Vault Integration

public interface VaultProvider extends Provider {
    /**
     * Obtains a raw secret from the vault.
     * 
     * @param vaultSecretId the vault secret identifier
     * @return vault raw secret or empty optional
     */
    VaultRawSecret obtainSecret(String vaultSecretId);
}

public interface VaultTranscriber {
    /**
     * Transcribes a value, replacing vault references with actual secret values.
     * 
     * @param value the value potentially containing vault references
     * @return transcribed value with secrets resolved
     */
    String transcribe(String value);
}

public interface VaultRawSecret extends AutoCloseable {
    /**
     * Gets the raw secret as byte array.
     * 
     * @return optional raw secret bytes
     */
    Optional<byte[]> get();

    /**
     * Gets the raw secret as byte array or default value.
     * 
     * @param defaultValue default value if secret not found
     * @return raw secret bytes or default
     */
    default byte[] getOrDefault(byte[] defaultValue) {
        return get().orElse(defaultValue);
    }

    @Override
    void close();
}

public interface VaultCharSecret extends VaultRawSecret {
    /**
     * Gets the secret as character array.
     * 
     * @return optional character array
     */
    Optional<char[]> getAsArray();

    /**
     * Gets the secret as character array or default value.
     * 
     * @param defaultValue default value if secret not found
     * @return character array or default
     */
    default char[] getAsArray(char[] defaultValue) {
        return getAsArray().orElse(defaultValue);
    }

    @Override
    default Optional<byte[]> get() {
        return getAsArray().map(chars -> {
            byte[] bytes = new byte[chars.length];
            for (int i = 0; i < chars.length; i++) {
                bytes[i] = (byte) chars[i];
            }
            return bytes;
        });
    }
}

public interface VaultStringSecret extends VaultCharSecret {
    /**
     * Gets the secret as string.
     * 
     * @return optional string value
     */
    Optional<String> get();

    /**
     * Gets the secret as string or default value.
     * 
     * @param defaultValue default value if secret not found
     * @return string value or default
     */
    default String getOrDefault(String defaultValue) {
        return get().orElse(defaultValue);
    }

    @Override
    default Optional<char[]> getAsArray() {
        return get().map(String::toCharArray);
    }
}

public interface VaultKeyResolver {
    /**
     * Checks if a value contains a vault key reference.
     * 
     * @param value the value to check
     * @return true if value contains vault reference
     */
    boolean isVaultKey(String value);

    /**
     * Extracts the vault key from a vault reference.
     * 
     * @param value the vault reference value
     * @return vault key or null if not a vault reference
     */
    String getVaultKey(String value);

    /**
     * Creates a vault reference from a key.
     * 
     * @param key the vault key
     * @return vault reference string
     */
    String createVaultReference(String key);
}

public class VaultSpi implements Spi {
    @Override
    public boolean isInternal() {
        return true;
    }

    @Override
    public String getName() {
        return "vault";
    }

    @Override
    public Class<? extends Provider> getProviderClass() {
        return VaultProvider.class;
    }

    @Override
    public Class<? extends ProviderFactory> getProviderFactoryClass() {
        return VaultProviderFactory.class;
    }
}

public interface VaultProviderFactory extends ProviderFactory<VaultProvider> {
    /**
     * Creates a vault provider instance.
     * 
     * @param session Keycloak session
     * @return vault provider
     */
    @Override
    VaultProvider create(KeycloakSession session);

    /**
     * Gets the provider ID.
     * 
     * @return provider ID
     */
    @Override
    String getId();
}

public class HashiCorpVaultProvider implements VaultProvider {
    private final VaultClient vaultClient;
    private final String mountPath;

    public HashiCorpVaultProvider(VaultClient vaultClient, String mountPath) {
        this.vaultClient = vaultClient;
        this.mountPath = mountPath;
    }

