#ifndef TEST_H__
#define TEST_H__
/***************************************************************************************
 * @file tinytest.h                                                                    *
 *                                                                                     *
 * @brief Defines structs and functions for implementing TinyTest.                     *
 * @copyright Copyright 2023 Tom Hicks <headhunter3@gmail.com>                         *
 * Licensed under the MIT license see the LICENSE file for details.                    *
 ***************************************************************************************/

#include <cstdint>
#include <functional>
#include <initializer_list>
#include <iostream>
#include <optional>
#include <regex>
#include <sstream>
#include <string>
#include <string_view>
#include <tuple>
#include <utility>
#include <vector>

namespace TinyTest {
// Begin EscapeForPrinting
template <typename TChar, typename TTraits>
std::basic_string_view<TChar, TTraits> EscapeForPrinting(const std::basic_string_view<TChar, TTraits>& text) {
  return std::regex_replace(text, std::regex("\033"), "\\033");
}

template <typename TChar, typename TTraits>
std::basic_string<TChar, TTraits> EscapeForPrinting(const std::basic_string<TChar, TTraits>& text) {
  return std::regex_replace(text, std::regex("\033"), "\\033");
}

template <typename TChar>
std::basic_string<TChar> EscapeForPrinting(const TChar* text) {
  return std::regex_replace(text, std::regex("\033"), "\\033");
}

// End EscapeForPrinting

// Begin PrettyPrint
// std::string_view.
template <typename TChar, typename TTraits>
auto& PrettyPrint(std::basic_ostream<TChar, TTraits>& os, const std::basic_string_view<TChar, TTraits>& item) {
  os << "\"" << EscapeForPrinting(item) << "\"";
  return os;
}

// std::string.
template <typename TChar, typename TTraits>
auto& PrettyPrint(std::basic_ostream<TChar, TTraits>& os, const std::basic_string<TChar, TTraits>& item) {
  os << "\"" << EscapeForPrinting(item) << "\"";
  return os;
}

// const char*.
template <typename TChar, typename TTraits>
auto& PrettyPrint(std::basic_ostream<TChar, TTraits>& os, const TChar* item) {
  os << "\"" << EscapeForPrinting(item) << "\"";
  return os;
}

// tuple<...>
template <typename TChar, typename TTraits, typename... TArgs>
auto& PrettyPrint(std::basic_ostream<TChar, TTraits> os, const std::tuple<TArgs...>& tuple) {
  std::apply(
      [&os](auto&&... args) {
        if (sizeof...(TArgs) == 0) {
          os << "[]";
          return;
        }
        size_t n = 0;
        os << "[ ";
        ((PrettyPrint(os, args) << (++n != sizeof...(TArgs) ? ", " : "")), ...);
        os << " ]";
      },
      tuple);
  return os;
}

// containers
template <typename TChar,
          typename TTraits,
          typename TContainer,
          typename = std::enable_if_t<
              std::is_same_v<decltype(std::declval<TContainer>().begin()), decltype(std::declval<TContainer>().end())>>,
          typename = std::enable_if_t<std::is_base_of_v<
              std::input_iterator_tag,
              typename std::iterator_traits<decltype(std::declval<TContainer>().begin())>::iterator_category>>>
auto& PrettyPrint(std::basic_ostream<TChar, TTraits>& os, TContainer container) {
  os << "[ ";
  for (auto it = container.begin(); it != container.end(); it++) {
    if (it != container.begin()) {
      os << ", ";
    }
    PrettyPrint(os, *it);
  }
  os << " ]";
  return os;
}

// Catch-all for everything else.
template <typename TChar, typename TTraits, typename TItem>
auto& PrettyPrint(std::basic_ostream<TChar, TTraits>& os, TItem item) {
  os << item;
  return os;
}

