/*
    * Portions of this software was developed by employees of the National Institute
    * of Standards and Technology (NIST), an agency of the Federal Government and is
    * being made available as a public service. Pursuant to title 17 United States
    * Code Section 105, works of NIST employees are not subject to copyright
    * protection in the United States. This software may be subject to foreign
    * copyright. Permission in the United States and in foreign countries, to the
    * extent that NIST may hold copyright, to use, copy, modify, create derivative
    * works, and distribute this software and its documentation without fee is hereby
   * granted on a non-exclusive basis, provided that this notice and disclaimer
   * of warranty appears in all copies.
   *
   * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
   * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
   * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
   * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
   * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
   * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
   * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
   * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
   * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
   * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
   * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
   */
  
  package gov.nist.secauto.metaschema.core.model.validation;
  
  import gov.nist.secauto.metaschema.core.model.constraint.IConstraint;
  import gov.nist.secauto.metaschema.core.util.ObjectUtils;
  
  import org.everit.json.schema.Schema;
  import org.everit.json.schema.ValidationException;
  import org.everit.json.schema.loader.SchemaLoader;
  import org.json.JSONException;
  import org.json.JSONObject;
  import org.json.JSONTokener;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.Reader;
  import java.net.URI;
  import java.util.Collections;
  import java.util.List;
  import java.util.Objects;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  public class JsonSchemaContentValidator
      extends AbstractContentValidator {
    @NonNull
    private final Schema schema;
  
    public JsonSchemaContentValidator(@NonNull Reader reader) {
      this(new JSONTokener(reader));
    }
  
    public JsonSchemaContentValidator(@NonNull InputStream is) {
      this(new JSONTokener(is));
    }
  
    public JsonSchemaContentValidator(@NonNull JSONObject jsonSchema) {
      this(ObjectUtils.notNull(SchemaLoader.load(jsonSchema)));
    }
  
    protected JsonSchemaContentValidator(@NonNull JSONTokener tokenizer) {
      this(new JSONObject(tokenizer));
    }
  
    protected JsonSchemaContentValidator(@NonNull Schema schema) {
      this.schema = ObjectUtils.requireNonNull(schema, "schema");
    }
  
    @Override
    public IValidationResult validate(InputStream is, URI documentUri) throws IOException {
      JSONObject json;
      try {
        json = new JSONObject(new JSONTokener(is));
      } catch (JSONException ex) {
        throw new IOException(String.format("Unable to parse JSON from '%s'", documentUri), ex);
      }
      return validate(json, documentUri);
    }
  
    @SuppressWarnings("null")
    @NonNull
    public IValidationResult validate(@NonNull JSONObject json, @NonNull URI documentUri) {
      IValidationResult retval;
      try {
        schema.validate(json);
        retval = IValidationResult.PASSING_RESULT;
      } catch (ValidationException ex) {
        retval = new JsonValidationResult(
            handleValidationException(ex, documentUri)
                .collect(Collectors.toList()));
      }
  
     return retval;
   }
 
   @SuppressWarnings("null")
   @NonNull
   protected Stream<JsonValidationFinding> handleValidationException(@NonNull ValidationException ex,
       @NonNull URI documentUri) {
     JsonValidationFinding finding = new JsonValidationFinding(ex, documentUri);
     Stream<JsonValidationFinding> childFindings = ex.getCausingExceptions().stream()
         .flatMap(exception -> {
           return handleValidationException(exception, documentUri);
         });
     return Stream.concat(Stream.of(finding), childFindings);
   }
 
   public static class JsonValidationFinding implements IValidationFinding {
     @NonNull
     private final ValidationException exception;
     @NonNull
     private final URI documentUri;
 
     public JsonValidationFinding(@NonNull ValidationException exception, @NonNull URI documentUri) {
       this.exception = ObjectUtils.requireNonNull(exception, "exception");
       this.documentUri = ObjectUtils.requireNonNull(documentUri, "documentUri");
     }
 
     @Override
     public IConstraint.Level getSeverity() {
       return IConstraint.Level.ERROR;
     }
 
     @Override
     public URI getDocumentUri() {
       return documentUri;
     }
 
     @SuppressWarnings("null")
     @Override
     public String getMessage() {
       return getCause().getLocalizedMessage();
     }
 
     @NonNull
     @Override
     public ValidationException getCause() {
       return exception;
     }
   }
 
   private static class JsonValidationResult implements IValidationResult {
     @NonNull
     private final List<JsonValidationFinding> findings;
 
     @SuppressWarnings("null")
     public JsonValidationResult(@NonNull List<JsonValidationFinding> findings) {
       this.findings = Collections.unmodifiableList(Objects.requireNonNull(findings, "findings"));
     }
 
     @Override
     public IConstraint.Level getHighestSeverity() {
       return findings.isEmpty() ? IConstraint.Level.INFORMATIONAL : IConstraint.Level.ERROR;
     }
 
     @Override
     public List<? extends IValidationFinding> getFindings() {
       return findings;
     }
 
   }
 }