#pragma once

#include <charconv>
#include <cmath>
#include <cstring>
#include <expected>
#include <format>
#include <numbers>
#include <ranges>
#include <regex>
#include "mcc_traits.h"

namespace mcc::utils
{

static const std::regex decimalNumberRx{" *[-+]?([0-9]*[.])?[0-9]+([eE][-+]?[0-9]+)? *"};
static const std::regex sexagesimalReprRx{" *[-+]?[0-9]{1,2}:[0-9]{1,2}:([0-9]{0,2}[.])?[0-9]+ *"};


constexpr static bool isEqual(std::floating_point auto const& v1, std::floating_point auto const& v2)
{
    constexpr auto eps = std::numeric_limits<std::common_type_t<decltype(v1), decltype(v2)>>::epsilon();

    return std::fabs(v1 - v2) <= eps * std::fmax(std::fabs(v1), std::fabs(v2));
}

enum class TrimType { TRIM_LEFT, TRIM_RIGHT, TRIM_BOTH };

template <std::ranges::contiguous_range R>
constexpr static std::string_view trimSpaces(R&& r, TrimType type = TrimType::TRIM_BOTH)
    requires std::same_as<char, std::remove_cvref_t<std::ranges::range_value_t<R>>>
{
    auto is_space = [](const auto& ch) { return ch == ' '; };

    auto end = std::forward<R>(r).end();

    auto f1 = std::forward<R>(r).begin();

    if (type != TrimType::TRIM_RIGHT) {
        // look for the first non-space symbol
        f1 = std::ranges::find_if_not(std::forward<R>(r), is_space);
        if (f1 == end) {  // all are spaces!
            return std::string_view();
        }
    }

    auto f2 = end;

    if (type != TrimType::TRIM_LEFT) {
        auto f3 = f1;

        do {
            f2 = std::ranges::find_if(++f3, end, is_space);
            if (f2 == end)
                break;
            f3 = std::ranges::find_if_not(f2 + 1, end, is_space);
        } while (f3 != end);
    }

    return std::string_view(f1, f2);
}

constexpr static std::string_view trimSpaces(const char* r, TrimType type = TrimType::TRIM_BOTH)
{
    return trimSpaces(std::string_view(r), type);
}

template <typename T, std::ranges::contiguous_range R>
std::optional<T> numFromStr(R&& r)
    requires((std::integral<T> || std::floating_point<T>) &&
             std::same_as<char, std::remove_cvref_t<std::ranges::range_value_t<R>>>)
{
    T val;
    const char* end_ptr = &*r.end();

    if constexpr (std::integral<T>) {
        auto cvt_res = std::from_chars(&*r.begin(), &*r.end(), val);
        if (cvt_res.ec != std::errc()) {
            return std::nullopt;
        } else if (cvt_res.ptr != end_ptr) {
            return std::nullopt;
        }
    } else {
#ifdef _LIBCPP_VERSION  // clang's libc++ does not have floating-point overloads for std::from_chars
        std::string s{str.begin(), str.end()};
        size_t pos;

        try {
            if constexpr (std::same_as<T, float>) {
                val = std::stof(s, &pos);
            } else if constexpr (std::same_as<T, double>) {
                val = std::stod(s, &pos);
            } else {
                val = std::stold(s, &pos);
            }
        } catch (...) {
            return std::nullopt;
        }

        if (pos != s.size()) {
            return std::nullopt;
        }
#else
        auto cvt_res = std::from_chars(&*r.begin(), &*r.end(), val);

        if (cvt_res.ec != std::errc()) {
            return std::nullopt;
        } else if (cvt_res.ptr != end_ptr) {
            return std::nullopt;
        }
#endif
    }

    return val;
}

template <std::ranges::contiguous_range R>
static std::optional<double> parsAngleString(R&& r, bool hms = false)
    requires std::same_as<char, std::remove_cvref_t<std::ranges::range_value_t<R>>>
{
    auto str = trimSpaces(std::forward<R>(r));

    bool ok = std::regex_match(str.begin(), str.end(), decimalNumberRx);

    if (ok) {
        return numFromStr<double>(str);
    }

    ok = std::regex_match(str.begin(), str.end(), sexagesimalReprRx);

    if (ok) {
        auto str = trimSpaces(std::forward<R>(r));
        auto parts = std::views::split(str, std::string_view(":"));

        double val;

        double p1 = numFromStr<double>(*parts.begin()).value();
        val = std::abs(p1);
        double dv = 60.0;
        for (auto const& v : parts | std::views::drop(1)) {
            val += numFromStr<double>(v).value() / dv;
            dv *= 60.0;
        }
        // val += numFromStr<double>(parts[1]) / 60.0;
        // val += numFromStr<double>(parts[2]) / 3600.0;
        if (p1 < 0) {
            val = -val;
        }

        if (hms) {
            val *= 15.0;
        }

        return val;
    }


    return std::nullopt;
}

static std::optional<double> parsAngleString(const char* s, bool hms = false)
{
    return parsAngleString(std::span{s, std::strlen(s)}, hms);
}


static constexpr auto deg2radCoeff = std::numbers::pi / 180.0;

