Parking Fee Calculator

You are tasked to build a Parking Fee Calculator, that will help to calculate parking fees and thus help users decide where to park. These are the carparks that will be considered in this application:

For each of the car park, it has different parking rules, the rules for weekday and weekend are also different, in general there are three kinds of parking rule,

Fixed per entry: Per Entry charge - $4.36

Fixed first X minutes, then subsequent Y mins charge: First hour(X=60) at $1.95 Every subsequent 15 minutes(Y=15) at $0.55

Fixed per X minutes: $0.55 every 15 minutes(X=15)

Project Structure

PARKING-FEE-CALCULATOR-CSHARP
├── ParkingFeeCalculator
│   ├── Controllers
│   │   └── FeeCalculationController.cs
│   ├── Models
│   │   └── CarPark.cs
│   │   └── CarParkConfig.cs
│   │   └── CalculateDaysResult.cs
│   │   └── CarParkFee.cs
│   │   └── FitResult.cs
│   │   └── FeeRuleCalculators
│   │       └── FixedFeePerEntryRuleCalculator.cs
│   │       └── FixedFeePerXMinutesRuleCalculator.cs
│   │       └── FixedFirstXMinutesRuleCalculator.cs
│   │       └── RuleCalculatorBase.cs
│   ├── Services
│   │   └── FeeCalculationService.cs
│   │   └── IFeeCalculationService.cs
│   ├── Utilities
│   │   └── DateTimeUtility.cs
│   │   └── DecimalUtility.cs
│   ├── Program.cs
├── ParkingFeeCalculator.Tests
│   ├── ApiTests
│   │   └── FeeCalculatorApiTest.cs
│   ├── ... test files
└── README.md

File Descriptions

• Program.cs: this is the application file to run it as the asp.net web api, and the place to register the dependency injection containers
• Controllers/FeeCalculationController.cs: This file exports a class FeeCalculationController which has a method GetLowestCarpark that handles the /api/feeCalculator/getLowestCarpark route of the application and returns the lowest carpark fee.
• Models/CarPark.cs: this is the model for the carpark fee rule, including the fee rule calculator for cars in weekday and weekend, and the fee rule calculator for motorcycle
• Models/CarParkConfig.cs: this is the configuration for the 3 carparks
• Models/CalculateDaysResult.cs: this is the model for CalculateDays method in FeeCalculationService class, it include the startTime and endTime for that day, for example, if a car entry the carpark at 1st Jan 1pm, exit the carpark at 2nd Jan 3am, in total there will be two days, then the startTime for the first day will be 1:00pm, endTime will be 11:59pm, the startTime for the second day will be 0:0am, endTime will be 3:00am
• Models/CarParkFee.cs: includes the carpark name and fee
• Models/FitResult.cs: this is the model for the result of IsFit method in RuleCalculatorBase class
• Models/FeeRuleCalculators/RuleCalculatorBase.cs: this file implements the IsFit method, which returns the time period that falls within the ruleset, or a false result if the inputted time period does not fall within the ruleset at all.
• Models/FeeRuleCalculators/FixedFeePerEntryRuleCalculator.cs: this file defines the ruleset for which there is a fixed fee per entry for the time period defined in the ruleset.
• Models/FeeRuleCalculators/FixedFeePerXMinutesRuleCalculator.cs: this file defines the ruleset for which there is a fixed fee per X minutes for the time period defined in the ruleset. Each block will be rounded up (i.e. if X=15, if the parking duration is 50minutes, it will be counted as 4 blocks of X)
• Models/FeeRuleCalculators/FixedFirstXMinutesRuleCalculator.cs: this file defines the ruleset for which there is a fixed fee for the first X minutes, and thereafter the remaining time is charged for another fixed fee per Y minutes. Similarly, each block will be rounded up. (i.e. if X=60 and Y=15, if the parking duration is 110minutes the parking charge will be xFee + 4 * yFee).
• Services/IFeeCalculationService.cs: this is the interface which include a CalculateParkingFee method, to calculate the parking fee based on the startTime endTime vehicleType and carPark
• Services/FeeCalculationService.cs: this implements the IFeeRuleCalculator interface
• Utilities/DateTimeUtility.cs: this file provide an extension method ToTimeOnly() for the DateTime type to convert the DateTime the time part to the TimeOnly type
• Utilities/DecimalUtility.cs: This file provide an extension method ToTwoDecimalPlaces() for the decimal type to fix it to 2 decimal places

