// constants
let latest_jquery = `https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.js`;

let pre_table_info = $(`div[style='float:right; font-weight: bold']`);
let announcement = [
  `<h1 style='text-align: center'>Note: IskoDuler DOES NOT automatically recompute probabilities when changing rankings. Click the button below to refresh the computations.</h1>`
];
let button = `<input style="width:100%;background-color: #e7e7e7;color: black;font-size:24px;" id="refreshButton" type="button" value="REFRESH" onclick="refresh();" />`;


let compute_probabilities = function () {
  // add a new "Probability" column
  $(`#tr_class-info-head`).append(`<th id='probability_header'>&nbsp;&nbsp;Probability&nbsp;&nbsp;</th>`);
  // add a new "Base Probability" column
  $(`#tr_class-info-head`).append(`<th id='base_probability_header'>Base Probability</th>`);

  // get list of enlisted classes
  x = document.getElementsByClassName(`preenlist_conflicts`);

  // define letiables
  slots_demand_info = [];
  probabilities = [];
  base_probabilities = [];
  conflicting_classes = Object.keys(conflictlist);
  class_statuses = $(`td[id^=td-icon]`);
  enlisted_classes_id = [];
  conflict_matrix = matrix(21,21, 0);

  // parse slots and demand and store it to slots_demand_info
  for (i = 0; i < x.length; i++) {
    tr_obj = $(x[i]).children();
    tr_obj = filter_for_nstp_and_econ11(tr_obj);
    s = tr_obj.find(`.td_classname`).text();
    s = s.substring(s.indexOf(`[`)+1, s.indexOf(`]`));
    s = s.split(`/`);
    slots_demand_info.push([parseInt(s[0]), parseInt(s[2])]);
  }

  // compute probabilities using slots_demand_info and store it to probabilities array
  for (i = 0; i < slots_demand_info.length; i++) {
    p = slots_demand_info[i][0]/slots_demand_info[i][1];
    if (p >=1.0) p = 1.0;
    probabilities.push(p);
  }

  // convert every element in conflicting classes from string to int
  for (i = 0; i < conflicting_classes.length; i++) {
    conflicting_classes[i] = parseInt(conflicting_classes[i]);
  }

  // get which classes are enlisted
  for (let i = 0; i < class_statuses.length; ++i) {
    if (class_statuses[i].querySelector(`img[title='Enlisted']`) !== null) {
      enlisted_classes_id.push(i);
    }
  }

  // set the base probs of enlisted classes to 100%
  for (let i = 0; i < enlisted_classes_id.length; ++i)
  {
    probabilities[enlisted_classes_id[i]] = 1.0;
  }



  // parse conflicting classes array to int
  for (let i = 0; i < conflicting_classes.length; ++i) {
    conflicting_classes[i] = parseInt(conflicting_classes[i]);
  }

  // traverse each class with conflicts
  for (let i = 0; i < conflicting_classes.length; ++i) {
    c = conflicting_classes[i];
    // get list of ids of classes in conflict with
    conflicts_with = Object.keys(conflictlist[c][`conflicts`]);

    for (let j = 0; j < conflicts_with.length; ++j) {
      conflict_id = parseInt(conflicts_with[j]);
      conflict_matrix[c][conflict_id] = 1;
      conflict_matrix[conflict_id][c] = 1;
    }
  }

  // save current probability list to base probability list
  base_probabilities = probabilities.slice();


  // computer final probs
  for (i = 0; i < probabilities.length; ++i) {
    p = base_probabilities[i];
    // check for all conflicting classes ranked higher
    for (j = 0; j < i; ++j) {
      if (conflict_matrix[i+1][j+1] == 1) {
        p *= (1.0 - base_probabilities[j]);
      }
    }
    probabilities[i] = p;
  }


  // round off final probabilities to the nearest percent
  for (i = 0; i < probabilities.length; i++) {
    probabilities[i] = parseInt(100 * probabilities[i] + 0.5);
  }

  // round off base probabilities to the nearest percent
  for (i = 0; i < base_probabilities.length; i++) {
    base_probabilities[i] = parseInt(100 * base_probabilities[i] + 0.5);
  }

  // add final probabilities to the table
  for (i = 0; i < x.length; i++) {
    var tr_obj = $(x[i]).children();
    tr_obj = filter_for_nstp_and_econ11(tr_obj);
    tr_obj.append(`<td class='td_probability'>` + probabilities[i] + `%</td>`);
    tr_obj.append(`<td class='td_base_probability'>` + base_probabilities[i] +  `%&nbsp;<a href='http://facebook.com/IskoDuler/photos/a.1102011849897053.1073741828.1101849453246626/1121795081252063'>(?)</a>` + `</td>`);

    empty_tr_objs = $(x[i]).children().filter(function() {
      return this != tr_obj[0];
    });
    empty_tr_objs.append(`<td class='td_filler'></td><td class='td_filler'></td>`); // filler
  }
}

let delete_added_columns = function () {
  // remove probability column
  while (document.getElementsByClassName('td_probability').length > 0) {
    document.getElementsByClassName('td_probability')[0].remove();
  }

  // remove base probability column
  while (document.getElementsByClassName('td_base_probability').length > 0) {
    document.getElementsByClassName('td_base_probability')[0].remove();
  }

  // remove all filler columns
  while (document.getElementsByClassName('td_filler').length > 0) {
    document.getElementsByClassName('td_filler')[0].remove();
  }

  // remove added table headers
  document.getElementById('probability_header').remove();
  document.getElementById('base_probability_header').remove();
}

let insert_announcements = function () {
    // insert announcments
  $(announcement[0]).insertBefore(pre_table_info);
  $(button).insertBefore(pre_table_info);
}

let matrix = function (rows, cols, defaultValue) {

  let arr = [];

  // Creates all lines:
  for (let i=0; i < rows; i++) {
    // Creates an empty line
    arr.push([]);

    // Adds cols to the empty line:
    arr[i].push(new Array(cols));

    for(let j=0; j < cols; j++) {
      // Initializes:
      arr[i][j] = defaultValue;
    }
  }

  return arr;
};

let filter_for_nstp_and_econ11 = function(tr_obj) {
  if (tr_obj.length > 1) {// special case for nstp & econ 11
    tr_obj = tr_obj.filter(function(i) {
      return i != 0 && $(this).find(`.td_credits`).html().indexOf(`0.0`) < 0;
    });
    tr_obj = $(tr_obj[0]); // not necessary but idk
  }
  return tr_obj;
}

let iskoduler = function () {
  // check if the Probability column already exist
  // if it exists, return immediately as there is no change in probability
  // note: this function might no longer be needed for IskoDuler 1.1 and above
  if ($(`#tr_class-info-head th`).last().text().trim() == `Base Probability`) {
    return;
  }

  insert_announcements();

  compute_probabilities();
};

// load latest jquery before loading the main function
jQuery.getScript(latest_jquery, function () {
  iskoduler();
});

let refresh = function () {
  delete_added_columns();
  compute_probabilities();
}