/**
 * 验证「按会话并行生成」的决策函数。
 *
 * 为什么要测：这几个函数决定「能不能发」「停止该停谁」「切会话要不要归一化」——
 * 旧版本的 bug 正是死在"停止该停谁"上（停止打在了用户当前看的会话，而不是
 * 真正在生成的那个）。这类错误不写断言很容易再犯。
 *
 * 怎么跑（在项目根目录）：
 *   npx esbuild harness/tools/_entry-chat-tasks.ts --bundle --format=esm \
 *     --outfile=harness/tools/_chat-tasks.mjs
 *   node harness/tools/verify-chat-task-utils.mjs
 */

import {
  isSessionGenerating,
  resolveSendAction,
  resolveStopTargetTaskId,
  shouldNormalizeSessionHistory,
  withTaskAdded,
  withTaskRemoved,
  ref,
  shallowRef,
  computed,
} from './_chat-tasks.mjs';

let pass = 0;
let fail = 0;
const check = (name, cond, extra = '') => {
  if (cond) {
    pass++;
    console.log('  ok   ' + name);
  } else {
    fail++;
    console.log('  FAIL ' + name + '  ' + extra);
  }
};

/** 造一个结构上够用的 stub task（决策函数只读 sessionId） */
const stubTask = (sessionId) => ({
  sessionId,
  aiMessageId: `ai_${sessionId}`,
  coordinator: null,
  chunkBuffer: { push() {}, flush() {}, cancel() {} },
  dmsAnswerWritten: false,
  finished: false,
});

const tasksOf = (...ids) => new Map(ids.map((id) => [id, stubTask(id)]));

console.log('场景：会话 A 正在生成，用户切到会话 B\n');
const withA = tasksOf('A');

console.log('【1】isSessionGenerating');
check('A 在生成 → true', isSessionGenerating(withA, 'A') === true);
check('B 没在生成 → false', isSessionGenerating(withA, 'B') === false);
check('空 Map 不抛错 → false', isSessionGenerating(new Map(), 'A') === false);
check('null Map 不抛错 → false', isSessionGenerating(null, 'A') === false);
check('null 会话 id → false', isSessionGenerating(withA, null) === false);
check('undefined 会话 id → false', isSessionGenerating(withA, undefined) === false);

console.log('\n【2】resolveSendAction（发送守卫只按会话算）');
check('在 B 发送 → 放行（**并行的关键**）', resolveSendAction(withA, 'B') === 'start', resolveSendAction(withA, 'B'));
check('在 A 发送 → 拦截 busy-same-session', resolveSendAction(withA, 'A') === 'busy-same-session', resolveSendAction(withA, 'A'));
check('没有会话（新建）→ 放行', resolveSendAction(withA, null) === 'start');
check('空 Map → 放行', resolveSendAction(new Map(), 'A') === 'start');
check('A、B 同时在生成时，C 仍可发', resolveSendAction(tasksOf('A', 'B'), 'C') === 'start');

console.log('\n【3】resolveStopTargetTaskId（停止只停自己）');
check('当前在 B、B 没生成 → null（按钮此时是"发送"）', resolveStopTargetTaskId(withA, 'B') === null, String(resolveStopTargetTaskId(withA, 'B')));
check('当前在 A、A 在生成 → 停 A', resolveStopTargetTaskId(withA, 'A') === 'A', String(resolveStopTargetTaskId(withA, 'A')));
check('**关键：当前在 B 时不会误停 A**', resolveStopTargetTaskId(withA, 'B') !== 'A');
check('null 会话 → null', resolveStopTargetTaskId(withA, null) === null);
check('空 Map → null', resolveStopTargetTaskId(new Map(), 'A') === null);

console.log('\n【4】shouldNormalizeSessionHistory');
check('生成中的会话 → 不归一化', shouldNormalizeSessionHistory(withA, 'A') === false);
check('没在生成的会话 → 归一化', shouldNormalizeSessionHistory(withA, 'B') === true);
check('null 会话 → 归一化（与旧行为一致）', shouldNormalizeSessionHistory(withA, null) === true);
check('空 Map → 归一化', shouldNormalizeSessionHistory(new Map(), 'A') === true);

console.log('\n【5】多会话并行时的组合语义');
const parallel = tasksOf('A', 'B');
check('A、B 同时生成：各自都算"生成中"', isSessionGenerating(parallel, 'A') && isSessionGenerating(parallel, 'B'));
check('A、B 同时生成：在 C 仍可发', resolveSendAction(parallel, 'C') === 'start');
check('A、B 同时生成：停 A 不影响 B', resolveStopTargetTaskId(parallel, 'A') === 'A' && isSessionGenerating(parallel, 'B'));
check('A、B 都在生成 → 两者都不归一化', shouldNormalizeSessionHistory(parallel, 'A') === false && shouldNormalizeSessionHistory(parallel, 'B') === false);

console.log('\n【6】任务表更新（不可变替换，不改原 Map）');
{
  const t1 = stubTask('A');
  const m0 = new Map();
  const m1 = withTaskAdded(m0, 'A', t1);
  check('加任务后：新 Map 有、原 Map 没有', m1.has('A') && !m0.has('A'));
  check('取出来的就是存进去的那个对象（同一性）', m1.get('A') === t1);
  const m2 = withTaskRemoved(m1, 'A');
  check('移除后：新 Map 没有、原 Map 仍有', !m2.has('A') && m1.has('A'));
  check('null / undefined 入参不抛错', withTaskAdded(null, 'A', t1).has('A') && withTaskRemoved(undefined, 'A').size === 0);
}

console.log('\n【7】⚠️ 响应式陷阱回归（这个坑真踩过）');
{
  // 背景：任务表曾写成 `ref(new Map())`，于是 `tasks.value.get(id) !== task` 永远成立
  // → 监听器全部提前返回 → mock 流跑完按钮不恢复、真实对话内容一帧不追加。
  // 下面几条把「必须用 shallowRef + 整体替换」钉死。
  const task = stubTask('A');

  const reactiveMap = ref(new Map());
  reactiveMap.value.set('A', task);
  check(
    'ref(new Map()) 取出来的**不是**原对象（这正是当年的 bug 源）',
    reactiveMap.value.get('A') !== task,
    '若这条失败说明 Vue 行为变了，需重新评估任务表写法'
  );

  const shallowMap = shallowRef(new Map());
  shallowMap.value = withTaskAdded(shallowMap.value, 'A', task);
  check('shallowRef + 整体替换：取出来就是原对象', shallowMap.value.get('A') === task);

  const size = computed(() => shallowMap.value.size);
  check('初始 size = 1', size.value === 1, String(size.value));
  shallowMap.value = withTaskRemoved(shallowMap.value, 'A');
  check('移除后 computed 感知到 size 变 0（响应式没丢）', size.value === 0, String(size.value));
  check('原地 mutate 不触发响应式（所以必须整体替换）', (() => {
    const s = shallowRef(new Map());
    const c = computed(() => s.value.size);
    const before = c.value; // ⚠️ 先求值填充缓存（computed 是惰性的，不先读就没缓存可失效）
    s.value.set('B', task); // 原地 set，不换 Map
    return before === 0 && c.value === 0; // 缓存仍在旧值 → 证明徒手 mutate 不会通知
  })());
}

console.log(`\n===== 通过 ${pass} 项，失败 ${fail} 项 =====`);
process.exit(fail ? 1 : 0);