feat: add export template api (#35)

README.md

@@ -1,18 +1,22 @@
 # Aam Digital Services (aam-backend-service)
+
 Collection of aam-digital services and tools
 
 [![Maintainability](https://api.codeclimate.com/v1/badges/57213b5887a579196d6d/maintainability)](https://codeclimate.com/github/Aam-Digital/aam-services/maintainability) [![Test Coverage](https://api.codeclimate.com/v1/badges/57213b5887a579196d6d/test_coverage)](https://codeclimate.com/github/Aam-Digital/aam-services/test_coverage)
 
 A modularize Spring Boot application that contains API modules for [Aam Digital's case management platform](https://github.com/Aam-Digital/ndb-core).
 
 ## Setup
+
 1. Create additional databases in CouchDB: `report-calculation` and `notification-webhook` (used by the Reporting Module to store details)
 2. Set up necessary environment variables (e.g. using an `application.env` file for docker compose):
-    - see [example .env](./docs/examples/application.env)
-    - CRYPTO_CONFIGURATION_SECRET: _a random secret used to encrypt data_
-3. See ndb-setup for instructions to enable the backend in an overall system: [ndb-setup README](https://github.com/Aam-Digital/ndb-setup?tab=readme-ov-file#api-integrations-and-sql-reports)
 
+- see [example .env](./docs/examples/application.env)
+- CRYPTO_CONFIGURATION_SECRET: _a random secret used to encrypt data_
+
+3. See ndb-setup for instructions to enable the backend in an overall system: [ndb-setup README](https://github.com/Aam-Digital/ndb-setup?tab=readme-ov-file#api-integrations-and-sql-reports)
 
 ## API Modules
 
 - **[Reporting](./docs/modules/reporting.md)**: Calculate aggregated reports and run queries on all data, accessible for external services for API integrations of systems
+- **[Export](./docs/modules/export.md)**: Template based file export API. Uses [carbone.io](https://carbone.io) as templating engine.

application/aam-backend-service/build.gradle.kts

@@ -66,10 +66,13 @@ dependencies {
     testImplementation("org.mockito.kotlin:mockito-kotlin:5.4.0")
     testImplementation("org.junit.jupiter:junit-jupiter-engine:5.10.2")
     testImplementation("net.joshka:junit-json-params:5.10.2-r0")
-    testImplementation("org.eclipse.parsson:parsson:1.1.1")
+    testImplementation("org.eclipse.parsson:parsson:1.1.7")
 
     testImplementation("io.projectreactor:reactor-test")
 
+    testImplementation("com.squareup.okhttp3:okhttp:4.12.0")
+    testImplementation("com.squareup.okhttp3:mockwebserver:4.12.0")
+
     testImplementation("org.testcontainers:junit-jupiter:1.19.7") {
         constraints {
             testImplementation("org.apache.commons:commons-compress:1.26.1") {
@@ -78,7 +81,7 @@ dependencies {
         }
     }
     testImplementation("org.testcontainers:rabbitmq:1.19.7")
-    testImplementation("com.github.dasniko:testcontainers-keycloak:3.3.0") {
+    testImplementation("com.github.dasniko:testcontainers-keycloak:3.4.0") {
         constraints {
             testImplementation("org.apache.james:apache-mime4j-core:0.8.11") {
                 because("previous versions have security issues")

application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/auth/core/AuthProvider.kt

@@ -0,0 +1,32 @@
+package com.aamdigital.aambackendservice.auth.core
+
+import reactor.core.publisher.Mono
+
+data class TokenResponse(val token: String)
+
+
+/**
+ * Configuration data class for handling authentication.
+ *
+ * @property clientId The client ID used for authentication.
+ * @property clientSecret The client secret used for authentication.
+ * @property tokenEndpoint The endpoint URL to request the token.
+ * @property grantType The OAuth grant type to be used.
+ * @property scope The scope of the access request.
+ */
+data class AuthConfig(
+    val clientId: String,
+    val clientSecret: String,
+    val tokenEndpoint: String,
+    val grantType: String,
+    val scope: String,
+)
+
+/**
+ * Interface representing an authentication provider responsible for fetching an authentication token.
+ *
+ * Used for fetching access tokens for third party systems.
+ */
+interface AuthProvider {
+    fun fetchToken(authClientConfig: AuthConfig): Mono<TokenResponse>
+}

application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/auth/core/KeycloakAuthProvider.kt

