Prototyped the barcode idea; Added a basic production system.

imports/api/Barcode.js

@@ -0,0 +1,81 @@
+import {Mongo} from "meteor/mongo";
+import { Meteor } from 'meteor/meteor';
+import { check } from 'meteor/check';
+import {SimpleSchema} from 'meteor/aldeed:simple-schema';
+
+Barcodes = new Mongo.Collection('Barcodes');
+
+// A simple mapping between a concatenation of the product & measure ID and a unique sequential number for the barcode.  This allows us to have a small number to keep our barcodes simple, while maintaining the more traditional MongoDB ID's for the Product and Measure.
+const BarcodesSchema = new SimpleSchema({
+	barcodeId: {
+		type: Number,
+		label: "Barcode ID",
+		optional: false,
+		index: 1,
+		unique: true
+	},
+	productAndMeasureId: {  //Just the two ids jammed together with a single space between them.
+		type: String,
+		label: "Product And Measure ID",
+		optional: false,
+		index: 1,
+		unique: true
+	}
+});
+
+if(Meteor.isServer) {
+	//Meteor.publish('barcodes', function() {
+	//	return Barcodes.find({});
+	//});
+	
+	Meteor.methods({
+		getBarcodeId: function(productId, measureId) {
+			check(productId, String);
+			check(measureId, String);
+			
+			let hasProduct = Meteor.collections.Products.findOne({_id: productId}, {fields: {}});
+			let hasMeasure = Meteor.collections.Measures.findOne({_id: measureId}, {fields: {}});
+			
+			if(hasProduct && hasMeasure) {
+				let existing = Barcodes.findOne({productAndMeasureId: productId + ' ' + measureId});
+				
+				if(existing) {
+					return existing.barcodeId;
+				}
+				else {
+					let c = 0;
+					
+					//Try a thousand times before failing.  Should never fail, should also not ever need to try a thousand times (unless we somehow automate label generation to the point where a 1000 processes at once are requesting labels that have never been generated before - highly unlikely).
+					while(c++ < 1000) {
+						//Lookup the most likely next barcode id from the db, then attempt to insert with it.  If it fails due to duplication, then increment and repeat.
+						let cursor = Products.find({}, {barcodeId: 1}).sort({barcodeId: -1}).limit(1);  //Since currently products are never removed, we shouldn't need to detect sequence gaps and fill them in (odds are we will never use more than 10k numbers anyway).
+						let barcodeId = cursor.hasNext() ? cursor.next().barcodeId + 1 : 1;
+						
+						Barcodes.insert({productAndMeasureId: productId + ' ' + measureId, barcodeId}, function(err, id) {
+							if(err) console.log(err);
+							else return barcodeId;
+						});
+					}
+					
+					//If we are still here, then there was a massive failure (c exceeded 1000).
+					console.log("We failed to generate a new barcode ID 1000 times, so we are giving up.  This should never happen.");
+					throw new Meteor.Error(403, "Unable to generate a barcode ID.");
+				}
+			}
+			else {
+				//Cannot find either the product or the measure in the db.  Cannot give an id.
+				console.log("Unable to generate a barcode ID because we could not find the product " + productId + " OR we could not find the measure " + measureId);
+				throw new Meteor.Error(403, "Unable to find the product or the measure.  Both must exist in order to generate a barcode ID.");
+			}
+		},
+	});
+}
+
+//Allows the client to do DB interaction without calling server side methods, while still retaining control over whether the user can make changes.
+Barcodes.allow({
+	insert: function() {return false;},
+	update: function() {return false;},
+	remove: function() {return false;}
+});
+
+export default Barcodes;