invoice-fs/lib/invoiceNumberGenerator.js

Nostalgic command-line invoicing application producing plain text invoices and JSON data structures. Uses the file system as a database

var obj = require('javascript-object-paraphernalia'),
    state = require('./state');

function InvoiceNumberGenerator() {}

InvoiceNumberGenerator.prototype.padWhenNarrow = function(width, number) {
    var text = "" + number;
    return text.length >= width ? text : new Array((width + 1) - text.length).join('0') + text;
};

InvoiceNumberGenerator.prototype.getInvoiceNumber = function(callback) {
    var invoiceNumber = state.get("numberPrefix") + this.padWhenNarrow(state.get("minimumNumberWidth"), state.get("number")) + state.get("numberSuffix");
    state.set('number', parseInt(state.get("number"), 10) + 1, callback);
    return invoiceNumber;
};

module.exports = new InvoiceNumberGenerator();