Please create a private version of this repo, complete the objectives, and once you are finished, send a link to your repo to us.

Part of what an insurance company needs to have in its backend is a record system. As an insurer, we need to keep an up-to-date record of each of our policy-holder's data points that go into the calculation of their rate. When a policy-holder updates their information, I.E. they change addresses, or add/remove new employees to their team we will be notified and we must keep our records up to date.

The current version of the repo is an extremely simplified version of exactly that. GET /api/v1/record/{id} will retrieve a record, which is just a json mapping strings to strings. and POST /api/v1/record/{id} will either create a new record or modify an existing record. However, it isn't enough to just keep a record of the current record state but we must maintain a reference to how the state has changed to be in full compliance.

Say that the policy-holder buys their insurance on the start of the year, and then two months later changes the address of their business but doesn't tell us about this change until 4 months after that. Since we were technically held liable if there was a claim event, we need to charge the customer the difference for the 4 months since they changed addresses. To do so accurately, we need to know the version of the records that we knew about them at the two points of time: at the time when the change happened and at the time when we were told of the change.

In this project, you'll make a simplified version of this system. At a high-level your goal is to do two things:

1. Change the storage backend to sqlite, and persist the data across turning off and on the server.
2. Add the time travel component so we can easily look up the state of each records at different timesteps.

The sections below outline these two objectives in more detail. You may use whatever libraries and tools you like to achieve this even as far as building this in an entirely different language.

The current implementation does not store the data. The data is lost once the server process is killed. You should change the code so that all changes are persisted on to sqlite.

Once you're done, the data should be persistent on to a sqlite file as the server is running. The server should tolerate restarting the process without data loss.

This part is far more open-ended. You might need to make major changes across nearly all files of the codebase. You'll be adding persistentence to the records.

Take a look at these slides on persistent data structures to learn what that means. The slides outline a few different types of persistence but I'll leave it to you to identify which makes sense for this problem.

You should create a set of /api/v2 endpoints that enable you to do run gets, creates, and updates. Unlike in v1, records are now versioned. Full requirements:

• You should have endpoints that allow the api client to get records at different versions. (not just the latest version).
• Updates should be able to add modifications on top of the latest version.
• There should be a way to get a list of the different versions too.
• /api/v1 should still work after these changes.

We expect you to work as if this task was a normal project at work. So please write your code in a way that fits your intuitive notion of operating within best practices. Additionally, you should at the very least have a different commmit for each individual objective, ideally more as you go through process of completing the take-home. Also we like to see your thought process and fixes as you make changes. So don't be afraid of committing code that you later edit. No need to squash those commits.

Many parts of the assignment is intentionally ambiguious. If you have a question, definitely reach out. But for many of these ambiguiuties, we want to see how you independently make software design decisions.

Can I Use Another Language? Definitely, we've had multiple people complete this assignment in Python and Java. You can pick whatever language you'd like although you should aim to replicate the functionality in the boilerplate.

Did you really end up implementing something like this at Rainbow? Yes, but unfortunately it wasn't as simple as this in practice. For insurance a number of requirements force us to maintain historic records across many different object types. So in fact we implemented this across multiple different tables in our database.

There are only two API endpoints GET /api/v1/records/{id} and POST /api/v1/records/{id}, all ids must be positive integers.

This endpoint will return the record if it exists.

> GET /api/v1/records/2323 HTTP/1.1

< HTTP/1.1 200 OK
< Content-Type: application/json; charset=utf-8
{"id":2323,"data":{"david":"hey","davidx":"hey"}}

> GET /api/v1/records/32 HTTP/1.1

< HTTP/1.1 400 Bad Request
< Content-Type: application/json; charset=utf-8
{"error":"record of id 32 does not exist"}

This endpoint will create a record if a does not exists. Otherwise it will update the record.

The payload is a json object mapping strings to strings and nulls. Values that are null indicate that the backend must delete that key of the record.

# Creating a record
> POST /api/v1/records/1 HTTP/1.1
{"hello":"world"}

< HTTP/1.1 200 OK
< Content-Type: application/json; charset=utf-8
{"id":1,"data":{"hello":"world"}}


# Updating that record
> POST /api/v1/records/1 HTTP/1.1
{"hello":"world 2","status":"ok"}

< HTTP/1.1 200 OK
< Content-Type: application/json; charset=utf-8
{"id":1,"data":{"hello":"world 2","status":"ok"}}


# Deleting a field
> POST /api/v1/records/1 HTTP/1.1
{"hello":null}

< HTTP/1.1 200 OK
< Content-Type: application/json; charset=utf-8
{"id":1,"data":{"status":"ok"}}