curve-challenge

Small project for simulating payments via credit cards.

Actors

There are two main entities, users and merchants.

A user can:

• Create a new card
• TopUp one of his cards
• Pay a merchant

A merchant can:

• Capture an authorized amount of money from a user's card
• Refund a user for a maximum of the captured amount
• Revert a given amount of the original authorized one

Extra

A transaction system has been implemented. In the latter, every action performed is reported like follows

// Transaction embeds all transaction information
type Transaction struct {
	// ID is the transaction unique identifier
	ID string `json:"ID"`
	// Receiver is receiver's unique identifier
	Receiver string `json:"receiver"`
	// Sender is receiver's unique identifier
	Sender string `json:"sender"`
	// Amount is the transaction amount
	Amount float64 `json:"amount"`
	// Date is the TS of the action
	Date string `json:"date"`
	// Type is the transaction type
	Type string `json:"type"`
}

Where transaction type can vary in:

const (

	// EXTERNAL is used to set a default sender for Top Ups
	EXTERNAL = "c9e35256-e831-49c8-8471-164e17a66e31"
	// TOPUP is used for top up actions
	TOPUP = "TOPUP"
	// PAYMENT is used for payment actions
	PAYMENT = "PAYMENT"
	// CAPTURE is used for capture actions
	CAPTURE = "CAPTURE"
	// REFUND is used for refund actions
	REFUND = "REFUND"
	// REVERT is used for revert actions
	REVERT = "REVERT"
)

For the TopUps, it is mandatory to generate a default external Merchant since external actors (e.g. top up with transfer) isn't covered.

Through such transaction system is possible for users to know their available and marked balances, which payments they performed and to whom, the location where they spent such money (since each merchant has a sample location) etc.

What's missing

• Any user can perform any action by having the right card, user, authorization and merchant IDs. No authentication has been implemented for the purposes of this project.
• Full test Coverage
• Better error handling expecially for the postgres part and for Refund/Revert actions
• Better code reuse

What you need to run the project

• go
• postgresql (create a table called curve)
• docker & docker-compose (optional)

Work in local:

• Install dep
• run dep ensure
• Edit internal/configuration/configuration.json by changing "ENVIRONMENT" : "production" to "ENVIRONMENT" : "development"
• run tests with go test ./...

N.B. Make sure to start postgresql and create a table called curve with default settings.

Deploy with docker

• Install Docker and Docker-Compose
• Make sure that you have "ENVIRONMENT" : "production" in internal/configuration/configuration.json
• run docker-compose up

N.B. make sure you have ports 8000 and 5432 available.

Endpoints

Create User:

POST /api/users -> 201 with an empty body

Create Merchant:

POST /api/merchants -> 201 with a body like

{
	"name" : "merchant100",
	"location" : "london"
}

Create a card:

POST /api/cards -> 201 with a body like

{
	"owner" : "0ca41fa2-4fee-4da8-ae2c-e3bea5ae56af",
	"name" : "mastercard3"
}

Where owner must be an already existing user.

TopUp a card:

POST /api/transactions/top-up -> 201 with a body like

{
	"card" : "8868e147-cfe4-465d-a365-93f7cafd07f7",
	"amount" : 100.0
}

Where card must be an already existing card.

Payment:

POST /api/transactions/payment -> 201 with a body like

{
	"sender" : "0ca41fa2-4fee-4da8-ae2c-e3bea5ae56af",
	"receiver" : "86c07840-aa72-456a-8bdb-4da6ae622564",
	"card" : "8868e147-cfe4-465d-a365-93f7cafd07f7",
	"amount" : 100.0
}

Where card must be an already existing card and owned by sender and receiver must be an existing merchant.

Capture:

POST /api/transactions/capture -> 201 with a body like

{
	"merchant" : "18b228c9-bf03-41e3-b7d6-4e875668a03b",
	"authorization" : "56ae9103-e91a-45df-8086-f28c7b98e1e3",
	"amount" : 10.0
}

Where authorization must be an already existing authorization and merchant an existing merchant.

Refund:

POST /api/transactions/refund -> 201 with a body like

{
	"amount" : 8.0,
	"authorization" : "56ae9103-e91a-45df-8086-f28c7b98e1e3"
}

Where authorization must be an already existing authorization and amount the amount to be refunded.

Revert:

POST /api/transactions/revert -> 201 with a body like

{
	"amount" : 8.0,
	"authorization" : "56ae9103-e91a-45df-8086-f28c7b98e1e3"
}

Where authorization must be an already existing authorization and amount the amount to be refunded.

Postman collection:

Postman collection to perform example calls is available here.