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 = [];
       
       try{
        lastRow = result.valueRanges[0].values.length;
       }catch(err){
         lastRow = 0;
       }

       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++){
       
      try{
        let name = result.valueRanges[0].values[i][0];
        let available = result.valueRanges[1].values[i][0];
        if (name && (available=='x')){
          names.push(name);
        }
      }catch(err){
      }
      
     }
     callback(names);
   }
  });
}

function getRandomInt(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

function MakePairs(callback){
  executeAPI(getAvailableNames,function(names){
    executeAPI(getPairs, function(pairs){
      const numOfPairs = Math.floor(names.length / 2);
      const left_side = [];
      const right_side = [];

      const newPairs = [];

      for (let i=0;i<numOfPairs;i++){

        let id1 = getRandomInt(0,names.length-1);
        left_side.push(names[id1]);
        names.splice(id1,1);
        let id2 = getRandomInt(0,names.length-1);
        right_side.push(names[id2]);
        names.splice(id2,1);
      }

      //make pairs using both sides

      for (let i=0;i<left_side.length;i++){
        if (i==left_side.length) break;
        for (let j=0;j<right_side.length;j++){
          let tmpName1 = left_side[i];
          let tmpName2 = right_side[j];
          let exist=false;
          pairs.filter((pair)=>{
            if (((pair.name1 == tmpName1)&&(pair.name2==tmpName2))||((pair.name1==tmpName2)&&(pair.name2==tmpName1))){
              exist = true;
              return;
            }
          });
          if (!exist){
            newPairs.push({name1:tmpName1, name2:tmpName2});
            left_side.splice(i,1);
            right_side.splice(j,1);
            i=-1;
            break;
          }
        }
      }

      //make pairs from names on left side
      for (let i=0;i<left_side.length;i++){
        for (let j=0;j<left_side.length;j++){
          if (i==j) continue;
          let tmpName1 = left_side[i];
          let tmpName2 = left_side[j];
          let exist=false;
          pairs.filter((pair)=>{
            if (((pair.name1 == tmpName1)&&(pair.name2==tmpName2))||((pair.name1==tmpName2)&&(pair.name2==tmpName1))){
              exist = true;
              return;
            }
          });
          if (!exist){
            newPairs.push({name1:tmpName1, name2:tmpName2});
            left_side.splice(i,1);
            if (i>j)
              left_side.splice(j,1);
            else
              left_side.splice(j-1,1);
            i=-1;
            break;
          }
        }
      }
      
      //make pairs from names on right side
      for (let i=0;i<right_side.length;i++){
        for (let j=0;j<right_side.length;j++){
          if (i==j) continue;
          let tmpName1 = right_side[i];
          let tmpName2 = right_side[j];
          let exist=false;
          pairs.filter((pair)=>{
            if (((pair.name1 == tmpName1)&&(pair.name2==tmpName2))||((pair.name1==tmpName2)&&(pair.name2==tmpName1))){
              exist = true;
              return;
            }
          });
          if (!exist){
            newPairs.push({name1:tmpName1, name2:tmpName2});
            right_side.splice(i,1);
            if (i>j)
              right_side.splice(j,1);
            else
              right_side.splice(j-1,1);
            i=-1;
            break;
          }
        }
      }
      
      //try to make pair using unused name from list of names and names on left side
      if (names.length>0){
        let tmpName1 = names[0];
        for (let i=0;i<left_side.length;i++){
          let tmpName2 = left_side[i];
          let exist=false;
          pairs.filter((pair)=>{
            if (((pair.name1 == tmpName1)&&(pair.name2==tmpName2))||((pair.name1==tmpName2)&&(pair.name2==tmpName1))){
              exist = true;
              return;
            }
          });
          if (!exist){
            newPairs.push({name1:tmpName1, name2:tmpName2});
            names=[];
            left_side.splice(i,1);
            break;
          }    
        }
      }

      //try to make pair using unused name from list of names and names on right side
      if (names.length>0){
        let tmpName1 = names[0];
        for (let i=0;i<right_side.length;i++){
          let tmpName2 = right_side[i];
          let exist=false;
          pairs.filter((pair)=>{
            if (((pair.name1 == tmpName1)&&(pair.name2==tmpName2))||((pair.name1==tmpName2)&&(pair.name2==tmpName1))){
              exist = true;
              return;
            }
          });
          if (!exist){
            newPairs.push({name1:tmpName1, name2:tmpName2});
            names=[];
            right_side.splice(i,1);
            break;
          }    
        }
      }

      pairsForSave = newPairs;

      let withoutPair = [];
      for (let i=0;i<left_side.length;i++)
        withoutPair.push(left_side[i]);
      for (let i=0;i<right_side.length;i++)
        withoutPair.push(right_side[i]);
      if (names.length>0)
        withoutPair.push(names[0]);

      if (withoutPair.length==0) withoutPair=null;
      
      callback.send({pairs: newPairs, left: withoutPair });
    });
  });
}

function SavePairs(callback){
  if (lastRow== null) {
    callback.send({result:true});
    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 = [];

  if (lastRow == 0) lastRow=-1;
  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 running - port 3005');
})