khesualdo/wave-interview-challenge

Project Description

Imagine that this is the early days of Wave's history, and that we are prototyping a new payroll system API. A front end (that hasn't been developed yet, but will likely be a single page application) is going to use our API to achieve two goals:

Upload a CSV file containing data on the number of hours worked per day per employee
Retrieve a report detailing how much each employee should be paid in each pay period

All employees are paid by the hour (there are no salaried employees.) Employees belong to one of two job groups which determine their wages; job group A is paid $20/hr, and job group B is paid $30/hr. Each employee is identified by a string called an "employee id" that is globally unique in our system.

Hours are tracked per employee, per day in comma-separated value files (CSV). Each individual CSV file is known as a "time report", and will contain:

A header, denoting the columns in the sheet (date, hours worked, employee id, job group)
0 or more data rows

In addition, the file name should be of the format time-report-x.csv, where x is the ID of the time report represented as an integer. For example, time-report-42.csv would represent a report with an ID of 42.

You can assume that:

Columns will always be in that order.
There will always be data in each column and the number of hours worked will always be greater than 0.
There will always be a well-formed header line.
There will always be a well-formed file name.

A sample input file named time-report-42.csv is included in this repo.

What your API must do:

We've agreed to build an API with the following endpoints to serve HTTP requests:

An endpoint for uploading a file.

This file will conform to the CSV specifications outlined in the previous section.
Upon upload, the timekeeping information within the file must be stored to a database for archival purposes.
If an attempt is made to upload a file with the same report ID as a previously uploaded file, this upload should fail with an error message indicating that this is not allowed.

An endpoint for retrieving a payroll report structured in the following way:

NOTE: It is not the responsibility of the API to return HTML, as we will delegate the visual layout and redering to the front end. The expectation is that this API will only return JSON data.

Return a JSON object payrollReport.
payrollReport will have a single field, employeeReports, containing a list of objects with fields employeeId, payPeriod, and amountPaid.
The payPeriod field is an object containing a date interval that is roughly biweekly. Each month has two pay periods; the first half is from the 1st to the 15th inclusive, and the second half is from the 16th to the end of the month, inclusive. payPeriod will have two fields to represent this interval: startDate and endDate.
Each employee should have a single object in employeeReports for each pay period that they have recorded hours worked. The amountPaid field should contain the sum of the hours worked in that pay period multiplied by the hourly rate for their job group.
If an employee was not paid in a specific pay period, there should not be an object in employeeReports for that employee + pay period combination.
The report should be sorted in some sensical order (e.g. sorted by employee id and then pay period start.)
The report should be based on all of the data across all of the uploaded time reports, for all time.

As an example, given the upload of a sample file with the following data:

date	hours worked	employee id	job group
4/1/2023	10	1	A
14/1/2023	5	1	A
20/1/2023	3	2	B
20/1/2023	4	1	A

A request to the report endpoint should return the following JSON response:

  {
    "payrollReport": {
      "employeeReports": [
        {
          "employeeId": "1",
          "payPeriod": {
            "startDate": "2023-01-01",
            "endDate": "2023-01-15"
          },
          "amountPaid": "$300.00"
        },
        {
          "employeeId": "1",
          "payPeriod": {
            "startDate": "2023-01-16",
            "endDate": "2023-01-31"
          },
          "amountPaid": "$80.00"
        },
        {
          "employeeId": "2",
          "payPeriod": {
            "startDate": "2023-01-16",
            "endDate": "2023-01-31"
          },
          "amountPaid": "$90.00"
        }
      ]
    }
  }

How to build the application

ruby version 3.1.4
rails version 7.0.8
sqlite3 version 3.39.5

To install the gems, execute the bundle install command from the root of the project
To run the migrations, execute the rails db:migrate command from the root of the project

How to run the application

To start the rails server, execute the rails s command from the root of the project
To start the rails console, execute the rails c command from the root of the project
To run the tests, execute the rspec spec command from the root of the project

How to test the application

Use Postman to test the endpoints manually.

To test the endpoint for uploading a time report, send a POST request to the http://127.0.0.1:3000/api/v1/time_reports URL, and attached the CSV by selecting Body, then form-data, entering time_report for key name and selecting file for key type, then selecting the CSV file through the Select Files button.

To test the endpoint for retrieving the payroll report, send a GET request to the http://127.0.0.1:3000/api/v1/time_report_details URL.

Test cases

no report
0 records
1 record
2 records
different report id, duplicate records
report with an id already in the DB
multiple years in a single report
many records in a single report

khesualdo / wave-interview-challenge