// End PrettyPrint

// Begin PrettyPrintWithSeparator
// Prints args with separator between them. std::string_view separator.
template <typename TChar, typename TTraits, typename... TArgs>
auto& PrettyPrintWithSeparator(std::basic_ostream<TChar, TTraits> os,
                               std::basic_string_view<TChar, TTraits> separator,
                               TArgs&&... args) {
  (((PrettyPrint(os, args), os), EscapeForPrinting(separator)), ...);
  return os;
}

// Prints args with separator between them. std::string separator.
template <typename TChar, typename TTraits, typename... TArgs>
auto& PrettyPrintWithSeparator(std::basic_ostream<TChar, TTraits> os,
                               std::basic_string<TChar, TTraits> separator,
                               TArgs&&... args) {
  (((PrettyPrint_item(os, args), os), EscapeForPrinting(separator)), ...);
  return os;
}

// Prints args with separator between them. const char* separator.
template <typename TChar, typename TTraits, typename... Args>
auto& PrettyPrintWithSeparator(std::basic_ostream<TChar, TTraits> os, const TChar* separator, Args&&... args) {
  ((os << args << EscapeForPrinting(separator)), ...);
  return os;
}

// End PrettyPrintWithSeparator

////////////////////

// TODO: Document this.
template <typename TResult, typename... TParameters>
std::string InterceptCout(std::function<TResult(TParameters...)> fnToExecute,
                          std::optional<std::tuple<TParameters...>> maybe_args = std::nullopt) {
  std::ostringstream os;
  auto saved_buffer = std::cout.rdbuf();
  std::cout.rdbuf(os.rdbuf());
  // TODO: run the function

  if (maybe_args.has_value()) {
    std::apply(fnToExecute, maybe_args.value());
  } else {
    std::invoke(fnToExecute);
  }
  std::cout.rdbuf(saved_buffer);
  return os.str();
}

/// @brief
class TestResults {
 public:
  /// @brief Creates an empty TestResults instance representing no tests run.
  TestResults();

  /// @brief Creates a new TestResults instance that is a copy of other.
  /// @param other
  TestResults(const TestResults& other);

  /// @brief Creates a new TestResults instance with specific counts.
  /// @param errors The number of errors while running the tests.
  /// @param failed The number of failed tests.
  /// @param passed The number of passed tests.
  /// @param skipped The number of skipped tests.
  /// @param total The total number of tests run. This should equal the sum of
  /// failed, passed, and skipped tests.
  /// @param error_messages The list of error messages.
  /// @param failure_messages The list of failure messages.
  /// @param skip_messages The list of skip messages.
  TestResults(uint32_t errors,
              uint32_t failed,
              uint32_t passed,
              uint32_t skipped,
              uint32_t total,
              std::vector<std::string> error_messages,
              std::vector<std::string> failure_messages,
              std::vector<std::string> skip_messages);

  /// @brief Adds an error. This increments errors.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Error();

  /// @brief Adds an error with a message. This increments errors as well as
  /// saving the error message.
  /// @param message The error message.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Error(std::string message);

  /// @brief Adds a failed test. This increments total and failed.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Fail();

  /// @brief Adds a failed test with a message. This increments total and failed
  /// as well as saving the failure message.
  /// @param message The reason the test failed.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Fail(const std::string& message);

  /// @brief Adds a passed test. This increments total and passed.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Pass();

  /// @brief Adds a skipped test. This increments total and skipped.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Skip();

  /// @brief Adds a skipped test with a message. This increments total and
  /// skipped as well as saving the skip message.
  /// @param message The reason the test was skipped.
  /// @return A reference to this instance. Used for chaining.
  TestResults& Skip(const std::string& message);

  /// @brief Getter for the list of error messages.
  /// @return
  std::vector<std::string> ErrorMessages() const;

  /// @brief Getter for the count of errors.
  /// @return
  uint32_t Errors() const;

  /// @brief Getter for the count of failed tests.
  /// @return The count of failed tests.
  uint32_t Failed() const;

  /// @brief Getter for the list of failure messages.
  /// @return The list of failure messages.
  std::vector<std::string> FailureMessages() const;

  /// @brief Getter for the count of passed tests.
  /// @return The count of passed tests.
  uint32_t Passed() const;

