// Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
// source code may only be used and distributed under the Widevine License
// Agreement.
//
// TestSleep - Controls sleep and clock adjustment during tests.
//
#ifndef WVCDM_UTIL_TEST_SLEEP_H_
#define WVCDM_UTIL_TEST_SLEEP_H_

#include <stdint.h>

namespace wvutil {

class TestSleep {
 public:
  // The callback is called when the test clock should be advanced. If the
  // system uses a real clock, it is used to sync the real and test
  // clock. Otherwise it is used to simulate sleep in the test clock.
  class CallBack {
   public:
    virtual void ElapseTime(int64_t milliseconds) = 0;

   protected:
    virtual ~CallBack(){};
  };

  // If real_sleep_ is true, then this sleeps for |seconds| of time.  If
  // real_sleep_ is false, then the fake clock is advanced by |seconds|. If the
  // callback exists, this calls the callback.
  static void Sleep(unsigned int seconds);

  // Like sleep, above, except it sleeps until the specified time.
  static void SleepUntil(int64_t desired_time);

  // If we are using a real clock and a fake clock, then the real clock advances
  // a little while we are doing work, but the fake one only advances when we
  // sleep. This function advances the fake clock to be in sync with the real
  // clock. This function should be called to prevent a slow flaky test from
  // failing due to this drift.
  static void SyncFakeClock();

  // Roll the system clock back by |seconds|. Returns true on success. A well
  // mannered test will call CanChangeSystemTime before attempting to call this
  // function and then assert that this is true. This function should *NOT* roll
  // back the clock used by OEMCrypto -- in fact, there are several tests that
  // verify this function does not roll back the clock used by OEMCrypto.
  static bool RollbackSystemTime(int seconds);

  // Set the system clock to the specified time. This is only expected to work
  // when real_sleep is false.
  static void SetFakeClock(int64_t time_seconds);

  // Roll the system clock forward to undo all previous calls to
  // RollBackSystemTime. Returns true on success.
  static bool ResetRollback() {
    return total_clock_rollback_seconds_ == 0 ||
           RollbackSystemTime(-total_clock_rollback_seconds_);
  }

  // Returns true if the system time can be rolled back. This is true on some
  // devices if the tests are run as root. It is also true when using a fake
  // clock with the reference version of OEMCrypto. This function is about the
  // system clock, *NOT* the clock used by OEMCrypto.
  static bool CanChangeSystemTime();

  static void set_real_sleep(bool real_sleep) { real_sleep_ = real_sleep; }
  static bool real_sleep() { return real_sleep_; }

  // The callback is notified whenever sleep is called.
  static void set_callback(CallBack* callback) { callback_ = callback; }

 private:
  // Controls if the test sleep should use real sleep.
  static bool real_sleep_;
  // Called when the clock should advance.
  static CallBack* callback_;
  // The sum of all calls to RollBackSystemTime. Kept so we can undo all changes
  // at the end of a test.
  static int total_clock_rollback_seconds_;
};

}  // namespace wvutil

#endif  // WVCDM_UTIL_TEST_SLEEP_H_