// radians to degrees
template <bool NORM = false>
static double rad2deg(double ang)
{
    auto r = ang / deg2radCoeff;

    if constexpr (NORM) {
        return std::fmod(r, 360.0);
    } else {
        return r;
    }
}


template <std::ranges::output_range<char> R, bool NORM = false>
static R rad2deg_str(double ang, int prec = 6)
{
    R res;

    std::string fmt = "{:0." + std::to_string(prec) + "f}";

    auto degs = rad2deg<NORM>(ang);

    std::vformat_to(std::back_inserter(res), {fmt.begin(), fmt.end()}, std::make_format_args(degs));

    return res;
}

template <bool NORM = false>
static std::string rad2deg_str(double ang, int prec = 6)
{
    return rad2deg_str<std::string, NORM>(ang, prec);
}


template <std::ranges::output_range<char> R, bool NORM = false>
static R rad2deg_str(double ang1, double ang2, std::string_view delim = ",", int prec1 = 6, int prec2 = 6)
{
    R res = rad2deg_str<R, NORM>(ang1, prec1);

    R r = rad2deg_str<R, NORM>(ang2, prec2);

    std::ranges::copy(delim, std::back_inserter(res));
    std::ranges::copy(r, std::back_inserter(res));

    return res;
}

template <bool NORM = false>
static std::string rad2deg_str(double ang1, double ang2, std::string_view delim = ",", int prec1 = 6, int prec2 = 6)
{
    return rad2deg_str<std::string, NORM>(ang1, ang2, delim, prec1, prec2);
}

// radians to sexagesimal
template <std::ranges::output_range<char> R, bool NORM = false>
static R rad2sxg(double ang, bool hms = false, int prec = 2)
{
    R res;

    if (!std::isfinite(ang)) {
        std::vformat_to(std::back_inserter(res), "{}", std::make_format_args(ang));
        return res;
    }

    std::string fmt = "{:02.0f}:{:02.0f}:{:0" + std::to_string(prec + 3) + "." + std::to_string(prec) + "f}";
    // std::string fmt = "{:02.0f}:{:02.0f}:{:02." + std::to_string(prec) + "f}";

    auto degs = rad2deg<NORM>(std::abs(ang));
    if (hms) {
        degs /= 15.0;
    }

    auto term = 10.0;
    for (int i = 1; i < prec; ++i) {
        term *= 10.0;
    }

    auto d = std::trunc(degs);
    auto s = (degs - d) * 60.0;
    auto m = std::trunc(s);

    s = (s - m) * 60.0;
    // round to given precision
    s = std::round(s * term) / term;
    if (isEqual(s, 60.0)) {
        m += 1.0;
        s = 0.0;
        if (isEqual(m, 60.0)) {
            d += 1.0;
            m = 0.0;
        }
    }

    if (ang < 0) {
        std::ranges::copy(std::string_view("-"), std::back_inserter(res));
    }

    std::vformat_to(std::back_inserter(res), std::string_view{fmt.begin(), fmt.end()}, std::make_format_args(d, m, s));

    return res;
}

template <bool NORM = false>
static std::string rad2sxg(double ang, bool hms = false, int prec = 2)
{
    return rad2sxg<std::string, NORM>(ang, hms, prec);
}


template <std::ranges::output_range<char> R, bool NORM = false>
static R RADEC_rad2sxg(double ra, double dec, std::string_view delim = ",", int ra_prec = 2, int dec_prec = 1)
{
    R res = rad2sxg<R, NORM>(ra, true, ra_prec);

    R r = rad2sxg(dec, false, dec_prec);

    std::ranges::copy(delim, std::back_inserter(res));
    std::ranges::copy(r, std::back_inserter(res));

    return res;
}

template <bool NORM = false>
static std::string RADEC_rad2sxg(double ra, double dec, std::string_view delim = ",", int ra_prec = 2, int dec_prec = 1)
{
    return RADEC_rad2sxg<std::string, NORM>(ra, dec, delim, ra_prec, dec_prec);
}


template <std::ranges::output_range<char> R, bool NORM = false>
static R AZZD_rad2sxg(double az, double zd, std::string_view delim = ",", int az_prec = 2, int zd_prec = 1)
{
    R res = rad2sxg<R, NORM>(az, false, az_prec);

