// required indicators: SMA;
// Bollinger Bands implementation;
var SMA = require('./SMA.js');
var Indicator = function(BBSettings) {
    this.input = 'price';
    this.settings = BBSettings;   
    this.center = new SMA(this.settings.TimePeriod);

    this.lower=0;
    this.middle=0;
    this.upper=0;
}

Indicator.prototype.calcstd = function(prices, Average)
{
    var squareDiffs = prices.map(function(value){
        var diff = value - Average;
        var sqr = diff * diff;
        return sqr;
    });

    var sum = squareDiffs.reduce(function(sum, value){
        return sum + value;
    }, 0);

    var avgSquareDiff = sum / squareDiffs.length;

    return Math.sqrt(avgSquareDiff);
}

Indicator.prototype.update = function(price) {
    this.center.update(price);

    this.middle = this.center.result;
    var std = this.calcstd(this.center.prices, this.middle);

    this.lower = this.middle - this.settings.NbDevDn * std;
    this.upper = this.middle + this.settings.NbDevUp * std;
}

module.exports = Indicator;