Class Diagram

Time Sequence Diagram

Install(Visual Studio Code Configuration)

1. install C# Dev Kit extension(https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.csdevkit)
2. install .net install tool(https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.vscode-dotnet-runtime)
3. install the .net 8.x SDK, press cmd+shift+p then install New .Net SDK

Build

cd ParkingFeeCalculator
dotnet build

Run(under ParkingFeeCalculator folder)

dotnet run

it will run localhost, like http://localhost:5180, can access the swagger by http://localhost:[port]/swagger/ can access the api by http://localhost:[port]/api/feeCalculator/getLowestCarpark

Test

cd ParkingFeeCalculator.Tests
dotnet test

How to use it

You need to finish 3 tasks. if all 3 tasks finished, when you run the test in ParkingFeeCalculator.Tests/Services/FeeCalculationServiceTest.cs, the test will pass!

Task 1

---

can checkout the branch step1 to start

git checkout step1

Requirement

You need to implement the CalculateCost method in FixedFirstXMinutesRuleCalculator.cs, it based on the rule first X mintues charge a fixed amount, for the subsequence, each Y mintues will charge a fee, for example:

10:00 - 16:00:

First 2 hour at $5

Every subsequent 15 minutes at $0.55

X=120, Y=15

test case:

entryTime: 10:00, exitTime: 13:07

10:00-12:00: $5

12:01-13:07 (1*4+1)*0.55=$2.75

in total: 5+2.75=$7.75

Definiation of Done

all test cases in FixedFirstXMinutesRuleCalculatorTest.cs are passed

Task 2

---

you can continue your implementation without the checkout command if you finished step1, or start directly by checkout the branch step2

git checkout step2

Requirement

You need to implement the IsFit method inside the RuleCalculatorBase class, it's to comparing the input startTime and endTime, whether it fit the current rule, if yes, need to return the actual start time and actual end time,

for example: rule configed: 10:00-13:00

case 1: input param: startTime: 9:00, endTime: 9:59 output: { isFit: false }

case 2: input param: startTime: 9:00, endTime: 11:01 output: { isFit: true, startTime: 10:00, endTime: 11:01 }

Definition of Done

All the test cases in RuleCalculatorBaseTest.cs are passed

Task 3

---

you can continue your implementation without the checkout command if you finished step2, or start directly by checkout the branch step3

git checkout step3

Requirement

You need to finish the final logic, the CalculateParkingFee method in FeeCalculationService to calculate the parking fee, can refer the time sequence diagram above

1. need to check whether it's within grace peroid, if yes return 0, the CheckGracePeriod method will return true if it's within grace period
2. need to check whether it's weekend, if yes need to use the weekend day rule instead of the week day, the CheckIsWeekend method will return true if it's weekend
3. split the start time and end time into days with CalculateDays method
4. iterate the rules with each days and sum the result

Test cases:

entryTime = "2021-01-01T10:00";

exitTime = "2021-01-02T11:00";

parking in plazaSingapura

day 1:

10:00-11:00: 1.95

11:01-17:59: 7*4*0.55 = 15.40

18:00-23:59: 3.25

day 2:

00:00-02:59: 3*4*0.55 = 6.60

3:00-5:00: 3.25

5:01-11:00: 6*4*0.55 = 13.2

total: 1.95 + 15.40 + 3.25 + 6.60 + 3.25 + 13.2 = 43.65

Definition of Done

All the test cases in FeeCalculationServiceTest.cs(unit test) are all passed and the test cases in FeeCalculatorApiTest.cs(api test) are passed