const store = require('../../utils/store.js');
const api = require('../../utils/api.js');
const { toastErr } = require('../../utils/ui.js');

const SESSION = 'chat';
const PRESETS = ['猫咪今天吐了一次怎么办？', '幼猫多久驱虫一次？', '换粮后软便怎么办？', '疫苗打完要注意什么？'];

// 打字机：每帧吐几个字。太快没效果，太慢让人等，30ms/2 字接近正常朗读速度。
const TYPE_STEP = 2;
const TYPE_INTERVAL = 30;

Page({
  data: {
    pet: {},
    messages: [],
    input: '',
    presets: PRESETS,
    sending: false,
    loaded: false,
  },
  onLoad() {
    this._unsub = store.subscribe((pet) => this.setData({ pet }));
    store
      .ready()
      .then(() => {
        this.setData({ pet: store.getPet() });
        this.loadHistory();
      })
      .catch((e) => toastErr(e));
  },
  onUnload() {
    if (this._unsub) this._unsub();
    this.stopTyping();
  },

  loadHistory() {
    const opening = {
      role: 'ai',
      text: '我是' + (store.getPet().name || '毛孩子') + '的养宠助手。我会优先根据档案、计划和历史记录回答，而不是泛泛聊天。',
    };
    api
      .aiMessages(SESSION, 50)
      .then((list) => {
        const history = (list || []).map((m) => ({ role: m.role === 'user' ? 'user' : 'ai', text: m.text }));
        this.setData({ messages: [opening].concat(history), loaded: true }, () => this.scrollToBottom());
      })
      .catch(() => this.setData({ messages: [opening], loaded: true }));
  },

  onInput(e) {
    this.setData({ input: e.detail.value });
  },

  onSend(e) {
    const preset = e.currentTarget && e.currentTarget.dataset.text;
    const text = (preset || this.data.input || '').trim();
    if (!text || this.data.sending) return;

    // 先把用户消息和一个空的 AI 气泡放上去，AI 气泡随后逐字填充
    const messages = this.data.messages.concat([
      { role: 'user', text },
      { role: 'ai', text: '', pending: true },
    ]);
    this.setData({ messages, input: '', sending: true }, () => this.scrollToBottom());

    api
      .aiChat({ pet_id: store.currentPetId() || null, session: SESSION, text })
      .then((res) => this.typewrite(res.reply || '（没有返回内容）'))
      .catch((e) => {
        const msg = (e && e.message) || '网络异常，请稍后再试。';
        // 额度用完不是故障，别让用户以为是网络问题反复重试
        this.typewrite(msg.indexOf('次数') >= 0 ? msg + '\n\n每天的次数是为了控制成本，明天 0 点恢复。' : msg);
      });
  },

  // 逐字把回复填进最后一个气泡
  typewrite(full) {
    this.stopTyping();
    const idx = this.data.messages.length - 1;
    let n = 0;
    this._timer = setInterval(() => {
      n = Math.min(full.length, n + TYPE_STEP);
      this.setData({ [`messages[${idx}].text`]: full.slice(0, n) });
      if (n % 20 === 0) this.scrollToBottom();
      if (n >= full.length) {
        this.stopTyping();
        this.setData({ [`messages[${idx}].pending`]: false, sending: false }, () => this.scrollToBottom());
      }
    }, TYPE_INTERVAL);
  },
  stopTyping() {
    if (this._timer) {
      clearInterval(this._timer);
      this._timer = null;
    }
  },
  // 打字过程中点一下可以跳过，不用干等
  onSkip() {
    if (!this.data.sending) return;
    this.stopTyping();
    this.setData({ sending: false });
  },

  scrollToBottom() {
    this.setData({ scrollInto: 'chat-bottom' });
  },

  goAIPlan() {
    wx.navigateTo({ url: '/pages/plan/plan?tab=aiPlan' });
  },
  onShareAppMessage() {
    return { title: '肉垫计划 · AI 养宠助手', path: '/pages/ai/ai' };
  },
});