package com.atlassian.asap.core.keys.publickey;
   
   import com.atlassian.asap.api.exception.CannotRetrieveKeyException;
   import com.atlassian.asap.core.exception.PublicKeyNotFoundException;
   import com.atlassian.asap.core.exception.PublicKeyRetrievalException;
   import com.atlassian.asap.core.keys.KeyProvider;
   import com.atlassian.asap.core.keys.PemReader;
   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.PublicKey;
  import java.util.Objects;
  
  /**
   * Reads public keys from the filesystem.
   */
  public class FilePublicKeyProvider implements KeyProvider<PublicKey> {
      private static final Logger logger = LoggerFactory.getLogger(FilePublicKeyProvider.class);
      private final File baseDirectory;
      private final PemReader pemReader;
  
      public FilePublicKeyProvider(File baseDirectory, PemReader pemReader) {
          this.baseDirectory = Objects.requireNonNull(baseDirectory);
          this.pemReader = Objects.requireNonNull(pemReader);
      }
  
      @Override
      public PublicKey getKey(ValidatedKeyId validatedKeyId) throws CannotRetrieveKeyException {
          File file = new File(baseDirectory, validatedKeyId.getKeyId());
          logger.debug("Reading public key from file system: {}", file);
  
          try (Reader reader = new InputStreamReader(new FileInputStream(file), StandardCharsets.US_ASCII)) {
              return pemReader.readPublicKey(reader);
          } catch (FileNotFoundException e) {
              // log at debug level because this can be caused by invalid input
              logger.debug("Public key file path {} was not found or it is not a file", file);
              throw new PublicKeyNotFoundException(
                      "Public key file path was not found or it is not a file", validatedKeyId, file.toURI());
          } catch (CannotRetrieveKeyException | IOException e) {
              logger.warn("A problem occurred when trying to retrieve public key from file: {}", file, e);
              throw new PublicKeyRetrievalException("Error reading public key from file", validatedKeyId, file.toURI());
          }
      }
  
      @Override
      public String toString() {
          return this.getClass().getSimpleName();
      }
  }