    @Override
    public VaultRawSecret obtainSecret(String vaultSecretId) {
        try {
            // Parse vault secret ID (e.g., "secret/myapp/database")
            String[] parts = vaultSecretId.split("/");
            if (parts.length < 2) {
                return new EmptyVaultSecret();
            }

            String path = vaultSecretId;
            if (!path.startsWith(mountPath)) {
                path = mountPath + "/" + path;
            }

            // Retrieve secret from HashiCorp Vault
            Map<String, Object> secretData = vaultClient.read(path);
            if (secretData == null || secretData.isEmpty()) {
                return new EmptyVaultSecret();
            }

            // Return the secret value
            Object secretValue = secretData.get("value");
            if (secretValue == null) {
                // Try default field names
                secretValue = secretData.get("password");
                if (secretValue == null) {
                    secretValue = secretData.get("secret");
                }
            }

            if (secretValue != null) {
                return new StringVaultSecret(secretValue.toString());
            }

            return new EmptyVaultSecret();

        } catch (Exception e) {
            logger.error("Failed to retrieve secret: " + vaultSecretId, e);
            return new EmptyVaultSecret();
        }
    }

    @Override
    public void close() {
        if (vaultClient != null) {
            vaultClient.close();
        }
    }

    // Inner class for string secrets
    private static class StringVaultSecret implements VaultStringSecret {
        private final String secret;
        private volatile boolean closed = false;

        public StringVaultSecret(String secret) {
            this.secret = secret;
        }

        @Override
        public Optional<String> get() {
            if (closed) {
                throw new IllegalStateException("Secret has been closed");
            }
            return Optional.ofNullable(secret);
        }

        @Override
        public void close() {
            closed = true;
            // Clear the secret from memory (not possible with String, but shown for demonstration)
        }
    }

    // Inner class for empty secrets
    private static class EmptyVaultSecret implements VaultStringSecret {
        @Override
        public Optional<String> get() {
            return Optional.empty();
        }

        @Override
        public void close() {
            // Nothing to close
        }
    }
}

public class HashiCorpVaultProviderFactory implements VaultProviderFactory {
    public static final String PROVIDER_ID = "hashicorp-vault";

    private volatile VaultClient vaultClient;

    @Override
    public VaultProvider create(KeycloakSession session) {
        if (vaultClient == null) {
            synchronized (this) {
                if (vaultClient == null) {
                    vaultClient = initializeVaultClient();
                }
            }
        }
        return new HashiCorpVaultProvider(vaultClient, getMountPath());
    }

    @Override
    public void init(Config.Scope config) {
        // Initialize configuration
    }

    @Override
    public void postInit(KeycloakSessionFactory factory) {
        // Post-initialization
    }

    @Override
    public void close() {
        if (vaultClient != null) {
            vaultClient.close();
        }
    }

    @Override
    public String getId() {
        return PROVIDER_ID;
    }

    @Override
    public List<ProviderConfigProperty> getConfigMetadata() {
        return Arrays.asList(
            new ProviderConfigProperty("vault.url", "Vault URL", "HashiCorp Vault server URL", 
                                       ProviderConfigProperty.STRING_TYPE, "https://vault.example.com:8200"),
            new ProviderConfigProperty("vault.token", "Vault Token", "Authentication token for Vault", 
                                       ProviderConfigProperty.PASSWORD, null),
            new ProviderConfigProperty("vault.mount-path", "Mount Path", "Vault mount path for secrets", 
                                       ProviderConfigProperty.STRING_TYPE, "secret"),
            new ProviderConfigProperty("vault.namespace", "Namespace", "Vault namespace (Enterprise feature)", 
                                       ProviderConfigProperty.STRING_TYPE, null),
            new ProviderConfigProperty("vault.timeout", "Timeout", "Connection timeout in seconds", 
                                       ProviderConfigProperty.STRING_TYPE, "30")
        );
    }

    private VaultClient initializeVaultClient() {
        String vaultUrl = getConfig().get("vault.url", "https://vault.example.com:8200");
        String vaultToken = getConfig().get("vault.token");
        String namespace = getConfig().get("vault.namespace");
        int timeout = getConfig().getInt("vault.timeout", 30);

