/*
 * Copyright 2015-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

/*
 * This file contains additional gtest-style check macros to use in unit tests.
 *
 * - SKIP(), SKIP_IF(EXPR)
 * - EXPECT_THROW_RE(), ASSERT_THROW_RE()
 * - EXPECT_THROW_ERRNO(), ASSERT_THROW_ERRNO()
 * - AreWithinSecs()
 *
 * Additionally, it includes a PrintTo() function for StringPiece.
 * Including this file in your tests will ensure that StringPiece is printed
 * nicely when used in EXPECT_EQ() or EXPECT_NE() checks.
 */

#include <chrono>
#include <regex>
#include <system_error>
#include <type_traits>

#include <folly/Conv.h>
#include <folly/ExceptionString.h>
#include <folly/Range.h>
#include <folly/portability/GTest.h>

// SKIP() is used to mark a test skipped if we could not successfully execute
// the test due to runtime issues or behavior that do not necessarily indicate
// a problem with the code.
//
// googletest does not have a built-in mechanism to report tests as skipped a
// run time.  We either report the test as successful or failure based on the
// FOLLY_SKIP_AS_FAILURE configuration setting.  The default is to report the
// test as successful.  Enabling FOLLY_SKIP_AS_FAILURE can be useful with a
// test harness that can identify the "Test skipped by client" in the failure
// message and convert this into a skipped test result.
#if FOLLY_SKIP_AS_FAILURE
#define SKIP() GTEST_FATAL_FAILURE_("Test skipped by client")
#else
#define SKIP() return GTEST_SUCCESS_("Test skipped by client")
#endif

// Encapsulate conditional-skip, since it's nontrivial to get right.
#define SKIP_IF(expr)           \
  GTEST_AMBIGUOUS_ELSE_BLOCKER_ \
  if (!(expr)) {                \
  } else                        \
    SKIP()

#define TEST_THROW_ERRNO_(statement, errnoValue, fail)       \
  GTEST_AMBIGUOUS_ELSE_BLOCKER_                              \
  if (::folly::test::detail::CheckResult gtest_result =      \
          ::folly::test::detail::checkThrowErrno(            \
              [&] { statement; }, errnoValue, #statement)) { \
  } else                                                     \
    fail(gtest_result.what())

/**
 * Check that a statement throws a std::system_error with the expected errno
 * value.  This is useful for checking code that uses the functions in
 * folly/Exception.h to throw exceptions.
 *
 * Like other EXPECT_* and ASSERT_* macros, additional message information
 * can be included using the << stream operator.
 *
 * Example usage:
 *
 *   EXPECT_THROW_ERRNO(readFile("notpresent.txt"), ENOENT)
 *     << "notpresent.txt should not exist";
 */
#define EXPECT_THROW_ERRNO(statement, errnoValue) \
  TEST_THROW_ERRNO_(statement, errnoValue, GTEST_NONFATAL_FAILURE_)
#define ASSERT_THROW_ERRNO(statement, errnoValue) \
  TEST_THROW_ERRNO_(statement, errnoValue, GTEST_FATAL_FAILURE_)

#define TEST_THROW_RE_(statement, exceptionType, pattern, fail)           \
  GTEST_AMBIGUOUS_ELSE_BLOCKER_                                           \
  if (::folly::test::detail::CheckResult gtest_result =                   \
          ::folly::test::detail::checkThrowRegex<exceptionType>(          \
              [&] { statement; }, pattern, #statement, #exceptionType)) { \
  } else                                                                  \
    fail(gtest_result.what())

/**
 * Check that a statement throws the expected exception type, and that the
 * exception message matches the specified regular expression.
 *
 * Partial matches (against just a portion of the error message) are accepted
 * if the regular expression does not explicitly start with "^" and end with
 * "$".  (The matching is performed using std::regex_search() rather than
 * std::regex_match().)
 *
 * This uses ECMA-262 style regular expressions (the default behavior of
 * std::regex).
 *
 * Like other EXPECT_* and ASSERT_* macros, additional message information
 * can be included using the << stream operator.
 *
 * Example usage:
 *
 *   EXPECT_THROW_RE(badFunction(), std::runtime_error, "oh noes")
 *     << "function did not throw the expected exception";
 */
#define EXPECT_THROW_RE(statement, exceptionType, pattern) \
  TEST_THROW_RE_(statement, exceptionType, pattern, GTEST_NONFATAL_FAILURE_)
#define ASSERT_THROW_RE(statement, exceptionType, pattern) \
  TEST_THROW_RE_(statement, exceptionType, pattern, GTEST_FATAL_FAILURE_)

namespace folly {
namespace test {

template <typename T1, typename T2>
::testing::AssertionResult
AreWithinSecs(T1 val1, T2 val2, std::chrono::seconds acceptableDeltaSecs) {
  auto deltaSecs =
      std::chrono::duration_cast<std::chrono::seconds>(val1 - val2);
  if (deltaSecs <= acceptableDeltaSecs &&
      deltaSecs >= -1 * acceptableDeltaSecs) {
    return ::testing::AssertionSuccess();
  } else {
    return ::testing::AssertionFailure()
        << val1.count() << " and " << val2.count() << " are not within "
        << acceptableDeltaSecs.count() << " secs of each other";
  }
}

namespace detail {

/**
 * Helper class for implementing test macros
 */
class CheckResult {
 public:
  explicit CheckResult(bool s) noexcept : success_(s) {}

  explicit operator bool() const noexcept {
    return success_;
  }
  const char* what() const noexcept {
    return message_.c_str();
  }

