/*
    * Copyright (C) 2023 B3Partners B.V.
    *
    * SPDX-License-Identifier: MIT
    */
   package org.tailormap.api.security;
   
   import static org.apache.commons.lang3.StringUtils.isNotBlank;
   
  import com.nimbusds.openid.connect.sdk.op.OIDCProviderMetadata;
  import jakarta.annotation.PostConstruct;
  import jakarta.validation.constraints.NotNull;
  import java.lang.invoke.MethodHandles;
  import java.net.URI;
  import java.net.http.HttpClient;
  import java.net.http.HttpRequest;
  import java.net.http.HttpResponse;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.security.oauth2.client.registration.ClientRegistration;
  import org.springframework.security.oauth2.client.registration.ClientRegistrationRepository;
  import org.springframework.security.oauth2.core.AuthorizationGrantType;
  import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
  import org.tailormap.api.persistence.OIDCConfiguration;
  import org.tailormap.api.repository.OIDCConfigurationRepository;
  
  public class OIDCRepository implements ClientRegistrationRepository, Iterable<ClientRegistration> {
    public static class OIDCRegistrationMetadata {
      private boolean showForViewer;
  
      public boolean getShowForViewer() {
        return showForViewer;
      }
    }
  
    private static final Logger logger =
        LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
    private final OIDCConfigurationRepository oidcConfigurationRepository;
  
    @Value("${tailormap-api.oidc.name:#{null}}")
    private String oidcName;
  
    @Value("${tailormap-api.oidc.issuer-uri:#{null}}")
    private String oidcIssuerUri;
  
    @Value("${tailormap-api.oidc.client-id:#{null}}")
    private String oidcClientId;
  
    @Value("${tailormap-api.oidc.client-secret:#{null}}")
    private String oidcClientSecret;
  
    @Value("${tailormap-api.oidc.user-name-attribute:#{null}}")
    private String oidcUserNameAttribute;
  
    @Value("${tailormap-api.oidc.show-for-viewer:false}")
    private boolean oidcShowForViewer;
  
    private final Map<String, ClientRegistration> registrations;
  
    public OIDCRepository(OIDCConfigurationRepository repository) {
      oidcConfigurationRepository = repository;
      registrations = new HashMap<>();
    }
  
    @Override
    public ClientRegistration findByRegistrationId(String registrationId) {
      return registrations.get(registrationId);
    }
  
    @Override
    public @NotNull Iterator<ClientRegistration> iterator() {
      return registrations.values().iterator();
    }
  
    public OIDCRegistrationMetadata getMetadataForRegistrationId(String id) {
      OIDCRegistrationMetadata metadata = new OIDCRegistrationMetadata();
      if ("static".equals(id)) {
        metadata.showForViewer = oidcShowForViewer;
      } else {
        metadata.showForViewer = true;
      }
  
      return metadata;
    }
  
    @PostConstruct
    public void synchronize() {
      Map<String, ClientRegistration> newMap = new HashMap<>();
  
      final HttpClient httpClient =
          HttpClient.newBuilder().followRedirects(HttpClient.Redirect.NORMAL).build();
      for (OIDCConfiguration configuration : oidcConfigurationRepository.findAll()) {
        String id = String.format("%d", configuration.getId());
        try {
          HttpRequest.Builder requestBuilder =
             HttpRequest.newBuilder()
                 .uri(new URI(configuration.getIssuerUrl() + "/.well-known/openid-configuration"));
         HttpResponse<String> response =
             httpClient.send(requestBuilder.build(), HttpResponse.BodyHandlers.ofString());
 
         OIDCProviderMetadata metadata = OIDCProviderMetadata.parse(response.body());
 
         newMap.put(
             id,
             ClientRegistration.withRegistrationId(id)
                 .clientId(configuration.getClientId())
                 .clientSecret(configuration.getClientSecret())
                 .clientName(configuration.getName())
                 .scope("openid")
                 .issuerUri(metadata.getIssuer().toString())
                 .clientAuthenticationMethod(
                     ClientAuthenticationMethod
                         .CLIENT_SECRET_BASIC) // TODO: fetch from OIDC metadata
                 .authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
                 .authorizationUri(metadata.getAuthorizationEndpointURI().toASCIIString())
                 .tokenUri(metadata.getTokenEndpointURI().toASCIIString())
                 .userInfoUri(metadata.getUserInfoEndpointURI().toASCIIString())
                 .providerConfigurationMetadata(metadata.toJSONObject())
                 .jwkSetUri(metadata.getJWKSetURI().toASCIIString())
                 .userNameAttributeName(configuration.getUserNameAttribute())
                 .redirectUri("{baseUrl}/api/oauth2/callback")
                 .build());
         if (configuration.getStatus() != null) {
           configuration.setStatus(null);
           oidcConfigurationRepository.save(configuration);
         }
       } catch (Exception e) {
         logger.error("Failed to create OIDC client registration for ID " + id, e);
         configuration.setStatus(e.toString());
         oidcConfigurationRepository.save(configuration);
       }
     }
 
     if (isNotBlank(oidcName) && isNotBlank(oidcIssuerUri) && isNotBlank(oidcClientId)) {
       try {
         // When copying the URI from some IdP control panels into an .env file, this suffix won't be
         // stripped by OIDCConfigurationEventHandler.handleBeforeCreateOrSave() so accept both
         if (!oidcIssuerUri.endsWith("/.well-known/openid-configuration")) {
           oidcIssuerUri = oidcIssuerUri + "/.well-known/openid-configuration";
         }
         HttpRequest.Builder requestBuilder = HttpRequest.newBuilder().uri(new URI(oidcIssuerUri));
         HttpResponse<String> response =
             httpClient.send(requestBuilder.build(), HttpResponse.BodyHandlers.ofString());
 
         OIDCProviderMetadata metadata = OIDCProviderMetadata.parse(response.body());
         String id = "static";
 
         newMap.put(
             id,
             ClientRegistration.withRegistrationId(id)
                 .clientId(oidcClientId)
                 .clientSecret(oidcClientSecret)
                 .clientName(oidcName)
                 .scope("openid")
                 .issuerUri(metadata.getIssuer().toString())
                 .clientAuthenticationMethod(
                     ClientAuthenticationMethod
                         .CLIENT_SECRET_BASIC) // TODO: fetch from OIDC metadata
                 .authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
                 .authorizationUri(metadata.getAuthorizationEndpointURI().toASCIIString())
                 .tokenUri(metadata.getTokenEndpointURI().toASCIIString())
                 .userInfoUri(metadata.getUserInfoEndpointURI().toASCIIString())
                 .providerConfigurationMetadata(metadata.toJSONObject())
                 .jwkSetUri(metadata.getJWKSetURI().toASCIIString())
                 .userNameAttributeName(oidcUserNameAttribute)
                 .redirectUri("{baseUrl}/api/oauth2/callback")
                 .build());
       } catch (Exception e) {
         logger.error("Failed to create static OIDC client registration", e);
       }
     }
 
     registrations.clear();
     registrations.putAll(newMap);
   }
 }