#ifndef SOPHIAR2_VERSATILE_BUFFER2_HPP
#define SOPHIAR2_VERSATILE_BUFFER2_HPP

#include "utility/bit_operations.hpp"
#include "utility/dynamic_pool.hpp"

#include <boost/noncopyable.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/read.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <boost/asio/write.hpp>

#include <Eigen/Core>

#include <algorithm>
#include <cassert>
#include <concepts>
#include <span>
#include <string>
#include <string_view>
#include <type_traits>

namespace sophiar {

    template<size_t Length>
    struct static_memory : private boost::noncopyable {

        char *data() { return buf.data(); }

        const char *data() const { return buf.data(); }

        constexpr size_t size() { return Length; }

        static auto new_instance() {
            using this_type = static_memory<Length>;
            return std::make_unique<this_type>();
        }

    private:
        std::array<char, Length> buf;
    };

    struct dynamic_memory : private boost::noncopyable {

        static constexpr size_t DYNAMIC_MEMORY_DEFAULT_SIZE = 32;

        using pointer = std::unique_ptr<dynamic_memory>;

        ~dynamic_memory() {
            DEALLOCATE_DYNAMIC_MEMORY((void *) buf, capacity_length);
        }

        char *data() { return buf; }

        const char *data() const { return buf; }

        size_t size() const { return used_length; }

        void resize(size_t req_size) {
            if (req_size > capacity_length) [[unlikely]] {
                auto ext_buf = (char *) ALLOCATE_DYNAMIC_MEMORY(req_size);
                memcpy(ext_buf, buf, used_length);
                DEALLOCATE_DYNAMIC_MEMORY((void *) buf, capacity_length);
                buf = ext_buf;
                capacity_length = ACTUAL_DYNAMIC_MEMORY_SIZE(req_size);
            }
            used_length = req_size;
        }

        void increase_size(ptrdiff_t extra_size) {
            assert(extra_size >= 0 || size() > -extra_size);
            resize(size() + extra_size);
        }

        static auto new_instance(size_t req_size = DYNAMIC_MEMORY_DEFAULT_SIZE) {
            return pointer{new dynamic_memory{req_size}};
        }

    private:
        char *buf;
        size_t used_length;
        size_t capacity_length;

        explicit dynamic_memory(size_t req_size) {
            buf = (char *) ALLOCATE_DYNAMIC_MEMORY(req_size);
            used_length = req_size;
            capacity_length = ACTUAL_DYNAMIC_MEMORY_SIZE(req_size);
        }

    };

    struct extern_memory {

        extern_memory(char *extern_buf, size_t buf_length)
                : buf(extern_buf), length(buf_length) {}

        extern_memory(const extern_memory &) = default;

        char *data() { return buf; }

        const char *data() const { return buf; }

        size_t size() const { return length; }

    private:
        char *buf;
        size_t length;
    };

    struct const_extern_memory {

        const_extern_memory(const char *extern_buf, size_t buf_length)
                : buf(extern_buf), length(buf_length) {}

        explicit const_extern_memory(const extern_memory &other)
                : buf(other.data()), length(other.size()) {}

        const_extern_memory(const const_extern_memory &) = default;

        const char *data() const { return buf; }

        size_t size() const { return length; }

    private:
        const char *buf;
        size_t length;
    };

    template<typename T>
    concept ReadableMemory = requires(T a) {
        { a.data() } -> std::convertible_to<const char *>;
        { a.size() } -> std::convertible_to<size_t>;
    };

    template<typename T>
    concept WriteableMemory = requires(T a) {
        { a.data() } -> std::convertible_to<char *>;
        { a.size() } -> std::convertible_to<size_t>;
    };