@@ -0,0 +1,73 @@
+package com.aamdigital.aambackendservice.auth.core
+
+import com.aamdigital.aambackendservice.error.ExternalSystemException
+import com.fasterxml.jackson.annotation.JsonProperty
+import com.fasterxml.jackson.databind.ObjectMapper
+import org.slf4j.LoggerFactory
+import org.springframework.http.MediaType
+import org.springframework.util.LinkedMultiValueMap
+import org.springframework.web.reactive.function.BodyInserters
+import org.springframework.web.reactive.function.client.WebClient
+import reactor.core.publisher.Mono
+
+data class KeycloakTokenResponse(
+    @JsonProperty("access_token") val accessToken: String,
+)
+
+/**
+ * This class is an implementation of the AuthProvider interface and is responsible for
+ * fetching tokens from a Keycloak authentication server. Used for accessing
+ * third party systems and services.
+ *
+ * Not related to authentication mechanics related to endpoints we provide to others.
+ *
+ * @property webClient The WebClient used for making HTTP requests.
+ * @property objectMapper The ObjectMapper used for parsing JSON responses.
+ */
+class KeycloakAuthProvider(
+    val webClient: WebClient,
+    val objectMapper: ObjectMapper,
+) : AuthProvider {
+
+    private val logger = LoggerFactory.getLogger(javaClass)
+
+    override fun fetchToken(authClientConfig: AuthConfig): Mono<TokenResponse> {
+        val formData = LinkedMultiValueMap(
+            mutableMapOf(
+                "client_id" to listOf(authClientConfig.clientId),
+                "client_secret" to listOf(authClientConfig.clientSecret),
+                "grant_type" to listOf(authClientConfig.grantType),
+            ).also {
+                if (authClientConfig.scope.isNotBlank()) {
+                    "scope" to listOf(authClientConfig.scope)
+                }
+            }
+        )
+
+        return webClient.post()
+            .uri(authClientConfig.tokenEndpoint)
+            .headers {
+                it.contentType = MediaType.APPLICATION_FORM_URLENCODED
+            }
+            .body(
+                BodyInserters.fromFormData(
+                    formData
+                )
+            ).exchangeToMono {
+                it.bodyToMono(String::class.java)
+            }.map {
+                parseResponse(it)
+            }.doOnError { logger.error(it.message, it) }
+    }
+
+    private fun parseResponse(raw: String): TokenResponse {
+        try {
+            val keycloakTokenResponse = objectMapper.readValue(raw, KeycloakTokenResponse::class.java)
+            return TokenResponse(
+                token = keycloakTokenResponse.accessToken
+            )
+        } catch (e: Exception) {
+            throw ExternalSystemException("Could not parse access token from KeycloakAuthProvider", e)
+        }
+    }
+}

application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/auth/di/AuthConfiguration.kt

@@ -0,0 +1,47 @@
+package com.aamdigital.aambackendservice.auth.di
+
+import com.aamdigital.aambackendservice.auth.core.AuthProvider
+import com.aamdigital.aambackendservice.auth.core.KeycloakAuthProvider
+import com.fasterxml.jackson.databind.ObjectMapper
+import org.springframework.beans.factory.annotation.Qualifier
+import org.springframework.boot.context.properties.ConfigurationProperties
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import org.springframework.http.client.reactive.ReactorClientHttpConnector
+import org.springframework.web.reactive.function.client.WebClient
+import reactor.netty.http.client.HttpClient
+
+
+@ConfigurationProperties("aam-keycloak-client-configuration")
+data class KeycloakConfiguration(
+    val maxInMemorySizeInMegaBytes: Int = 16,
+)
+
+@Configuration
+class AuthConfiguration {
+    companion object {
+        const val MEGA_BYTES_MULTIPLIER = 1024 * 1024
+    }
+
+    @Bean(name = ["aam-keycloak-client"])
+    fun aamKeycloakWebClient(
+        configuration: KeycloakConfiguration,
+    ): WebClient {
+        val clientBuilder =
+            WebClient.builder()
+                .codecs {
+                    it.defaultCodecs()
+                        .maxInMemorySize(configuration.maxInMemorySizeInMegaBytes * MEGA_BYTES_MULTIPLIER)
+                }
+
+        return clientBuilder.clientConnector(ReactorClientHttpConnector(HttpClient.create())).build()
+    }
+
+    @Bean(name = ["aam-keycloak"])
+    fun aamKeycloakAuthProvider(
+        @Qualifier("aam-keycloak-client") webClient: WebClient,
+        objectMapper: ObjectMapper,
+    ): AuthProvider =
+        KeycloakAuthProvider(webClient = webClient, objectMapper = objectMapper)
+
+}

application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/couchdb/core/DefaultCouchDbClient.kt