        VaultConfig vaultConfig = new VaultConfig()
            .address(vaultUrl)
            .token(vaultToken)
            .openTimeout(timeout)
            .readTimeout(timeout);

        if (namespace != null && !namespace.isEmpty()) {
            vaultConfig.nameSpace(namespace);
        }

        return new Vault(vaultConfig).logical();
    }

    private String getMountPath() {
        return getConfig().get("vault.mount-path", "secret");
    }

    private Config.Scope getConfig() {
        // Return configuration scope
        return Config.scope("vault", PROVIDER_ID);
    }
}

// Using vault transcriber to resolve secrets in configuration
try (KeycloakSession session = sessionFactory.create()) {
    VaultTranscriber transcriber = session.vault();
    
    // Configuration values with vault references
    String dbPassword = "${vault.secret/myapp/database}";
    String apiKey = "${vault.api-keys/external-service}";
    String certificateKeystore = "${vault.certificates/ssl-keystore}";
    
    // Transcribe vault references to actual secret values
    String actualDbPassword = transcriber.transcribe(dbPassword);
    String actualApiKey = transcriber.transcribe(apiKey);
    String actualKeystorePassword = transcriber.transcribe(certificateKeystore);
    
    // Use the resolved secrets
    DataSource dataSource = createDataSource("jdbc:postgresql://localhost/mydb", 
                                            "dbuser", actualDbPassword);
    
    HttpClient httpClient = createHttpClient(actualApiKey);
    
    KeyStore keyStore = loadKeyStore("keystore.p12", actualKeystorePassword);
}

// Direct usage of vault provider
try (KeycloakSession session = sessionFactory.create()) {
    VaultProvider vaultProvider = session.getProvider(VaultProvider.class);
    
    // Retrieve database password
    try (VaultStringSecret dbSecret = (VaultStringSecret) vaultProvider.obtainSecret("secret/myapp/database")) {
        String dbPassword = dbSecret.getOrDefault("defaultPassword");
        
        // Use the password
        Connection connection = DriverManager.getConnection(
            "jdbc:postgresql://localhost/mydb", "dbuser", dbPassword);
    }
    
    // Retrieve API key
    try (VaultStringSecret apiSecret = (VaultStringSecret) vaultProvider.obtainSecret("api-keys/payment-gateway")) {
        String apiKey = apiSecret.get().orElse(null);
        if (apiKey != null) {
            PaymentGatewayClient client = new PaymentGatewayClient(apiKey);
        }
    }
    
    // Retrieve certificate data
    try (VaultRawSecret certSecret = vaultProvider.obtainSecret("certificates/client-cert")) {
        byte[] certData = certSecret.getOrDefault(new byte[0]);
        if (certData.length > 0) {
            X509Certificate certificate = loadCertificate(certData);
        }
    }
}

public class CustomVaultKeyResolver implements VaultKeyResolver {
    private static final Pattern VAULT_PATTERN = Pattern.compile("\\$\\{vault\\.([^}]+)\\}");
    private static final String VAULT_PREFIX = "${vault.";
    private static final String VAULT_SUFFIX = "}";

    @Override
    public boolean isVaultKey(String value) {
        return value != null && value.startsWith(VAULT_PREFIX) && value.endsWith(VAULT_SUFFIX);
    }

    @Override
    public String getVaultKey(String value) {
        if (!isVaultKey(value)) {
            return null;
        }
        
        Matcher matcher = VAULT_PATTERN.matcher(value);
        if (matcher.matches()) {
            return matcher.group(1);
        }
        
        return null;
    }

    @Override
    public String createVaultReference(String key) {
        if (key == null || key.isEmpty()) {
            throw new IllegalArgumentException("Vault key cannot be null or empty");
        }
        
        return VAULT_PREFIX + key + VAULT_SUFFIX;
    }
}

// Configure vault provider based on environment
public class EnvironmentVaultProviderFactory implements VaultProviderFactory {
    public static final String PROVIDER_ID = "environment-vault";

