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.

At a Glance

• Pair, stage 2 project
• Due end of day Friday August 31st

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
• Writing pseudocode and creating tests to drive the creation of our code
• Using Inheritance to extend classes
• Using Composition to add functionality to classes

Context

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

• Users
• 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, Users and Trips.

We are going to continue making functionality that works with this data, such as determining the duration of a specific trip and the total amount of money a user has spent, as well as the amount of money a driver has made and also add functionality to create a new trip and assign available drivers.

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The Code So Far

User

A User represents a person with an account in our Rideshare service. Users can use the service to take trips and can become Drivers with the service.

Each User has:

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

User Methods

Method	Description
add_trip	Adds a trip to the user's list of trips

Trip

A Trip represents a journey a User has taken with the service.

Each Trip has:

Attribute	Description
id	The Trip's ID number
passenger	The User being transported on the trip
start_time	When did this trip begin?
end_time	When did this trip finish?
rating	The rating given by the User, a number 1-5
cost	How much did the passenger pay?

TripDispatcher

The TripDispatcher class is designed to load trips & users from a CSV file and provides methods to find and add trips.

The TripDispatcher has:

Attribute	Description	Returns
passengers	A list of all users in the system	a collection of User instances
trips	A list of all trips taken in the system	a collection of Trip instances

The TripDispatcher has the following responsibilities:

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

The TripDispatcher does the following:

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

The TripDispatcher instance is able to:

Methods	Description
load_users	A method which loads users from a CSV file, returning the list
load_trips	A method which loads trips from a CSV file, returning the list
find_passenger	find an instance of User given an ID

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

• create new trips assigning appropriate passengers and drivers

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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. You'll be working with an assigned pair. High-five your pair.
2. Choose one person to fork this repository in GitHub
3. Add the person who didn't fork the repository as a collaborator.
4. Both individuals will clone the forked repo: $ git clone [YOUR FORKED REPO URL]
5. Both partners cd into their project directory
6. Run rake to run the tests
7. Together review the provided tests and code.

Process

You should use the following process as much as possible:

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

Requirements

Pair Plan

First, come up with a "plan of action" for how you want to work as a pair. Discuss your learning style, how you prefer to receive feedback, and one team communication skill you want to improve with this experience. Second, review the requirements for Wave 1 and come up with a "plan of action" for your implementation.

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/users.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 user, calculate their total expenditure for all trips". Spend some time writing pseudocode for this.

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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.

1.2: User 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 User.

1. Add an instance method, net_expenditures, to User that will return the total amount of money that user has spent on their trips
2. Add an instance method, total_time_spent to User that will return the total amount of time that user has spent on their trips

Each of these methods must have tests.

Wave 2

Our program needs a data type to represent Drivers in our service.

We will do this by creating a Driver class which inherits from User. A Driver will add the following data attributes:

Attribute	Description
vehicle_id	The driver's Vehicle Identification Number (VIN Number), Each vehicle identification number should be a specific length of 17 to ensure it is a valid vehicle identification number
driven_trips	A list of trips the user has acted as a driver for.
status	Indicating availability, a driver's availability should be either :AVAILABLE or :UNAVAILABLE

Use the provided tests to ensure that a Driver instance can be created successfully and insure that an ArgumentError is raised for an invalid status.

Updating Trip

To make use of the new Driver class we will need to update the Trip class to include a reference to the trip's driver. Add the following attribute to the Trip class.

Attribute	Description
driver	The Driver for the trip

Each Trip instance should also be able to do the following:

Method	Description
driver	retrieve the associated Driver instance

Loading Drivers

Update the TripDispatcher class to add or update the following Methods:

Method	Description
load_drivers	Load the Drivers from the support/drivers.csv file and return a collection of Driver instances, note that drivers can be passengers too! Replace the instance of User in the passengers array with a cooresponding instance of Driver
find_driver	This method takes an id number and returns the corresponding Driver instance.
load_trips	This method should be updated to add a corresponding Driver to the trip instance.

Driver methods

After each trip has a reference to its Driver and TripDispatcher can load a list of Drivers, add the following functionality to the Driver class:

Method	Description
average_rating	This method sums up the ratings from all a Driver's trips and returns the average
add_driven_trip	This method adds a trip to the driver's collection of trips for which they have acted as a driver
total_revenue	This method calculates that driver's total revenue across all their trips. Each driver gets 80% of the trip cost after a fee of $1.65 per trip is subtracted.
net_expenditures	This method will override the cooresponding method in User and take the total amount a driver has spent as a passenger and subtract the amount they have earned as a driver (see above). If the number is negative the driver will earn money.

All the new methods above should have tests

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