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 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
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 * KIND, either express or implied.  See the License for the
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package org.apache.padaf.preflight.xmp;

import java.util.ArrayList;
import java.util.List;

import org.apache.padaf.preflight.ValidationConstants;
import org.apache.padaf.preflight.ValidationException;
import org.apache.padaf.preflight.ValidationResult.ValidationError;
import org.apache.padaf.xmpbox.XMPMetadata;
import org.apache.padaf.xmpbox.schema.PDFAIdentificationSchema;
import org.apache.padaf.xmpbox.schema.XMPBasicSchema;


/**
 * Class which check if PDF/A Identification Schema contains good information
 * 
 * @author Germain Costenobel
 * 
 */
public class PDFAIdentificationValidation {

  /**
   * Check if PDFAIdentification is valid
   * 
   * @param document
   *          the PDF Document
   * @param metadata
   *          the XMP MetaData
   * @return List of validation errors
   * @throws ValidationException
   */
  public List<ValidationError> validatePDFAIdentifer(XMPMetadata metadata)
      throws ValidationException {
    List<ValidationError> ve = new ArrayList<ValidationError>();
    PDFAIdentificationSchema id = metadata.getPDFIdentificationSchema();
    if (id == null) {
      ve.add(new ValidationError(ValidationConstants.ERROR_METADATA_PDFA_ID_MISSING));
      return ve;
    }

    // According to the PDF/A specification, the prefix must be pdfaid for this schema.
    if (!id.getPrefix().equals(PDFAIdentificationSchema.IDPREFIX)) {
      if (metadata.getSchema(PDFAIdentificationSchema.IDPREFIX, XMPBasicSchema.XMPBASICURI) == null) {
        ve.add(UnexpectedPrefixFoundError(id.getPrefix(),
            PDFAIdentificationSchema.IDPREFIX, PDFAIdentificationSchema.class.getName()));
      } else {
        id = (PDFAIdentificationSchema) metadata.getSchema(
            PDFAIdentificationSchema.IDPREFIX, PDFAIdentificationSchema.IDURI);
      }
    }
    checkConformanceLevel(ve, id.getConformanceValue());
    checkPartNumber(ve, id.getPartValue());
    return ve;
  }

  /**
   * Return a validationError formatted when a schema has not the expected
   * prefix
   * 
   * @param prefFound
   * @param prefExpected
   * @param schema
   * @return
   */
  protected ValidationError UnexpectedPrefixFoundError(String prefFound,
      String prefExpected, String schema) {
    StringBuilder sb = new StringBuilder(80);
    sb.append(schema).append(" found but prefix used is '").append(prefFound)
        .append("', prefix '").append(prefExpected).append("' is expected.");

    return new ValidationError(
        ValidationConstants.ERROR_METADATA_WRONG_NS_PREFIX, sb.toString());
  }

  protected void checkConformanceLevel(List<ValidationError> ve, String value) {
    if (!(value.equals("A") || value.equals("B"))) {
      ve.add(new ValidationError(
          ValidationConstants.ERROR_METADATA_INVALID_PDFA_CONFORMANCE));
    }
  }

  protected void checkPartNumber(List<ValidationError> ve, int value) {
    if (value != 1) {
      ve.add(new ValidationError(
          ValidationConstants.ERROR_METADATA_INVALID_PDFA_VERSION_ID));
    }
  }
}