    @Override
    public VaultProvider create(KeycloakSession session) {
        String environment = System.getProperty("keycloak.environment", "development");
        
        switch (environment.toLowerCase()) {
            case "production":
                return createProductionVaultProvider();
            case "staging":
                return createStagingVaultProvider();
            case "development":
            default:
                return createDevelopmentVaultProvider();
        }
    }

    private VaultProvider createProductionVaultProvider() {
        // Use HashiCorp Vault for production
        return new HashiCorpVaultProvider(
            createVaultClient("https://vault.prod.example.com:8200"),
            "prod-secrets"
        );
    }

    private VaultProvider createStagingVaultProvider() {
        // Use HashiCorp Vault for staging
        return new HashiCorpVaultProvider(
            createVaultClient("https://vault.staging.example.com:8200"),
            "staging-secrets"
        );
    }

    private VaultProvider createDevelopmentVaultProvider() {
        // Use file-based vault for development
        return new FileBasedVaultProvider("/etc/keycloak/dev-secrets");
    }

    @Override
    public String getId() {
        return PROVIDER_ID;
    }
}

// Simple file-based vault for development
public class FileBasedVaultProvider implements VaultProvider {
    private final Path secretsDirectory;

    public FileBasedVaultProvider(String secretsPath) {
        this.secretsDirectory = Paths.get(secretsPath);
    }

    @Override
    public VaultRawSecret obtainSecret(String vaultSecretId) {
        try {
            Path secretFile = secretsDirectory.resolve(vaultSecretId + ".txt");
            if (!Files.exists(secretFile)) {
                return new EmptyVaultSecret();
            }

            String content = Files.readString(secretFile, StandardCharsets.UTF_8).trim();
            return new StringVaultSecret(content);
            
        } catch (IOException e) {
            logger.error("Failed to read secret file: " + vaultSecretId, e);
            return new EmptyVaultSecret();
        }
    }

    @Override
    public void close() {
        // Nothing to close for file-based implementation
    }
}

// Vault provider with caching for better performance
public class CachedVaultProvider implements VaultProvider {
    private final VaultProvider delegate;
    private final Cache<String, VaultRawSecret> secretCache;
    private final Duration cacheExpiration;

    public CachedVaultProvider(VaultProvider delegate, Duration cacheExpiration) {
        this.delegate = delegate;
        this.cacheExpiration = cacheExpiration;
        this.secretCache = Caffeine.newBuilder()
            .expireAfterWrite(cacheExpiration)
            .maximumSize(1000)
            .removalListener((key, value, cause) -> {
                if (value instanceof VaultRawSecret) {
                    ((VaultRawSecret) value).close();
                }
            })
            .build();
    }

    @Override
    public VaultRawSecret obtainSecret(String vaultSecretId) {
        return secretCache.get(vaultSecretId, key -> {
            VaultRawSecret secret = delegate.obtainSecret(key);
            
            // Convert to cacheable secret
            if (secret instanceof VaultStringSecret) {
                VaultStringSecret stringSecret = (VaultStringSecret) secret;
                String value = stringSecret.getOrDefault(null);
                secret.close(); // Close original
                
                return value != null ? new CacheableStringSecret(value) : new EmptyVaultSecret();
            }
            
            return secret;
        });
    }

    @Override
    public void close() {
        secretCache.invalidateAll();
        delegate.close();
    }

    private static class CacheableStringSecret implements VaultStringSecret {
        private final String value;

        public CacheableStringSecret(String value) {
            this.value = value;
        }

        @Override
        public Optional<String> get() {
            return Optional.ofNullable(value);
        }

        @Override
        public void close() {
            // Nothing to close for cached values
        }
    }
}