wf1101/oo-ride-share

Ride Share

Remember the ride share exercise we did with designing and creating a system to track the ride share data from a CSV file? We did a lot of great work on this exercise in creating arrays and hashes of data, but we've learned a lot since we did that exercise!

Now, we're going to use our understanding of classes, methods and attributes to create an object-oriented implementation of our ride share system.

This is a level 2 individual project.

Learning Goals

Reinforce and practice all of the Ruby and programming concepts we've covered in class so far:

• Creating and instantiating classes with attributes
• Creating class methods and instance methods within our classes
• Writing pseudocode and creating tests to drive the creation of our code

Context

We have a code base that already pulls data from CSV files and turns them into collections of the following objects:

• Drivers
• Passengers
• Trips

All of this data is managed in a class called TripDispatcher. Our program will contain one instance of TripDispatcher, which will load and manage the lists of Drivers, Passengers and Trips.

We are going to continue making functionality that works with this data, such as finding the duration of a specific trip or the total amount of money a passenger has spent, and also make functionality to create a new trip.

The Code So Far

Driver

Each Driver has:

Attribute	Description
id	The Driver's ID number
name	The name of the Driver
vehicle_identification	The driver's Vehicle Identification Number (VIN Number), Each vehicle identification number should be a specific length to ensure it is a valid vehicle identification number
status	Indicating availability, a driver's availability should be either :AVAILABLE or :UNAVAILABLE

Each Driver instance is able to:

Method	Description
average_rating	retrieve an average rating for that driver based on all trips taken

Passenger

Each Passenger has:

Attribute	Description
id	The Driver's ID number
name	The name of the Driver
Phone Number	The Passenger's Phone Number which must be in phone number format (XXX) XXX-XXXX
trips	A list of trips that only this passenger has taken

Each Passenger instance is able to:

Method	Description
get_drivers	retrieve the list of all previous driver instances associated with trips this passenger has taken

Trip

Each Trip has:

Attribute	Description
id	The Driver's ID number
passenger	The passenger on the trip
driver	The driver for the trip
rating	The rating given by the passenger, a number 1-5

Each Trip instance is able to:

Method	Description
driver	retrieve the associated driver instance
passenger	retrieve the associated passenger instance

TripDispatcher

The TripDispatcher has:

Attribute	Description
drivers	A list of all drivers in the system
passengers	A list of all passengers in the system
trips	A list of all trips taken in the system

The TripDispatcher has the following responsibilities:

• load collections of Drivers, Passengers, and Trips from CSV files
• store and manage this data into separate collections

The TripDispatcher does the following:

• on instantiation, loads and creates Trips, Passengers, and Drivers and stores them into collections

The TripDispatcher instance is able to:

Methods	Description
drivers, passengers, trips	retrieve the collection of Trips, Passengers, and Drivers
find_driver	find an instance of Driver given an ID
find_passenger	find an instance of Passenger given an ID

By the end of this project, a TripDispatcher will be able to:

• create new trips with assigning appropriate passengers and drivers

Getting Started

We will use the same project structure we used for the previous project. Classes should be in files in the lib folder, and tests should be in files in the specs folder. You will run tests by executing the rake command, as configured in a Rakefile.

The support folder contains CSV files which will drive your system design. Each CSV corresponds to a different type of object as well as creating a relationship between different objects.

Setup

1. Fork this repository in GitHub
2. Clone the repository to your computer
3. Run rake to run the tests

Process

You should use the following process as much as possible:

1. Write pseudocode
2. Write test(s)
3. Write code
4. Refactor

Requirements

Baseline

To start this project, take some time to get familiar with the code. Do the following in this order:

1. Read through all of the tests
2. Look at the provided CSV files: support/drivers.csv, support/passengers.csv, support/trips.csv
3. Then look through the ruby files in the lib folder

Create a diagram that describes how each of these classes and methods (messages) interact with one another as well as with the CSV files.

Exercise: Look at this requirement in Wave 1: "For a given driver, calculate their total revenue for all trips. Each driver gets 80% of the trip cost after a fee of $1.65 is subtracted." Spend some time writing pseudocode for this.

