#define BOOST_TEST_MODULE unicode_test

#include <boost/test/included/unit_test.hpp>
#include <boost/test/data/dataset.hpp>
#include <boost/test/data/monomorphic.hpp>
#include <boost/test/data/test_case.hpp>

#include <exception>
#include <string>
#include <tuple>
#include <type_traits>
#include <vector>

#include <unicode.h>

typedef std::tuple<std::basic_string<char8_t>, std::basic_string<char16_t>, std::basic_string<char32_t>> types_collection_type;

// create tuple of the same string, in UTF-8, UTF-16 and UTF-32
#define SUCCESS_TUPLE(x) {u8 ## x, u ## x, U ## x}

// Success cases: convert string to all other types, respectively
std::vector<types_collection_type> success_sets {
 SUCCESS_TUPLE(""),
 SUCCESS_TUPLE("ASCII string1"),
 SUCCESS_TUPLE("Täst just looks like German"),
 SUCCESS_TUPLE("\u732b is chinese for cat"),
 SUCCESS_TUPLE("\U0001F63A"),
 SUCCESS_TUPLE("\U0001F63A is a smiling cat"),
};

// Error cases: throwing upon convert to all other types
std::vector<std::basic_string<char8_t>> failure_strings_char8_t {
 u8"\x80",
 u8"\x81"
};

std::vector<std::basic_string<char16_t>> failure_strings_char16_t {
 u"\xD801",
};

std::vector<std::basic_string<char32_t>> failure_strings_char32_t {
 U"\xD801",
 U"\x10000000",
};

// output operators must be in same namespace as the type itself
namespace std {

std::ostream& operator<<(std::ostream& os, std::basic_string<char8_t> const& s)
{
 os << "[";
 for (auto& c: s)
  os << " " << std::to_string(static_cast<uint8_t>(c));
 os << "]";

 return os;
}

std::ostream& operator<<(std::ostream& os, std::basic_string<char16_t> const& s)
{
 os << "[";
 for (auto& c: s)
  os << " " << std::to_string(static_cast<uint16_t>(c));
 os << "]";

 return os;
}

std::ostream& operator<<(std::ostream& os, std::basic_string<char32_t> const& s)
{
 os << "[";
 for (auto& c: s)
  os << " " << std::to_string(static_cast<uint32_t>(c));
 os << "]";

 return os;
}

}

template<size_t i = 0, size_t j = 0, typename... Ts>
void test_utf_to_utf(std::tuple<Ts...>& t)
{
 typedef typename std::tuple_element<i,typename std::remove_reference<decltype(t)>::type>::type From;
 typedef typename std::tuple_element<j,typename std::remove_reference<decltype(t)>::type>::type To;

 // test
 To result { unicode::utf_to_utf<typename From::value_type, typename To::value_type>(std::get<i>(t)) };

 BOOST_CHECK_MESSAGE(std::get<j>(t) == result, "From " << typeid(From).name() << "(" << i << ", " << std::get<i>(t) << ") to " << typeid(To).name() << "(" << j << ", " << std::get<j>(t) << "), got " << result);

 //std::cout << std::to_string(std::tuple_size<typename std::remove_reference<decltype(t)>::type>::value) << "," << std::to_string(i) << "," << std::to_string(j) << std::endl;

 // iterate over other combinations
 if constexpr (i + 1 < std::tuple_size<typename std::remove_reference<decltype(t)>::type>::value)
  test_utf_to_utf<i + 1, j>(t);
 else if constexpr (j + 1 < std::tuple_size<typename std::remove_reference<decltype(t)>::type>::value)
  test_utf_to_utf<0, j + 1>(t);
}

// We don't use BOOST_DATA_TEST_CASE here because boost::test tries to assign
// a new variable to each tuple element which we don't want
// https://lists.boost.org/boost-bugs/2016/05/45214.php

BOOST_AUTO_TEST_CASE(utf_to_utf_success)
{
 for (auto& t: success_sets)
  test_utf_to_utf(t);
}

// iterate over std::tuple T types
template<typename From, typename Collection, size_t index = 0>
void test_utf_to_utf_failure(std::basic_string<From>& s)
{
 typedef typename std::tuple_element<index, Collection>::type::value_type To;

 try {
  unicode::utf_to_utf<From,To>(s);
  BOOST_FAIL("Expected exception at index: " << index << ", " << typeid(From).name() << " -> " << typeid(To).name());
 } catch (...) {
  // OK
 };

 // iterate over remaining types 
 if constexpr (index + 1 < std::tuple_size<Collection>::value)
  test_utf_to_utf_failure<From, Collection, index + 1>(s);
}

BOOST_AUTO_TEST_CASE(utf_to_utf_failure)
{
 for (auto& s: failure_strings_char8_t)
  test_utf_to_utf_failure<typename std::remove_reference<decltype(s)>::type::value_type, types_collection_type>(s);
 
 for (auto& s: failure_strings_char16_t)
  test_utf_to_utf_failure<typename std::remove_reference<decltype(s)>::type::value_type, types_collection_type>(s);

 for (auto& s: failure_strings_char32_t)
  test_utf_to_utf_failure<typename std::remove_reference<decltype(s)>::type::value_type, types_collection_type>(s);
}

BOOST_AUTO_TEST_CASE(is_valid_unicode)
{
 BOOST_CHECK(unicode::is_valid_unicode('\0'));
 BOOST_CHECK(unicode::is_valid_unicode(U'a'));
 BOOST_CHECK(unicode::is_valid_unicode(U'ä'));
 BOOST_CHECK(unicode::is_valid_unicode(U'\u732b')); // cat chinese
 BOOST_CHECK(unicode::is_valid_unicode(U'\U0001F63A')); // cat chinese
 BOOST_CHECK(unicode::is_valid_unicode(0x0001F63A)); // cat smiley

 BOOST_CHECK(!unicode::is_valid_unicode(0x00110000));
 BOOST_CHECK(!unicode::is_valid_unicode(0xFFFFFFFF)); // U"\UFFFFFFFF" is invalid C++
 BOOST_CHECK(!unicode::is_valid_unicode(0x01234567));
 BOOST_CHECK(!unicode::is_valid_unicode(0x12345678));
 BOOST_CHECK(!unicode::is_valid_unicode(0xD800));
 BOOST_CHECK(!unicode::is_valid_unicode(0xD987));
 BOOST_CHECK(!unicode::is_valid_unicode(0xDFFF));
}

// TODO:
// UTF-8
//  invalid bytes
//  an unexpected continuation byte
//  a non-continuation byte before the end of the character
//  the string ending before the end of the character (which can happen in simple string truncation)
//  an overlong encoding
//  a sequence that decodes to an invalid code point
//
//  high and low surrogate halves used by UTF-16 (U+D800 through U+DFFF) and code points not encodable by UTF-16 (those after U+10FFFF)
//
// char8_t, char16_t, char32_t, char, wchar_t (UTF-16 on Windows, UTF-32 on Linux)
// string, vector?
// uint8_t, uint16_t, uint32_t?