Points API

See DESIGN.md for assumptions and design plan

Prerequisites

• gnu make or equivalent: use either system package manager or Homebrew, if on windows see http://gnuwin32.sourceforge.net/packages/make.htm
• go (tested with >1.14): See instructions at https://golang.org/doc/install
• docker: See instructions at https://docs.docker.com/get-docker/

Building

To build standalone with go

make build

Running

The program can either be run with

make run

Or by simply executing

./RunRewardsAPI

Default port is 8080, but can be changed with -host flag

./RunRewardsAPI -port 8888

Tests

To run tests

make test

Dockerized

To run with docker (no build necessary)

make run-docker

To run tests with docker

make test-docker

API

Add Points

---

Add transactions to points store

• URL

  /add-points

• Method:

  POST

• Data Params

  JSON array

  REQUIRED PER OBJECT
  timestamp: [string] - time of transaction
  points: [int64] - points added or subtracted
  payer: [string] - with whom transaction is being made

• Success Response:

  On success you should see a 200 HTTP Status and json object

  • Code: 200
    Content: JSON encoded body
    success: [bool] - if addition was succesful

• Example:

curl -X POST http://localhost:8080/add-points \
   -H 'Content-Type: application/json' \
   -d '[{"timestamp": "2021-10-10T00:00:00Z", "points": 200, "payer": "GENERAL MILLS"}]'

Check Balance

---

Request balance for all payers in transaction history

• URL

  /check-balance

• Method:

  GET

• Data Params

  None

• Success Response:

  On success you should see a 200 HTTP Status and json encoded body

  • Code: 200
    Content: JSON encoded body
    success: [bool] - if checking was successful
    data: [Object] - json object with payers as keys and points as values

• Example:

curl http://localhost:8080/check-balance

Use Points

---

Use points from points store

• URL

  /use-points

• Method:

  POST

• Data Params

  JSON object

  REQUIRED
  points: [int64] - points added or subtracted
  

• Success Response:

  On success you should see a 200 HTTP Status and json encoded body

  • Code: 200
    Content: JSON encoded body
    success: [bool] - if using points was successful
    data: [Array] - array of objects containing payers and amounts deducted

• Example:

curl -X POST http://localhost:8080/use-points
   -H 'Content-Type: application/json'
   -d '{"points": 200}'

Prompt

Our users have points in their accounts. Users only see a single balance in their accounts. But for reporting purposes we actually track their points per payer/partner. In our system, each transaction record contains: payer (string), points (integer), timestamp (date).

For earning points it is easy to assign a payer, we know which actions earned the points. And thus which partner should be paying for the points.

When a user spends points, they don't know or care which payer the points come from. But, our accounting team does care how the points are spent. There are two rules for determining what points to "spend" first:

• We want the oldest points to be spent first (oldest based on transaction timestamp, not the order they’re received)
• We want no payer's points to go negative.

Provide routes that:

• Add transactions for a specific payer and date.
• Spend points using the rules above and return a list of { "payer": , "points": } for each call.
• Return all payer point balances.

Note:

• We are not defining specific requests/responses. Defining these is part of the exercise.
• We don’t expect you to use any durable data store. Storing transactions in memory is acceptable for the exercise.

Example

Suppose you call your add transaction route with the following sequence of calls:

{ "payer": "DANNON", "points": 1000, "timestamp": "2020-11-02T14:00:00Z" }
{ "payer": "UNILEVER", "points": 200, "timestamp": "2020-10-31T11:00:00Z" }
{ "payer": "DANNON", "points": -200, "timestamp": "2020-10-31T15:00:00Z" }
{ "payer": "MILLER COORS", "points": 10000, "timestamp": "2020-11-01T14:00:00Z" }
{ "payer": "DANNON", "points": 300, "timestamp": "2020-10-31T10:00:00Z" }

Then you call your spend points route with the following request:

{ "points": 5000 }

The expected response from the spend call would be:

[
    { "payer": "DANNON", "points": -100 },
    { "payer": "UNILEVER", "points": -200 },
    { "payer": "MILLER COORS", "points": -4,700 }
]

A subsequent call to the points balance route, after the spend, should returns the following results:

{
    "DANNON": 1000,
    "UNILEVER": 0,
    "MILLER COORS": 5300
}