results.js

var db = require('./db/db.json');

const GPV = {
  "A+" : 4.25,
  "A" : 4,
  "A-" : 3.75,
  "B+" : 3.25,
  "B" : 3,
  "B-" : 2.75,
  "C+": 2.25,
  "C" : 2,
  "C-" : 1.75,
  "D+" : 1.25,
  "D" : 1,
  "D-" : 0.75,
  "E" : 0,
  "F" : 0
}

var getTotalCredits = function(results){

  var gpaResults = results.filter(function(res){
    return !res.code.startsWith("EN") && res.grade != undefined;
  });
  console.log("res", gpaResults);

  return gpaResults.reduce(function(a, b){
    return a + parseInt(b.credits);
  }, 0);
};

var calculateGPA = function(results, totalCredits){

  var gpaResults = results.filter(function(res){
    return res.grade !== undefined && !res.code.startsWith("EN");
  });

  var totalGpv = gpaResults.reduce(function(a, b){
    return a + (parseInt(b.credits) * GPV[b.grade]);
  }, 0);

  totalGpv = totalGpv || 0;

  return totalGpv / totalCredits;
};

var calculateCGPA = function(gpa, credits) {
  var totalGpv = gpa.reduce(function(r,a,i){
    return r + a * credits[i]
  }, 0)

  var sumCredits = credits.reduce(function(a, b) { return a + b; }, 0);

  return totalGpv/sumCredits;
};

var fetchResults = function(index){
    var final = {};
    var gpas = [];
    var credits = [];

    for (year in db) {
      final[year] = {};
      for (semester in db[year]) {
        final[year][semester] = {};
        var results = db[year][semester].results.map(function(subject){
          return {
            title: subject.Title,
            code: subject.Subject_Code,
            credits: subject.Credits,
            grade: subject.Marks[index]
          }
        });
        var totalCredits = getTotalCredits(results);
        var gpa = calculateGPA(results, totalCredits);
        gpas.push(gpa);
        credits.push(totalCredits);
        final[year][semester]['gpa'] = gpa
        final[year][semester]['result'] = results;
      }


    };

    finalGpa = calculateCGPA(gpas, credits);
    final['gpa'] = finalGpa;
    return final;
}

var calculateGPAs = function(){
	var results = [];
	var indexNumbers = db['year1']['sem1']['results'][0]['Marks'];

  for(index in indexNumbers){
    var result = fetchResults(index);
    results.push({ index: index, results: result });
  }
  return results;
}

fourth_years = ["14020084","14020106","14020122","14020157","14020191","14020203","14020246","14020297","14020343","14020408","14020582","14020602","14020696","14020734","14020752","14020823","14020874","14020912","14020939"]
var calculateRanks = function(){
  var all_gpas = calculateGPAs();

  var gpas = []
  for(i in all_gpas) {
    if (fourth_years.indexOf(all_gpas[i]['index']) > -1) {
      gpas.push(all_gpas[i]);
    }
  }
  // console.log(gpas);

  gpas.sort(function(a, b){ return a.results.gpa > b.results.gpa? -1: 1 })
                         .forEach(function(rslt, i, arr) { console.log(rslt); rslt['results']['rank'] = i + 1; });

  for(year in db){
    for(sem in db[year]){
      gpas.sort(function(a, b){ return a.results[year][sem].gpa > b.results[year][sem].gpa? -1: 1})
                             .forEach(function(rslt, i, arr){ rslt['results'][year][sem]['rank'] = i + 1; });
    }
  }
  console.log(gpas);
  return gpas;
}

module.exports = calculateRanks();