// Copyright 2013-2025 Daniel Parker
// Distributed under the Boost license, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

// See https://github.com/danielaparker/jsoncons for latest version

#ifndef JSONCONS_EXT_UBJSON_UBJSON_ENCODER_HPP
#define JSONCONS_EXT_UBJSON_UBJSON_ENCODER_HPP

#include <cstddef>
#include <cstdint>
#include <limits> // std::numeric_limits
#include <memory>
#include <system_error>
#include <utility> // std::move
#include <vector>

#include <jsoncons/config/compiler_support.hpp>
#include <jsoncons/config/jsoncons_config.hpp>
#include <jsoncons/detail/parse_number.hpp>
#include <jsoncons/json_exception.hpp>
#include <jsoncons/json_visitor.hpp>
#include <jsoncons/ser_context.hpp>
#include <jsoncons/sink.hpp>
#include <jsoncons/tag_type.hpp>
#include <jsoncons/utility/binary.hpp>
#include <jsoncons/utility/unicode_traits.hpp>

#include <jsoncons_ext/ubjson/ubjson_error.hpp>
#include <jsoncons_ext/ubjson/ubjson_options.hpp>
#include <jsoncons_ext/ubjson/ubjson_type.hpp>

namespace jsoncons { namespace ubjson {

enum class ubjson_container_type {object, indefinite_length_object, array, indefinite_length_array};

template <typename Sink=jsoncons::binary_stream_sink,typename Allocator=std::allocator<char>>
class basic_ubjson_encoder final : public basic_json_visitor<char>
{

    enum class decimal_parse_state { start, integer, exp1, exp2, fraction1 };
public:
    using allocator_type = Allocator;
    using typename basic_json_visitor<char>::string_view_type;
    using sink_type = Sink;

private:
    struct stack_item
    {
        ubjson_container_type type_;
        std::size_t length_{0};
        std::size_t count_{0};

        stack_item(ubjson_container_type type, std::size_t length = 0) noexcept
           : type_(type), length_(length)
        {
        }
        
        ~stack_item() = default;

        std::size_t length() const
        {
            return length_;
        }

        std::size_t count() const
        {
            return count_;
        }

        bool is_object() const
        {
            return type_ == ubjson_container_type::object || type_ == ubjson_container_type::indefinite_length_object;
        }

        bool is_indefinite_length() const
        {
            return type_ == ubjson_container_type::indefinite_length_array || type_ == ubjson_container_type::indefinite_length_object;
        }

    };

    Sink sink_;
    const ubjson_encode_options options_;
    allocator_type alloc_;

    std::vector<stack_item> stack_;
    int nesting_depth_{0};
public:

    // Noncopyable and nonmoveable
    basic_ubjson_encoder(const basic_ubjson_encoder&) = delete;
    basic_ubjson_encoder(basic_ubjson_encoder&&) = delete;

    basic_ubjson_encoder(Sink&& sink, 
                         const Allocator& alloc = Allocator())
       : basic_ubjson_encoder(std::forward<Sink>(sink), ubjson_encode_options(), alloc)
    {
    }

    explicit basic_ubjson_encoder(Sink&& sink, 
                                  const ubjson_encode_options& options, 
                                  const Allocator& alloc = Allocator())
       : sink_(std::forward<Sink>(sink)),
         options_(options),
         alloc_(alloc)
    {
    }

    ~basic_ubjson_encoder() noexcept
    {
        JSONCONS_TRY
        {
            sink_.flush();
        }
        JSONCONS_CATCH(...)
        {
        }
    }

    basic_ubjson_encoder& operator=(const basic_ubjson_encoder&) = delete;
    basic_ubjson_encoder& operator=(basic_ubjson_encoder&&) = delete;

    void reset()
    {
        stack_.clear();
        nesting_depth_ = 0;
    }

    void reset(Sink&& sink)
    {
        sink_ = std::move(sink);
        reset();
    }

private:
    // Implementing methods

    void visit_flush() override
    {
        sink_.flush();
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_begin_object(semantic_tag, const ser_context&, std::error_code& ec) override
    {
        if (JSONCONS_UNLIKELY(++nesting_depth_ > options_.max_nesting_depth()))
        {
            ec = ubjson_errc::max_nesting_depth_exceeded;
            JSONCONS_VISITOR_RETURN;
        } 
        stack_.emplace_back(ubjson_container_type::indefinite_length_object);
        sink_.push_back(jsoncons::ubjson::ubjson_type::start_object_marker);

