function symmetricRand() {
  return 2 * Math.random() - 1;
}

var slope = symmetricRand();
var intercept = symmetricRand();
var amplitudeSlope = symmetricRand();
var amplitudeIntercept = symmetricRand();
var frequency = symmetricRand();
var phase = symmetricRand();

function f(x) {
  return slope * x + intercept + (amplitudeSlope * x + amplitudeIntercept) * Math.sin(frequency * x + phase);
}

function g(x, params) {
  return params[0] * x + params[1] + (params[2] * x + params[3]) * Math.sin(params[4] * x + params[5]);
}

// Generate some samples
var numPoints = 200;
var points = new Array(numPoints);
for (var i = 0; i < numPoints; i++) {
  var x = -20 + i * .2;
  points[i] = {x: x, y: f(x)};
}

// Initialize swarm
var swarm = new PSO.Swarm(30, 6);

console.log(points)
var canvas = $('canvas')[0];
var ctx = canvas.getContext('2d');

function draw() {
  canvas.width = innerWidth;
  canvas.height = innerHeight;
  
  var xmin, xmax, ymin, ymax;
  for (var i in points) {
    var x = points[i].x;
    var y = points[i].y;
    xmin = Math.min(x, xmin || x);
    xmax = Math.max(x, xmax || x);
    ymin = Math.min(y, ymin || y);
    ymax = Math.max(y, ymax || y);
  }
  console.log(xmin, xmax, ymin, ymax);
  
  ctx.fillStyle = '#ff0000';
  var xmul = canvas.width / (xmax - xmin);
  var ymul = canvas.height / (ymax - ymin);
  for (var i in points) {
    var x = (points[i].x - xmin) * xmul;
    var y = (points[i].y - ymin) * ymul;
    
    ctx.beginPath();
    ctx.arc(x, y, 2, 0, 2 * Math.PI, false);
    ctx.fill();
  }
  
  for (var i in swarm.particles) {
    var params = swarm.particles[i].params;
    var errorSum = 0;
    var pathStarted = false;
    ctx.beginPath();
    
    for (var j in points) {
      var x = points[j].x;
      var y = params[0] * x + params[1] + (params[2] * x + params[3]) * Math.sin(params[4] * x + params[5]);
      
      var error = points[j].y - y;
      errorSum += error * error;
      
      // Draw
      var xt = (x - xmin) * xmul;
      var yt = (y - ymin) * ymul;
      if (pathStarted) {
        ctx.lineTo(xt, yt);
      } else {
        ctx.moveTo(xt, yt);
        pathStarted = true;
      }
    }
    
    ctx.stroke();
    swarm.particles[i].setFitness(errorSum);
  }
  
  swarm.update();
  
  for (var i = 0; i < 1; i++) {
    swarm.particles[parseInt(Math.random() * swarm.numParticles)].jitter();
  }
  
  requestAnimationFrame(draw);
}

draw();