Application in goLang to work in a simple pricing engine considering various factors from the customer who is trying to rent a vehicle from a rental service provider.

The requirement of this application is to bring up a go based REST API which will determine the rental cost of a car bases on the attributes of the customer who is purchasing it. You can go through the detailed requirements Here. The essential attributes that play key aspects in the pricing calculation are as follows:

• Rent Duration
• Age of the customer
• Insurance Group
• Validity of the licence held by the customer

Total Rental Cost = BaseFare based on the Duration * Factor based on Age * Factor based on the Insurance Group * Factor based on Licence Validity

The current application is built on top on an existing code as per the Requirements. The setup typically had a layered data flow among the components as follows:

• The main.go file which typically invoked the service.
• The service that serves various REST end point for the application and passing on the data to RPC layer.
• The RPC which typically takes care of doing the conversion from HTTP middleware understandable data to the Application understandable data.
• Then the RPC passes the application understandable data to the App component which has all the business logics of computing the pricing and serving the required data.

POST /generate_pricing HTTP/1.1
Host: localhost:3000
Content-Type: application/json

{
    "date_of_birth": "1970-12-04",
    "insurance_group": 12,
    "license_held_since": "1988-08-01"
}

date_of_birth – Date of Birth of the customer who is trying to rent the vehicle insurance_group – the insurance group to which the customer belongs to license_held_since – The date of acquiring of the Driver's licence by the existing customer

Returns: Empty body with one of the following:

200 – in case of success

HTTP/1.1 200 OK
Content-Type: application/json
{
  "input": {
          "date_of_birth": "1970-12-04",
          "insurance_group": 12,
          "license_held_since": "1988-08-01"
      },
      "is-eligible": true,
      "message": "Success",
      "pricing": [
          {
              "premium": 278.28254999999996,
              "currency": "£",
              "fare_group": "0.5 hours, Driver Age >26, Insurance Group:9-16, Licence Validity:6"
          },
          {....},
          {....},
          .....
      ]
}

GET /statistics HTTP/1.1
Host: localhost:3000

Returns: The computed statistics for all the posted transaction or empty if there are no transactions present.

HTTP/1.1 200
Content-Type: application/json;charset=UTF-8
{
  "base-rate": [
        {
            "Start": 0,
            "End": 1800,
            "IsEligible": true,
            "Value": 273,
            "Label": "0.5 hours"
        },
        {....}
        ....
        ],
    "driver-age-factor": [
        {
            "Start": 0,
            "End": 16,
            "IsEligible": false,
            "Value": 0,
            "Label": "Driver Age:0-16"
        },
        {...}
        ....
      ],
      "insurance-group-factor": [
          {
              "Start": 1,
              "End": 8,
              "IsEligible": true,
              "Value": 1,
              "Label": "Insurance Group:1-8"
          },
          {...},
          ....
      ],
      "licence-validity-factor": [
        {
            "Start": 0,
            "End": 1,
            "IsEligible": true,
            "Value": 1.1,
            "Label": "Licence Validity:0-1"
        },
        {...}
        .....
      ]
    }

This application is purely build on goLang. To run this application in your local you need to follow the below steps

go build ./cmd/.

go run ./cmd/.

go test ./test/.

• setting up go environment : https://pkg.go.dev/cmd/go
• go packages : https://medium.com/rungo/everything-you-need-to-know-about-packages-in-go-b8bac62b74cc
• maps and struts : https://tour.golang.org/moretypes/19
• getting query params : https://golangbyexample.com/net-http-package-get-query-params-golang/
• current working directory: https://stackoverflow.com/a/31464648
• parsing json: https://www.sohamkamani.com/golang/parsing-json/
• reading json file : https://tutorialedge.net/golang/parsing-json-with-golang/
• generic struct type parsing unmarshall : https://stackoverflow.com/a/49002939
• fix for implicit assignment of unexported field issue: https://stackoverflow.com/a/48130761
• logging in go: https://www.loggly.com/use-cases/logging-in-golang-how-to-start/
• logging in detail: https://www.honeybadger.io/blog/golang-logging/
• passing functions as parameters: https://stackoverflow.com/a/12655719
• fixing cast exception from interface{} to other structs array : https://stackoverflow.com/a/42740448
• unbounded list creation, updation : https://stackoverflow.com/a/3387362
• sorting struct list : https://yourbasic.org/golang/how-to-sort-in-go/
• https://stackoverflow.com/a/42382736
• https://stackoverflow.com/a/29000001
• time/date formatting : https://stackoverflow.com/a/54314594
• days between dates: https://yourbasic.org/golang/days-between-dates/
• https://stackoverflow.com/a/46298277
• collections-functions : https://gobyexample.com/collection-functions
• String to int: https://stackoverflow.com/a/4279644
• int to String : https://stackoverflow.com/a/10105983
• max integer value : https://stackoverflow.com/a/6878625
• check empty string : https://stackoverflow.com/a/18594463
• splitting string: https://stackoverflow.com/a/16551613
• https://www.educative.io/edpresso/how-to-split-a-string-in-golang
• pointers and references: https://medium.com/wesionary-team/pointers-and-passby-value-reference-in-golang-a00c8c59b7f1
• string formatting : https://gobyexample.com/string-formatting
• https://pkg.go.dev/fmt
• handling error messages: https://stackoverflow.com/a/22171548
• no nil check for struct variables: https://stackoverflow.com/a/25350005
• https://stackoverflow.com/a/28447372