// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
package com.android.tools.r8;

import com.android.tools.r8.origin.Origin;
import java.io.IOException;
import java.io.InputStream;
import java.util.Set;

/**
 * Program resource provider for program resources of class-file kind.
 *
 * <p>Note that the classes are generally lazily requested and the corresponding class structures
 * only created on-demand when they are needed by the compiler. If never needed, the resource will
 * never be loaded.
 */
public interface ClassFileResourceProvider {

  /**
   * Get the set of all class descriptors that can be provided.
   *
   * <p>For user program classes (eg, not class-path or library resources), this set must be
   * defined.
   *
   * @return Set of all class descriptors that can be provided or null if the set is unknown.
   */
  Set<String> getClassDescriptors();

  /**
   * Get the program resource associated with the descriptor, or null if this provider does not have
   * a resource for the descriptor.
   *
   * <p>Method may be called several times for the same resource, and should support concurrent
   * calls from different threads.
   */
  default ProgramResource getProgramResource(String descriptor) {
    Resource resource = getResource(descriptor);
    return resource == null ? null : new ClassFileResource(resource);
  }

  @Deprecated
  Resource getResource(String descriptor);

  @Deprecated
  class ClassFileResource implements ProgramResource {
    private final Resource resource;

    public ClassFileResource(Resource resource) {
      this.resource = resource;
      assert resource.getClassDescriptors() == null || resource.getClassDescriptors().size() == 1;
    }

    @Override
    public Kind getKind() {
      return Kind.CF;
    }

    @Override
    public InputStream getByteStream() throws ResourceException {
      try {
        return resource.getStream();
      } catch (IOException e) {
        throw new ResourceException(resource.getOrigin(), e);
      }
    }

    @Override
    public Set<String> getClassDescriptors() {
      return resource.getClassDescriptors();
    }

    @Override
    public Origin getOrigin() {
      return resource.getOrigin();
    }

    @Override
    public InputStream getStream() throws IOException {
      return resource.getStream();
    }
  };
}