        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_begin_object(std::size_t length, semantic_tag, const ser_context&, std::error_code& ec) override
    {
        if (JSONCONS_UNLIKELY(++nesting_depth_ > options_.max_nesting_depth()))
        {
            ec = ubjson_errc::max_nesting_depth_exceeded;
            JSONCONS_VISITOR_RETURN;
        } 
        stack_.emplace_back(ubjson_container_type::object, length);
        sink_.push_back(jsoncons::ubjson::ubjson_type::start_object_marker);
        sink_.push_back(jsoncons::ubjson::ubjson_type::count_marker);
        put_length(length);

        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_end_object(const ser_context&, std::error_code& ec) override
    {
        JSONCONS_ASSERT(!stack_.empty());
        --nesting_depth_;

        if (stack_.back().is_indefinite_length())
        {
            sink_.push_back(jsoncons::ubjson::ubjson_type::end_object_marker);
        }
        else
        {
            if (stack_.back().count() < stack_.back().length())
            {
                ec = ubjson_errc::too_few_items;
                JSONCONS_VISITOR_RETURN;
            }
            if (stack_.back().count() > stack_.back().length())
            {
                ec = ubjson_errc::too_many_items;
                JSONCONS_VISITOR_RETURN;
            }
        }
        stack_.pop_back();
        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_begin_array(semantic_tag, const ser_context&, std::error_code& ec) override
    {
        if (JSONCONS_UNLIKELY(++nesting_depth_ > options_.max_nesting_depth()))
        {
            ec = ubjson_errc::max_nesting_depth_exceeded;
            JSONCONS_VISITOR_RETURN;
        } 
        stack_.emplace_back(ubjson_container_type::indefinite_length_array);
        sink_.push_back(jsoncons::ubjson::ubjson_type::start_array_marker);

        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_begin_array(std::size_t length, semantic_tag, const ser_context&, std::error_code& ec) override
    {
        if (JSONCONS_UNLIKELY(++nesting_depth_ > options_.max_nesting_depth()))
        {
            ec = ubjson_errc::max_nesting_depth_exceeded;
            JSONCONS_VISITOR_RETURN;
        } 
        stack_.emplace_back(ubjson_container_type::array, length);
        sink_.push_back(jsoncons::ubjson::ubjson_type::start_array_marker);
        sink_.push_back(jsoncons::ubjson::ubjson_type::count_marker);
        put_length(length);

        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_end_array(const ser_context&, std::error_code& ec) override
    {
        JSONCONS_ASSERT(!stack_.empty());
        --nesting_depth_;

        if (stack_.back().is_indefinite_length())
        {
            sink_.push_back(jsoncons::ubjson::ubjson_type::end_array_marker);
        }
        else
        {
            if (stack_.back().count() < stack_.back().length())
            {
                ec = ubjson_errc::too_few_items;
                JSONCONS_VISITOR_RETURN;
            }
            if (stack_.back().count() > stack_.back().length())
            {
                ec = ubjson_errc::too_many_items;
                JSONCONS_VISITOR_RETURN;
            }
        }
        stack_.pop_back();
        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_key(const string_view_type& name, const ser_context&, std::error_code& ec) override
    {
        auto sink = unicode_traits::validate(name.data(), name.size());
        if (sink.ec != unicode_traits::conv_errc())
        {
            ec = ubjson_errc::invalid_utf8_text_string;
            JSONCONS_VISITOR_RETURN;
        }

