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Welcome to the BiteSpeed_Interview_Task wiki!

Bitespeed needs a way to identify and keep track of a customer's identity across multiple purchases.

We know that orders on FluxKart.com will always have either an email or phoneNumber in the checkout event.

Bitespeed keeps track of the collected contact information in a relational database table named Contact.

{
  id                   Int                   
  phoneNumber          String?
  email                String?
  linkedId             Int? // the ID of another Contact linked to this one
  linkPrecedence       "secondary"|"primary" // "primary" if it's the first Contact in the link
  createdAt            DateTime              
  updatedAt            DateTime              
  deletedAt            DateTime?
}

One customer can have multiple Contact rows in the database against them. All of the rows are linked together with the oldest one being treated as "primary” and the rest as “secondary” .

**Contact** rows are linked if they have either of email or phone as common.

For example:

If a customer placed an order with email=lorraine@hillvalley.edu & phoneNumber=123456 and later came back to place another order with email=mcfly@hillvalley.edu & phoneNumber=123456 , database will have the following rows:

{
   id                   1                   
  phoneNumber          "123456"
  email                "lorraine@hillvalley.edu"
  linkedId             null
  linkPrecedence       "primary"
  createdAt            2023-04-01 00:00:00.374+00              
  updatedAt            2023-04-01 00:00:00.374+00              
  deletedAt            null
},
{
   id                   23                   
  phoneNumber          "123456"
  email                "mcfly@hillvalley.edu"
  linkedId             1
  linkPrecedence       "secondary"
  createdAt            2023-04-20 05:30:00.11+00              
  updatedAt            2023-04-20 05:30:00.11+00              
  deletedAt            null
}

Requirements

You are required to design a web service with an endpoint /identify that will receive HTTP POST requests with JSON body of the following format:

{
	"email"?: string,
	"phoneNumber"?: number
}

The web service should return an HTTP 200 response with a JSON payload containing the consolidated contact.

Your response should be in this format:

	{
		"contact":{
			"primaryContatctId": number,
			"emails": string[], // first element being email of primary contact 
			"phoneNumbers": string[], // first element being phoneNumber of primary contact
			"secondaryContactIds": number[] // Array of all Contact IDs that are "secondary" to the primary contact
		}
	}

Extending the previous example:

Request:

{
	"email": "mcfly@hillvalley.edu",
	"phoneNumber": "123456"
}

will give the following response

	{
		"contact":{
			"primaryContatctId": 1,
			"emails": ["lorraine@hillvalley.edu","mcfly@hillvalley.edu"]
			"phoneNumbers": ["123456"]
			"secondaryContactIds": [23]
		}
	}

• In fact, all of the following requests will return the above response

  {
  	"email": null,
  	"phoneNumber":"123456"
  }

  {
  	"email": "lorraine@hillvalley.edu",
  	"phoneNumber": null
  }

  {
  	"email": "mcfly@hillvalley.edu",
  	"phoneNumber": null
  }

But what happens if there are no existing contacts against an incoming request?

The service will simply create a new **Contact** row with linkPrecedence=”primary" treating it as a new customer and return it with an empty array for secondaryContactIds

When is a secondary contact created?

If an incoming request has either of phoneNumber or email common to an existing contact but contains new information, the service will create a “secondary” Contact row.

Example:

Existing state of database:

{
   id                   1                   
  phoneNumber          "123456"
  email                "lorraine@hillvalley.edu"
  linkedId             null
  linkPrecedence       "primary"
  createdAt            2023-04-01 00:00:00.374+00              
  updatedAt            2023-04-01 00:00:00.374+00              
  deletedAt            null
}

Identify request:

{
"email":"mcfly@hillvalley.edu",
"phoneNumber":"123456"
}

New state of database:

{
   id                   1                   
  phoneNumber          "123456"
  email                "lorraine@hillvalley.edu"
  linkedId             null
  linkPrecedence       "primary"
  createdAt            2023-04-01 00:00:00.374+00              
  updatedAt            2023-04-01 00:00:00.374+00              
  deletedAt            null
},
{
   id                   23                   
  phoneNumber          "123456"
  email                "mcfly@hillvalley.edu"
  linkedId             1
  linkPrecedence       "secondary"
  createdAt            2023-04-20 05:30:00.11+00              
  updatedAt            2023-04-20 05:30:00.11+00              
  deletedAt            null
},

Can primary contacts turn into secondary?

Yes. Let’s take an example

Existing state of database:

{
   id                   11                   
  phoneNumber          "919191"
  email                "george@hillvalley.edu"
  linkedId             null
  linkPrecedence       "primary"
  createdAt            2023-04-11 00:00:00.374+00              
  updatedAt            2023-04-11 00:00:00.374+00              
  deletedAt            null
},
{
   id                   27                   
  phoneNumber          "717171"
  email                "biffsucks@hillvalley.edu"
  linkedId             null
  linkPrecedence       "primary"
  createdAt            2023-04-21 05:30:00.11+00              
  updatedAt            2023-04-21 05:30:00.11+00              
  deletedAt            null
}

Request:

{
"email":"george@hillvalley.edu",
"phoneNumber": "717171"
}

New state of database:

{
	id                   11                   
  phoneNumber          "919191"
  email                "george@hillvalley.edu"
  linkedId             null
  linkPrecedence       "primary"
  createdAt            2023-04-11 00:00:00.374+00              
  updatedAt            2023-04-11 00:00:00.374+00              
  deletedAt            null
},
{
	id                   27                   
  phoneNumber          "717171"
  email                "biffsucks@hillvalley.edu"
  linkedId             11
  linkPrecedence       "secondary"
  createdAt            2023-04-21 05:30:00.11+00              
  updatedAt            2023-04-28 06:40:00.23+00              
  deletedAt            null
}

Response:

	{
		"contact":{
			"primaryContatctId": 11,
			"emails": ["george@hillvalley.edu","biffsucks@hillvalley.edu"]
			"phoneNumbers": ["919191","717171"]
			"secondaryContactIds": [27]
		}
	}