// Copyright 2021 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.

// This file does not actually implement logging, it merely provides enough of
// logging code for QUICHE to compile and pass the unit tests.  QUICHE embedders
// are encouraged to override this file with their own logic.  If at some point
// logging becomes a part of Abseil, this file will likely start using that
// instead.

#ifndef QUICHE_COMMON_PLATFORM_DEFAULT_QUICHE_PLATFORM_IMPL_QUICHE_LOGGING_IMPL_H_
#define QUICHE_COMMON_PLATFORM_DEFAULT_QUICHE_PLATFORM_IMPL_QUICHE_LOGGING_IMPL_H_

#include <cstdlib>
#include <iostream>
#include <sstream>
#include <string>

#include "absl/base/attributes.h"
#include "quiche/common/platform/api/quiche_export.h"
#include "quiche_platform_impl/quiche_stack_trace_impl.h"

namespace quiche {

class QUICHE_EXPORT_PRIVATE LogStreamVoidHelper {
 public:
  // This operator has lower precedence than << but higher than ?:, which is
  // useful for implementing QUICHE_DISREGARD_LOG_STREAM below.
  constexpr void operator&(std::ostream&) {}
};

// NoopLogSink provides a log sink that does not put the data that it logs
// anywhere.
class QUICHE_EXPORT_PRIVATE NoopLogSink {
 public:
  NoopLogSink() {}

  template <typename T>
  constexpr NoopLogSink(const T&) {}

  template <typename T1, typename T2>
  constexpr NoopLogSink(const T1&, const T2&) {}

  constexpr std::ostream& stream() { return stream_; }

 protected:
  std::string str() { return stream_.str(); }

 private:
  std::stringstream stream_;
};

// We need to actually implement LOG(FATAL), otherwise some functions will fail
// to compile due to the "failed to return value from non-void function" error.
class QUICHE_EXPORT_PRIVATE FatalLogSink : public NoopLogSink {
 public:
  ABSL_ATTRIBUTE_NORETURN ~FatalLogSink() {
    std::cerr << str() << std::endl;
    std::cerr << quiche::QuicheStackTraceImpl() << std::endl;
    abort();
  }
};

class QUICHE_EXPORT_PRIVATE CheckLogSink : public NoopLogSink {
 public:
  CheckLogSink(bool condition) : condition_(condition) {}
  ~CheckLogSink() {
    if (!condition_) {
      std::cerr << "Check failed: " << str() << std::endl;
      std::cerr << quiche::QuicheStackTraceImpl() << std::endl;
      abort();
    }
  }

 private:
  const bool condition_;
};

}  // namespace quiche

// This is necessary because we sometimes call QUICHE_DCHECK inside constexpr
// functions, and then write non-constexpr expressions into the resulting log.
#define QUICHE_CONDITIONAL_LOG_STREAM(stream, condition) \
  !(condition) ? (void)0 : ::quiche::LogStreamVoidHelper() & (stream)
#define QUICHE_DISREGARD_LOG_STREAM(stream) \
  QUICHE_CONDITIONAL_LOG_STREAM(stream, /*condition=*/false)
#define QUICHE_NOOP_STREAM() \
  QUICHE_DISREGARD_LOG_STREAM(::quiche::NoopLogSink().stream())
#define QUICHE_NOOP_STREAM_WITH_CONDITION(condition) \
  QUICHE_DISREGARD_LOG_STREAM(::quiche::NoopLogSink(condition).stream())

#define QUICHE_DVLOG_IMPL(verbose_level) QUICHE_NOOP_STREAM()
#define QUICHE_DVLOG_IF_IMPL(verbose_level, condition) \
  QUICHE_NOOP_STREAM_WITH_CONDITION(condition)
#define QUICHE_DLOG_IMPL(severity) QUICHE_NOOP_STREAM()
#define QUICHE_VLOG_IMPL(verbose_level) QUICHE_NOOP_STREAM()
#define QUICHE_LOG_FIRST_N_IMPL(severity, n) QUICHE_NOOP_STREAM()
#define QUICHE_LOG_EVERY_N_SEC_IMPL(severity, seconds) QUICHE_NOOP_STREAM()

