// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "quiche/quic/core/quic_time.h"

#include <cstdint>
#include <cstdlib>
#include <limits>
#include <string>

#include "absl/strings/str_cat.h"

namespace quic {

std::string QuicTime::Delta::ToDebuggingValue() const {
  constexpr int64_t kMillisecondInMicroseconds = 1000;
  constexpr int64_t kSecondInMicroseconds = 1000 * kMillisecondInMicroseconds;

  int64_t absolute_value = std::abs(time_offset_);

  // For debugging purposes, always display the value with the highest precision
  // available.
  if (absolute_value >= kSecondInMicroseconds &&
      absolute_value % kSecondInMicroseconds == 0) {
    return absl::StrCat(time_offset_ / kSecondInMicroseconds, "s");
  }
  if (absolute_value >= kMillisecondInMicroseconds &&
      absolute_value % kMillisecondInMicroseconds == 0) {
    return absl::StrCat(time_offset_ / kMillisecondInMicroseconds, "ms");
  }
  return absl::StrCat(time_offset_, "us");
}

uint64_t QuicWallTime::ToUNIXSeconds() const { return microseconds_ / 1000000; }

uint64_t QuicWallTime::ToUNIXMicroseconds() const { return microseconds_; }

bool QuicWallTime::IsAfter(QuicWallTime other) const {
  return microseconds_ > other.microseconds_;
}

bool QuicWallTime::IsBefore(QuicWallTime other) const {
  return microseconds_ < other.microseconds_;
}

bool QuicWallTime::IsZero() const { return microseconds_ == 0; }

QuicTime::Delta QuicWallTime::AbsoluteDifference(QuicWallTime other) const {
  uint64_t d;

  if (microseconds_ > other.microseconds_) {
    d = microseconds_ - other.microseconds_;
  } else {
    d = other.microseconds_ - microseconds_;
  }

  if (d > static_cast<uint64_t>(std::numeric_limits<int64_t>::max())) {
    d = std::numeric_limits<int64_t>::max();
  }
  return QuicTime::Delta::FromMicroseconds(d);
}

QuicWallTime QuicWallTime::Add(QuicTime::Delta delta) const {
  uint64_t microseconds = microseconds_ + delta.ToMicroseconds();
  if (microseconds < microseconds_) {
    microseconds = std::numeric_limits<uint64_t>::max();
  }
  return QuicWallTime(microseconds);
}

// TODO(ianswett) Test this.
QuicWallTime QuicWallTime::Subtract(QuicTime::Delta delta) const {
  uint64_t microseconds = microseconds_ - delta.ToMicroseconds();
  if (microseconds > microseconds_) {
    microseconds = 0;
  }
  return QuicWallTime(microseconds);
}

}  // namespace quic