@@ -3,7 +3,9 @@ package com.aamdigital.aambackendservice.couchdb.core
 import com.aamdigital.aambackendservice.couchdb.dto.CouchDbChangesResponse
 import com.aamdigital.aambackendservice.couchdb.dto.DocSuccess
 import com.aamdigital.aambackendservice.couchdb.dto.FindResponse
+import com.aamdigital.aambackendservice.error.ExternalSystemException
 import com.aamdigital.aambackendservice.error.InternalServerException
+import com.aamdigital.aambackendservice.error.InvalidArgumentException
 import com.aamdigital.aambackendservice.error.NotFoundException
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.node.ObjectNode
@@ -102,13 +104,21 @@ class DefaultCouchDbClient(
         queryParams: MultiValueMap<String, String>,
         kClass: KClass<T>,
     ): Mono<T> {
-        return webClient.get().uri {
-            it.path("/$database/$documentId")
-            it.queryParams(queryParams)
-            it.build()
-        }.accept(MediaType.APPLICATION_JSON).exchangeToMono {
-            handleResponse(it, kClass)
-        }
+        return webClient.get()
+            .uri {
+                it.path("/$database/$documentId")
+                it.queryParams(queryParams)
+                it.build()
+            }
+            .accept(MediaType.APPLICATION_JSON)
+            .exchangeToMono { response: ClientResponse ->
+                if (response.statusCode().is4xxClientError) {
+                    throw InvalidArgumentException(
+                        message = "Document \"$documentId\" could not be found in database \"$database\""
+                    )
+                }
+                handleResponse(response, kClass)
+            }
     }
 
     override fun putDatabaseDocument(
@@ -264,10 +274,20 @@ class DefaultCouchDbClient(
     }
 
     private fun <T : Any> handleResponse(
-        response: ClientResponse, typeReference: KClass<T>
+        response: ClientResponse,
+        typeReference: KClass<T>
     ): Mono<T> {
-        return response.bodyToMono(typeReference.java).mapNotNull {
-            it
-        }
+        return response.bodyToMono(String::class.java)
+            .mapNotNull {
+                try {
+                    val renderApiClientResponse = objectMapper.readValue(it, typeReference.java)
+                    renderApiClientResponse
+                } catch (ex: Exception) {
+                    throw ExternalSystemException(
+                        message = ex.localizedMessage,
+                        cause = ex,
+                    )
+                }
+            }
     }
 }

application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/domain/DomainUseCase.kt

@@ -0,0 +1,36 @@
+package com.aamdigital.aambackendservice.domain
+
+import reactor.core.publisher.Mono
+
+
+interface UseCaseRequest
+interface UseCaseData
+interface UseCaseErrorCode
+
+sealed interface UseCaseOutcome<D : UseCaseData, E : UseCaseErrorCode> {
+    data class Success<D : UseCaseData, E : UseCaseErrorCode>(
+        val outcome: D
+    ) : UseCaseOutcome<D, E>
+
+    data class Failure<D : UseCaseData, E : UseCaseErrorCode>(
+        val errorCode: E,
+        val errorMessage: String? = "An unspecific error occurred, while executing this use case",
+        val cause: Throwable? = null
+    ) : UseCaseOutcome<D, E>
+}
+
+interface DomainUseCase<R : UseCaseRequest, D : UseCaseData, E : UseCaseErrorCode> {
+    fun apply(request: R): Mono<UseCaseOutcome<D, E>>
+    fun handleError(it: Throwable): Mono<UseCaseOutcome<D, E>>
+
+    fun execute(request: R): Mono<UseCaseOutcome<D, E>> {
+        return try {
+            apply(request)
+                .onErrorResume {
+                    handleError(it)
+                }
+        } catch (ex: Exception) {
+            handleError(ex)
+        }
+    }
+}

application/aam-backend-service/src/main/kotlin/com/aamdigital/aambackendservice/error/AamException.kt

@@ -11,37 +11,43 @@ sealed class AamException(
 }
 
 class InternalServerException(
-    message: String = "",
+    message: String = "Unspecific InternalServerException",
     cause: Throwable? = null,
     code: String = "INTERNAL_SERVER_ERROR"
 ) : AamException(message, cause, code)
 
 class ExternalSystemException(
-    message: String = "",
+    message: String = "Unspecific ExternalSystemException",
     cause: Throwable? = null,
     code: String = "EXTERNAL_SYSTEM_ERROR"
 ) : AamException(message, cause, code)
 
+class NetworkException(
+    message: String = "Unspecific NetworkException",
+    cause: Throwable? = null,
+    code: String = "NETWORK_EXCEPTION"
+) : AamException(message, cause, code)
+
 class InvalidArgumentException(
-    message: String = "",
+    message: String = "Unspecific InvalidArgumentException",
     cause: Throwable? = null,
     code: String = "BAD_REQUEST"
 ) : AamException(message, cause, code)
 
 class UnauthorizedAccessException(
-    message: String = "",
+    message: String = "Unspecific UnauthorizedAccessException",
     cause: Throwable? = null,
     code: String = "UNAUTHORIZED"
 ) : AamException(message, cause, code)
 
 class ForbiddenAccessException(
-    message: String = "",
+    message: String = "Unspecific ForbiddenAccessException",
     cause: Throwable? = null,
     code: String = "FORBIDDEN"
 ) : AamException(message, cause, code)
 
 class NotFoundException(
-    message: String = "",
+    message: String = "Unspecific NotFoundException",
     cause: Throwable? = null,
     code: String = "NOT_FOUND"
 ) : AamException(message, cause, code)