/* The db module was intended to be used to store all the data needed to run the Point
* of Sale in offline mode. (Products, Categories, Orders, ...) It would also use WebSQL
* or IndexedDB to make the searching and sorting products faster. It turned out not to be
* a so good idea after all.
* First it is difficult to make the Point of Sale truly independant of the server. A lot
* of functionality cannot realistically run offline, like generating invoices.
* IndexedDB turned out to be complicated and slow as hell, and loading all the data at the
* start made the point of sale take forever to load over small connections.
* LocalStorage has a hard 5.0MB on chrome. For those kind of sizes, it is just better
* to put the data in memory and it's not too big to download each time you launch the PoS.
* So at this point we are dropping the support for offline mode, and this module doesn't really
* make sense anymore. But if at some point you want to store millions of products and if at
* that point indexedDB has improved to the point it is usable, you can just implement this API.
* You would also need to change the way the models are loaded at the start to not reload all your
* product data.
/ PosLS is a localstorage based implementation of the point of sale database.
* FIXME: The Products definitions and categories are stored on the locastorage even tough they're
* always reloaded at launch. This could induce a slowdown because the data needs to be reparsed from
* JSON before each operation. If you have a huge amount of products (around 25000) it can also
* blow the 5.0MB localstorage limit.