/*

******************

LINE DRAWING ANIMATION WITH SNAP SVG

I coded a line drawing animating with snap svg. The graph is not created out of a single line because the animating with separate paths and easing on each section simply looks better :)

1.The step of the points is evenly spread on the x axis depending on how many points your graph has.

2.Values passed to the graph should have a negative prefix because of the graph's coordinate system (-x = up).

3.Below you will find an array of prices into which you can insert your own custom values.

******************
*/





//INVERTED VALUES BECAUSE -X = Up direction because of coord system
// FEEL FREE TO INSERT YOUR OWN VALUES
var price = [0,-95, -30, -65, -35, -215, -95, -70, -115];
/* FOR FUTURE USE OF PARSING DATA.
function updatePrice(){
  var inputPrices = $('#values').val();
  var priceArr = inputPrices.split(',');
  price = priceArr;
  for (i=0;i<priceArr.length;i++){
    var parsedPrice = parseInt(priceArr[i]);
    function isNeg(parsedPrice){
      if(parsedPrice > 0){
        parsedPrice *= -1;
        return parsedPrice
      }else {
        parsedPrice = 0;
        return parsedPrice;
      }
    }
    price[i] = isNeg(parsedPrice);
    }
  console.log(price);
}*/
//CHART VALUES
var chartH = $('#svg').height();
var chartW = $('#svg').width();

// PARSE PRICES TO ALIGN WITH BOTTOM OF OUR SVG
var prices = [];
for (i = 0; i < price.length; i++) {
    prices[i] = price[i] + $('#svg').height();
}

function draw() {
    //DEFINE SNAP SVG AND DETERMINE STEP NO.
    var paper = Snap('#svg');
    var steps = prices.length;

    // EVENLY DISTRIBUTE OUR POINTS ALONG THE X AXIS

    function step(i, chartW) {
        return chartW / prices.length * i;
    }

    var points = [];
    var breakPointsX = [];
    var breakPointsY = [];
    var point = {};

    for (i = 1; i < prices.length; i++) {

        //CALCULATE CURRENT POINT

        var currStep = step(i, chartW);
        var y = prices[i];
        point.x = Math.floor(currStep);
        point.y = y;

        //CALCULATE PREVIOUS POINT

        var prev = i - 1;
        var prevStep = step(prev, chartW);
        var prevY = prices[prev];
        point.prevX = Math.floor(prevStep);
        point.prevY = prevY;
        if (point.prevX === 0 || point.prevY === 0){
          point.prevX = 15;
          point.prevY = chartH - 15;
        }
        // SAVE PATH TO ARRAY
        points[i] = " M" + point.prevX + "," + point.prevY + " L" + point.x + "," + point.y;

        // SAVE BREAKPOINTS POSITION

        var r = 30;
        breakPointsX[i] = point.x;
        breakPointsY[i] = point.y;
    }

    // DRAW LINES

    for (i = 0; i < points.length; i++) {
        var myPath = paper.path(points[i]);
        var len = myPath.getTotalLength();
        myPath.attr({
            'stroke-dasharray': len,
                'stroke-dashoffset': len,
                'stroke': 'white',
                'stroke-linecap': 'round',
                'stroke-width': 4,
                'stroke-linejoin': 'round',
                'id': 'myLine' + i,
                'class': 'line'
        });
    }
    // DRAW BREAKPOINTS
    for (i = 0; i < points.length; i++) {
        var circle = paper.circle(breakPointsX[i], breakPointsY[i], 5);
        circle.attr({
            'fill': '#FF4864',
                'stroke': 'white',
                'stroke-width': 3,
                'id': 'myCirc' + i,
                'class':'breakpoint'
        });
    }
  // DRAW COORDINATE SYSTEM
    var xAxis = paper.path('M0,'+chartH+'L'+chartW+","+chartH);
    var yAxis = paper.path('M0,'+chartH+'L0,0');
  
  var xOff = xAxis.getTotalLength();
  var yOff = yAxis.getTotalLength();
  var start = (prices.length*250+"ms");

  yAxis.attr({
    'stroke':'white',
    'stroke-width':1,
    'stroke-dasharray':yOff,
    'stroke-dashoffset':yOff,
    'id':'yAxis'
  });
  xAxis.attr({
    'stroke':'white',
    'stroke-width':1,
    'stroke-dasharray':xOff,
    'stroke-dashoffset':xOff,
    'id':'xAxis'
  });
  console.log(start);
  $('#yAxis').css({
    '-webkit-transition-delay':start,
    '-webkit-transition':'all 200ms ease-in'
  });
   $('#xAxis').css({
    '-webkit-transition-delay':start,
    '-webkit-transition':'all 200ms ease-in'
  });
  $('#xAxis').animate({
    'stroke-dashoffset':'0'
  });
  $('#yAxis').animate({
    'stroke-dashoffset': '0'
  });
}
function animate(){
  for (i=0;i<prices.length;i++){
    var circ = $('#myCirc'+i);
    var line = $('#myLine'+i);
    circ.css({
      '-webkit-transition':'all 550ms cubic-bezier(.84,0,.2,1)',
      '-webkit-transition-delay':375+(i*125)+"ms"
      });
    line.css({
      '-webkit-transition':'all 250ms cubic-bezier(.84,0,.2,1)',
      '-webkit-transition-delay':i*125+"ms"
      });
    line.animate({
      'stroke-dashoffset':0
    });
    circ.css({
      'transform':'scale(1)'
    });
  }
}
$(window).load(function(){
  draw();
  animate();
})
$('#draw').on('click',function(){
  $('#svg').empty();
  draw();
  animate();
});