  /// @brief Getter for the count of skipped tests.
  /// @return The count of skipped tests.
  uint32_t Skipped() const;

  /// @brief Getter for the list of skip messages.
  /// @return The list of skip messages.
  std::vector<std::string> SkipMessages() const;

  /// @brief Getter for the count of total tests.
  /// @return The count of total tests run.
  uint32_t Total() const;

  /// @brief Returns the combination of this and another TestResults instance.
  /// @param other The other TestResults instance to add to this one.
  /// @return The combination of the two TestResults instances.
  TestResults operator+(const TestResults& other) const;

  /// @brief Adds another TestResults to this one and returns a reference to
  /// this instance.
  /// @param other The other TestResults instance to add to this one.
  /// @return A reference to this instance.
  TestResults& operator+=(const TestResults& other);

 private:
  std::vector<std::string> error_messages_;
  uint32_t errors_;
  uint32_t failed_;
  std::vector<std::string> failure_messages_;
  uint32_t passed_;
  std::vector<std::string> skip_messages_;
  uint32_t skipped_;
  uint32_t total_;
};

/// @brief
/// @tparam TResult
template <typename TResult>
using TestCompareFunction = std::function<bool(const TResult& expected, const TResult& actual)>;

/// @brief
/// @tparam TResult
template <typename TResult>
using MaybeTestCompareFunction = std::optional<TestCompareFunction<TResult>>;

// TODO: Document this.
template <typename TResult>
MaybeTestCompareFunction<TResult> DefaultTestCompareFunction() {
  return std::nullopt;
}

// TODO: Document this.
using TestConfigureFunction = std::function<void()>;
// TODO: Document this.
using MaybeTestConfigureFunction = std::optional<TestConfigureFunction>;
// TOD: Document this.
MaybeTestConfigureFunction DefaultTestConfigureFunction();

// TODO: For some reason all hell breaks loose if test_name or expected output
// are const&. Figure out why. Probably need to use decay and make const& where we want it explicitly.
/// @brief
/// @tparam TResult
/// @tparam ...TInputParams
template <typename TResult, typename... TInputParams>
using TestTuple =
    std::tuple<std::string /* test_name */,
               TResult /* expected_output */,
               std::tuple<TInputParams...> /* input_params - The input parameters for this test. These will be used when
                                              calling std::apply with function_to_test to execute the test. */
               ,
               MaybeTestCompareFunction<TResult> /* test_Compare_function - If this is not nullprt then this function
                                                    will be called instead of suite_Compare_function to determine if the
                                                    test passes. Use this to check for side effects of the test. Return
                                                    true if the test passes and false otherwise. */
               ,
               MaybeTestConfigureFunction /* test_setup_function - If this is not nullptr this function is called before
                                             each test to setup the environment. It is called with std::apply and
                                             input_params so you can use them to mock records with specific IDs or
                                             calculate an expected result. */
               ,
               MaybeTestConfigureFunction /* test_teardown_function If this is not nullptr this function is called after
                                             each test to cleanup any allocated/shared resources. */
               ,
               bool /* is_enabled If this is false the test, setup, and teardown functions are not run. */>;

/// @brief
/// @tparam TResult
/// @tparam TFunctionToTest
/// @tparam ...TInputParams
template <typename TResult, typename... TInputParams>
using TestSuite = std::tuple<std::string,
                             std::function<TResult(TInputParams...)>,
                             std::initializer_list<TestTuple<TResult, TInputParams...>>,
                             MaybeTestCompareFunction<TResult>,
                             MaybeTestConfigureFunction,
                             MaybeTestConfigureFunction,
                             bool>;

TestResults& SkipTest(TestResults& results,
                      const std::string& suite_label,
                      const std::string& test_label,
                      std::optional<const std::string> reason = std::nullopt);