    // 分多次读取数据
    template<boost::endian::order net_order>
    class versatile_reader : private boost::noncopyable {
    public:

        template<ReadableMemory MemoryType>
        explicit versatile_reader(const MemoryType &mem, size_t offset = 0)
                :buf(mem.data(), mem.size()),
                 pos(buf.begin() + offset) {
        }

        template<typename T>
        std::enable_if_t<std::is_arithmetic_v<T>, T>
        read_value() {
            assert(pos + sizeof(T) <= buf.end());
            T tmp_val;
            std::copy_n(pos, sizeof(T), (char *) &tmp_val);
            swap_net_loc_endian<net_order>(tmp_val);
            pos += sizeof(T);
            return tmp_val;
        }

        template<typename T>
        std::enable_if_t<std::is_arithmetic_v<T>>
        read_value(T &val) {
            val = read_value<T>();
        }

        template<typename Derived>
        void read_value(Eigen::MatrixBase<Derived> &matrix) {
            for (Eigen::Index i = 0; i < matrix.size(); ++i) {
                read_value(matrix(i));
            }
        }

        template<typename T, size_t Length>
        void read_value(std::array<T, Length> &arr) {
            for (auto &val: arr) {
                read_value(val);
            }
        }

        std::string_view read_string(size_t read_length) {
            auto end_pos = pos + read_length;
            assert(end_pos <= buf.end());
            auto ret = std::string_view{pos, end_pos};
            pos = end_pos;
            return ret;
        }

        void read_string(std::string &str, size_t length) {
            str = read_string(length);
        }

        std::string_view read_string_until(char sep) {
            auto end_pos = pos;
            while (*end_pos != sep && end_pos != buf.end()) ++end_pos;
            auto ret = std::string_view{pos, end_pos};
            pos = end_pos;
            if (pos != buf.end()) ++pos; // skip the separator
            return ret;
        }

        void read_string_until(std::string &str, char sep) {
            str = read_string_until(sep);
        }

        template<typename T>
        auto &operator>>(T &val) {
            read_value(val);
            return *this;
        }

        // 从当前位置开始调整 offset
        void manual_offset(ptrdiff_t offset) {
            pos += offset;
            assert(pos >= buf.begin());
            assert(pos <= buf.end());
        }

        auto current_offset() const {
            return pos - buf.begin();
        }

        bool empty() const {
            return pos == buf.end();
        }

    private:
        using buffer_type = std::span<const char>;
        using iterator_type = buffer_type::iterator;
        buffer_type buf;
        iterator_type pos;
    };

    // 分多次写入数据
    template<boost::endian::order net_order>
    class versatile_writer {
    public:

        template<WriteableMemory MemoryType>
        explicit versatile_writer(MemoryType &mem, size_t offset = 0)
                :buf(mem.data(), mem.size()),
                 pos(buf.begin() + offset) {
        }

        template<typename T>
        std::enable_if_t<std::is_arithmetic_v<T>>
        write_value(T val) {
            assert(pos + sizeof(T) <= buf.end());
            swap_net_loc_endian<net_order>(val);
            std::copy_n((char *) &val, sizeof(T), pos);
            pos += sizeof(T);
        }

        void write_value(std::string_view str) {
            assert(pos + str.length() <= buf.end());
            std::copy(str.begin(), str.end(), pos);
            pos += str.length();
        }

        template<typename Derived>
        void write_value(const Eigen::MatrixBase<Derived> &matrix) {
            for (Eigen::Index i = 0; i < matrix.size(); ++i) {
                write_value(matrix(i));
            }
        }

        template<typename T, size_t Length>
        void write_value(const std::array<T, Length> &arr) {
            for (auto val: arr) {
                write_value(val);
            }
        }

        template<typename T>
        auto &operator<<(const T &val) {
            write_value(val);
            return *this;
        }

