Ballerina conversion API

conversion_api.bal

import ballerina/http;

type ConvertionRate record {|
    string fromCurrency;
    string toCurrency;
    decimal conversionRate;
|};

type ConversionRateUpdate record {|
    decimal conversionRate;
|};

type ConversionRates record {|
    ConvertionRate[] conversionRates;
|};

type ConversionRateNotFound record {|
    *http:NotFound;
    record {|
        string message;
        string 'fromCurrency;
        string toCurrency;
        string...;
    |} body;
|};

type ConversionResult record {|
    decimal amount;
|};

type ConversionRateCreated record {|
    *http:Created;
    record {|
        string message;
    |} body;
|};

type ConversionRateUpdated record {|
    *http:Ok;
    record {|
        string message;
    |} body;
|};

type ConversionRateConflict record {|
    *http:Conflict;
    record {|
        string message;
        string 'fromCurrency;
        string toCurrency;
    |} body;
|};

type UnauthorizedError record {|
    *http:Unauthorized;
    record {|
        string message;
    |} body;
|};

service class Authorizer {
    *http:RequestInterceptor;

    resource function 'default [string... path](http:RequestContext ctx, @http:Header string X\-API\-KEY)
            returns UnauthorizedError|http:NextService|error? {
        // add your logic here
        return ctx.next();
    }
}

type BadRequest record {|
    *http:BadRequest;
    record {|
        string message;
    |} body;
|};

type InternalServerError record {|
    *http:InternalServerError;
    record {|
        string message;
    |} body;
|};

service class ErrorInterceptor {
    *http:ResponseErrorInterceptor;

    remote function interceptResponseError(error err, http:RequestContext ctx) returns BadRequest|InternalServerError {
        // add your logic here
        return <InternalServerError>{
            body: {
                message: err.message()
            }
        };
    }
}

@http:ServiceConfig {
    mediaTypeSubtypePrefix: "conversion.api"
}
service http:InterceptableService /api on new http:Listener(9090) {

    public function createInterceptors() returns [Authorizer, ErrorInterceptor] {
        return [new Authorizer(), new ErrorInterceptor()];
    }

    @http:ResourceConfig {
        name: "conversion-rates",
        linkedTo: [
            {name: "conversion-rate", method: http:GET, relation: "get-conversion-rate"},
            {name: "conversion", relation: "get-conversion"}
        ]
    }
    resource function get conversion\-rates() returns @http:Cache {maxAge: 18000} ConversionRates {
        return {
            conversionRates: []
        };
    }

    @http:ResourceConfig {
        name: "conversion-rate",
        linkedTo: [
            {name: "conversion-rate", method: http:PUT, relation: "update-conversion-rate"},
            {name: "conversion-rate", method: http:DELETE, relation: "delete-conversion-rate"},
            {name: "conversion", relation: "get-conversion"}
        ]
    }
    resource function get conversion\-rate(string 'from, string to) returns @http:Cache {maxAge: 18000} ConvertionRate|ConversionRateNotFound {
        return {
            fromCurrency: 'from,
            toCurrency: to,
            conversionRate: 1.25
        };
    }

    @http:ResourceConfig {
        name: "conversion",
        linkedTo: [
            {name: "conversion-rates", relation: "get-conversion-rates"},
            {name: "conversion-rate", method: http:GET, relation: "get-conversion-rate"}
        ]
    }
    resource function get conversion(string 'from, string to, decimal amount) returns @http:Cache {maxAge: 18000} ConversionResult|ConversionRateNotFound {
        return {
            amount: amount * 1.25
        };
    }

    @http:ResourceConfig {
        name: "conversion-rate",
        linkedTo: [
            {name: "conversion-rate", method: http:GET, relation: "get-conversion-rate"},
            {name: "conversion-rate", method: http:PUT, relation: "update-conversion-rate"},
            {name: "conversion-rate", method: http:DELETE, relation: "delete-conversion-rate"},
            {name: "conversion", relation: "get-conversion"}
        ]
    }
    resource function post conversion\-rate(ConvertionRate convertionRate) returns ConversionRateCreated|ConversionRateConflict {
        return {
            body: {
                message: "Conversion rate created successfully"
            }
        };
    }

    @http:ResourceConfig {
        name: "conversion-rate",
        linkedTo: [
            {name: "conversion-rate", method: http:GET, relation: "get-conversion-rate"},
            {name: "conversion-rate", method: http:DELETE, relation: "delete-conversion-rate"},
            {name: "conversion", relation: "get-conversion"}
        ]
    }
    resource function put conversion\-rate(string 'from, string to, ConversionRateUpdate convertionRate) returns ConversionRateUpdated|ConversionRateNotFound {
        return {
            body: {
                message: "Conversion rate updated successfully"
            }
        };
    }

    @http:ResourceConfig {
        name: "conversion-rate"
    }
    resource function delete conversion\-rate(string 'from, string to) returns http:NoContent|ConversionRateNotFound {
        return {};
    }
}