    R r = rad2sxg(zd, false, zd_prec);

    std::ranges::copy(delim, std::back_inserter(res));
    std::ranges::copy(r, std::back_inserter(res));

    return res;
}

template <bool NORM = false>
static std::string AZZD_rad2sxg(double az, double zd, std::string_view delim = ",", int az_prec = 2, int zd_prec = 1)
{
    return AZZD_rad2sxg<std::string, NORM>(az, zd, delim, az_prec, zd_prec);
}


// string to pair of angles
// " 12.3453467,102.4345346"
// "12:43:23.423,  102:43:12.124"
// "  12.3453467, 102:43:12.124  "
template <mcc::traits::mcc_input_char_range R>
std::pair<double, double> parseAnglePair(R&& str, bool hms1 = false, bool hms2 = false, std::string_view delim = ",")
{
    std::pair<double, double> res{std::numeric_limits<double>::quiet_NaN(), std::numeric_limits<double>::quiet_NaN()};
    auto found1 = std::ranges::search(std::forward<R>(str), delim);

    if (found1.empty()) {
        return res;
    }

    std::string s1, s2;
    std::ranges::copy(str.begin(), found1.begin(), std::back_inserter(s1));

    auto rem_len = std::distance(found1.end(), str.end());
    if (!rem_len) {
        return res;
    }

    auto found2 = std::ranges::search(found1.end(), str.end(), delim.begin(), delim.end());
    if (found2.empty()) {
        std::ranges::copy(found1.end(), str.end(), std::back_inserter(s2));
    } else {
        std::ranges::copy(found1.end(), found2.end(), std::back_inserter(s2));
    }

    auto vo1 = parsAngleString(s1, hms1);
    if (vo1) {
        auto vo2 = parsAngleString(s2, hms2);
        if (vo2) {
            res = {vo1.value(), vo2.value()};
        }
    }

    return res;
}


template <traits::mcc_input_char_range R>
static constexpr size_t FNV1aHash(const R& r)
{
    static_assert(sizeof(size_t) == 8 || sizeof(size_t) == 4, "ONLY FOR 32 or 64-bit size_t!!!");

    size_t hash = 0, prime = 0;
    if constexpr (sizeof(size_t) == 8) {  // 64-bit
        prime = 1099511628211UL;
        hash = 14695981039346656037UL;
    } else if constexpr (sizeof(size_t) == 4) {  // 32-bit
        prime = 16777619;
        hash = 2166136261;
    }

    for (const char& ch : r) {
        hash ^= ch;
        hash *= prime;
    }

    return hash;
}

static constexpr size_t FNV1aHash(std::forward_iterator auto begin, std::sentinel_for<decltype(begin)> auto end)
    requires std::same_as<std::remove_cv_t<std::iter_value_t<decltype(begin)>>, char>
{
    static_assert(sizeof(size_t) == 8 || sizeof(size_t) == 4, "ONLY FOR 32 or 64-bit size_t!!!");

    size_t hash = 0, prime = 0;
    if constexpr (sizeof(size_t) == 8) {  // 64-bit
        prime = 1099511628211UL;
        hash = 14695981039346656037UL;
    } else if constexpr (sizeof(size_t) == 4) {  // 32-bit
        prime = 16777619;
        hash = 2166136261;
    }

    for (auto it = begin; it != end; ++it) {
        hash ^= *it;
        hash *= prime;
    }

    return hash;
}


class MccSimpleDeserializer
{
public:
    static constexpr std::string_view RANGE_DELIM_SEQ = ",";