/// @brief
/// @tparam TResult The result type of the test.
/// @tparam TInputParams... The types of parameters sent to the test function.
/// @param suite_label The label for this test suite. For example a class name
/// such as "MortgageCalculator".
/// @param function_to_test The function to be tested. It will be called with
/// std::apply and a std::tuple<TInputParams...> made from each item in tests.
/// @param tests A std::vector of test runs.
/// @param suite_Compare A function used to Compare the expected and actual test
/// results. This can be overridden per test by setting test_Compare.
/// @param after_all This is called before each suite is started to setup the
/// environment. This is where you should build mocks, setup spies, and test
/// fixtures.
/// @param before_all This is called after each suite has completed to cleanup
/// anything allocated in suite_before_each.
/// @param is_enabled If false the test is reported as skipped. If true the test
/// is run as normal.
template <typename TResult, typename... TInputParams>
TestResults ExecuteSuite(std::string suite_label,
                         std::function<TResult(TInputParams...)> function_to_test,
                         std::initializer_list<TestTuple<TResult, TInputParams...>> tests,
                         MaybeTestCompareFunction<TResult> suite_Compare = std::nullopt,
                         MaybeTestConfigureFunction before_all = std::nullopt,
                         MaybeTestConfigureFunction after_all = std::nullopt,
                         bool is_enabled = true) {
  TestResults results;
  if (!is_enabled) {
    std::cout << "🚧Skipping suite: " << suite_label << " because it is disabled." << std::endl;
    for (auto test : tests) {
      std::string test_label = std::get<0>(test);
      SkipTest(results, suite_label, test_label, "the suite is disabled.");
    }
    return results;
  }
  if (tests.size() == 0) {
    std::cout << "🚧Skipping suite: " << suite_label << " because it is empty." << std::endl;
    return results;
  }
  std::cout << "🚀Beginning Suite: " << suite_label << std::endl;

  // Step 1: Suite Setup

  if (before_all.has_value()) {
    (*before_all)();
  }

  // Step 2: Execute Tests
  for_each(tests.begin(),
           tests.end(),
           [&suite_label, &function_to_test, &results, &suite_Compare](TestTuple<TResult, TInputParams...> test_data) {
             // Step 2a: Extract our variables from the TestTuple.
             const std::string& test_label = std::get<0>(test_data);
             const std::string qualified_test_label = suite_label + "::" + test_label;
             const TResult& expected_output = std::get<1>(test_data);
             std::tuple<TInputParams...> input_params = std::get<2>(test_data);
             MaybeTestCompareFunction<TResult> maybe_Compare_function = std::get<3>(test_data);
             TestCompareFunction<TResult> Compare_function =
                 maybe_Compare_function.has_value() ? *maybe_Compare_function
                 : suite_Compare.has_value()        ? *suite_Compare
                                                    : [](const TResult& l, const TResult& r) { return l == r; };
             MaybeTestConfigureFunction before_each = std::get<4>(test_data);
             MaybeTestConfigureFunction after_each = std::get<5>(test_data);
             bool is_enabled = std::get<6>(test_data);

             if (!is_enabled) {
               SkipTest(results, suite_label, test_label);
               return;
             }

             // Step 2b: Test Setup
             std::cout << "  Beginning Test: " << test_label << std::endl;
             if (before_each.has_value()) {
               (*before_each)();
             }

             TResult actual;
             try {
               // Step 2c: Execute the test method.
               actual = std::apply(function_to_test, input_params);
             } catch (const std::exception& ex) {
               std::ostringstream os;
               os << "Caught exception \"" << ex.what() << "\".";
               results.Error(qualified_test_label + " " + os.str());
               std::cout << "    🔥ERROR: " << os.str() << std::endl;
             } catch (const std::string& message) {
               std::ostringstream os;
               os << "Caught string \"" << message << "\".";
               results.Error(qualified_test_label + " " + os.str());
               std::cout << "    🔥ERROR: " << os.str() << std::endl;
             } catch (const char* message) {
               std::ostringstream os;
               os << "Caught c-string \"" << message << "\".";
               results.Error(qualified_test_label + " " + os.str());
               std::cout << "    🔥ERROR: " << os.str() << std::endl;
             } catch (...) {
               std::string message =
                   "Caught something that is neither an std::exception "
                   "nor an std::string.";
               results.Error(qualified_test_label + " " + message);
               std::cout << "    🔥ERROR: " << message << std::endl;
             }

