// 云函数入口文件
const cloud = require('wx-server-sdk');

const user_db_name = "cocos_users";
cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV }); // 使用当前云环境

// 云函数入口函数
exports.main = async (event, context) => {
  let cmd = event.cmd;
  if (cmd == null) {
    return {
      code: -1,
      msg: "no cmd!"
    };
  }

  const wxContext = cloud.getWXContext();
  const db = cloud.database({
    env: cloud.DYNAMIC_CURRENT_ENV,
    throwOnNotFound: false
  });
  const _ = db.command;

  if (cmd === "login") {
    let user = await getOrCreaterUser(db, wxContext.OPENID);
    return {
      code: 200,
      data: user,
    };
  } else if (cmd === "save") {
    let data = event.data;
    let user = await getOrCreaterUser(db, wxContext.OPENID);
    let saveDataRes = await db.collection(user_db_name).doc(user._id).update({
      data: {
        game_data: _.set(data)
      }
    });

    console.log("Save data:", saveDataRes, data);
    if (saveDataRes?.stats?.updated >= 1) {
      return {
        code: 200,
        data: saveDataRes
      };
    } else {
      return {
        code: -1,
        msg: `Save fail, ${JSON.stringify(saveDataRes)}`
      };
    }
  } else if (cmd === "sync") {
    // 双向同步：比较客户端与云端时间戳，新的一方覆盖另一方
    let clientData = event.data || {};
    let user = await getOrCreaterUser(db, wxContext.OPENID);
    if (!user) {
      return { code: -1, msg: "Get or create user fail" };
    }

    let cloudData = user.game_data || {};
    let clientTs = clientData.timestamp || 0;
    let cloudTs = cloudData.timestamp || 0;

    if (clientTs > cloudTs) {
      // 客户端较新：写入云端
      let saveDataRes = await db.collection(user_db_name).doc(user._id).update({
        data: {
          game_data: _.set(clientData)
        }
      });
      console.log("Sync: client newer, saved to cloud:", saveDataRes, clientData);
      if (saveDataRes?.stats?.updated >= 1) {
        return {
          code: 200,
          updated: true, // 云端已被客户端数据覆盖
          data: {
            openid: wxContext.OPENID,
            game_data: clientData
          }
        };
      } else {
        return {
          code: -1,
          msg: `Sync save fail, ${JSON.stringify(saveDataRes)}`
        };
      }
    } else {
      // 云端较新或一致：下发云端数据
      console.log("Sync: cloud newer, return cloud data");
      return {
        code: 200,
        updated: false, // 客户端应使用云端数据
        data: {
          openid: wxContext.OPENID,
          game_data: cloudData
        }
      };
    }
  }

  return {
    code: -2,
    msg: `Unknow cmd: ${event?.cmd}`,
  };
};

async function getOrCreaterUser(db, openid) {
  try {
    let res = await db.collection(user_db_name).where({ _openid: openid }).get();
    let userData = null;
    if (res == null || res.data == null || res.data.length <= 0) {
      userData = {
        _openid: openid,
        regist_time: Date.now(),
      };
      let addResult = await db.collection(user_db_name).add({
        data: userData
      });
      userData._id = addResult._id;
    } else {
      userData = res.data[0];
    }
    return userData;
  } catch (err) {
    console.error(`Get or create user err`, err);
    return null;
  }
}