#define QUICHE_LOG_IMPL(severity) QUICHE_LOG_IMPL_##severity()
#define QUICHE_LOG_IMPL_FATAL() ::quiche::FatalLogSink().stream()
#define QUICHE_LOG_IMPL_ERROR() ::quiche::NoopLogSink().stream()
#define QUICHE_LOG_IMPL_WARNING() ::quiche::NoopLogSink().stream()
#define QUICHE_LOG_IMPL_INFO() ::quiche::NoopLogSink().stream()

#define QUICHE_LOG_IF_IMPL(severity, condition) \
  QUICHE_CONDITIONAL_LOG_STREAM(QUICHE_LOG_IMPL_##severity(), condition)

#ifdef NDEBUG
#define QUICHE_LOG_IMPL_DFATAL() ::quiche::NoopLogSink().stream()
#define QUICHE_DLOG_IF_IMPL(severity, condition) \
  QUICHE_NOOP_STREAM_WITH_CONDITION(condition)
#else
#define QUICHE_LOG_IMPL_DFATAL() ::quiche::FatalLogSink().stream()
#define QUICHE_DLOG_IF_IMPL(severity, condition) \
  QUICHE_CONDITIONAL_LOG_STREAM(QUICHE_LOG_IMPL_##severity(), condition)
#endif

#define QUICHE_PLOG_IMPL(severity) QUICHE_NOOP_STREAM()

#define QUICHE_DLOG_INFO_IS_ON_IMPL() false
#define QUICHE_LOG_INFO_IS_ON_IMPL() false
#define QUICHE_LOG_WARNING_IS_ON_IMPL() false
#define QUICHE_LOG_ERROR_IS_ON_IMPL() false

#define QUICHE_CHECK_IMPL(condition) \
  ::quiche::CheckLogSink(static_cast<bool>(condition)).stream()
#define QUICHE_CHECK_EQ_IMPL(val1, val2) \
  ::quiche::CheckLogSink((val1) == (val2)).stream()
#define QUICHE_CHECK_NE_IMPL(val1, val2) \
  ::quiche::CheckLogSink((val1) != (val2)).stream()
#define QUICHE_CHECK_LE_IMPL(val1, val2) \
  ::quiche::CheckLogSink((val1) <= (val2)).stream()
#define QUICHE_CHECK_LT_IMPL(val1, val2) \
  ::quiche::CheckLogSink((val1) < (val2)).stream()
#define QUICHE_CHECK_GE_IMPL(val1, val2) \
  ::quiche::CheckLogSink((val1) >= (val2)).stream()
#define QUICHE_CHECK_GT_IMPL(val1, val2) \
  ::quiche::CheckLogSink((val1) > (val2)).stream()

#ifdef NDEBUG
#define QUICHE_DCHECK_IMPL(condition) \
  QUICHE_NOOP_STREAM_WITH_CONDITION((condition))
#else
#define QUICHE_DCHECK_IMPL(condition) \
  QUICHE_LOG_IF_IMPL(DFATAL, !static_cast<bool>(condition))
#endif
#define QUICHE_DCHECK_EQ_IMPL(val1, val2) QUICHE_DCHECK_IMPL((val1) == (val2))
#define QUICHE_DCHECK_NE_IMPL(val1, val2) QUICHE_DCHECK_IMPL((val1) != (val2))
#define QUICHE_DCHECK_LE_IMPL(val1, val2) QUICHE_DCHECK_IMPL((val1) <= (val2))
#define QUICHE_DCHECK_LT_IMPL(val1, val2) QUICHE_DCHECK_IMPL((val1) < (val2))
#define QUICHE_DCHECK_GE_IMPL(val1, val2) QUICHE_DCHECK_IMPL((val1) >= (val2))
#define QUICHE_DCHECK_GT_IMPL(val1, val2) QUICHE_DCHECK_IMPL((val1) > (val2))

#define QUICHE_NOTREACHED_IMPL() QUICHE_DCHECK_IMPL(false)

#endif  // QUICHE_COMMON_PLATFORM_DEFAULT_QUICHE_PLATFORM_IMPL_QUICHE_LOGGING_IMPL_H_