        put_length(name.length());

        for (auto c : name)
        {
            sink_.push_back(c);
        }
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_null(semantic_tag, const ser_context&, std::error_code&) override
    {
        // nil
        binary::native_to_big(static_cast<uint8_t>(jsoncons::ubjson::ubjson_type::null_type), std::back_inserter(sink_));
        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_string(const string_view_type& sv, semantic_tag tag, const ser_context&, std::error_code& ec) override
    {
        switch (tag)
        {
            case semantic_tag::bigint:
            case semantic_tag::bigdec:
            {
                sink_.push_back(jsoncons::ubjson::ubjson_type::high_precision_number_type);
                break;
            }
            default:
            {
                sink_.push_back(jsoncons::ubjson::ubjson_type::string_type);
                break;
            }
        }

        auto sink = unicode_traits::validate(sv.data(), sv.size());
        if (sink.ec != unicode_traits::conv_errc())
        {
            ec = ubjson_errc::invalid_utf8_text_string;
            JSONCONS_VISITOR_RETURN;
        }

        put_length(sv.length());

        for (auto c : sv)
        {
            sink_.push_back(c);
        }

        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    void put_length(std::size_t length)
    {
        if (length <= (std::numeric_limits<uint8_t>::max)())
        {
            sink_.push_back(ubjson_type::uint8_type);
            binary::native_to_big(static_cast<uint8_t>(length), std::back_inserter(sink_));
        }
        else if (length <= (std::size_t)(std::numeric_limits<int16_t>::max)())
        {
            sink_.push_back(ubjson_type::int16_type);
            binary::native_to_big(static_cast<uint16_t>(length), std::back_inserter(sink_));
        }
        else if (length <= (std::size_t)(std::numeric_limits<int32_t>::max)())
        {
            sink_.push_back(ubjson_type::int32_type);
            binary::native_to_big(static_cast<uint32_t>(length),std::back_inserter(sink_));
        }
        else if (length <= (std::size_t)(std::numeric_limits<int64_t>::max)())
        {
            sink_.push_back(ubjson_type::int64_type);
            binary::native_to_big(static_cast<uint64_t>(length),std::back_inserter(sink_));
        }
        else
        {
            JSONCONS_THROW(ser_error(ubjson_errc::too_many_items));
        }
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_byte_string(const byte_string_view& b, 
                              semantic_tag, 
                              const ser_context&,
                              std::error_code&) override
    {

        const size_t length = b.size();
        sink_.push_back(jsoncons::ubjson::ubjson_type::start_array_marker);
        sink_.push_back(static_cast<uint8_t>(jsoncons::ubjson::ubjson_type::type_marker));
        sink_.push_back(static_cast<uint8_t>(jsoncons::ubjson::ubjson_type::uint8_type));
        sink_.push_back(jsoncons::ubjson::ubjson_type::count_marker);
        put_length(length);

        for (auto c : b)
        {
            sink_.push_back(c);
        }

        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_double(double val, 
                         semantic_tag,
                         const ser_context&,
                         std::error_code&) override
    {
        float valf = (float)val;
        if ((double)valf == val)
        {
            // float 32
            sink_.push_back(static_cast<uint8_t>(jsoncons::ubjson::ubjson_type::float32_type));
            binary::native_to_big(valf,std::back_inserter(sink_));
        }
        else
        {
            // float 64
            sink_.push_back(static_cast<uint8_t>(jsoncons::ubjson::ubjson_type::float64_type));
            binary::native_to_big(val,std::back_inserter(sink_));
        }