  /**
   * Support the << operator for building up the error message.
   *
   * The arguments are treated as with folly::to<string>(), and we do not
   * support iomanip parameters.  The main reason we use the << operator
   * as opposed to a variadic function like folly::to is that clang-format
   * formats long statements using << much nicer than function call arguments.
   */
  template <typename T>
  CheckResult& operator<<(T&& t) {
    toAppend(std::forward<T>(t), &message_);
    return *this;
  }

 private:
  bool success_;
  std::string message_;
};

/**
 * Helper function for implementing EXPECT_THROW
 */
template <typename Fn>
CheckResult checkThrowErrno(Fn&& fn, int errnoValue, const char* statementStr) {
  try {
    fn();
  } catch (const std::system_error& ex) {
    // TODO: POSIX errno values should use std::generic_category(), but
    // folly/Exception.h incorrectly throws them using std::system_category()
    // at the moment.
    // For now we also accept std::system_category so that we will also handle
    // exceptions from folly/Exception.h correctly.
    if (ex.code().category() != std::generic_category() &&
        ex.code().category() != std::system_category()) {
      return CheckResult(false)
          << "Expected: " << statementStr << " throws an exception with errno "
          << errnoValue << " (" << std::generic_category().message(errnoValue)
          << ")\nActual: it throws a system_error with category "
          << ex.code().category().name() << ": " << ex.what();
    }
    if (ex.code().value() != errnoValue) {
      return CheckResult(false)
          << "Expected: " << statementStr << " throws an exception with errno "
          << errnoValue << " (" << std::generic_category().message(errnoValue)
          << ")\nActual: it throws errno " << ex.code().value() << ": "
          << ex.what();
    }
    return CheckResult(true);
  } catch (const std::exception& ex) {
    return CheckResult(false)
        << "Expected: " << statementStr << " throws an exception with errno "
        << errnoValue << " (" << std::generic_category().message(errnoValue)
        << ")\nActual: it throws a different exception: " << exceptionStr(ex);
  } catch (...) {
    return CheckResult(false)
        << "Expected: " << statementStr << " throws an exception with errno "
        << errnoValue << " (" << std::generic_category().message(errnoValue)
        << ")\nActual: it throws a non-exception type";
  }
  return CheckResult(false)
      << "Expected: " << statementStr << " throws an exception with errno "
      << errnoValue << " (" << std::generic_category().message(errnoValue)
      << ")\nActual: it throws nothing";
}

/**
 * Helper function for implementing EXPECT_THROW_RE
 */
template <typename ExType, typename Fn>
CheckResult checkThrowRegex(
    Fn&& fn,
    const char* pattern,
    const char* statementStr,
    const char* excTypeStr) {
  static_assert(
      std::is_base_of<std::exception, ExType>::value,
      "EXPECT_THROW_RE() exception type must derive from std::exception");

  try {
    fn();
  } catch (const std::exception& ex) {
    const auto* derived = dynamic_cast<const ExType*>(&ex);
    if (!derived) {
      return CheckResult(false)
          << "Expected: " << statementStr << "throws a " << excTypeStr
          << ")\nActual: it throws a different exception type: "
          << exceptionStr(ex);
    }

    std::regex re(pattern);
    if (!std::regex_search(derived->what(), re)) {
      return CheckResult(false)
          << "Expected: " << statementStr << " throws a " << excTypeStr
          << " with message matching \"" << pattern
          << "\"\nActual: message is: " << derived->what();
    }
    return CheckResult(true);
  } catch (...) {
    return CheckResult(false)
        << "Expected: " << statementStr << " throws a " << excTypeStr
        << ")\nActual: it throws a non-exception type";
  }
  return CheckResult(false) << "Expected: " << statementStr << " throws a "
                            << excTypeStr << ")\nActual: it throws nothing";
}

} // namespace detail
} // namespace test

// Define a PrintTo() function for StringPiece, so that gtest checks
// will print it as a string.  Without this gtest identifies StringPiece as a
// container type, and therefore tries printing its elements individually,
// despite the fact that there is an ostream operator<<() defined for
// StringPiece.
inline void PrintTo(StringPiece sp, ::std::ostream* os) {
  // gtest's PrintToString() function will quote the string and escape internal
  // quotes and non-printable characters, the same way gtest does for the
  // standard string types.
  *os << ::testing::PrintToString(sp.str());
}

} // namespace folly