },
    );
  }
}

module.exports = GenerateMetaPlugin;