#pragma once

#include <cstdint>

#include <functional>

#include <memory>

#include <string>

#include "envoy/common/platform.h"

#include "envoy/common/pure.h"

#include "absl/status/status.h"

#include "absl/status/statusor.h"

#include "absl/strings/string_view.h"

namespace Envoy {

namespace Filesystem {

/**

 * Abstraction for a file watcher.

 */

class Watcher {

public:

  using OnChangedCb = std::function<absl::Status(uint32_t events)>;

  struct Events {

    static constexpr uint32_t MovedTo = 0x1;

    static constexpr uint32_t Modified = 0x2;

  };

  /**

   * Add a file watch.

   * @param path supplies the path to watch.

   *        If path is a file, callback is called on events for the given file.

   *        If path is a directory (ends with "/"), callback is called on events

   *        for the given directory.

   * @param events supplies the events to watch.

   * @param cb supplies the callback to invoke when a change occurs.

   * @return a failure status if the file does not exist

   */

  virtual absl::Status addWatch(absl::string_view path, uint32_t events, OnChangedCb cb) PURE;

};

using WatcherPtr = std::unique_ptr<Watcher>;

} // namespace Filesystem

} // namespace Envoy