Antaeus (/ænˈtiːəs/), in Greek mythology, a giant of Libya, the son of the sea god Poseidon and the Earth goddess Gaia. He compelled all strangers who were passing through the country to wrestle with him. Whenever Antaeus touched the Earth (his mother), his strength was renewed, so that even if thrown to the ground, he was invincible. Heracles, in combat with him, discovered the source of his strength and, lifting him up from Earth, crushed him to death.
Welcome to our challenge.
As most "Software as a Service" (SaaS) companies, Pleo needs to charge a subscription fee every month. Our database contains a few invoices for the different markets in which we operate. Your task is to build the logic that will schedule payment of those invoices on the first of the month. While this may seem simple, there is space for some decisions to be taken and you will be expected to justify them.
Fork this repo with your solution. Ideally, we'd like to see your progression through commits, and don't forget to update the README.md to explain your thought process.
Please let us know how long the challenge takes you. We're not looking for how speedy or lengthy you are. It's just really to give us a clearer idea of what you've produced in the time you decided to take. Feel free to go as big or as small as you want.
Requirements:
- >= Java 11 environment
Open the project using your favorite text editor. If you are using IntelliJ, you can open the build.gradle.kts file and it is gonna setup the project in the IDE for you.
./gradlew build
There are 2 options for running Anteus. You either need libsqlite3 or docker. Docker is easier but requires some docker knowledge. We do recommend docker though.
Running Natively
Native java with sqlite (requires libsqlite3):
If you use homebrew on MacOS brew install sqlite.
./gradlew run
Running through docker
Install docker for your platform
docker build -t antaeus
docker run antaeus
The code given is structured as follows. Feel free however to modify the structure to fit your needs.
├── buildSrc
| | gradle build scripts and project wide dependency declarations
| └ src/main/kotlin/utils.kt
| Dependencies
|
├── pleo-antaeus-app
| main() & initialization
|
├── pleo-antaeus-core
| This is probably where you will introduce most of your new code.
| Pay attention to the PaymentProvider and BillingService class.
|
├── pleo-antaeus-data
| Module interfacing with the database. Contains the database
| models, mappings and access layer.
|
├── pleo-antaeus-models
| Definition of the Internal and API models used throughout the
| application.
|
└── pleo-antaeus-rest
Entry point for HTTP REST API. This is where the routes are defined.
- Exposed - DSL for type-safe SQL
- Javalin - Simple web framework (for REST)
- kotlin-logging - Simple logging framework for Kotlin
- JUnit 5 - Testing framework
- Mockk - Mocking library
- Sqlite3 - Database storage engine
Happy hacking 😁!
Not a Java/Kotlin expert at all but I enjoy solving puzzles...
Challenge: "few invoices for the different markets ... schedule payment of those invoices on the first of the month".
Backend to charge invoices on a specific day of month.
Above is a simple diagram showing the existing Functionality within the backend service.
Below diagram, I have identified the typical functions needed in order to handle invoices charging.
- Check Status / keep track
- Update Status
- Check Customer Currency / Convert
- Retry Failed Invoices
- Apply Discount
- Charge Interest due to Overdue Invoices
The backend should handle exceptions like:
- Network
- Currency Mismatches
- Insufficient balance
- Customers Not Found
- Suspend Customer
- Update Customer Details (Currency)
- Mark Invoices to be Charged for Next Run
- Schedule a Monthly Job
- Get a List of Failed Invoices to be checked -> Escalate
- Create a Notification Message
- Inform Customer about Invoice Status
My implementation is basic and does not cover all the aspects of Error handling logging encryption etc.
Present: Functions ->
- Fetch All Invoices
- Fetch Invoice By ID
ToDo: Functions ->
- Update Invoice: Paid to be done (Not Paid / Error) - Done
My implementation calls the updateInvoice within the DAL, it allows to updateStatus of any sort.
- Fetch Invoice(s) by Status - Done
I have implemented an abstract fetchInvoiceByStatus function in order to cater for various statuses when charging happens or various other processes might need.
- convertCurrency
The convert currency function could be called if the Customer' currency is different than the charging company' currency before a charge is made - outstanding
Present: Functions ->
- Charge (TODO)
ToDO: Functions ->
- Charge Single Invoice - Done Basic Only
When calling the PaymentProvider check for execeptions like mentioned above which is returned.
- Check status of Invoice before trying to Charge(paymentProvider) - Done Basic Only
Before I update the invoice I check if the PaymentProvider was successful.
- Charge All Invoices create logger - Done Basic Only
The schedule Job would need a functionality in order to charge multiple invoices / multiple customers. ChargeInvoices(by unpaid status) calls the chargeSingleInvoice function and writes a logger. This is still very basic. Here I will implement a Logging Service that can track each charge of when and what happened.
- HandleFailedInvoices - retry - outstanding
This function should be created to retry when there were failed invoices, it could be called ad-hoc or by a scheduling service.
- applyDiscount - outstanding
It could be that discounts could be applied and the invoice amt should be adjusted.
- chargeInterest - outstanding
If a customer is unsuccessful and the invoice is already overdue based on payment terms the backend func can be called to add interest.
Present: Functions ->
- FectchAll Customers
- FecthByID
ToDo: Functions ->
- suspendCustomerSubscription - outstanding
If a customer is not paying the subscription service should be terminated.
- updateCustomerDetails
If a customer' details change like currency etc. This func can assist.
ToDo: Functions ->
- markInvoicesToBeCharged - outstanding
For the schedule Job Service to work a function needs to be created to check which of the invoices should be charged. This could then be used as a status or indicator for the billing Service.
- createInvoiceRun
Actual Job that will executed perhaps with a cron etc.
ToDo: Functions ->
- getListOfFailedInvoices - outstanding
If a company has a process for the financial clerks to follow-up on unpaid invoices.
- createNotificationMessage - outstanding
Actual function to create a template message / email.
- InformCustomeraboutStatus - outstanding
Call the CreateNotificationMessage for customers with unpaid Invoices.
- createStatements - outstanding
Provide a statement for the account based on invoice status
- handleFailedNotifications - outstanding
If the email was unsuccessful retry send or provide a list of issues.
Try
-
Scheduled monthly job
-
logging output that shows successful/failed charges as they occur
-
Some way to test/verify/trigger the monthly scheduled job
-
Network retries - Tight for my existing work schedule.
I have revisted ..\antaeus\core\services\BillingService.kt - With my previous implementation it was not possible to have a schedule.
Found documentation to use Kotlin with a Scheduler you could implement it by using quartz - https://www.baeldung.com/quartz
Imported the nessary org.quartz* libraries. Attempted the CronTriggers
http://www.quartz-scheduler.org/documentation/2.4.0-SNAPSHOT/tutorials/
Imported the org.slf4j.LoggerFactory given that it was already available in the API.
Also see more info + comments in BillingService.kt
Added the API for Quartz
Added the Monthly Schedule - the Cron expression will translate the following schedule as shown below:
- 0 0 23 L 1/1 ? * ** Mon Aug 31 23:00:00 UTC 2020
Adjusted Billing Service with addtional Parameters
Created the JobSchedule that that will call the BillingService Invoice charge Used the slf4j.LoggerFactory