import path from 'node:path';
import fs from 'node:fs/promises';
import { readJSON } from 'utility';
import type { EggCore, MiddlewareFunc } from '@eggjs/core';
import { getSourceFile, isTimingFile } from '../../utils.js';

export default (_: unknown, app: EggCore): MiddlewareFunc => {
  return async (ctx, next) => {
    if (ctx.path !== '/__loader_trace__') {
      return await next();
    }
    const template = await fs.readFile(getSourceFile('config/loader_trace.html'), 'utf8');
    const data = await loadTimingData(app);
    ctx.body = template.replace('{{placeholder}}', JSON.stringify(data));
  };
};

async function loadTimingData(app: EggCore) {
  const rundir = app.config.rundir;
  const files = await fs.readdir(rundir);
  const data: any[] = [];
  for (const file of files) {
    if (!isTimingFile(file)) continue;
    const json = await readJSON(path.join(rundir, file));
    const isAgent = /^agent/.test(file);
    for (const item of json) {
      if (isAgent) {
        item.type = 'agent';
      } else {
        item.type = `app_${item.pid}`;
      }
      item.pid = String(item.pid);
      item.range = [ item.start, item.end ];
      item.title = `${item.type}(${item.index})`;
      data.push(item);
    }
  }
  return data;
}