let width;
let height;
let margin;
let nodes_list = [];
let nodes = [];
let edges = [];
let area ;
let k ;
let t ;

function preload() {
  edges_table = loadTable('3980.edges.csv','csv');
}

function setup() {
  width = 1000;
  height = 1000;
  margin = 100;

  createCanvas(width,height);
  background(245,255,250);

  for(var j=0;j<edges_table.getRowCount();j++)
  {
    nodes_list.push(edges_table.getNum(j,0));
    nodes_list.push(edges_table.getNum(j,1));
  }
  nodes_list = Array.from(new Set(nodes_list))
  nodes_list.sort(function(a, b){return a - b});
  no_of_nodes = nodes_list.length;
  area = width * height;
  k = Math.sqrt(area/no_of_nodes);
  t = width/10;

  for(var i=0;i<no_of_nodes;i++)
  {
    var x = Math.random() * (width - 2*margin) + margin;
    var y = Math.random() * (height - 2*margin) + margin;
    nodes.push(new Node(nodes_list[i],new vector(x,y)));
  }

  for(var i=0;i<edges_table.getRowCount();i++)
  {
    var node1_x;
    var node2_x;
    var node1_name;
    var node2_name;
    var node1_y;
    var node2_y;
    let node1;
    let node2;
    for(var j=0;j<no_of_nodes;j++)
    {
      if(nodes[j].getName() == edges_table.getNum(i,0).toString())
      {
        node1 = nodes[j];
        break;
      }
    }

    for(var j=0;j<no_of_nodes;j++)
    {
      if(nodes[j].getName() == edges_table.getNum(i,1).toString())
      {
        node2 = nodes[j];
        break;
      }
    }
    edges.push(new Edge(node1,node2));
  }

}

function draw() {
  clear();

  push();
  textSize(25);
  textStyle(BOLD);
  textAlign(CENTER);
  text("Force Directed Layout - Facebook data",width/2,margin/2);
  pop();

  //repulsive forces
  for(var j=0;j<no_of_nodes;j++)
  {
    nodes[j].setDisp(0,0);
    for(var m=0;m<no_of_nodes;m++)
    {
      if(nodes[j].getName() != nodes[m].getName())
      {
        let delta_x = nodes[j].getPos().getX()-nodes[m].getPos().getX();
        let delta_y = nodes[j].getPos().getY()-nodes[m].getPos().getY();
        let delta = new vector(delta_x,delta_y);
        let delta_mag = Math.sqrt(Math.pow(delta_x,2)+Math.pow(delta_y,2));
        let disp_x = nodes[j].getDisp().getX() +
                    (delta_x/delta_mag)*calculate_repulsive_force(delta_mag,k);
        let disp_y = nodes[j].getDisp().getY() +
                    (delta_y/delta_mag)*calculate_repulsive_force(delta_mag,k);
        nodes[j].setDisp(disp_x,disp_y);
      }
    }
  }
  //attractive forces
  for(var j=0;j<edges.length;j++)
  {
    let delta_x = edges[j].getNode1().getPos().getX() - edges[j].getNode2().getPos().getX();
    let delta_y = edges[j].getNode1().getPos().getY() - edges[j].getNode2().getPos().getY();
    let delta = new vector(delta_x,delta_y);
    let delta_mag = Math.sqrt(Math.pow(delta_x,2)+Math.pow(delta_y,2));
    let disp_x = edges[j].getNode1().getDisp().getX()-
                (delta_x/delta_mag)*calculate_attractive_force(delta_mag,k);
    let disp_y = edges[j].getNode1().getDisp().getY()-
                (delta_y/delta_mag)*calculate_attractive_force(delta_mag,k);
    edges[j].getNode1().setDisp(disp_x,disp_y);

    disp_x = edges[j].getNode2().getDisp().getX()+
                (delta_x/delta_mag)*calculate_attractive_force(delta_mag,k);
    disp_y = edges[j].getNode2().getDisp().getY()+
                (delta_y/delta_mag)*calculate_attractive_force(delta_mag,k);
    edges[j].getNode2().setDisp(disp_x,disp_y);
  }
  //limit max displacement to temperature t and prevent from displacement outside frame
  for(var j=0;j<no_of_nodes;j++)
  {
    let disp_mag = Math.sqrt(Math.pow(nodes[j].getDisp().getX(),2) +
                             Math.pow(nodes[j].getDisp().getY(),2));
    let pos_x = nodes[j].getPos().getX() +
                (nodes[j].getDisp().getX()/disp_mag)*Math.min(disp_mag,t);
    let pos_y = nodes[j].getPos().getY() +
                (nodes[j].getDisp().getY()/disp_mag)*Math.min(disp_mag,t);
    pos_x = Math.min(width-margin,Math.max(margin,pos_x));
    pos_y = Math.min(height-margin,Math.max(margin,pos_y));
    nodes[j].setPos(new vector(pos_x,pos_y));
  }
  //t =  1 - Math.pow(1/2,t);
  t =  t*Math.exp(-0.12987);


  for(var j=0;j<edges.length;j++)
  {
    edges[j].show();
  }
  for(var j=0;j<nodes_list.length;j++)
  {
    nodes[j].show();
    push();
    textSize(6);
    text(nodes[j].getName(),nodes[j].getPos().getX()-15,nodes[j].getPos().getY()-15);
    pop();
  }

  for(var j=0;j<nodes_list.length;j++)
  {
    if(mouseX < nodes[j].getPos().getX() +10 &&
       mouseX > nodes[j].getPos().getX() -10 &&
       mouseY < nodes[j].getPos().getY() +10 &&
       mouseY > nodes[j].getPos().getY() -10)
    {
      textSize(15);
      fill(0,0,0);
      text(nodes[j].getName(),mouseX+5,mouseY-15);
    }
  }

}

function calculate_attractive_force(x,k) {
  return Math.pow(x,2)/k;
}

function calculate_repulsive_force(x,k) {
  return Math.pow(k,2)/x;
}

function calculate_slope_and_intercept(node1, node2) {
  let slope;
  let intercept;
  slope = (node2.getPos().getY() - node1.getPos().getY())/(node2.getPos().getX() - node1.getPos().getX());
  intercept = node1.getPos().getY() - (slope*node1.getPos().getX());
  return [slope,intercept];
}

class vector {
  constructor(x,y) {
    this.x = x;
    this.y = y;
  }

  getX() {
    return this.x ;
  }

  getY() {
    return this.y ;
  }
}

 class Node {
   constructor(name,pos) {
     this.name = name;
     this.pos = pos;
     this.disp = new vector(0,0);
   }

   getName() {
     return this.name;
   }

   getPos() {
     return this.pos;
   }

   setPos(pos) {
     this.pos = pos;
   }

   setDisp(x,y) {
     this.disp = new vector(x,y);
   }

   getDisp() {
     return this.disp;
   }

   show() {
     push();
     strokeWeight(1);
     stroke(139,0,139);
     fill(11,211,211);
     ellipse(this.pos.getX(),this.pos.getY(),10,10);
     pop();
   }
 }

 class Edge {
   constructor(node1,node2) {
     this.node1 = node1;
     this.node2 = node2;
   }

   getNode1() {
     return this.node1;
   }

   getNode2() {
     return this.node2;
   }

   show() {
     push();
     push();
     strokeWeight(1);
     stroke(220,220,220);
     line(this.node1.getPos().getX(),this.node1.getPos().getY(),
          this.node2.getPos().getX(),this.node2.getPos().getY());
     pop();
     pop();
   }
 }