const glob = require("glob");
const path = require("path");

const configs = [];
glob.sync("./lh-reports/*.json").forEach(file => {
  configs.push(require(path.resolve(file)));
});

const stats = {
  FCP: { value: 0, unit: "s" },
  TTI: { value: 0, unit: "s" },
  TBT: { value: 0, unit: "ms" },
  SI: { value: 0, unit: "s" },
  InitialServerResponseTime: { value: 0, unit: "ms" },
  ScriptEvaluation: { value: 0, unit: "ms" },
  ScriptParsingAndCompilation: { value: 0, unit: "ms" },
};

const printStats = result => {
  for (let [key, value] of Object.entries(result)) {
    console.log(
      `${key} : ${(value.value / configs.length).toFixed(2)} ${value.unit}`
    );
  }
};

const getStats = () => {
  configs.reduce((acc, config) => {
    const { audits } = config;
    const mainThreadInfo = audits["mainthread-work-breakdown"].details.items;
    acc.FCP.value += audits["first-contentful-paint"].numericValue / 1000;
    acc.TTI.value += audits["interactive"].numericValue / 1000;
    acc.TBT.value += audits["total-blocking-time"].numericValue;
    acc.InitialServerResponseTime.value +=
      audits["server-response-time"].numericValue;
    acc.SI.value += audits["speed-index"].numericValue;
    mainThreadInfo.forEach(info => {
      if (info.group === "scriptEvaluation") {
        acc.ScriptEvaluation.value += info.duration;
      } else if (info.group === "scriptParseCompile") {
        acc.ScriptParsingAndCompilation.value += info.duration;
      }
    });
    return acc;
  }, stats);
  printStats(stats);
};

getStats();