// 全局状态：登录、宠物列表、当前宠物；服务端驱动 + 发布订阅
const api = require('./api.js');

const state = {
  user: null,
  pets: [],
  currentId: 0,
};

const listeners = new Set();
let bootstrapPromise = null;

function getPets() {
  return state.pets;
}
function getPet() {
  return state.pets.find((p) => p.id === state.currentId) || state.pets[0] || {};
}
function currentPetId() {
  const p = getPet();
  return p && p.id;
}

function notify() {
  const pet = getPet();
  listeners.forEach((fn) => {
    try {
      fn(pet);
    } catch (e) {
      /* noop */
    }
  });
}

function subscribe(fn) {
  listeners.add(fn);
  return () => listeners.delete(fn);
}

// 登录 + 拉宠物列表（只跑一次）
function ready() {
  if (!bootstrapPromise) {
    bootstrapPromise = (async () => {
      const res = await api.login();
      state.user = res.user;
      await loadPets();
    })().catch((e) => {
      bootstrapPromise = null; // 允许重试
      throw e;
    });
  }
  return bootstrapPromise;
}

async function loadPets() {
  const pets = await api.getPets();
  state.pets = pets || [];
  if (!state.currentId && state.pets[0]) {
    state.currentId = state.pets[0].id;
  }
  // 当前宠物被删或不存在时回退第一只
  if (!state.pets.find((p) => p.id === state.currentId) && state.pets[0]) {
    state.currentId = state.pets[0].id;
  }
  notify();
  return state.pets;
}

function switchPet(id) {
  if (state.currentId === id) return;
  state.currentId = id;
  notify();
}

// 本地更新当前宠物字段（服务端已改动后同步 UI）
function patchCurrent(patch) {
  const pet = getPet();
  Object.assign(pet, patch);
  notify();
}

function setUser(u) {
  state.user = u;
}
function getUser() {
  return state.user;
}

module.exports = {
  ready,
  loadPets,
  getPets,
  getPet,
  currentPetId,
  switchPet,
  patchCurrent,
  subscribe,
  setUser,
  getUser,
};