Wave 1

The purpose of Wave 1 is to help you become familiar with the existing code, and to practice working with enumerables.

1.1: Upgrading Dates

Currently our implementation saves the start and end time of each trip as a string. This is our first target for improvement. Instead of storing these values as strings, we will use Ruby's built-in Time class. You should:

1. Spend some time reading the docs for Time - you might be particularly interested in Time.parse
2. Modify TripDispatcher#load_trips to store the start_time and end_time as Time instances
3. Add a check in Trip#initialize that raises an ArgumentError if the end time is before the start time, and a corresponding test
4. Add an instance method to the Trip class to calculate the duration of the trip in seconds, and a corresponding test

Hint: If you're hitting a NoMethodError for Time.parse, be aware that you need to require 'time' in order for it to work. This is a weird quirk of how the library is designed.

1.2: Aggregate Statistics

Now that we have data for cost available for every trip, we can do some interesting data processing. Each of these should be implemented as an instance method on Driver or Passenger.

1. Add an instance method to Passenger that will return the total amount of money that passenger has spent on their trips
2. Add an instance method to Passenger that will return the total amount of time that passenger has spent on their trips
3. Add an instance method to Driver to calculate that driver's total revenue across all their trips. Each driver gets 80% of the trip cost after a fee of $1.65 is subtracted.
4. Add an instance method to Driver to calculate that driver's average revenue per hour spent driving, using the above formula for revenue

All of these methods must have tests.

Wave 2

Our program needs a way to make new trips and appropriately assign a driver and passenger.

This logic will be handled by our TripDispatcher in a new instance method: TripDispatcher#request_trip(passenger_id). When we create a new trip with this method, the following will be true:

• The passenger ID will be supplied (this is the person requesting a trip)
• Your code should automatically assign a driver to the trip
  • For this initial version, choose the first driver whose status is :AVAILABLE
• Your code should use the current time for the start time
• The end date, cost and rating will all be nil
  • The trip hasn't finished yet!

You should use this information to:

• Create a new instance of Trip
• Modify this selected driver using a new helper method in Driver:
  • Add the new trip to the collection of trips for that Driver
  • Set the driver's status to :UNAVAILABLE
• Modify the passenger for the trip using a new helper method in Passenger:
  • Add the new trip to the collection of trips for the Passenger
• Add the new trip to the collection of all Trips in TripDispatcher
• Return the newly created trip

All of this code must have tests. Things to pay attention to:

• Was the trip created properly?
• Were the trip lists for the driver and passenger updated?
• Was the driver who was selected AVAILABLE?
• What happens if you try to request a trip when there are no AVAILABLE drivers?

Interaction with Wave 1

One thing you may notice is that this change breaks your code from Wave 1, possibly in subtle ways. We've added a new kind of trip, an in-progress trip, that is missing some of the values you need to compute those numbers.

Your code from wave 1 should ignore any in-progress trips. That is to say, any trip where the end time is nil should not be included in your totals.

You should also add explicit tests for this new situation. For example, what happens if you attempt to calculate the total money spent for a Passenger with an in-progress trip, or the average hourly revenue of a Driver with an in-progress trip?

Wave 3

We want to evolve TripDispatcher so it assigns drivers in more intelligent ways. Every time we make a new trip, we want to pick drivers who haven't completed a trip in a long time.

In other words, we should assign the driver to the available driver whose most recent trip ending is the oldest compared to today.

Modify TripDispatcher#request_trip to use the following rules to select a Driver:

• The Driver must have a status of AVAILABLE
• The Driver must not have any in-progress trips (end time of nil)
• From the Drivers that remain, select the one whose most recent trip ended the longest time ago

For example, if we have three drivers, each with two trips:

Driver Name	Status	Trip 1 end time	Trip 2 end time
Ada	AVAILABLE	Jan 3, 2018	Jan 9, 2018
Katherine	AVAILABLE	Jan 1, 2018	Jan 12, 2018
Grace	UNAVAILABLE	Jan 5, 2018	nil

Grace is excluded because they are not AVAILABLE, and because they have one in-progress trip.

Of Ada and Katherine, we prefer Ada, because their most recent trip is older.

All of this code must have tests. -->

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