# Hudarsono Hu - System Design Interview

## Context
Users can have up to 4 documents:

ID front
ID back
Proof of address
Selfie
If all 4 documents are verified, user is verified else user is unverified.

User can resubmit for documents that have been rejected.

## API Endpoint Design
Design APIs for clients to query for user statuses
Design APIs for clients to submit user documents

## Database Design
Design tables to store user documents

## Add On
- Use 3rd party to verify documents
- 3rd party takes up to 24 hours to process documents
- 3rd party sends callbacks once verification is completed

Task:
How should we integrate with 3rd party verification system

---

# Solution

Database
==================
users
---------
id(bigint)
email(varchar)
name(varchar)

user_documents
--------------
user_id(bigint)
type(tinyint)
url(text)
status(bool) ; default: false

3party_document_verification
---------------------------
user_id
external_record_id
status 'FINISHED'

Endpoints
====================
POST /users/{hash_id}/upload
- images
- hash_id(user_id)
- type

GET /users/{hash_id}/status
statuses = Users.find(id).user_documents.pluck(:status)
return verified/unverified

POST /users/{hash_id}/verify_document
return submited
queue

POST /3party/upload_documents
{
'user_id':
'documents': [
{
type: "ID_FRONT",
file: file,
}
]
}

POST /3party_callback/complete_verification
{
user_id:
record_id:
'documents': [
{
type: "ID_FRONT",
status: "valid",
}
]

}