Requirements

Functional Requirements:

1) User should be able to search a parking lot near him.

2) User should be able to book the parking slot

3) Parking slot should be selected from car to relevant size and bigger size ( like car should be parked to medium and large slot )

4) User should get notification and check booking order

Non-Functional Requirements:

No double booking should be allowed

Highly available

Capacity Estimation

1 million active users

10000 parking lots

API Design

Get /parking/{location} -> returns all parking lots near a certain radius

Get /parking/{parking lot} -> status of available slots

Post /parking/{parkinglot}/{slot} -> book the slot else throw the error (orderId)

Post /payment/{orderId} [idempotentId]

Get /order/{userId}

Get /order/{userId}/{orderId}

High-Level Design

There main services

Parking

1) Get nearby parking lots

2) Get available slots

3) Book the parking slot

Payment

1) Booking service generate a payment link

2) Links with other third party system and handles order in database

Order/Booking

1) Parking send it order to generate a Id for booking a slot

2) Order Id can be queried

Database Design

1) Sql based database for parking lot, transaction and order id

2) Redis for caching slot id

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.