betfair-sports-api/lib/betfair_price.js

Betfair Sports API for Node

//(C) 2012 Anton Zemlyanov

//This module describes Betfair price
//see Sports API documentation on http://bdp.betfair.com

exports.newBetfairPrice = function(size) {
    return new BetfairPrice(size);
}

var epsilon = 0.001;

function BetfairPrice(size) {
    if (!size)
        size = 1.01;

    this.setStake(size);
}

BetfairPrice.prototype.setStake = function(size) {
    if (!size)
        size = 1.01;
    if (typeof (size) === 'string')
        size = parseFloat(size);

    if (size < 1.01)
        size = 1.01;
    else if (size < 2)
        size = Math.round(size * 100.0) / 100.0;
    else if (size < 3)
        size = Math.round(size * 50.0) / 50.0;
    else if (size < 4)
        size = Math.round(size * 20.0) / 20.0;
    else if (size < 6)
        size = Math.round(size * 10.0) / 10.0;
    else if (size < 10)
        size = Math.round(size * 5.0) / 5.0;
    else if (size < 20)
        size = Math.round(size * 2.0) / 2.0;
    else if (size < 30)
        size = Math.round(size * 1.0) / 1.0;
    else if (size < 50)
        size = Math.round(size * 0.5) / 0.5;
    else if (size < 100)
        size = Math.round(size * 0.2) / 0.2;
    else if (size < 1000)
        size = Math.round(size * 0.1) / 0.1;
    else
        size = 1000.0;

    this.size = size;
    return;
}

BetfairPrice.prototype.toString = function(size) {
    var str = this.size.toFixed(2);
    if (str.charAt(str.length - 1) === '0')
        str = str.substr(0, str.length - 1);
    // if( str.charAt(str.length-1)==='0' )
    // str = str.substr(0, str.length-2);
    return str;
}

BetfairPrice.prototype.increasePrice = function() {
    var size = this.size;

    if (size < (2.0 - epsilon))
        size += 0.01;
    else if (size < (3.0 - epsilon))
        size += 0.02;
    else if (size < (4.0 - epsilon))
        size += 0.05;
    else if (size < (6.0 - epsilon))
        size += 0.1;
    else if (size < (10.0 - epsilon))
        size += 0.2;
    else if (size < (20.0 - epsilon))
        size += 0.5;
    else if (size < (30.0 - epsilon))
        size += 1.0;
    else if (size < (50.0 - epsilon))
        size += 2.0;
    else if (size < (100.0 - epsilon))
        size += 5.0;
    else if (size < (1000.0 - epsilon))
        size += 10.0;
    else
        size = 1000.0;

    this.size = size;
    return this;
}

BetfairPrice.prototype.decreasePrice = function() {
    var size = this.size;

    if (size > (100.0 + epsilon))
        size -= 10.0;
    else if (size > (50.0 + epsilon))
        size -= 5.0;
    else if (size > (30.0 + epsilon))
        size -= 2.0;
    else if (size > (20.0 + epsilon))
        size -= 1.0;
    else if (size > (10.0 + epsilon))
        size -= 0.5;
    else if (size > (6.0 + epsilon))
        size -= 0.2;
    else if (size > (4.0 + epsilon))
        size -= 0.1;
    else if (size > (3.0 + epsilon))
        size -= 0.05;
    else if (size > (2.0 + epsilon))
        size -= 0.02;
    else if (size > (1.01 + epsilon))
        size -= 0.01;
    else
        size = 1.01;

    this.size = size;
    return this;
}

BetfairPrice.prototype.spreadToPrice = function(size) {
    var other = new BetfairPrice(size);
    if (Math.abs(this.size - other.size) < epsilon)
        return 0;
    var spread = 0;
    if (other.size < this.size) {
        // negative spread
        while (other.size < (this.size - epsilon)) {
            other.increasePrice();
            --spread;
        }
    } else {
        // positive spread
        while (other.size > (this.size + epsilon)) {
            other.decreasePrice();
            ++spread;
        }
    }
    return spread;
}