        // 从当前位置开始调整 offset
        void manual_offset(ptrdiff_t offset) {
            pos += offset;
            assert(pos >= buf.begin());
            assert(pos <= buf.end());
        }

        auto current_offset() const {
            return pos - buf.begin();
        }

        auto remaining_bytes() const {
            return buf.end() - pos;
        }

    private:
        using buffer_type = std::span<char>;
        using iterator_type = buffer_type::iterator;
        buffer_type buf;
        iterator_type pos;
    };

    template<boost::endian::order net_order>
    class dynamic_memory_writer {
    public:

        explicit dynamic_memory_writer(dynamic_memory *mem,
                                       size_t offset = 0)
                : buf(mem) {
            buf->resize(offset);
        }

        template<typename T>
        std::enable_if_t<std::is_arithmetic_v<T>>
        write_value(T val) {
            swap_net_loc_endian<net_order>(val);
            auto ptr = end_ptr();
            buf->increase_size(sizeof(T));
            memcpy(ptr, &val, sizeof(T));
        }

        void write_value(std::string_view str) {
            auto ptr = end_ptr();
            buf->increase_size(str.length());
            std::copy(str.begin(), str.end(), ptr);
        }

        template<typename Derived>
        void write_value(const Eigen::MatrixBase<Derived> &matrix) {
            for (Eigen::Index i = 0; i < matrix.size(); ++i) {
                write_value(matrix(i));
            }
        }

        template<typename T, size_t Length>
        void write_value(const std::array<T, Length> &arr) {
            for (auto val: arr) {
                write_value(val);
            }
        }

        template<typename T>
        auto &operator<<(const T &val) {
            write_value(val);
            return *this;
        }

    private:
        dynamic_memory *buf;

        char *end_ptr() {
            return buf->data() + buf->size();
        }
    };

    template<boost::endian::order net_order,
            typename T>
    std::enable_if_t<std::is_arithmetic_v<T>, T>
    read_binary_value(const char *data) {
        T tmp_val;
        memcpy(&tmp_val, data, sizeof(T));
        swap_net_loc_endian<net_order>(tmp_val);
        return tmp_val;
    }

    template<boost::endian::order net_order,
            typename T>
    std::enable_if_t<std::is_arithmetic_v<T>>
    read_binary_value(const char *data, T &val) {
        val = read_binary_value<net_order>(data);
    }

    template<boost::endian::order net_order,
            typename T>
    std::enable_if_t<std::is_arithmetic_v<T>>
    write_binary_value(char *data, T val) {
        swap_net_loc_endian<net_order>(val);
        memcpy(data, &val, sizeof(T));
    }

    template<WriteableMemory MemoryType, typename AsyncReadStream>
    auto async_fill_memory_from(AsyncReadStream &s, MemoryType &mem) {
        return boost::asio::async_read(s,
                                       boost::asio::buffer(mem.data(), mem.size()),
                                       boost::asio::use_awaitable);
    }

    template<ReadableMemory MemoryType, typename AsyncWriteStream>
    auto async_write_memory_to(AsyncWriteStream &s, const MemoryType &mem) {
        return boost::asio::async_write(s,
                                        boost::asio::buffer(mem.data(), mem.size()),
                                        boost::asio::use_awaitable);
    }

    template<boost::endian::order net_order,
            typename AsyncWriteStream, typename T>
    std::enable_if_t<std::is_arithmetic_v<T>, boost::asio::awaitable<void>>
    inline async_write_value(AsyncWriteStream &s, T val) {
        swap_net_loc_endian<net_order>(val);
        co_await boost::asio::async_write(s,
                                          boost::asio::buffer(&val, sizeof(T)),
                                          boost::asio::use_awaitable);
        co_return;
    }

    template<boost::endian::order net_order,
            typename T, typename AsyncReadStream>
    std::enable_if_t<std::is_arithmetic_v<T>, boost::asio::awaitable<T>>
    inline async_read_value(AsyncReadStream &s) {
        T tmp_val;
        co_await boost::asio::async_read(s,
                                         boost::asio::buffer(&tmp_val, sizeof(T)),
                                         boost::asio::use_awaitable);
        swap_net_loc_endian<net_order>(tmp_val);
        co_return tmp_val;
    }

    template<boost::endian::order net_order,
            typename T, typename AsyncReadStream>
    std::enable_if_t<std::is_arithmetic_v<T>, boost::asio::awaitable<void>>
    inline async_read_value(AsyncReadStream &s, T &val) {
        val = co_await async_read_value<net_order, T>(s);
        co_return;
    }

}

#endif //SOPHIAR2_VERSATILE_BUFFER2_HPP