Added ReEncryptInstructionFileRequest class

Author: Anirav Kareddy

src/main/java/software/amazon/encryption/s3/internal/ReEncryptInstructionFileRequest.java

@@ -0,0 +1,80 @@
+package software.amazon.encryption.s3.internal;
+
+import software.amazon.encryption.s3.S3EncryptionClientException;
+import software.amazon.encryption.s3.materials.AesKeyring;
+import software.amazon.encryption.s3.materials.KmsKeyring;
+import software.amazon.encryption.s3.materials.RsaKeyring;
+import software.amazon.encryption.s3.materials.S3Keyring;
+
+/** Request object for re-encrypting instruction files.
+ * Supports both AES and RSA keyring with different instruction file suffixes.
+ */
+public class ReEncryptInstructionFileRequest {
+  private final String bucket;
+  private final String key;
+  private final S3Keyring newKeyring;
+  private final String instructionFileSuffix;
+
+  private ReEncryptInstructionFileRequest(Builder builder) {
+    bucket = builder.bucket;
+    key = builder.key;
+    newKeyring = builder.newKeyring;
+    instructionFileSuffix = builder.instructionFileSuffix;
+  }
+  public static Builder builder() {
+    return new Builder();
+  }
+  public static class Builder {
+    private static final String DEFAULT_INSTRUCTION_FILE_SUFFIX = ".instruction";
+    private String bucket;
+    private String key;
+    private S3Keyring newKeyring;
+    private String instructionFileSuffix = DEFAULT_INSTRUCTION_FILE_SUFFIX;
+
+    public Builder bucket(String bucket) {
+      this.bucket = bucket;
+      return this;
+    }
+
+    public Builder key(String key) {
+      this.key = key;
+      return this;
+    }
+
+    public Builder newKeyring(S3Keyring newKeyring) {
+      this.newKeyring = newKeyring;
+      return this;
+    }
+
+    public Builder instructionFileSuffix(String instructionFileSuffix) {
+      this.instructionFileSuffix = instructionFileSuffix;
+      return this;
+    }
+
+    public ReEncryptInstructionFileRequest build() {
+      if (bucket == null || bucket.isEmpty()) {
+        throw new S3EncryptionClientException("Bucket must be provided!");
+      }
+      if (key == null || key.isEmpty()) {
+        throw new S3EncryptionClientException("Key must be provided!");
+      }
+      if (newKeyring == null) {
+        throw new S3EncryptionClientException("New keyring must be provided!");
+      }
+      if (newKeyring instanceof AesKeyring) {
+        if (!instructionFileSuffix.equals(DEFAULT_INSTRUCTION_FILE_SUFFIX)) {
+          throw new S3EncryptionClientException("Instruction file suffix is not applicable for AES keyring!");
+        }
+      } else if (newKeyring instanceof RsaKeyring) {
+        if (instructionFileSuffix.equals(DEFAULT_INSTRUCTION_FILE_SUFFIX)) {
+          throw new S3EncryptionClientException("Instruction file suffix must be different than the default one for RSA keyring!");
+        }
+      } else if (newKeyring instanceof KmsKeyring){
+        throw new S3EncryptionClientException("KMS keyring is not supported for re-encrypting instruction file!");
+      }
+      return new ReEncryptInstructionFileRequest(this);
+    }
+
+  }
+
+}