/*
 * Copyright (c) 2011-2019, The DART development contributors
 * All rights reserved.
 *
 * The list of contributors can be found at:
 *   https://github.com/dartsim/dart/blob/master/LICENSE
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 *   without modification, are permitted provided that the following
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 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
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 *     disclaimer in the documentation and/or other materials provided
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#ifndef DART_UTILS_COMPOSITERESOURCERETRIEVER_HPP_
#define DART_UTILS_COMPOSITERESOURCERETRIEVER_HPP_

#include <unordered_map>
#include <vector>
#include "dart/common/ResourceRetriever.hpp"

namespace dart {
namespace utils {

/// CompositeResourceRetriever allows multiple \ref ResourceRetriever to be
/// used interchangably by: (1) associating each \ref ResourceRetriever with a
/// particular URI schema and/or (2) providing a precedence order for trying
/// multiple retrievers.
class CompositeResourceRetriever : public virtual common::ResourceRetriever
{
public:
  virtual ~CompositeResourceRetriever() = default;

  /// \brief Add a default \ref ResourceRetriever for all URIs.
  /// This \ref ResourceRetriever will be called after all schema-specific
  /// ResourceRetrievers, if any, have failed. This method may be called
  /// multiple times. In that case, the ResourceRetrievers will be queried
  /// in the same order in which they were added.
  void addDefaultRetriever(
    const common::ResourceRetrieverPtr& _resourceRetriever);

  /// \brief Add a default \ref ResourceRetriever for \a _schema
  /// This \ref ResourceRetriever will be called after URIs that match the
  /// specified schema. This method may be called multiple times. In that
  /// case, the ResourceRetrievers will be queried in the same order in which
  /// they were added.
  bool addSchemaRetriever(
    const std::string& _schema,
    const common::ResourceRetrieverPtr& _resourceRetriever);

  // Documentation inherited.
  bool exists(const common::Uri& _uri) override;

  // Documentation inherited.
  common::ResourcePtr retrieve(const common::Uri& _uri) override;

  // Documentation inherited.
  std::string getFilePath(const common::Uri& uri) override;

private:
  std::vector<common::ResourceRetrieverPtr> getRetrievers(
    const common::Uri& _uri) const;

  std::unordered_map<std::string,
    std::vector<common::ResourceRetrieverPtr> > mResourceRetrievers;
  std::vector<common::ResourceRetrieverPtr> mDefaultResourceRetrievers;
};

using CompositeResourceRetrieverPtr
  = std::shared_ptr<CompositeResourceRetriever>;

} // namespace utils
} // namespace dart

#endif // ifndef DART_UTILS_COMPOSITERESOURCERETRIEVER_HPP_
