#pragma once
#ifndef _NB_ERRORS_IMPL
#define _NB_ERRORS_IMPL

#include <exception>
#include <memory>
#include <string>
#include <type_traits>
#include <unordered_map>

#include "StringUtils.hpp"
#include "TypeTraits.hpp"

namespace nb {

typedef std::unordered_map<unsigned int, std::string> ErrorCodeMap;

template <class ErrorType=NoneType>
class Error;

class ErrorBase {
    protected:

    public:
    const unsigned int code;
    const std::string msg;
    const std::string type;
    const std::shared_ptr<ErrorBase> trace;

    ErrorBase(const ErrorBase&) = default;
    ErrorBase(const std::exception&) noexcept;
    virtual std::string what() const noexcept {
        std::string ret = msg;
        if (trace) {
            std::string trace_msg = msg;
            ret += nb::NEWLINE + indent_strblock(
                trace_msg,
                nb::TABOVER,
                nb::TABOVER+"Trace: "
            );
        }
        return ret;
    }
    
    protected:
    ErrorBase(
    unsigned int code_,
    std::string msg_,
    std::string type_,
    std::shared_ptr<ErrorBase> trace_
) noexcept :
    code(code_),
    msg(msg_),
    type(type_),
    trace{trace_}
{}
};

template <class ErrorType>
class Error : public ErrorBase {
    private:
    void inline check_asserts() {
        static_assert(std::is_same<const ErrorCodeMap, decltype(ErrorType::ErrorMessages)>::value,
            "const std::unordered_map<unsigned int, const char*> ErrorMessages must be "
            "a class member."
        );
        static_assert(std::is_enum_v<typename ErrorType::Codes>, "enum Codes must be a class member.");
        static_assert(std::is_same<std::underlying_type_t<typename ErrorType::Codes>, unsigned int>::value,
            "enum Codes must be of underlying type unsigned int."
        );
        static_assert(std::is_same<const std::string, decltype(ErrorType::type)>::value,
            "const std::string type must be a class member."
        );
    }

    protected:
    using ErrorBase::ErrorBase;

    public:
    Error(
        unsigned int code_,
        const ErrorBase& trace_
    ) noexcept : ErrorBase(
        code_, 
        ErrorType::ErrorMessages.at(code_),
        ErrorType::type,
        std::make_shared<ErrorBase>(trace_)
    ) { check_asserts(); }

    Error(
        std::string msg_,
        const ErrorBase& trace_
    ) noexcept : ErrorBase(
        0, 
        msg_,
        ErrorType::type,
        std::make_shared<ErrorBase>(trace_)
    ) { check_asserts(); }

    Error(unsigned int code_) noexcept : ErrorBase(
        code_, 
        ErrorType::ErrorMessages.at(code_),
        ErrorType::type,
        nullptr
    ) { check_asserts(); }

    Error(std::string msg_) noexcept : ErrorBase(
        0, 
        msg_,
        ErrorType::type,
        nullptr
    ) { check_asserts(); }

    Error(
        unsigned int code_,
        const std::string& note_,
        const ErrorBase& trace_
    ) noexcept : ErrorBase(
        code_,
        ErrorType::ErrorMessages.at(code_) + " (" + note_ + ")",
        ErrorType::type,
        std::make_shared<ErrorBase>(trace_)
    ) { check_asserts(); }

    Error(unsigned int code_, const std::string& note_) noexcept : ErrorBase(
        code_,
        ErrorType::ErrorMessages.at(code_) + " (" + note_ + ")",
        ErrorType::type,
        nullptr
    ) { check_asserts(); }

    using ErrorBase::what;
    using ErrorBase::code;
    using ErrorBase::msg;
    using ErrorBase::trace;
    using ErrorBase::type;
};


template<>
class Error<NoneType> : public Error<Error<NoneType>> {
    using Base = Error<Error<NoneType>>;
    
    public:
    using Base::Base;
    
    Error(unsigned int code_=1) noexcept : Base(code_) {}

    Error(const std::exception& err) : Base(
        Codes::STANDARD,
        std::string(err.what()),
        "std::exception",
        nullptr
    ) {}

    // fix
    Error(std::string msg_) noexcept : Base(
        Codes::UNDEFINED, 
        msg_
    ) {}

    enum Codes : unsigned int {
        STANDARD, UNDEFINED
    };

    using Base::what;
    using Base::code;
    using Base::msg;
    using Base::trace;
    static const std::string type;
    static const ErrorCodeMap ErrorMessages;
};
} // namespace nb

#endif // _NB_ERRORS_IMPL