ylib/include/util/json.h

#pragma once

#include <nlohmann/json.hpp>

#include <string>
#include <vector>
#include <type_traits>

#include "base/define.h"
#include "base/exception.h"

namespace ylib
{
    /**
     * @brief JSON 封装（基于 nlohmann/json）
     * 保留历史常用 API：from / to_string / to<T> / keys / exist / is_* / type 赋值
     * private 继承：隐藏基类隐式 operator ValueType()，保证 if (j["key"]) 走 truthy()
     * 无额外数据成员；需要底层 API 时用 raw()
     */
    class json : private nlohmann::json
    {
    public:
        using base = nlohmann::json;

        // 常用底层能力（不导出 begin/end，避免被当成 range 构造成 nlohmann 数组）
        using base::dump;
        using base::contains;
        using base::find;
        using base::at;
        using base::get;
        using base::get_ref;
        using base::get_ptr;

        enum type
        {
            null,
            obj,
            empty,
            array,
            boolean,
            number,
            string
        };

        json() : base(nullptr) {}
        json(const json& other) = default;
        json(json&& other) noexcept = default;
        json(const base& other) : base(other) {}
        json(base&& other) noexcept : base(std::move(other)) {}
        json(std::nullptr_t) : base(nullptr) {}

        /// 按 type 枚举构造（避免 json x = type::array 退化成整数）
        json(type t) : base(nullptr) { *this = t; }

        json(const std::string& value) : base(value) {}
        json(const char* value) : base(value ? value : "") {}
        json(bool value) : base(value) {}
        json(int32 value) : base(value) {}
        json(uint32 value) : base(value) {}
        json(int64 value) : base(value) {}
        json(uint64 value) : base(value) {}
        json(double value) : base(value) {}
        json(float value) : base(value) {}

        json& operator=(const json& other) = default;
        json& operator=(json&& other) noexcept = default;

        json& operator=(const base& other)
        {
            base::operator=(other);
            return *this;
        }
        json& operator=(base&& other) noexcept
        {
            base::operator=(std::move(other));
            return *this;
        }
        json& operator=(std::nullptr_t)
        {
            base::operator=(nullptr);
            return *this;
        }
        json& operator=(const std::string& value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(const char* value)
        {
            if (value == nullptr)
                base::operator=(nullptr);
            else
                base::operator=(value);
            return *this;
        }
        json& operator=(bool value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(int32 value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(uint32 value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(int64 value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(uint64 value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(double value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(float value)
        {
            base::operator=(value);
            return *this;
        }
        json& operator=(type t)
        {
            switch (t)
            {
            case type::null:
            case type::empty:
                base::operator=(nullptr);
                break;
            case type::obj:
                base::operator=(base::object());
                break;
            case type::array:
                base::operator=(base::array());
                break;
            case type::boolean:
                base::operator=(false);
                break;
            case type::number:
                base::operator=(0);
                break;
            case type::string:
                base::operator=("");
                break;
            }
            return *this;
        }

        /// 显式拿到底层 nlohmann::json（private 继承后不可隐式转换）
        base& raw() noexcept { return *this; }
        const base& raw() const noexcept { return *this; }

        static json from(const std::string& value)
        {
            if (value.empty())
                return json();
            try
            {
                // cb=nullptr, allow_exceptions=true, ignore_comments=true（支持 // 与 /* */）
                return json(base::parse(value, nullptr, true, true));
            }
            catch (...)
            {
                return json();
            }
        }

        bool parse(const std::string& value)
        {
            try
            {
                // cb=nullptr, allow_exceptions=true, ignore_comments=true（支持 // 与 /* */）
                *this = base::parse(value, nullptr, true, true);
                return true;
            }
            catch (...)
            {
                base::operator=(nullptr);
                return false;
            }
        }

        // 兼容旧签名；path / safe 已废弃为空操作
        void path(const std::string&) {}
        void safe(bool) {}
        bool safe() { return false; }

        std::string to_string(bool format = false) const
        {
            return dump(format ? 2 : -1);
        }

        uint32 size() const { return static_cast<uint32>(base::size()); }

        void resize(uint32 n)
        {
            if (!base::is_array())
                *this = base::array();
            base::get_ref<base::array_t&>().resize(n);
        }

        // null / 空对象 / 空数组 / 空字符串 视为 empty（比旧实现语义更清晰）
        bool is_empty() const { return base::empty(); }
        bool is_null() const { return base::is_null(); }
        bool is_obj() const { return base::is_object(); }
        bool is_array() const { return base::is_array(); }
        bool is_bool() const { return base::is_boolean(); }
        bool is_number() const { return base::is_number(); }
        bool is_string() const { return base::is_string(); }

        /**
         * @brief 真值：null / "" / 空数组 / 空对象 → false；其余（含 0、false）为 true
         */
        bool truthy() const
        {
            if (is_null())
                return false;
            if (is_string())
                return !get_ref<const base::string_t&>().empty();
            if (is_array() || is_object())
                return !base::empty();
            return true;
        }

