#include <poe/util/utf.hpp>

#include <vector>

#ifdef _WIN32
#include <Windows.h>
#else
#include <unicase.h>
#include <unistr.h>
#endif

namespace poe::util {
	bool less_without_case_predicate::operator()(std::u16string_view a, std::u16string_view b) const {
#if _WIN32
		return CompareStringEx(LOCALE_NAME_INVARIANT, LINGUISTIC_IGNORECASE, reinterpret_cast<LPCWCH>(a.data()),
			static_cast<int>(a.size()), reinterpret_cast<LPCWCH>(b.data()), static_cast<int>(b.size()),
			nullptr, nullptr, 0) == CSTR_LESS_THAN;
#else
		return lowercase(a) < lowercase(b);
#endif
	}

	std::u16string lowercase(std::u16string_view s) {
		if (s.empty()) {
			return std::u16string(s);
		}
#ifdef _WIN32
		auto src = reinterpret_cast<LPCWSTR>(s.data());
		auto src_cch = static_cast<int>(s.size());
		auto dst_cch = LCMapStringEx(LOCALE_NAME_INVARIANT, LCMAP_LOWERCASE, src, src_cch, nullptr, 0, nullptr, nullptr, 0);
		std::vector<char16_t> dst(dst_cch);
		LCMapStringEx(LOCALE_NAME_INVARIANT, LCMAP_LOWERCASE, src, src_cch, reinterpret_cast<LPWSTR>(dst.data()), dst_cch,
			nullptr, nullptr, 0);
		return std::u16string(std::u16string_view(dst.data(), dst.size()));
#else
		// TODO(LV): implement

		auto src = reinterpret_cast<uint16_t const*>(s.data());
		size_t dst_cch = 0;
		u16_tolower(src, s.size(), nullptr, nullptr, nullptr, &dst_cch);
		std::vector<char16_t> dst(dst_cch);
		u16_tolower(src, s.size(), nullptr, nullptr, reinterpret_cast<uint16_t*>(dst.data()), &dst_cch);
		return std::u16string(std::u16string_view(dst.data(), dst.size()));
#endif
	}

	namespace {
		template <typename String> void convert_string(std::u16string_view src, String& dest) {
            using CharT = typename String::value_type;
#ifdef _WIN32
			LPCWCH src_p = reinterpret_cast<LPCWCH>(src.data());
			int src_n = static_cast<int>(src.size());
			int cch = WideCharToMultiByte(CP_UTF8, 0, src_p, src_n, nullptr, 0, nullptr, nullptr);
			std::vector<char> buf(cch);
			WideCharToMultiByte(CP_UTF8, 0, src_p, src_n, buf.data(), static_cast<int>(buf.size()), nullptr, nullptr);
			dest.assign(reinterpret_cast<typename String::value_type*>(buf.data()), buf.size());
#else
			size_t cch{};
			uint8_t* p = u16_to_u8(reinterpret_cast<uint16_t const*>(src.data()), src.size(), nullptr, &cch);
			dest.assign(reinterpret_cast<CharT*>(p), cch);
			free(p);
#endif
		}

		void convert_string(std::string_view src, std::u16string& dest) {
#ifdef _WIN32
			LPCCH src_p = reinterpret_cast<LPCCH>(src.data());
			int src_n = static_cast<int>(src.size());
			int cch = MultiByteToWideChar(CP_UTF8, 0, src_p, src_n, nullptr, 0);
			std::vector<wchar_t> buf(cch);
			MultiByteToWideChar(CP_UTF8, 0, src_p, src_n, buf.data(), static_cast<int>(buf.size()));
			dest.assign(reinterpret_cast<char16_t*>(buf.data()), buf.size());
#else
			size_t cch{};
			uint16_t* p = u8_to_u16(reinterpret_cast<uint8_t const*>(src.data()), src.size(), nullptr, &cch);
			dest.assign(reinterpret_cast<char16_t*>(p), cch);
			free(p);
#endif
		}
	} // namespace

	std::string to_string(std::u16string_view s) {
		std::string ret;
		convert_string(s, ret);
		return ret;
	}
	std::u16string to_u16string(std::string_view s) {
		std::u16string ret;
		convert_string(s, ret);
		return ret;
	}
} // namespace poe::util