working on key management

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.oidc.datastore.file/src/main/java/de/srsoftware/oidc/datastore/file/PlaintextKeyStore.java

@@ -0,0 +1,58 @@
+/* © SRSoftware 2024 */
+package de.srsoftware.oidc.datastore.file;
+
+import static java.lang.System.Logger.Level.ERROR;
+
+import de.srsoftware.oidc.api.KeyManager;
+import de.srsoftware.oidc.api.KeyStorage;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import org.jose4j.jwk.PublicJsonWebKey;
+import org.jose4j.lang.JoseException;
+
+public class PlaintextKeyStore implements KeyStorage {
+	public static System.Logger LOG = System.getLogger(PlaintextKeyStore.class.getSimpleName());
+
+	private final Path dir;
+
+	public PlaintextKeyStore(Path storageDir) {
+		this.dir = storageDir;
+		storageDir.toFile().mkdirs();
+	}
+	@Override
+	public KeyStorage drop(String keyId) {
+		return null;
+	}
+
+	@Override
+	public List<String> listKeys() {
+		try {
+			return Files.list(dir).map(Path::toString).filter(filename -> filename.endsWith(".key")).map(filename -> filename.substring(0, filename.length() - 4)).toList();
+		} catch (IOException e) {
+			LOG.log(ERROR, "Failed to list files in {0}:", dir, e);
+			return List.of();
+		}
+	}
+
+	@Override
+	public PublicJsonWebKey load(String keyId) throws IOException, KeyManager.KeyCreationException {
+		var json = Files.readString(filename(keyId));
+		try {
+			return PublicJsonWebKey.Factory.newPublicJwk(json);
+		} catch (JoseException e) {
+			throw new KeyManager.KeyCreationException(e);
+		}
+	}
+
+	@Override
+	public KeyStorage store(PublicJsonWebKey jsonWebKey) throws IOException {
+		Files.writeString(filename(jsonWebKey.getKeyId()), jsonWebKey.toJson());
+		return this;
+	}
+
+	private Path filename(String keyId) {
+		return dir.resolve("%s.key".formatted(keyId));
+	}
+}