//SUMMARIZER 
function split_into_paragraphs(content){   
  return(content.split("\n\n").map(function(p){
    return(p.trim())
  }));
}

function split_into_sentences(s){
  var s = s.split('.');
  s.pop();
  return(s);
}

function sentences_insersection(sent1, sent2){
  var s1 = set(sent1.split(" "));
  var s2 = set(sent2.split(" "));
  if(s1.length + s2.length === 0) return 0;
  return(intersection(s1, s2)/((s1.length+s2.length)/2));
}

function format_sentence(sent){
  var s = sent.replace(/\W+/g, "");
  return s;
}

function set(arr){
  var n =[];
  for(var i=0; i<arr.length; i++){
    if(n.indexOf(arr[i]) < 0){
      n.push(arr[i]);
    }
  }
  return n;
}

function intersection(arr1, arr2){
  var l1 = arr1.length; 
  var inter = 0;
  for(var i=0; i<l1; i++){
    if(arr2.indexOf(arr1[i]) >= 0)inter++;
  }
  return inter;
}

function get_sentences_rank(content){
  var sentences = split_into_sentences(content);
  var len = sentences.length;  
  var values = [];
  for(var i=0; i<len; i++){
    values.push([]);
    for(var j=0; j<len; j++){
      values[i].push(null);
      values[i][j] = sentences_insersection(sentences[i], sentences[j]);
    }    
  }

  //build the dictionary
  var dict = {};
  for(var i=0; i<len; i++){   
    var score = 0; 
    for(var j=0; j<len; j++){
      if(i === j) continue;
      score += values[i][j]; 
    }
    dict[format_sentence(sentences[i])] = score;
  }

  return dict;
}

function get_best_sentence(paragraph, dict){
  var sentences = split_into_sentences(paragraph);
  //ignore short sentences
  if(sentences.length < 2) return "";
  //get best sentences according to sentence dictonary
  var best_sentence = "";
  var max_value = 0;
  for(var i = 0; i<sentences.length; i++){
    var s = sentences[i];
    var strip = format_sentence(s);
    if(dict[strip] > max_value){
      max_value = dict[strip];
      best_sentence = s;
    }
  }
  return best_sentence;
}

function get_summary(content){
  var paragraphs = split_into_paragraphs(content);
  var dict = get_sentences_rank(content);
  var summary = "";
  for(var i=0; i<paragraphs.length; i++){
    var s = get_best_sentence(paragraphs[i], dict);
    if(s){
      summary += "\n" + s + ". ";
    }
  }
  return summary;
}