    MccSimpleDeserializer() : _rangeDelim(RANGE_DELIM_SEQ) {}

    template <traits::mcc_input_char_range R>
    MccSimpleDeserializer(R&& r) : MccSimpleDeserializer()
    {
        setRangeDelim(std::forward<R>(r));
    }

    template <traits::mcc_input_char_range R>
    MccSimpleDeserializer& setRangeDelim(R&& r)
    {
        if (std::ranges::size(std::forward<R>(r))) {
            _rangeDelim.clear();
            std::ranges::copy(std::forward<R>(r), std::back_inserter(_rangeDelim));
        }

        return *this;
    }

    template <traits::mcc_output_char_range R>
    R getRangeDelim() const
    {
        R r;

        std::ranges::copy(_rangeDelim, std::back_inserter(r));

        return r;
    }

    std::string getRangeDelim() const
    {
        return getRangeDelim<std::string>();
    }

    template <traits::mcc_input_char_range IR, typename VT>
    std::error_code operator()(IR&& bytes, VT& value)
    {
        std::error_code ret{};

        if constexpr (std::is_arithmetic_v<VT>) {
            auto v = mcc::utils::numFromStr<VT>(trimSpaces(bytes));
            if (!v.has_value()) {
                return std::make_error_code(std::errc::invalid_argument);
            }

            value = v.value();
        } else if constexpr (mcc::traits::mcc_output_char_range<VT>) {
            VT r;
            std::ranges::copy(bytes, std::back_inserter(r));
            value = r;
        } else if constexpr (std::ranges::range<VT>) {
            using el_t = std::ranges::range_value_t<VT>;

            if constexpr (std::is_reference_v<el_t> || std::is_const_v<el_t>) {  // no reference or constants allowed
                return std::make_error_code(std::errc::invalid_argument);
            }

            VT r;
            el_t elem;

            auto els = std::views::split(bytes, _rangeDelim);

            for (auto const& el : els) {
                ret = (*this)(std::string_view(el), elem);
                if (!ret) {
                    std::back_inserter(r) = elem;
                } else {
                    return std::make_error_code(std::errc::invalid_argument);
                }
            }

            value = r;
        } else if constexpr (mcc::traits::mcc_time_duration_c<VT>) {
            typename VT::rep vd;

            ret = (*this)(trimSpaces(bytes), vd);
            if (!ret) {
                value = VT{vd};
            }
        } else {
            ret = std::make_error_code(std::errc::invalid_argument);
        }

        return ret;
    }

protected:
    std::string _rangeDelim;
};


/*    key-value pair holder    */

// to follow std::variant requirements (not references, not array, not void)
template <typename T>
concept variant_valid_type_c = requires { !std::is_array_v<T> && !std::is_void_v<T> && !std::is_reference_v<T>; };


template <typename T>
concept keyvalue_record_c = requires(T t) {
    requires std::same_as<decltype(t.key), std::string_view>;
    requires variant_valid_type_c<decltype(t.value)>;
};


template <typename T>
concept keyvalue_desc_c = requires(T t) { []<keyvalue_record_c... Ts>(std::tuple<Ts...>) {}(t); };


template <keyvalue_desc_c DESCR_T>
class KeyValueHolder
{
public:
    static constexpr std::string_view COMMENT_SEQ{"#"};
    static constexpr std::string_view KEY_VALUE_DELIM{"="};
    static constexpr std::string_view VALUE_ARRAY_DELIM{","};

    inline static auto defaultDeserializeFunc = []<typename VT>(this auto&& self, std::string_view str, VT& value) {
        std::error_code ret{};

        if constexpr (std::is_arithmetic_v<VT>) {
            auto v = mcc::utils::numFromStr<VT>(trimSpaces(str));
            if (!v.has_value()) {
                return std::make_error_code(std::errc::invalid_argument);
            }

            value = v.value();
        } else if constexpr (mcc::traits::mcc_output_char_range<VT>) {
            VT r;
            std::ranges::copy(str, std::back_inserter(r));
            value = r;
        } else if constexpr (std::ranges::range<VT>) {
            using el_t = std::ranges::range_value_t<VT>;

            if constexpr (std::is_reference_v<el_t> || std::is_const_v<el_t>) {  // no reference or constants allowed
                return std::make_error_code(std::errc::invalid_argument);
            }

            VT r;
            el_t elem;

            auto els = std::views::split(str, VALUE_ARRAY_DELIM);

            for (auto const& el : els) {
                ret = std::forward<decltype(self)>(self)(std::string_view(el), elem);
                if (!ret) {
                    std::back_inserter(r) = elem;
                } else {
                    return std::make_error_code(std::errc::invalid_argument);
                }
            }

            value = r;
        } else if constexpr (mcc::traits::mcc_time_duration_c<VT>) {
            typename VT::rep vd;

            ret = std::forward<decltype(self)>(self)(trimSpaces(str), vd);
            if (!ret) {
                value = VT{vd};
            }
        } else {
            ret = std::make_error_code(std::errc::invalid_argument);
        }

        return ret;
    };

