import test from 'node:test';
import assert from 'node:assert/strict';

import {
  mergeConversationSnapshot,
  mergeSessionMessagesAfterFinish,
} from './chat-finish-sync.mjs';

const msg = (id, role, text) => ({
  id,
  role,
  metadata: { userVisible: true },
  content: [{ type: 'text', text }],
});

test('mergeConversationSnapshot keeps local-only messages when server snapshot is shorter', () => {
  const local = [
    msg('u1', 'user', '生成一个页面'),
    msg('a1', 'assistant', '正在写入 public/demo.html…'),
    msg('a2', 'assistant', '页面已生成'),
  ];
  const server = [msg('u1', 'user', '生成一个页面')];
  const merged = mergeConversationSnapshot(local, server);
  assert.equal(merged.length, 3);
  assert.deepEqual(
    merged.map((message) => message.id),
    ['u1', 'a1', 'a2'],
  );
});

test('mergeConversationSnapshot prefers server content for shared message ids', () => {
  const local = [msg('u1', 'user', '旧文案')];
  const server = [msg('u1', 'user', '新文案')];
  const merged = mergeConversationSnapshot(local, server);
  assert.equal(merged.length, 1);
  assert.equal(merged[0].content[0].text, '新文案');
});

test('mergeConversationSnapshot returns current when incoming is empty', () => {
  const local = [msg('u1', 'user', 'hello')];
  assert.deepEqual(mergeConversationSnapshot(local, []), local);
});

test('mergeSessionMessagesAfterFinish matches Finish sync merge semantics', () => {
  const local = [
    msg('u1', 'user', '根据图片做主题页'),
    msg('a1', 'assistant', '已完成'),
  ];
  const server = [msg('u1', 'user', '根据图片做主题页')];
  assert.deepEqual(
    mergeSessionMessagesAfterFinish(local, server).map((message) => message.id),
    ['u1', 'a1'],
  );
});

test('mergeConversationSnapshot keeps an omitted middle message between its anchors', () => {
  const local = [
    msg('u1', 'user', '第一轮'),
    msg('a1', 'assistant', '第一轮回复'),
    msg('u2', 'user', '第二轮'),
    msg('a2', 'assistant', '第二轮回复'),
  ];
  const server = [local[0], local[1], local[3]];
  assert.deepEqual(
    mergeConversationSnapshot(local, server).map((message) => message.id),
    ['u1', 'a1', 'u2', 'a2'],
  );
});

test('mergeConversationSnapshot keeps local messages before the first and after the last server anchor', () => {
  const local = [
    msg('u0', 'user', '本地前置'),
    msg('u1', 'user', '服务端消息'),
    msg('a1', 'assistant', '服务端回复'),
    msg('a2', 'assistant', '本地尾部'),
  ];
  const server = [local[1], local[2]];
  assert.deepEqual(
    mergeConversationSnapshot(local, server).map((message) => message.id),
    ['u0', 'u1', 'a1', 'a2'],
  );
});

test('mergeConversationSnapshot keeps local-only messages at their streamed position', () => {
  const local = [
    msg('u1', 'user', '生成页面'),
    msg('a1', 'assistant', '开始分析'),
    msg('a2', 'assistant', '调用工具'),
    msg('a3', 'assistant', '页面完成'),
  ];
  const server = [
    msg('u1', 'user', '生成页面'),
    msg('a3', 'assistant', '页面完成（服务端）'),
  ];
  const merged = mergeConversationSnapshot(local, server);
  assert.deepEqual(merged.map((message) => message.id), ['u1', 'a1', 'a2', 'a3']);
  assert.equal(merged[3].content[0].text, '页面完成（服务端）');
});

test('mergeConversationSnapshot preserves multiple local messages before the next server anchor', () => {
  const local = [
    msg('u1', 'user', '任务'),
    msg('a1', 'assistant', '步骤一'),
    msg('a2', 'assistant', '步骤二'),
    msg('a3', 'assistant', '完成'),
  ];
  const server = [msg('u1', 'user', '任务'), msg('a3', 'assistant', '完成')];
  assert.deepEqual(
    mergeConversationSnapshot(local, server).map((message) => message.id),
    ['u1', 'a1', 'a2', 'a3'],
  );
});