const express = require('express')
const bodyParser = require("body-parser");
var fs = require('fs');
var readline = require('readline');
var google = require('googleapis');
var googleAuth = require('google-auth-library');

const app = express()
const router = express.Router();

router.use(bodyParser.urlencoded({ extended: false }));
router.use(bodyParser.json());

require('dotenv').config()

const PEOPLE_DB = process.env.PEOPLE_DB.split('/')[5];
const PAIRS_LIST = process.env.PAIRS_LIST.split('/')[5];

var SCOPES = ['https://www.googleapis.com/auth/spreadsheets'];
var TOKEN_DIR = (process.env.HOME || process.env.HOMEPATH ||
    process.env.USERPROFILE) + '/.credentials/';
var TOKEN_PATH = TOKEN_DIR + 'sheets.googleapis.com-nodejs-quickstart.json';

var oauth2Client = null;

var pairsForSave = [];
var lastRow = null; //last row with names


function executeAPI(callback1,callback2){
  fs.readFile('client_secret.json', function processClientSecrets(err, content) {
    console.log("reading client secret");
    if (err) {
      console.log('Error loading client secret file: ' + err);
      return;
    }
    // Authorize a client with the loaded credentials, then call the
    // Google Sheets API.
    authorize(JSON.parse(content), callback1, callback2);
  });
}

function authorize(credentials, callback1, callback2){
    var clientSecret = credentials.installed.client_secret;
    var clientId = credentials.installed.client_id;
    var redirectUrl = credentials.installed.redirect_uris[0];
    var auth = new googleAuth();
    
    oauth2Client = new auth.OAuth2(clientId, clientSecret, redirectUrl);
  
    // Check if we have previously stored a token.
    fs.readFile(TOKEN_PATH, function(err, token) {
      console.log(TOKEN_PATH);
      if (err) {
        getNewToken(callback1, callback2);
      } else {
        oauth2Client.credentials = JSON.parse(token);
        callback1(callback2);
      }
    });
}

function getNewToken(callback1, callback2) {
    var authUrl = oauth2Client.generateAuthUrl({
      access_type: 'offline',
      scope: SCOPES
    });
    console.log('Authorize this app by visiting this url: ', authUrl);
    var rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout
    });
    rl.question('Enter the code from that page here: ', function(code) {
      rl.close();
      oauth2Client.getToken(code, function(err, token) {
        if (err) {
          console.log('Error while trying to retrieve access token', err);
          return;
        }
        oauth2Client.credentials = token;
        storeToken(token);
        callback1(callback2);
      });
    });
}

function storeToken(token) {
  try {
    fs.mkdirSync(TOKEN_DIR);
  } catch (err) {
    if (err.code != 'EEXIST') {
      throw err;
    }
  }
  console.log(JSON.stringify(token));
  fs.writeFile(TOKEN_PATH, JSON.stringify(token));
  console.log('Token stored to ' + TOKEN_PATH);
}

function getPairs(callback){
    auth=oauth2Client;
    ranges = ['2017!A:A','2017!B:B']; //get all rows with names
    var sheets = google.sheets('v4');
    sheets.spreadsheets.values.batchGet({
      auth: auth,
      spreadsheetId: PAIRS_LIST,
      ranges: ranges
    }, function(err, result) {
     if(err) {
       // Handle error
       console.log(err);
       return null;
     } else {
       const pairs = [];
       
       lastRow = result.valueRanges[0].values.length;

       for (let i=0;i<lastRow;i++){
         let name1 = result.valueRanges[0].values[i][0];
         if (name1){
          let name2 = result.valueRanges[1].values[i][0];
          pairs.push({name1:name1,name2:name2});
         }
       }
       callback(pairs);
     }
    });
}

function getAvailableNames(callback){
  auth=oauth2Client;
  ranges = ['\'Other preferences\'!A2:A','\'Other preferences\'!E2:E']; //get all rows with names
  var sheets = google.sheets('v4');
  sheets.spreadsheets.values.batchGet({
    auth: auth,
    spreadsheetId: PEOPLE_DB,
    ranges: ranges
  }, function(err, result) {
   if(err) {
     // Handle error
     console.log(err);
     return null;
   } else {
     const names = [];
     
     for (let i=0;i<result.valueRanges[0].values.length;i++){
       let name = result.valueRanges[0].values[i][0];
       let available = result.valueRanges[1].values[i][0];
       
       if (name && (available=='x')){
         names.push(name);
       }
     }
     callback(names);
   }
  });
}

function MakePairs(callback){
  executeAPI(getAvailableNames,function(names){
    executeAPI(getPairs, function(pairs){
      let next_i=false;
      const newPairs = [];
      const usedNames = [];
      for (let i=0;i<names.length;i++){
        next_i=false;
        for (let j=0;j<names.length;j++){
          if (i!=j){
            
            let found=false;
            
            pairs.filter((pair)=>{
              if ((pair.name1==names[i] && pair.name2==names[j])||(pair.name1==names[j] && pair.name2==names[i])){
                console.log("Par pronaden !");
                console.log(names[i] + " i " + names[j]);
                found=true;
                return;
              }
            });

            if (!found){
              usedNames.filter((name)=>{
                if (names[i] === name || names[j] === name){
                  console.log("Ime vec koristeno");
                  found=true;
                  return;
                }
              });
            }
            

            if (!found){
              next_i=true;
              newPairs.push({name1:names[i], name2:names[j]});
              usedNames.push(names[i]);
              usedNames.push(names[j]);
              break;
            }
          }
        }
        if (next_i) continue;
      }
      pairsForSave=newPairs;
      callback.send(newPairs);
    });
  });
  //Napravi par -> Provjeri da li postoji -> Snimi ili ponovi postupak

}

function SavePairs(callback){
  if (lastRow== null) return;

  auth=oauth2Client;

  const values_column1 = [];
  const values_column2 = [];

  for (let i=0;i<pairsForSave.length;i++){
    values_column1.push([pairsForSave[i].name1]);
    values_column2.push([pairsForSave[i].name2]);
  }

  const data = [];

  let range1= '2017!A'+(lastRow+2)+':A'+(lastRow+2+pairsForSave.length);
  let range2= '2017!B'+(lastRow+2)+':B'+(lastRow+2+pairsForSave.length);
  

  data.push({
    range:range1,
    values: values_column1
  });

  data.push({
    range:range2,
    values: values_column2
  });

  var body = {
    data: data,
    valueInputOption:"RAW"
  };
  var sheets = google.sheets('v4');
  sheets.spreadsheets.values.batchUpdate({
     spreadsheetId: PAIRS_LIST,
     auth:auth,
     resource: body
  }, function(err, result) {
    if(err) {
      // Handle error
      console.log(err);
      callback.send({result:false});
    } else {
      lastRow=null;
      pairsForSave=[];
      callback.send({result:true});
    }
  });

}

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, X-Last-Record-Id, X-Total-Count");
  res.header("Access-Control-Expose-Headers", "X-Last-Record-Id, X-Total-Count");
  res.header("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
  res.header('Access-Control-Allow-Credentials', 'true');
  next();
});

app.get('/getPairs',(req,resp)=>{
  pairsForSave=[];
  lastRow=null;
  MakePairs(resp);
});

app.get('/savePairs', (req,resp)=>{
  SavePairs(resp);
  //resp.send({result:true});
});


app.listen(3005, function () {
  console.log('server na portu 3005');
})