import assert from 'node:assert/strict';
import { readFileSync } from 'node:fs';
import { resolve } from 'node:path';

const modules = [
  'api',
  'database',
  'api-database',
  'tasks',
  'redis',
  'docker',
  'linux',
  'troubleshooting',
  'distributed',
];
let lessonsChecked = 0;
let stepsChecked = 0;
for (const slug of modules) {
  const lessons = JSON.parse(
    readFileSync(
      resolve(
        slug === 'api' ? 'app/lessons.json' : `public/content/${slug}.json`,
      ),
      'utf8',
    ).replace(/^\uFEFF/, ''),
  );
  const markdown = readFileSync(
    resolve(`public/downloads/${slug}-lessons.md`),
    'utf8',
  );
  for (const [index, lesson] of lessons.entries()) {
    const label = `${slug}/${lesson.id}`;
    const marker = `## ${lesson.id} ${lesson.title}\n`;
    const start = markdown.indexOf(marker);
    assert(start >= 0, `${label}: missing downloaded lesson`);
    const next = lessons[index + 1];
    const end = next
      ? markdown.indexOf(`## ${next.id} ${next.title}\n`, start + marker.length)
      : markdown.length;
    assert(end > start, `${label}: lesson order changed`);
    const lessonText = markdown.slice(start, end);
    assert(
      !lessonText.includes('### 必要概念'),
      `${label}: concepts still front-loaded`,
    );
    const theory = lesson.kind === 'theory';
    const positions = [
      '### 从一个问题开始',
      '### 这节课要完成什么',
      `### ${theory ? '一步步推演场景' : '一步步完成案例'}`,
      `### ${theory ? '检查推演结果' : '检查学习结果'}`,
      `### ${theory ? '自己设计一次' : '自己试一次'}`,
      '### 核心概念回顾',
      `### ${theory ? '延伸阅读' : '技术文档'}`,
    ].map((heading) => {
      const position = lessonText.indexOf(heading);
      assert(position >= 0, `${label}: missing section ${heading}`);
      return position;
    });
    assert(
      positions.every((position, i) => !i || position > positions[i - 1]),
      `${label}: self-study reading order is incorrect`,
    );
    for (const content of [
      lesson.intro.scenario,
      lesson.intro.outcome,
      ...lesson.intro.startingPoint,
    ]) {
      assert(
        lessonText.slice(0, positions[2]).includes(content),
        `${label}: preparation missing from download`,
      );
    }
    let cursor = positions[2];
    for (const [stepIndex, step] of lesson.steps.entries()) {
      const heading = `#### ${stepIndex + 1}. ${step.title}\n`;
      const at = lessonText.indexOf(heading, cursor);
      assert(
        at >= cursor && at < positions[3],
        `${label}: step ${stepIndex + 1} missing or misplaced`,
      );
      const nextStep = lesson.steps[stepIndex + 1];
      const until = nextStep
        ? lessonText.indexOf(
            `#### ${stepIndex + 2}. ${nextStep.title}\n`,
            at + heading.length,
          )
        : positions[3];
      assert(until > at, `${label}: step boundaries are incorrect`);
      const stepText = lessonText.slice(at, until);
      const actionAt = stepText.indexOf(step.body);
      const expectedAt = stepText.indexOf(
        `**${theory ? '对照你的推演' : '你应该看到什么'}**`,
      );
      const explainAt = stepText.indexOf(
        `**${theory ? '从这里理解原因' : '刚才发生了什么'}**`,
      );
      assert(
        actionAt >= 0 && expectedAt > actionAt && explainAt > expectedAt,
        `${label}/step-${stepIndex + 1}: action → observation → explanation broken`,
      );
      assert(
        stepText.slice(expectedAt, explainAt).includes(step.expected),
        `${label}: expected result lost`,
      );
      assert(
        stepText.slice(explainAt).includes(step.explanation),
        `${label}: explanation lost`,
      );
      if (step.code) {
        const codeAt = stepText.indexOf(step.code, actionAt + step.body.length);
        assert(
          codeAt > actionAt && codeAt < expectedAt,
          `${label}: code must precede observation`,
        );
      }
      cursor = until;
      stepsChecked++;
    }
    for (const concept of lesson.concepts) {
      assert(
        lessonText.slice(positions[5], positions[6]).includes(concept.body),
        `${label}: concept recap lost`,
      );
    }
    lessonsChecked++;
  }
}
console.log(
  `Self-study downloads: ${lessonsChecked} lessons and ${stepsChecked} steps preserve preparation, action, observation, explanation and final recap.`,
);