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);
   }
  });
}

var matrix = [];
var tree = [];
let done = false;

function count_pairs(row, col, cntr){
  if (done) return;

  matrix[row][col] = 2;

  //mark all fields in matrix related to row and col names
  for(let i=0;i<row;i++) matrix[row][i] = (matrix[row][i]===0)? cntr: matrix[row][i];
  for(let i=0;i<col;i++) matrix[col][i] = (matrix[col][i]===0)? cntr: matrix[col][i];

  for(let i=row;i<matrix.length;i++) matrix[i][row] = (matrix[i][row]===0)? cntr: matrix[i][row];
  for(let i=col;i<matrix.length;i++) matrix[i][col] = (matrix[i][col]===0)? cntr: matrix[i][col];

  //find next pair

  let found = false;
  for (let i=0;i<matrix.length;i++){
    for (let j=0;j<=i;j++){
      if (matrix[i][j]===0){
        count_pairs(i,j,cntr+1);
        found=true;
      }
    }
  }

  if (!found){
    let inner_tree = [];
    for (let i=0;i<matrix.length;i++){
      for (let j=0;j<=i;j++){
        if (matrix[i][j]===2){
          inner_tree.push({row: i, col:j});
        }
      }
    }
    if (inner_tree.length === max_pairs) {
      done=true;
      tree.push(inner_tree);
    }
  }

  //remove marks from matrix 
  for(let i=0;i<row;i++) matrix[row][i] = (matrix[row][i]===cntr)? 0: matrix[row][i];
  for(let i=0;i<col;i++) matrix[col][i] = (matrix[col][i]===cntr)? 0: matrix[col][i];

  for(let i=row;i<matrix.length;i++) matrix[i][row] = (matrix[i][row]===cntr)? 0: matrix[i][row];
  for(let i=col;i<matrix.length;i++) matrix[i][col] = (matrix[i][col]===cntr)? 0: matrix[i][col];

  matrix[row][col] = 0;
}

function MakePairsV3(callback){
  executeAPI(getAvailableNames,function(names){
    executeAPI(getPairs, function(pairs){
      max_pairs = Math.floor(names.length/2);
      matrix=[];

      for (let i=0;i<names.length;i++){
        let matrix_row = [];
        for (let j=0;j<=i;j++) (i===j)? matrix_row.push(1):matrix_row.push(0);
        matrix.push(matrix_row);
      }

      //Mark existing pairs, put 3 in matrix fields 
      pairs.filter((pair)=>{

        let name1_id = names.indexOf(pair.name1);
        let name2_id = names.indexOf(pair.name2);

        if (name1_id !== -1 && name2_id !== -1){
          if (name1_id > name2_id){
            matrix[name1_id][name2_id] = 3;
          }else{
            matrix[name2_id][name1_id] = 3;
          }
        }
      });

      

      tree = [];
      done=false;

      for (let i=0;i<names.length;i++){
        for (let j=0;j<=i;j++){
          if (matrix[i][j] === 0){
            count_pairs(i,j,5);
            if (done) break;
          }
        }
        if (done) break;
      }

      let max_count_index = 0;
      
      for (let i=0;i<tree.length;i++){
        if (tree[i].length > tree[max_count_index].length)
          max_count_index = i;
      }

      let result_pairs = [];
      if (tree.length > 0){
        for (let i=0;i<tree[max_count_index].length;i++){
          result_pairs.push({name1: names[tree[max_count_index][i].row],name2: names[tree[max_count_index][i].col] });
        }

        let indexToRemove = [];

        for (let i=0;i<tree[max_count_index].length;i++){
          indexToRemove.push(tree[max_count_index][i].row);
          indexToRemove.push(tree[max_count_index][i].col);
        }

        indexToRemove.sort((a,b)=>{
          if (a>b) return -1; else return 1;
        });

        for (let i=0;i<indexToRemove.length;i++)
          names.splice(indexToRemove[i],1);
      }

      if (names.length === 0) names=null;
      pairsForSave = result_pairs;
      callback.send({pairs: result_pairs, left: names});
    });
  });
}

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;
  MakePairsV3(resp);
});

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

app.listen(3005, function () {
  console.log("Server running - Port 3005");
})