/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * 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
   * "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 org.apache.maven.plugins.shade.resource.rule;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.lang.annotation.Retention;
  import java.lang.annotation.Target;
  import java.nio.charset.StandardCharsets;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.jar.JarEntry;
  import java.util.jar.JarInputStream;
  import java.util.jar.JarOutputStream;
  
  import org.apache.maven.plugins.shade.relocation.Relocator;
  import org.apache.maven.plugins.shade.resource.ReproducibleResourceTransformer;
  import org.codehaus.plexus.component.configurator.ComponentConfigurationException;
  import org.codehaus.plexus.component.configurator.converters.ConfigurationConverter;
  import org.codehaus.plexus.component.configurator.converters.lookup.ConverterLookup;
  import org.codehaus.plexus.component.configurator.converters.lookup.DefaultConverterLookup;
  import org.codehaus.plexus.component.configurator.expression.DefaultExpressionEvaluator;
  import org.codehaus.plexus.configuration.DefaultPlexusConfiguration;
  import org.codehaus.plexus.configuration.PlexusConfiguration;
  import org.junit.rules.TestRule;
  import org.junit.runner.Description;
  import org.junit.runners.model.Statement;
  
  import static java.lang.annotation.ElementType.METHOD;
  import static java.lang.annotation.RetentionPolicy.RUNTIME;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  public class TransformerTesterRule implements TestRule {
      @Override
      public Statement apply(final Statement base, final Description description) {
          return new Statement() {
              @Override
              public void evaluate() throws Throwable {
                  final TransformerTest spec = description.getAnnotation(TransformerTest.class);
                  if (spec == null) {
                      base.evaluate();
                      return;
                  }
  
                  final Map<String, String> jar;
                  try {
                      final ReproducibleResourceTransformer transformer = createTransformer(spec);
                      visit(spec, transformer);
                      jar = captureOutput(transformer);
                  } catch (final Exception ex) {
                      if (Exception.class.isAssignableFrom(spec.expectedException())) {
                          assertTrue(
                                  ex.getClass().getName(),
                                  spec.expectedException().isAssignableFrom(ex.getClass()));
                          return;
                      } else {
                          throw ex;
                      }
                  }
                  asserts(spec, jar);
              }
          };
      }
  
      private void asserts(final TransformerTest spec, final Map<String, String> jar) {
          if (spec.strictMatch() && jar.size() != spec.expected().length) {
              fail("Strict match test failed: " + jar);
          }
          for (final Resource expected : spec.expected()) {
              final String content = jar.get(expected.path());
              assertNotNull(expected.path(), content);
              assertTrue(
                      expected.path() + ", expected=" + expected.content() + ", actual=" + content,
                      content.replace(System.lineSeparator(), "\n").matches(expected.content()));
          }
      }
  
      private Map<String, String> captureOutput(final ReproducibleResourceTransformer transformer) throws IOException {
          final ByteArrayOutputStream out = new ByteArrayOutputStream();
         try (final JarOutputStream jar = new JarOutputStream(out)) {
             transformer.modifyOutputStream(jar);
         }
 
         final Map<String, String> created = new HashMap<>();
         try (final JarInputStream jar = new JarInputStream(new ByteArrayInputStream(out.toByteArray()))) {
             JarEntry entry;
             while ((entry = jar.getNextJarEntry()) != null) {
                 created.put(entry.getName(), read(jar));
             }
         }
         return created;
     }
 
     private void visit(final TransformerTest spec, final ReproducibleResourceTransformer transformer)
             throws IOException {
         for (final Resource resource : spec.visited()) {
             if (transformer.canTransformResource(resource.path())) {
                 transformer.processResource(
                         resource.path(),
                         new ByteArrayInputStream(resource.content().getBytes(StandardCharsets.UTF_8)),
                         Collections.<Relocator>emptyList(),
                         0);
             }
         }
     }
 
     private String read(final JarInputStream jar) throws IOException {
         final StringBuilder builder = new StringBuilder();
         final byte[] buffer = new byte[512];
         int read;
         while ((read = jar.read(buffer)) >= 0) {
             builder.append(new String(buffer, 0, read));
         }
         return builder.toString();
     }
 
     private ReproducibleResourceTransformer createTransformer(final TransformerTest spec) {
         final ConverterLookup lookup = new DefaultConverterLookup();
         try {
             final ConfigurationConverter converter = lookup.lookupConverterForType(spec.transformer());
             final PlexusConfiguration configuration = new DefaultPlexusConfiguration("configuration");
             for (final Property property : spec.configuration()) {
                 configuration.addChild(property.name(), property.value());
             }
             return ReproducibleResourceTransformer.class.cast(converter.fromConfiguration(
                     lookup,
                     configuration,
                     spec.transformer(),
                     spec.transformer(),
                     Thread.currentThread().getContextClassLoader(),
                     new DefaultExpressionEvaluator()));
         } catch (final ComponentConfigurationException e) {
             throw new IllegalStateException(e);
         }
     }
 
     /**
      * Enables to describe a test without having to implement the logic itself.
      */
     @Target(METHOD)
     @Retention(RUNTIME)
     public @interface TransformerTest {
         /**
          * @return the list of resource the transformer will process.
          */
         Resource[] visited();
 
         /**
          * @return the expected output created by the transformer.
          */
         Resource[] expected();
 
         /**
          * @return true if only expected resources must be found.
          */
         boolean strictMatch() default true;
 
         /**
          * @return type of transformer to use.
          */
         Class<?> transformer();
 
         /**
          * @return transformer configuration.
          */
         Property[] configuration();
 
         /**
          * @return if set to an exception class it ensures it is thrown during the processing.
          */
         Class<?> expectedException() default Object.class;
     }
 
     @Target(METHOD)
     @Retention(RUNTIME)
     public @interface Property {
         String name();
 
         String value();
     }
 
     @Target(METHOD)
     @Retention(RUNTIME)
     public @interface Resource {
         String path();
 
         String content();
     }
 }