package com.atlassian.asap.core.keys.privatekey;
   
   import com.atlassian.asap.api.exception.CannotRetrieveKeyException;
   import com.atlassian.asap.core.keys.KeyProvider;
   import com.atlassian.asap.core.keys.KeyReader;
   import com.atlassian.asap.core.validator.ValidatedKeyId;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.Reader;
  import java.nio.charset.StandardCharsets;
  import java.security.PrivateKey;
  import java.util.Objects;
  
  /**
   * Reads private keys from the filesystem.
   */
  public class FilePrivateKeyProvider implements KeyProvider<PrivateKey> {
      private static final Logger logger = LoggerFactory.getLogger(FilePrivateKeyProvider.class);
  
      private final File baseDirectory;
      private final KeyReader keyReader;
  
      /**
       * Creates a new instance of {@link FilePrivateKeyProvider}.
       *
       * @param baseDirectory the base directory in filesystem where private keys are stored
       * @param keyReader     the key reader to use for reading private keys
       */
      public FilePrivateKeyProvider(File baseDirectory, KeyReader keyReader) {
          this.baseDirectory = Objects.requireNonNull(baseDirectory);
          this.keyReader = Objects.requireNonNull(keyReader);
      }
  
      @Override
      public PrivateKey getKey(ValidatedKeyId validatedKeyId) throws CannotRetrieveKeyException {
          File file = new File(baseDirectory, validatedKeyId.getKeyId());
          logger.debug("Reading private key from file system: {}", validatedKeyId.getKeyId());
  
          try (Reader reader = new InputStreamReader(new FileInputStream(file), StandardCharsets.US_ASCII)) {
              return keyReader.readPrivateKey(reader);
          } catch (FileNotFoundException e) {
              logger.debug("Private key file path {} does not exist or is not a file", file);
              throw new CannotRetrieveKeyException("Private key file path does not exist or is not a file");
          } catch (IOException e) {
              throw new CannotRetrieveKeyException(String.format("Error retrieving private key from file: '%s'", file), e);
          }
      }
  
      @Override
      public String toString() {
          return this.getClass().getSimpleName();
      }
  }