README

Set up

rake db:setup Should create 100 vehicles, and park them around Brooklyn

Server

rails server

Tests

bundle exec rspec spec/controllers/api

Intro and Background

Some kick scooter share startups like Lime and Bird are dependent on independent contractors known as Juicers or Chargers, who collect scooters at night, bring them home to charge, and then set them out first thing in the morning at designated locations. Others like Lyft use employees for this task, but it still presents a novel type of traveling salesman problem for the sharing economy: how to find the most efficient route that "visits" a given number of scooters in a given area.*

This app is designed to address a similar issue with some key differences. Rather than kick scooters, here the vehicle in question is a moped, which because of the obvious size difference, have their batteries swapped out wholesale on the spot rather than being brought to a charging location (which is conveniently more straightforward to mock out in code!). And like Lyft, this work is done by employees rather than contractors. At its core is an API which supports the creation and management of "battery swapping shifts", via the following core functions/endpoints:

shift creation
adding vehicles to a shift -- both manually and automatically, the latter which given a starting latitude and longitude pair, assigns the 20 closest vehicles to a shift and returns them in the optimal order to be serviced
reviewing all vehicles in a shift
completing a battery swap for a particular vehicle
checking if a swap has been completed for any given vehicle in a particular shift
checking if all vehicles in a shift have had their battery swaps

One can envision this API being consumed both by a mobile app used by battery swappers on the job, as well as a web app used by management to monitor employee efficiency and performance.

Half of a sample shift's route

*This is a gross oversimplification of how juicing bounty programs work in practice. Often, the scooters are hard to find, competition is cutthroat, and the system easily gamed.

Other notes

For simplicity here, there is no battery mode and instead is currently just mocked out by just setting the vehicle's battery_level to 1. In reality, batteries are precious inventory we would definitely want to track in a database by serial number etc.
Also for simplicity, route order is based on Euclidean distance rather than actual roads that need to be traveled upon and their associated traffic levels.
Auto shift creation is currently achieved by hitting the same shift creation endpoint but with optional lat/long params
I'm using the geocoder gem for distance calculation, which uses Nominatim by default, and has some interesting user-created display names for neighborhoods

TODO

Move remaining logic out of controllers, and use serializers or model methods where appropriate
Model tests where appropriate
Serializer tests
Nothing is currently ever setting shift complete status to true (all shift assignment statuses are being set individually and the status of an entire shift is checked by checking all assignment statuses). It's possible this doesn't need to be a column on Shift at all and just an instance method?
If a shift is happening during operating hours, a vehicle may be in use and long gone from its original given location at shift creation. Perhaps for daytime shifts, for optimal route finding a separate endpoint is necessary which only doles out one vehicle at a time, based on which is a) closest to the swapper's current location b) not in use c) below a certain battery level?
Should BatteryShift be in charge of assigning vehicles to itself, or does this call for a service object like a VehicleAssigner?
Improvements to auto-assign algo. See kdtree gem.