/*
    * Copyright 2018 LINE Corporation
    *
    * LINE Corporation licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package com.linecorp.centraldogma.server.auth.saml;
  
  import static com.google.common.base.MoreObjects.firstNonNull;
  import static com.linecorp.centraldogma.server.CentralDogmaConfig.convertValue;
  import static java.util.Objects.requireNonNull;
  
  import java.util.Map;
  
  import javax.annotation.Nullable;
  
  import org.opensaml.xmlsec.signature.support.SignatureConstants;
  
  import com.fasterxml.jackson.annotation.JsonCreator;
  import com.fasterxml.jackson.annotation.JsonProperty;
  import com.fasterxml.jackson.core.JsonProcessingException;
  import com.google.common.collect.ImmutableMap;
  import com.google.common.collect.ImmutableMap.Builder;
  
  import com.linecorp.armeria.server.saml.SamlBindingProtocol;
  import com.linecorp.armeria.server.saml.SamlEndpoint;
  import com.linecorp.armeria.server.saml.SamlNameIdFormat;
  import com.linecorp.centraldogma.internal.Jackson;
  
  /**
   * Properties which are used to configure SAML authentication for Central Dogma server.
   * A user can specify them as the authentication property in the {@code dogma.json} as follows:
   * <pre>{@code
   * "authentication": {
   *     "factoryClassName": "com.linecorp.centraldogma.server.auth.saml.SamlAuthProviderFactory",
   *     "properties": {
   *         "entityId": "...the service provider ID...",
   *         "hostname": "dogma-example.linecorp.com",
   *         "signingKey": "...the name of signing key (optional)...",
   *         "encryptionKey": "...the name of encryption key (optional)...",
   *         "keyStore": {
   *             "type": "...the type of the keystore (optional)...",
   *             "path": "...the path where keystore file exists...",
   *             "password": "...the password of the keystore (optional)...",
   *             "keyPasswords": {
   *                 "signing": "...the password of the signing key...",
   *                 "encryption": "...the password of the encryption key..."
   *             },
   *             "signatureAlgorithm": "...the signature algorithm for signing and encryption (optional)..."
   *         },
   *         "idp": {
   *             "entityId": "...the identity provider ID...",
   *             "uri": "https://idp-example.linecorp.com/saml/sso",
   *             "binding": "HTTP_POST or HTTP_REDIRECT (optional)",
   *             "signingKey": "...the name of signing certificate (optional)...",
   *             "encryptionKey": "...the name of encryption certificate (optional)...",
   *             "subjectLoginNameIdFormat":
   *                  "...the name ID format of a subject which holds a login name (optional)...",
   *             "attributeLoginName": "...the attribute name which holds a login name (optional)..."
   *         }
   *     }
   * }
   * }</pre>
   */
  final class SamlAuthProperties {
      /**
       * A default key name for signing.
       */
      private static final String DEFAULT_SIGNING_KEY = "signing";
  
      /**
       * A default key name for encryption.
       */
      private static final String DEFAULT_ENCRYPTION_KEY = "encryption";
  
      /**
       * An ID of this service provider.
       */
      private final String entityId;
  
      /**
       * A hostname of this service provider.
       */
      private final String hostname;
  
      /**
       * A key name which is used for signing. The default name is {@value DEFAULT_SIGNING_KEY}.
       */
      private final String signingKey;
  
     /**
      * A key name which is used for encryption. The default name is {@value DEFAULT_ENCRYPTION_KEY}.
      */
     private final String encryptionKey;
 
     /**
      * A configuration for the keystore.
      */
     private final KeyStore keyStore;
 
     /**
      * An identity provider configuration. A single identity provider is supported.
      */
     private final Idp idp;
 
     @JsonCreator
     SamlAuthProperties(
             @JsonProperty("entityId") String entityId,
             @JsonProperty("hostname") String hostname,
             @JsonProperty("signingKey") @Nullable String signingKey,
             @JsonProperty("encryptionKey") @Nullable String encryptionKey,
             @JsonProperty("keyStore") KeyStore keyStore,
             @JsonProperty("idp") Idp idp) {
         this.entityId = requireNonNull(entityId, "entityId");
         this.hostname = requireNonNull(hostname, "hostname");
         this.signingKey = firstNonNull(signingKey, DEFAULT_SIGNING_KEY);
         this.encryptionKey = firstNonNull(encryptionKey, DEFAULT_ENCRYPTION_KEY);
         this.keyStore = requireNonNull(keyStore, "keyStore");
         this.idp = requireNonNull(idp, "idp");
     }
 
     @JsonProperty
     public String entityId() {
         return entityId;
     }
 
     @JsonProperty
     public String hostname() {
         return hostname;
     }
 
     @JsonProperty
     public String signingKey() {
         return signingKey;
     }
 
     @JsonProperty
     public String encryptionKey() {
         return encryptionKey;
     }
 
     @JsonProperty
     public KeyStore keyStore() {
         return keyStore;
     }
 
     @JsonProperty
     public Idp idp() {
         return idp;
     }
 
     @Override
     public String toString() {
         try {
             return Jackson.writeValueAsPrettyString(this);
         } catch (JsonProcessingException e) {
             throw new IllegalStateException(e);
         }
     }
 
     static class KeyStore {
         /**
          * A default signature algorithm.
          */
         private static final String DEFAULT_SIGNATURE_ALGORITHM = SignatureConstants.ALGO_ID_SIGNATURE_RSA;
 
         /**
          * A type of the keystore. The default value is retrieved from
          * {@code java.security.KeyStore.getDefaultType()}.
          */
         private final String type;
 