        // write double

        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_int64(int64_t val, semantic_tag, const ser_context&, 
        std::error_code&) override
    {
        if (val >= 0)
        {
            if (val <= (std::numeric_limits<uint8_t>::max)())
            {
                // uint 8 stores a 8-bit unsigned integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::uint8_type);
                binary::native_to_big(static_cast<uint8_t>(val),std::back_inserter(sink_));
            }
            else if (val <= (std::numeric_limits<int16_t>::max)())
            {
                // uint 16 stores a 16-bit big-endian unsigned integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int16_type);
                binary::native_to_big(static_cast<int16_t>(val),std::back_inserter(sink_));
            }
            else if (val <= (std::numeric_limits<int32_t>::max)())
            {
                // uint 32 stores a 32-bit big-endian unsigned integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int32_type);
                binary::native_to_big(static_cast<int32_t>(val),std::back_inserter(sink_));
            }
            else if (val <= (std::numeric_limits<int64_t>::max)())
            {
                // int 64 stores a 64-bit big-endian signed integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int64_type);
                binary::native_to_big(val,std::back_inserter(sink_));
            }
            else
            {
                // big integer
            }
        }
        else
        {
            if (val >= (std::numeric_limits<int8_t>::lowest)())
            {
                // int 8 stores a 8-bit signed integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int8_type);
                binary::native_to_big(static_cast<int8_t>(val),std::back_inserter(sink_));
            }
            else if (val >= (std::numeric_limits<int16_t>::lowest)())
            {
                // int 16 stores a 16-bit big-endian signed integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int16_type);
                binary::native_to_big(static_cast<int16_t>(val),std::back_inserter(sink_));
            }
            else if (val >= (std::numeric_limits<int32_t>::lowest)())
            {
                // int 32 stores a 32-bit big-endian signed integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int32_type);
                binary::native_to_big(static_cast<int32_t>(val),std::back_inserter(sink_));
            }
            else if (val >= (std::numeric_limits<int64_t>::lowest)())
            {
                // int 64 stores a 64-bit big-endian signed integer
                sink_.push_back(jsoncons::ubjson::ubjson_type::int64_type);
                binary::native_to_big(val,std::back_inserter(sink_));
            }
        }
        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_uint64(uint64_t val, 
                      semantic_tag, 
                      const ser_context&,
                      std::error_code&) override
    {
        if (val <= (std::numeric_limits<uint8_t>::max)())
        {
            sink_.push_back(jsoncons::ubjson::ubjson_type::uint8_type);
            binary::native_to_big(static_cast<uint8_t>(val),std::back_inserter(sink_));
        }
        else if (val <= static_cast<uint64_t>((std::numeric_limits<int16_t>::max)()))
        {
            sink_.push_back(jsoncons::ubjson::ubjson_type::int16_type);
            binary::native_to_big(static_cast<int16_t>(val),std::back_inserter(sink_));
        }
        else if (val <= static_cast<uint64_t>((std::numeric_limits<int32_t>::max)()))
        {
            sink_.push_back(jsoncons::ubjson::ubjson_type::int32_type);
            binary::native_to_big(static_cast<int32_t>(val),std::back_inserter(sink_));
        }
        else if (val <= static_cast<uint64_t>((std::numeric_limits<int64_t>::max)()))
        {
            sink_.push_back(jsoncons::ubjson::ubjson_type::int64_type);
            binary::native_to_big(static_cast<int64_t>(val),std::back_inserter(sink_));
        }
        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    JSONCONS_VISITOR_RETURN_TYPE visit_bool(bool val, semantic_tag, const ser_context&, std::error_code&) override
    {
        // true and false
        sink_.push_back(static_cast<uint8_t>(val ? jsoncons::ubjson::ubjson_type::true_type : jsoncons::ubjson::ubjson_type::false_type));

        end_value();
        JSONCONS_VISITOR_RETURN;
    }

    void end_value()
    {
        if (!stack_.empty())
        {
            ++stack_.back().count_;
        }
    }
};

using ubjson_stream_encoder = basic_ubjson_encoder<jsoncons::binary_stream_sink>;
using ubjson_bytes_encoder = basic_ubjson_encoder<jsoncons::bytes_sink<std::vector<uint8_t>>>;

} // namespace ubjson
} // namespace jsoncons

#endif // JSONCONS_EXT_UBJSON_UBJSON_ENCODER_HPP