    KeyValueHolder(DESCR_T desc) : _keyValue(desc)
    {
        [this]<size_t... I>(std::index_sequence<I...>) {
            ((_hashes[I] = FNV1aHash(std::get<I>(_keyValue).key)), ...);
        }(std::make_index_sequence<std::tuple_size_v<DESCR_T>>());
    }

    template <typename T>
    std::expected<T, std::error_code> getValue(std::string_view key)
    {
        T v;
        auto err = forKey(key, [&v]<typename VT>(const VT& val) {
            if constexpr (std::convertible_to<VT, T>) {
                v = val;
                return std::error_code();
            } else {
                return std::make_error_code(std::errc::invalid_argument);
            }
        });

        if (err) {
            return std::unexpected(err);
        } else {
            return v;
        }
    }

    template <typename T>
    std::error_code setValue(std::string_view key, const T& value)
    {
        return forKey(key, [value]<typename VT>(VT& val) {
            if constexpr (std::convertible_to<T, VT>) {
                val = value;
                return std::error_code();
            } else {
                return std::make_error_code(std::errc::invalid_argument);
            }
        });
    }


    template <std::ranges::contiguous_range R, std::ranges::input_range RecDelimT = std::string_view>
    std::error_code fromCharRange(const R& buffer, RecDelimT rec_delim = std::string_view("\n"))
    {
        // return fromCharRange(buffer, KeyValueHolder::defaultDeserializeFunc, std::move(rec_delim));
        return fromCharRange(buffer, MccSimpleDeserializer{}.setRangeDelim(VALUE_ARRAY_DELIM), std::move(rec_delim));
    }

    template <std::ranges::contiguous_range R,
              typename DeserFuncT,
              std::ranges::input_range RecDelimT = std::string_view>
    std::error_code fromCharRange(const R& buffer,
                                  DeserFuncT&& deser_func,
                                  RecDelimT rec_delim = std::string_view("\n"))
    {
        // static_assert(mcc::traits::mcc_callable_c<std::decay_t<DeserFuncT>>, "!!!!!!!");

        if constexpr (std::is_array_v<std::decay_t<R>>) {  // char*, const char*
            if constexpr (std::is_array_v<std::decay_t<RecDelimT>>) {
                return fromCharRange(std::string_view{buffer}, std::forward<DeserFuncT>(deser_func),
                                     std::string_view(rec_delim));
            } else {
                return fromCharRange(std::string_view{buffer}, std::forward<DeserFuncT>(deser_func),
                                     std::move(rec_delim));
            }
        } else {
            if constexpr (std::is_array_v<std::decay_t<RecDelimT>>) {
                return fromCharRange(buffer, std::forward<DeserFuncT>(deser_func), std::string_view(rec_delim));
            }
        }


        std::error_code ec{};
        std::string_view rec, key, value;


        auto recs = std::views::split(buffer, std::move(rec_delim));
        for (auto const& el : recs) {
            rec = mcc::utils::trimSpaces(el, TrimType::TRIM_LEFT);

            if (rec.size()) {
                auto found = std::ranges::search(rec, COMMENT_SEQ);
                if (found.begin() != rec.end()) {  // there was the comment sequence in record
                    rec = std::string_view(rec.begin(), found.begin());
                }

                if (rec.size()) {
                    found = std::ranges::search(rec, KEY_VALUE_DELIM);
                    if (found.begin() != rec.begin()) {  // ignore an empty key
                        key = trimSpaces(std::string_view(rec.begin(), found.begin()), TrimType::TRIM_RIGHT);
                        value = std::string_view(found.end(), rec.end());

                        ec = forKey(key, [value, &deser_func]<typename VT>(VT& v) { return deser_func(value, v); });
                    }
                }  // just comment string starting from the beginning, just skip it (no error)

            }  // empty record, just skip it (no error)

            if (ec) {
                break;
            }
        }

        return ec;
    }

protected:
    DESCR_T _keyValue;

    std::array<size_t, std::tuple_size_v<DESCR_T>> _hashes;


    std::error_code forKey(std::string_view key, auto&& func)
    {
        return forHash<0>(FNV1aHash(key), std::forward<decltype(func)>(func));
    }


    template <size_t I = 0>
    std::error_code forHash(size_t hash, auto&& func)
    {
        if constexpr (I < std::tuple_size_v<DESCR_T>) {
            if (hash == _hashes[I]) {
                return std::forward<decltype(func)>(func)(std::get<I>(_keyValue).value);
            } else {
                return forHash<I + 1>(hash, std::forward<decltype(func)>(func));
            }
        }

        return std::make_error_code(std::errc::argument_out_of_domain);
    }
};

}  // namespace mcc::utils