OAuth2 MockMvc helper to retrieve valid oauth2 tokens

OAuth2Helper.kt

import org.springframework.security.authentication.TestingAuthenticationToken
import org.springframework.security.core.authority.SimpleGrantedAuthority
import org.springframework.security.core.userdetails.User
import org.springframework.security.oauth2.common.OAuth2AccessToken
import org.springframework.security.oauth2.provider.ClientDetailsService
import org.springframework.security.oauth2.provider.OAuth2Authentication
import org.springframework.security.oauth2.provider.OAuth2Request
import org.springframework.security.oauth2.provider.token.AuthorizationServerTokenServices
import org.springframework.security.oauth2.provider.token.store.JwtAccessTokenConverter
import org.springframework.stereotype.Component
import org.springframework.test.web.servlet.request.RequestPostProcessor
import java.io.Serializable
import java.util.Collections

@Component
class OAuth2Helper(
    val clientDetailsService: ClientDetailsService,
    val tokenservice: AuthorizationServerTokenServices,
    val tokenenhancer: JwtAccessTokenConverter) {

    // For use with MockMvc
    fun bearerTokenForClient(clientid: String): RequestPostProcessor {
        return RequestPostProcessor { mockRequest ->
            val token = createAccessToken(clientid)
            mockRequest.addHeader("Authorization", "Bearer " + token.value)
            mockRequest
        }
    }

    // For use with MockMvc
    fun bearerTokenForUser(username: String, authorities: Array<String>, clientid: String = "client_id"): RequestPostProcessor {
        return RequestPostProcessor { mockRequest ->
            val token = createAccessToken(clientid, username, authorities)
            mockRequest.addHeader("Authorization", "Bearer " + token.value)
            mockRequest
        }
    }

    // For use with MockMvc
    fun bearerToken(token: String): RequestPostProcessor {
        return RequestPostProcessor { mockRequest ->
            mockRequest.addHeader("Authorization", "Bearer " + token)
            mockRequest
        }
    }

    fun createAccessToken(clientId: String, username: String? = null, userAuthorities: Array<String> = emptyArray()): OAuth2AccessToken {
        // Look up authorities, resourceIds and scopes based on clientId
        val client = clientDetailsService.loadClientByClientId(clientId)
        val clientAuthorities = client.authorities
        val resourceIds = client.resourceIds
        val scopes = client.scope

        // Default values for other parameters
        val requestParameters: Map<String, String> = Collections.emptyMap()
        val approved = true
        val redirectUrl: String? = null
        val responseTypes = Collections.emptySet<String>()
        val extensionProperties = Collections.emptyMap<String, Serializable>()


        // Create request
        val oAuth2Request = OAuth2Request(requestParameters, clientId, clientAuthorities, approved, scopes,
            resourceIds, redirectUrl, responseTypes, extensionProperties)

        // Create OAuth2AccessToken
        val auth = if (username != null) {
            val grantedAuthorities = userAuthorities.map(::SimpleGrantedAuthority)
            val userPrincipal = User(username, "", true, true, true, true, emptyList())
            val authenticationToken = TestingAuthenticationToken(userPrincipal, null, grantedAuthorities)
            OAuth2Authentication(oAuth2Request, authenticationToken)
        } else {
            OAuth2Authentication(oAuth2Request, null)
        }

        val token = tokenservice.createAccessToken(auth)
        return tokenenhancer.enhance(token, auth)
    }
}