<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-oauth2-client</artifactId>
</dependency>

@Configuration
public class SampleAutoConfiguration {

    @Bean
    @ConditionalOnProperty(name = "ics-expenditure.enabled", havingValue = "true")
    @ConditionalOnMissingBean(ClaimExpenditureRepository.class)
    public ClaimExpenditureRepository icsExpenditureRepository(IcsClaimExpenditureClient client,
                                                               IcsClaimExpenditureMapper mapper) {
        return new IcsClaimExpenditureRepository(client, mapper);
    }

    @Bean
    @ConditionalOnProperty(name = "ics-expenditure.enabled", havingValue = "true")
    @ConditionalOnMissingBean(IcsClaimExpenditureClient.class)
    public IcsClaimExpenditureClient icsExpenditureClient(WebClient webClient,
                                                          @Value("${ics-expenditure.endpoint:/expenditure}") String expenditureEndpoint) {
        return new IcsClaimExpenditureClient(webClient, ExpendituresResultDto.class, expenditureEndpoint);
    }

    @Bean
    @ConditionalOnProperty(name = "ics-expenditure.enabled", havingValue = "true")
    @ConditionalOnMissingBean(WebClient.class)
    public WebClient icsExpenditureWebClient(WebClient.Builder builder,
                                             @Value("${ics-expenditure.rest-url:http://localhost:8080/ics/rest}") String baseUrl) {
        return builder.baseUrl(baseUrl).build();
    }
}

@Configuration
public class WebClientConfiguration {

    @Bean
    public WebClientCustomizer configureWebClients(ClientRegistrationRepository clientRegistrationRepository,
                                                   OAuth2AuthorizedClientRepository authorizedClientRepository,
                                                   @Value("${ics-expenditure.oauth2.client-registration-id:oauth}") String oauth2ClientRegistrationId) {
        return builder -> builder
                .filter(this::setAcceptLanguageHeader)
                .apply(oauth2Configuration(clientRegistrationRepository, authorizedClientRepository))
                .defaultRequest(setRegistrationId(oauth2ClientRegistrationId))
                .filter(ExchangeFilterFunction.ofRequestProcessor(this::checkOAuth2Configured));
    }

    private Mono<ClientResponse> setAcceptLanguageHeader(ClientRequest clientRequest,
                                                         ExchangeFunction exchangeFunction) {
        var languageTag = LocaleContextHolder.getLocale().toLanguageTag();
        var newClientRequest = ClientRequest.from(clientRequest)
                .header(HttpHeaders.ACCEPT_LANGUAGE, languageTag)
                .build();
        return exchangeFunction.exchange(newClientRequest);
    }

    private Consumer<WebClient.Builder> oauth2Configuration(ClientRegistrationRepository clientRegistrationRepo,
                                                            OAuth2AuthorizedClientRepository authorizedClientRepo) {
        return new ServletOAuth2AuthorizedClientExchangeFilterFunction(clientRegistrationRepo, authorizedClientRepo)
                .oauth2Configuration();
    }

    private Consumer<WebClient.RequestHeadersSpec<?>> setRegistrationId(String oauth2ClientRegistrationId) {
        return spec -> spec.attributes(ServletOAuth2AuthorizedClientExchangeFilterFunction
                                               .clientRegistrationId(oauth2ClientRegistrationId));
    }

    private Mono<ClientRequest> checkOAuth2Configured(ClientRequest clientRequest) {
        if (clientRequest.attribute(OAuth2AuthorizedClient.class.getName()).isEmpty()) {
            return Mono.error(illegalStateException("OAuth2 client is not configured correctly."));
        } else {
            return Mono.just(clientRequest);
        }
    }
}

ics-expenditure:
    enabled: false
    rest-url: http://localhost:8080/ics/rest
    endpoint: /expenditure
    oauth2:
        client-registration-id: oauth
    auth:
        username: ics-api
        password: ics-api