//以下的四列require裡的內容，請確認是否已經用npm裝進node.js

var linebot = require('linebot');

var express = require('express');

var google = require('googleapis');

var googleAuth = require('google-auth-library');

//以下的引號內請輸入申請LineBot取得的各項資料，逗號及引號都不能刪掉

var bot = linebot({

  channelId: '請輸入LineBot的channelId',

  channelSecret: '請輸入LineBot的channelSecret',

  channelAccessToken: '請輸入LineBot的channelAccessToken'

});

//底下輸入client_secret.json檔案的內容

var myClientSecret=請將client_secret.json檔案的內容放在這裡，前後不能加引號

var auth = new googleAuth();

var oauth2Client = new auth.OAuth2(myClientSecret.installed.client_id,myClientSecret.installed.client_secret, myClientSecret.installed.redirect_uris[0]);

//底下輸入sheetsapi.json檔案的內容

oauth2Client.credentials =請將sheetsapi.json檔案的內容放在這裡，前後不能加引號

//試算表的ID，引號不能刪掉

var mySheetId='請輸入試算表的ID編號';

var myQuestions=[];

var users=[];

var totalSteps=0;

var myReplies=[];

//程式啟動後會去讀取試算表內的問題

getQuestions();

//這是讀取問題的函式

function getQuestions() {

  var sheets = google.sheets('v4');

  sheets.spreadsheets.values.get({

     auth: oauth2Client,

     spreadsheetId: mySheetId,

     range:encodeURI('問題'),

  }, function(err, response) {

     if (err) {

        console.log('讀取問題檔的API產生問題：' + err);

        return;

     }

     var rows = response.values;

     if (rows.length == 0) {

        console.log('No data found.');

     } else {

       myQuestions=rows;

       totalSteps=myQuestions[0].length;

       console.log('要問的問題已下載完畢！');

     }

  });

}

//這是將取得的資料儲存進試算表的函式

function appendMyRow(userId) {

   var request = {

      auth: oauth2Client,

      spreadsheetId: mySheetId,

      range:encodeURI('表單回應 1'),

      insertDataOption: 'INSERT_ROWS',

      valueInputOption: 'RAW',

      resource: {

        "values": [

          users[userId].replies

        ]

      }

   };

   var sheets = google.sheets('v4');

   sheets.spreadsheets.values.append(request, function(err, response) {

      if (err) {

         console.log('The API returned an error: ' + err);

         return;

      }

   });

}

//LineBot收到user的文字訊息時的處理函式

bot.on('message', function(event) {

   if (event.message.type === 'text') {

      var myId=event.source.userId;

      if (users[myId]==undefined){

         users[myId]=[];

         users[myId].userId=myId;

         users[myId].step=-1;

         users[myId].replies=[];

      }

      var myStep=users[myId].step;

      if (myStep===-1)

         sendMessage(event,myQuestions[0][0]);

      else{

         if (myStep==(totalSteps-1))

            sendMessage(event,myQuestions[1][myStep]);

         else

            sendMessage(event,myQuestions[1][myStep]+'\n'+myQuestions[0][myStep+1]);

         users[myId].replies[myStep+1]=event.message.text;

      }

      myStep++;

      users[myId].step=myStep;

      if (myStep>=totalSteps){

         myStep=-1;

         users[myId].step=myStep;

         users[myId].replies[0]=new Date();

         appendMyRow(myId);

      }

   }

});

//這是發送訊息給user的函式

function sendMessage(eve,msg){

   eve.reply(msg).then(function(data) {

      // success 

      return true;

   }).catch(function(error) {

      // error 

      return false;

   });

}

const app = express();

const linebotParser = bot.parser();

app.post('/', linebotParser);

//因為 express 預設走 port 3000，而 heroku 上預設卻不是，要透過下列程式轉換

var server = app.listen(process.env.PORT || 8080, function() {

  var port = server.address().port;

  console.log("App now running on port", port);

});