         /**
          * A path of the keystore.
          */
         private final String path;
 
         /**
          * A password of the keystore. The empty string is used by default.
          */
         @Nullable
         private final String password;
 
         /**
          * A map of the key name and its password.
          */
         @Nullable
         private final Map<String, String> keyPasswords;
 
         /**
          * A signature algorithm for signing and encryption. The default algorithm is
          * {@value DEFAULT_SIGNATURE_ALGORITHM}.
          *
          * @see SignatureConstants for more information about the signature algorithm
          */
         private final String signatureAlgorithm;
 
         @JsonCreator
         KeyStore(@JsonProperty("type") @Nullable String type,
                  @JsonProperty("path") String path,
                  @JsonProperty("password") @Nullable String password,
                  @JsonProperty("keyPasswords") @Nullable Map<String, String> keyPasswords,
                  @JsonProperty("signatureAlgorithm") @Nullable String signatureAlgorithm) {
             this.type = firstNonNull(type, java.security.KeyStore.getDefaultType());
             this.path = requireNonNull(path, "path");
             this.password = password;
             this.keyPasswords = keyPasswords;
             this.signatureAlgorithm = firstNonNull(signatureAlgorithm, DEFAULT_SIGNATURE_ALGORITHM);
         }
 
         @JsonProperty
         public String type() {
             return type;
         }
 
         @JsonProperty
         public String path() {
             return path;
         }
 
         @Nullable
         @JsonProperty
         public String password() {
             return convertValue(password, "keyStore.password");
         }
 
         @JsonProperty
         public Map<String, String> keyPasswords() {
             return sanitizePasswords(keyPasswords);
         }
 
         private static Map<String, String> sanitizePasswords(@Nullable Map<String, String> keyPasswords) {
             if (keyPasswords == null) {
                 return ImmutableMap.of();
             }
             final ImmutableMap.Builder<String, String> builder = new Builder<>();
             keyPasswords.forEach((key, password) -> builder.put(key, firstNonNull(
                     convertValue(password, "keyStore.keyPasswords"), "")));
             return builder.build();
         }
 
         @JsonProperty
         public String signatureAlgorithm() {
             return signatureAlgorithm;
         }
     }
 
     static class Idp {
         /**
          * An ID of the identity provider.
          */
         private final String entityId;
 
         /**
          * A location of the single sign-on service.
          */
         private final String uri;
 
         /**
          * A name of a {@link SamlBindingProtocol}. The default name is the
          * {@link SamlBindingProtocol#HTTP_POST}.
          */
         private final SamlBindingProtocol binding;
 
         /**
          * A certificate name which is used for signing. The default name is the {@link #entityId()}.
          */
         private final String signingKey;
 
         /**
          * A certificate name which is used for encryption. The default name is the {@link #entityId()}.
          */
         private final String encryptionKey;
 
         /**
          * A name ID format of a subject which holds a login name of an authenticated user. If both
          * {@code subjectLoginNameIdFormat} and {@code attributeLoginName} are {@code null},
          * {@code urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress} is set by default.
          */
         @Nullable
         private final String subjectLoginNameIdFormat;
 
         /**
          * An attribute name which holds a login name of an authenticated user.
          */
         @Nullable
         private final String attributeLoginName;
 
         @JsonCreator
         Idp(@JsonProperty("entityId") String entityId,
             @JsonProperty("uri") String uri,
             @JsonProperty("binding") @Nullable String binding,
             @JsonProperty("signingKey") @Nullable String signingKey,
             @JsonProperty("encryptionKey") @Nullable String encryptionKey,
             @JsonProperty("subjectLoginNameIdFormat") @Nullable String subjectLoginNameIdFormat,
             @JsonProperty("attributeLoginName") @Nullable String attributeLoginName) {
             this.entityId = requireNonNull(entityId, "entityId");
             this.uri = requireNonNull(uri, "uri");
             this.binding = binding != null ? SamlBindingProtocol.valueOf(binding)
                                            : SamlBindingProtocol.HTTP_POST;
             this.signingKey = firstNonNull(signingKey, entityId);
             this.encryptionKey = firstNonNull(encryptionKey, entityId);
 
             if (subjectLoginNameIdFormat == null && attributeLoginName == null) {
                 this.subjectLoginNameIdFormat = SamlNameIdFormat.EMAIL.urn();
                 this.attributeLoginName = null;
             } else {
                 this.subjectLoginNameIdFormat = subjectLoginNameIdFormat;
                 this.attributeLoginName = attributeLoginName;
             }
         }
 
         @JsonProperty
         public String entityId() {
             return entityId;
         }
 
         @JsonProperty
         public String uri() {
             return uri;
         }
 
         @JsonProperty
         public String binding() {
             return binding.name();
         }
 
         @JsonProperty
         public String signingKey() {
             return signingKey;
         }
 
         @JsonProperty
         public String encryptionKey() {
             return encryptionKey;
         }
 
         @Nullable
         @JsonProperty
         public String subjectLoginNameIdFormat() {
             return subjectLoginNameIdFormat;
         }
 
         @Nullable
         @JsonProperty
         public String attributeLoginName() {
             return attributeLoginName;
         }
 
         public SamlEndpoint endpoint() {
             switch (binding) {
                 case HTTP_POST:
                     return SamlEndpoint.ofHttpPost(uri);
                 case HTTP_REDIRECT:
                     return SamlEndpoint.ofHttpRedirect(uri);
                 default:
                     throw new IllegalStateException("Failed to get an endpoint of the IdP: " + entityId);
             }
         }
     }
 }