// Copyright 2011 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package adaptorlib;

import java.net.*;

/**
 * Codec for encoding and decoding {@code DocId}s to {@code URI}s.
 */
class DocIdCodec implements DocIdEncoder, DocIdDecoder {
  private Config config;

  public DocIdCodec(Config config) {
    this.config = config;
  }

  public URI encodeDocId(DocId docId) {
    if (config.isDocIdUrl()) {
      return URI.create(docId.getUniqueId());
    } else {
      URI base = config.getServerBaseUri(docId);
      URI resource;
      String uniqueId = docId.getUniqueId();
      // Add two dots to any sequence of only dots. This is to allow "/../" and
      // "/./" within DocIds.
      uniqueId = uniqueId.replaceAll("(^|/)(\\.+)(?=$|/)", "$1$2..");
      try {
        resource = new URI(null, null, base.getPath()
                           + config.getServerDocIdPath() + uniqueId, null);
      } catch (URISyntaxException ex) {
        throw new IllegalStateException(ex);
      }
      return base.resolve(resource);
    }
  }

  /** Given a URI that was used in feed file, convert back to doc id. */
  public DocId decodeDocId(URI uri) {
    if (config.isDocIdUrl()) {
      return new DocId(uri.toString());
    } else {
      String basePath = config.getServerBaseUri().getPath();
      String id = uri.getPath().substring(basePath.length()
          + config.getServerDocIdPath().length());
      // Remove two dots from any sequence of only dots. This is to remove the
      // addition we did in {@link #encodeDocId}.
      id = id.replaceAll("(^|/)(\\.+)\\.\\.(?=$|/)", "$1$2");
      return new DocId(id);
    }
  }
}