const reviewer = {
  name: "林晨",
  stage: "final-review",
  showTitle() {
    console.log(`${this.name} 的学习营总复盘`);
  },
};

const lessons = [
  { title: "变量", score: 80, finished: true },
  { title: "闭包", score: 92, finished: true },
  { title: "this", score: 87, finished: true },
  { title: "补漏练习", score: null, finished: false },
  { title: "综合回顾", score: 95, finished: true },
];

let mentorNote;
const reviewComment = null;

function getStageText(stage) {
  switch (stage) {
    case "basic":
      return "基础阶段";
    case "advanced":
      return "补充阶段";
    case "final-review":
      return "总复习阶段";
    default:
      return "未知阶段";
  }
}

reviewer.showTitle();
console.log("阶段说明：", getStageText(reviewer.stage));
console.log("mentorNote 是否为 undefined：", mentorNote === undefined);
console.log("reviewComment 是否为 null：", reviewComment === null);

const validLessons = [];

for (let index = 0; index < lessons.length; index += 1) {
  const lesson = lessons[index];

  if (lesson.score === undefined || lesson.score === null) {
    console.log(`在《${lesson.title}》处遇到空成绩，停止读取后续项目。`);
    break;
  }

  validLessons.push(lesson);
}

const lessonTitles = validLessons.map(function (lesson) {
  return lesson.title;
});

const averageScore =
  validLessons.reduce(function (total, lesson) {
    return total + lesson.score;
  }, 0) / validLessons.length;

const allFinished = validLessons.every(function (lesson) {
  return lesson.finished === true;
});

const reviewerAlias = reviewer;
reviewerAlias.stage = "advanced";

console.log("引用修改后的 reviewer.stage：", reviewer.stage);
console.log("有效课程：", lessonTitles.join("、"));
console.log("平均分：", averageScore);
console.log("是否全部完成：", allFinished);