        /**
         * @brief 支持 if (j["key"])；private 继承后不会再落到基类 get<bool>()
         */
        explicit operator bool() const { return truthy(); }

        bool exist(const std::string& name) const { return contains(name); }

        void erase(const std::string& key) { base::erase(key); }
        void erase(uint32 index)
        {
            if (is_array() && index < base::size())
                base::erase(begin() + static_cast<difference_type>(index));
        }

        void clear() { base::clear(); }

        std::vector<std::string> keys() const
        {
            std::vector<std::string> result;
            if (!is_object())
                return result;
            result.reserve(base::size());
            for (auto it = cbegin(); it != cend(); ++it)
                result.push_back(it.key());
            return result;
        }

        json& operator[](const std::string& name)
        {
            return static_cast<json&>(base::operator[](name));
        }
        const json& operator[](const std::string& name) const
        {
            auto it = find(name);
            if (it == cend())
            {
                static const json null_json;
                return null_json;
            }
            return static_cast<const json&>(*it);
        }
        // const char* 重载：配合 operator bool，避免 body["key"] 与内建下标歧义
        json& operator[](const char* name) { return (*this)[std::string(name ? name : "")]; }
        const json& operator[](const char* name) const
        {
            return (*this)[std::string(name ? name : "")];
        }
        json& operator[](size_t idx)
        {
            return static_cast<json&>(base::operator[](idx));
        }
        const json& operator[](size_t idx) const
        {
            return static_cast<const json&>(base::at(idx));
        }
        json& operator[](int idx)
        {
            return static_cast<json&>(base::operator[](idx));
        }
        const json& operator[](int idx) const
        {
            return static_cast<const json&>(base::at(idx));
        }
        json& operator[](unsigned int idx)
        {
            return static_cast<json&>(base::operator[](idx));
        }
        const json& operator[](unsigned int idx) const
        {
            return static_cast<const json&>(base::at(idx));
        }

        using base::push_back;
        void push_back(const json& value)
        {
            base::push_back(static_cast<const base&>(value));
        }
        // 字面量重载：避免与基类 push_back(basic_json) 因隐式转换产生歧义
        void push_back(bool value) { base::push_back(value); }
        void push_back(int32 value) { base::push_back(value); }
        void push_back(uint32 value) { base::push_back(value); }
        void push_back(int64 value) { base::push_back(value); }
        void push_back(uint64 value) { base::push_back(value); }
        void push_back(double value) { base::push_back(value); }
        void push_back(float value) { base::push_back(value); }
        void push_back(const char* value) { base::push_back(value ? value : ""); }
        void push_back(const std::string& value) { base::push_back(value); }

        bool operator==(const json& rhs) const
        {
            return static_cast<const base&>(*this) == static_cast<const base&>(rhs);
        }
        bool operator!=(const json& rhs) const { return !(*this == rhs); }

        template<typename T_TO>
        T_TO to(bool /*check*/ = false) const
        {
            using T = T_TO;

            if constexpr (std::is_same_v<T, std::string>)
            {
                if (is_string())
                    return get<std::string>();
                if (is_null())
                    return std::string();
                if (is_boolean())
                    return get<bool>() ? "true" : "false";
                if (is_number_unsigned())
                    return std::to_string(get<uint64_t>());
                if (is_number_integer())
                    return std::to_string(get<int64_t>());
                if (is_number_float())
                    return std::to_string(get<double>());
                return dump();
            }
            else if constexpr (std::is_same_v<T, bool>)
            {
                if (is_boolean())
                    return get<bool>();
                if (is_number())
                    return get<double>() != 0.0;
                if (is_string())
                {
                    const auto& s = get_ref<const base::string_t&>();
                    return s == "1" || s == "true" || s == "TRUE" || s == "True";
                }
                return false;
            }
            else if constexpr (std::is_arithmetic_v<T>)
            {
                if (is_number())
                    return get<T>();
                if (is_boolean())
                    return static_cast<T>(get<bool>() ? 1 : 0);
                if (is_string())
                {
                    try
                    {
                        const auto& s = get_ref<const base::string_t&>();
                        if constexpr (std::is_floating_point_v<T>)
                            return static_cast<T>(std::stod(s));
                        else if constexpr (std::is_signed_v<T>)
                            return static_cast<T>(std::stoll(s));
                        else
                            return static_cast<T>(std::stoull(s));
                    }
                    catch (...)
                    {
                        return T{};
                    }
                }
                return T{};
            }
            else if constexpr (std::is_same_v<T, std::vector<std::string>>)
            {
                std::vector<std::string> result;
                if (!is_array())
                    return result;
                for (const auto& el : *this)
                    result.push_back(static_cast<const json&>(el).template to<std::string>());
                return result;
            }
            else if constexpr (std::is_same_v<T, std::vector<json>>)
            {
                std::vector<json> result;
                if (!is_array())
                    return result;
                for (const auto& el : *this)
                    result.push_back(static_cast<const json&>(el));
                return result;
            }
            else
            {
                throw ylib::exception("json::to unsupported type");
            }
        }
    };
}