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    * #%L
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    * %%
    * Copyright (C) 2024 wcm.io
    * %%
    * 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.
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   */
  package io.wcm.handler.mediasource.ngdm.impl;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.commons.lang3.StringUtils;
  import org.apache.commons.lang3.Strings;
  import org.apache.sling.api.resource.Resource;
  import org.apache.sling.api.resource.ResourceResolver;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.day.cq.dam.api.Asset;
  
  /**
   * Parses and validates Dynamic Media with OpenAPI asset references.
   *
   * <p>
   * Example: <code>/urn:aaid:aem:12345678-abcd-abcd-abcd-abcd12345678/my-image.jpg</code>
   * </p>
   */
  public final class NextGenDynamicMediaReference {
  
    private static final Pattern REFERENCE_PATTERN = Pattern.compile("^/(urn:[^/]+)/([^/]+)$");
    private static final String ASSET_ID_PREFIX = "urn:";
  
    private final String assetId;
    private final String fileName;
    private final Asset asset;
  
    private static final Logger log = LoggerFactory.getLogger(NextGenDynamicMediaReference.class);
  
    /**
     * @param assetId Asset ID (has to start with "urn:")
     * @param fileName File name
     */
    public NextGenDynamicMediaReference(@NotNull String assetId, @NotNull String fileName) {
      this(assetId, fileName, null);
    }
  
    /**
     * @param assetId Asset ID (has to start with "urn:")
     * @param fileName File name
     */
    public NextGenDynamicMediaReference(@NotNull String assetId, @NotNull String fileName, @Nullable Asset asset) {
      if (!Strings.CS.startsWith(assetId, ASSET_ID_PREFIX)) {
        throw new IllegalArgumentException("Asset ID must start with '" + ASSET_ID_PREFIX + "'");
      }
      this.assetId = assetId;
      this.fileName = fileName;
      this.asset = asset;
    }
  
    /**
     * @return Asset ID
     */
    public @NotNull String getAssetId() {
      return assetId;
    }
  
    /**
     * @return File name
     */
    public @NotNull String getFileName() {
      return fileName;
    }
  
    /**
     * @return Asset (if reference points to local asset)
     */
    public @Nullable Asset getAsset() {
      return asset;
    }
  
    /**
     * @return True if reference points to local asset.
     */
    public boolean isLocal() {
     return asset != null;
   }
 
   /**
    * @return Reference
    */
   public @NotNull String toReference() {
     return "/" + assetId + "/" + fileName;
   }
 
   /**
    * Parses a next generation dynamic media reference.
    * @param reference Reference
    * @return Parsed reference or null if reference is invalid
    */
   public static @Nullable NextGenDynamicMediaReference fromReference(@Nullable String reference) {
     if (reference == null) {
       return null;
     }
     Matcher matcher = REFERENCE_PATTERN.matcher(reference);
     if (!matcher.matches()) {
       return null;
     }
     String assetId = matcher.group(1);
     String fileName = matcher.group(2);
     return new NextGenDynamicMediaReference(assetId, fileName);
   }
 
   /**
    * Parses a next generation dynamic media reference.
    * @param reference Reference
    * @return Parsed reference or null if reference is invalid
    */
   public static @Nullable NextGenDynamicMediaReference fromDamAssetReference(@Nullable String reference, @NotNull ResourceResolver resourceResolver) {
     if (reference == null) {
       return null;
     }
     Resource resource = resourceResolver.getResource(reference);
     if (resource == null) {
       return null;
     }
     Asset asset = resource.adaptTo(Asset.class);
     if (asset == null) {
       return null;
     }
     String uuid = asset.getID();
     if (StringUtils.isBlank(uuid)) {
       log.trace("Ignoring DAM asset without UUID: {}", asset.getPath());
       return null;
     }
     String assetId = "urn:aaid:aem:" + uuid;
     String fileName = asset.getName();
     return new NextGenDynamicMediaReference(assetId, fileName, asset);
   }
 
   /**
    * Checks if given string is a valid next generation dynamic media reference.
    * @param reference Reference
    * @return true if reference is valid
    */
   public static boolean isReference(@Nullable String reference) {
     return reference != null && REFERENCE_PATTERN.matcher(reference).matches();
   }
 
   @Override
   public String toString() {
     return toReference();
   }
 
 }