             // Step 2d: Pass or fail.
             if (Compare_function(expected_output, actual)) {
               results.Pass();
               std::cout << "    ✅PASSED" << std::endl;
             } else {
               std::ostringstream os;
               os << "expected: \"" << expected_output << "\", actual: \"" << actual << "\"";
               results.Fail(qualified_test_label + " " + os.str());
               std::cout << "    ❌FAILED: " << os.str() << std::endl;
             }

             // Step 2e: Test Teardown
             if (after_each.has_value()) {
               (*after_each)();
             }
             std::cout << "  Ending Test: " << test_label << std::endl;
           });

  // Step 3: Suite Teardown
  if (after_all.has_value()) {
    (*after_all)();
  }
  std::cout << "Ending Suite: " << suite_label << std::endl;
  return results;
}

/// @brief
/// @tparam TResult The result type of the test.
/// @tparam TInputParams... The types of parameters sent to the test function.
/// @param test_suite A tuple representing the test suite configuration.
template <typename TResult, typename... TInputParams>
TestResults ExecuteSuite(const TestSuite<TResult, TInputParams...>& test_suite) {
  std::string suite_label = std::get<0>(test_suite);
  std::function<TResult(TInputParams...)> function_to_test = std::get<1>(test_suite);
  std::initializer_list<TestTuple<TResult, TInputParams...>> tests = std::get<2>(test_suite);
  MaybeTestCompareFunction<TResult> suite_Compare = sizeof(test_suite) > 3 ? std::get<3>(test_suite) : std::nullopt;
  MaybeTestConfigureFunction before_all = sizeof(test_suite) > 4 ? std::get<4>(test_suite) : std::nullopt;
  MaybeTestConfigureFunction after_all = sizeof(test_suite) > 5 ? std::get<5>(test_suite) : std::nullopt;
  bool is_enabled = sizeof(test_suite) > 6 ? std::get<6>(test_suite) : true;
  return ExecuteSuite(suite_label, function_to_test, tests, suite_Compare, before_all, after_all, is_enabled);
}

/// @brief
/// @tparam TResult The result type of the test.
/// @tparam ...TInputParams The types of parameters sent to the test function.
/// @param test_name The label for this test. For example "should calculate the
/// interest".
/// @param expected The expected output of calling the test function with these
/// input parameters.
/// @param input_params The input parameters to use when calling the test
/// function.
/// @param test_Compare_fn An optional function that can be used to Compare the
/// expected and actual return values. This is good for when you only care about
/// certain fields being equal.
/// @param before_each This is called to setup the environment before running
/// the test. This is where you should build mocks, setup spies, and set any
/// other values you need before calling the test function.
/// @param after_each This is called after each test run to cleanup anything
/// allocated in before_each.
/// @param is_enabled If false this test run is not executed and considered
/// skipped for reporting purposes.
/// @return A TestTuple suitable for use as a test run when calling test_fn.
template <typename TResult, typename... TInputParams>
TestTuple<TResult, TInputParams...> MakeTest(const std::string& test_name,
                                             const TResult& expected,
                                             std::tuple<TInputParams...> input_params,
                                             MaybeTestCompareFunction<TResult> test_Compare_fn = std::nullopt,
                                             MaybeTestConfigureFunction before_each = std::nullopt,
                                             MaybeTestConfigureFunction after_each = std::nullopt,
                                             bool is_enabled = true) {
  return make_tuple(test_name, expected, input_params, test_Compare_fn, before_each, after_each, is_enabled);
}

