// 云函数 dogManage — 狗狗 create/update/list，建档与编辑复用
// 契约见 docs/03-云函数设计.md §2
const cloud = require('wx-server-sdk');
cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV });
const db = cloud.database();

// 体型档位 → 步幅模型（与 miniprogram/utils/dogStep.js 保持一致，docs/05 R3）
const BASE_STRIDE = { xs: 0.20, s: 0.25, m: 0.35, l: 0.45, xl: 0.55 }; // 米/步
const STD_WEIGHT = { xs: 3, s: 7, m: 15, l: 28, xl: 45 };              // 档位标准体重 kg
// 犬种 → 体型档位；未列出的（中华田园犬/串串/其他）需前端让用户手动选 sizeLevel
const BREED_SIZE = {
  柯基: 's', 比熊: 'xs', 泰迪: 's', 柴犬: 'm', 金毛: 'l',
  拉布拉多: 'l', 哈士奇: 'l', 边境牧羊犬: 'm', 萨摩耶: 'l', 法斗: 's',
};
const resolveSize = (breed, clientSize) => BREED_SIZE[breed] || clientSize || null;

function computeStride(sizeLevel, weight) {
  const base = BASE_STRIDE[sizeLevel];
  if (!base) return { baseStride: null, stride: null };
  let stride = base;
  if (weight) {
    let f = 1 + (Number(weight) - STD_WEIGHT[sizeLevel]) * 0.005;
    f = Math.max(0.85, Math.min(1.15, f));
    stride = +(base * f).toFixed(3);
  }
  return { baseStride: base, stride };
}

// 规范化狗狗字段；返回 { error } 表示校验失败
function normalize(dog) {
  const sizeLevel = resolveSize(dog.breed, dog.sizeLevel);
  if (!sizeLevel) return { error: '请选择体型档位' }; // 未知犬种必须手动选
  const weight = dog.weight != null ? Number(dog.weight) : null;
  const { baseStride, stride } = computeStride(sizeLevel, weight);
  return {
    data: {
      name: String(dog.name || '').trim(),
      breed: String(dog.breed || '').trim(),
      sizeLevel,
      baseStride,
      stride,
      gender: dog.gender || null,
      ageStage: dog.ageStage || null,
      ageText: dog.ageText || '',
      weight,
      avatar: dog.avatar || '',
    },
  };
}

exports.main = async (event, context) => {
  const { OPENID } = cloud.getWXContext();
  const { action, dog } = event;
  const dogsCol = db.collection('dogs');

  // ---- list：列出我的狗 ----
  if (action === 'list') {
    const res = await dogsCol.where({ _openid: OPENID }).orderBy('createdAt', 'asc').get();
    return { ok: true, data: res.data };
  }

  // ---- create：建档 ----
  if (action === 'create') {
    if (!dog || !dog.name || !dog.breed) {
      return { ok: false, code: 'INVALID', msg: '名字和犬种必填' };
    }
    const norm = normalize(dog);
    if (norm.error) return { ok: false, code: 'INVALID', msg: norm.error };
    const now = Date.now();
    const doc = {
      _openid: OPENID,
      ...norm.data,
      stats: { totalWalks: 0, totalDistance: 0, totalSteps: 0, currentStreak: 0, lastWalkDate: '' },
      createdAt: now,
    };
    const addRes = await dogsCol.add({ data: doc });
    return { ok: true, data: { _id: addRes._id, ...doc } };
  }

  // ---- update：编辑（校验归属，防越权改他人狗）----
  if (action === 'update') {
    if (!dog || !dog._id) return { ok: false, code: 'INVALID', msg: '缺少狗狗ID' };
    if (!dog.name || !dog.breed) return { ok: false, code: 'INVALID', msg: '名字和犬种必填' };

    const target = await dogsCol.doc(dog._id).get().catch(() => null);
    if (!target || !target.data || target.data._openid !== OPENID) {
      return { ok: false, code: 'FORBIDDEN', msg: '无权操作' };
    }
    const norm = normalize(dog);
    if (norm.error) return { ok: false, code: 'INVALID', msg: norm.error };
    await dogsCol.doc(dog._id).update({ data: norm.data });
    return { ok: true, data: { ...target.data, ...norm.data } };
  }

  return { ok: false, code: 'UNKNOWN_ACTION', msg: '未知操作' };
};