/// @brief
/// @tparam TResult
/// @tparam TFunctionToTest
/// @tparam ...TInputParams
/// @param suite_name
/// @param function_to_test
/// @param test_data
/// @param Compare
/// @param before_each
/// @param after_each
/// @param is_enabled
/// @return
template <typename TResult, typename TFunctionToTest, typename... TInputParams>
TestSuite<TResult, TInputParams...> MakeTestSuite(const std::string& suite_name,
                                                  TFunctionToTest function_to_test,
                                                  std::initializer_list<TestTuple<TResult, TInputParams...>> test_data,
                                                  MaybeTestCompareFunction<TResult> Compare = std::nullopt,
                                                  MaybeTestConfigureFunction before_each = std::nullopt,
                                                  MaybeTestConfigureFunction after_each = std::nullopt,
                                                  bool is_enabled = true) {
  return make_tuple(suite_name, function_to_test, test_data, Compare, before_each, after_each, is_enabled);
}

/// @brief Writes a friendly version of results to the provided stream.
/// @param os The stream to write to.
/// @param results The TestResults to write.
void PrintResults(std::ostream& os, TestResults results);

/// @brief
/// @param first
/// @param second
/// @return
MaybeTestConfigureFunction Coalesce(MaybeTestConfigureFunction first, MaybeTestConfigureFunction second);

// TODO: Document this.
// Tuple printer based on code from:
// https://stackoverflow.com/questions/6245735/pretty-print-stdtuple/31116392#58417285
template <typename TChar, typename TTraits, typename... TArgs>
auto& operator<<(std::basic_ostream<TChar, TTraits>& os, std::tuple<TArgs...> const& t) {
  std::apply(
      [&os](auto&&... args) {
        if (sizeof...(TArgs) == 0) {
          os << "[]";
          return;
        }
        size_t n = 0;
        os << "[ ";
        ((TinyTest::PrettyPrint(os, args) << (++n != sizeof...(TArgs) ? ", " : "")), ...);
        os << " ]";
      },
      t);
  return os;
}

// TODO: Document this.
template <typename TChar, typename TTraits>
auto& operator<<(std::basic_ostream<TChar, TTraits>& os, const void* pointer) {
  os << pointer;
}

// TODO: Simplify this.
template <typename TChar,
          typename TTraits,
          typename TContainer,
          typename = std::enable_if_t<
              std::is_same_v<decltype(std::declval<TContainer>().begin()), decltype(std::declval<TContainer>().end())>>,
          typename = std::enable_if_t<std::is_base_of_v<
              std::input_iterator_tag,
              typename std::iterator_traits<decltype(std::declval<TContainer>().begin())>::iterator_category>>>
auto& operator<<(std::basic_ostream<TChar, TTraits>& os, TContainer container) {
  os << "[ ";
  for (auto it = container.begin(); it != container.end(); it++) {
    if (it != container.begin()) {
      os << ", ";
    }
    TinyTest::PrettyPrint(os, *it);
  }
  os << " ]";
  return os;
}

// TODO: Document this.
template <typename TChar, typename TTraits, typename TItem>
auto& operator<<(std::basic_ostream<TChar, TTraits>& os, std::initializer_list<TItem> container) {
  os << "[ ";
  for (auto it = container.begin(); it != container.end(); it++) {
    if (it != container.begin()) {
      os << ", ";
    }
    TinyTest::PrettyPrint(os, *it);
  }
  os << " ]";
  return os;
}

// TODO: Document this.
template <typename TChar, typename TTraits, typename TItem>
auto& Compare(std::basic_ostream<TChar, TTraits>& error_message,
              std::vector<TItem> expected,
              std::vector<TItem> actual) {
  if (expected.size() != actual.size()) {
    error_message << "size mismatch expected: " << expected.size() << ", actual: " << actual.size();
    return error_message;
  }

  for (size_t index = 0; index < expected.size(); index++) {
    if (expected[index] != actual[index]) {
      error_message << "vectors differ at index " << index << ", \"" << expected[index] << "\" != \"" << actual[index]
                    << "\", expected: \"" << expected << "\", actual: \"" << actual << "\"";
      return error_message;
    }
  }
  return error_message;
}

}  // End namespace TinyTest

#endif  // End !defined TEST_H__