geode/loader/include/Geode/utils/Result.hpp

#pragma once

#include "../DefaultInclude.hpp"

#include <string>
#include <string_view>
#include <variant>
#include <fmt/format.h>

namespace geode {
    namespace {
        struct AnyType {
            explicit AnyType() = delete;
        };

        template <class V, class RV>
        concept ConvertibleToResult =
            std::is_convertible_v<std::remove_reference_t<V>, std::remove_reference_t<RV>> ||
            std::is_same_v<std::remove_reference_t<V>, std::remove_reference_t<RV>>;

        using DefaultValue = std::monostate;
        using DefaultError = std::string;
    }

    template <class T = DefaultValue, class E = DefaultError>
    class [[nodiscard]] Result {
    public:
        using value_type = std::remove_reference_t<T>;
        using error_type = std::remove_reference_t<E>;

        // for some reason doing requires causes errors with pch...
        static_assert(
            std::is_copy_constructible_v<value_type> || std::is_move_constructible_v<value_type>,
            "T must be copiable or movable!"
        );
        static_assert(
            std::is_copy_constructible_v<error_type> || std::is_move_constructible_v<error_type>,
            "E must be copiable or movable!"
        );

    protected:
        std::variant<value_type, error_type> m_value;

    public:
        bool isOk() const {
            return std::holds_alternative<value_type>(m_value);
        }

        bool isErr() const {
            return std::holds_alternative<error_type>(m_value);
        }

        template<class ... Args>
        Result<T, std::string> expect(const char* str, Args&&... args) {
            if (isErr()) {
                return Result(fmt::format(str, std::forward<Args>(args)...));
            } else {
                return *this;
            }
        }

        explicit Result(value_type const& value
        ) requires std::is_copy_constructible_v<value_type> : m_value(value) {}

        explicit Result(value_type&& value) requires std::is_move_constructible_v<value_type> :
            m_value(std::forward<value_type>(value)) {}

        explicit Result(error_type const& value
        ) requires std::is_copy_constructible_v<error_type> : m_value(value) {}

        explicit Result(error_type&& value) requires std::is_move_constructible_v<error_type> :
            m_value(std::forward<error_type>(value)) {}

        Result(Result<T, E> const& other) requires std::is_copy_constructible_v<value_type> &&
            std::is_copy_constructible_v<error_type>
        = default;

        Result(Result<T, E>&& other
        ) requires(!std::is_copy_constructible_v<value_type> || !std::is_copy_constructible_v<error_type>) =
            default;

        template <class T2, class E2>
        requires ConvertibleToResult<T2, T> && ConvertibleToResult<E2, E> Result(
            Result<T2, E2> const& other
        )

        requires std::is_copy_constructible_v<value_type> &&
            std::is_copy_constructible_v<error_type>
        {
            if (other.isOk()) {
                m_value = other.unwrap();
            } else {
                m_value = other.unwrapErr();
            }
        }

        template <class T2, class E2>
        requires ConvertibleToResult<T2, T> && ConvertibleToResult<E2, E> Result(
            Result<T2, E2>&& other
        )

        requires(!std::is_copy_constructible_v<value_type> || !std::is_copy_constructible_v<error_type>) :
            m_value(other.isOk() ? other.unwrap() : other.unwrapErr()) {}

        template <class T2>
        requires ConvertibleToResult<T2, T> Result(Result<T2, AnyType> const& other)

        requires std::is_copy_constructible_v<value_type> &&
            std::is_copy_constructible_v<error_type> : Result(value_type(other.unwrap())) {}

        template <class E2>
        requires ConvertibleToResult<E2, E> Result(Result<AnyType, E2> const& other)

        requires std::is_copy_constructible_v<value_type> &&
            std::is_copy_constructible_v<error_type> :
            m_value(std::forward<E2>(other.unwrapErr())) {}

        template <class T2>
        requires ConvertibleToResult<T2, T> Result(Result<T2, AnyType>&& other)

        requires(!std::is_copy_constructible_v<value_type> || !std::is_copy_constructible_v<error_type>) :
            m_value(other.unwrap()) {}

        template <class E2>
        requires ConvertibleToResult<E2, E> Result(Result<AnyType, E2>&& other)

        requires(!std::is_copy_constructible_v<value_type> || !std::is_copy_constructible_v<error_type>) :
            Result(std::forward<error_type>(other.unwrapErr())) {}

        value_type unwrap() const requires std::is_copy_constructible_v<value_type> {
            return std::get<value_type>(m_value);
        }

        value_type&& unwrap() requires(!std::is_copy_constructible_v<value_type>) {
            return std::move(std::get<value_type>(m_value));
        }

        error_type unwrapErr() const requires std::is_copy_constructible_v<error_type> {
            return std::get<error_type>(m_value);
        }

        error_type&& unwrapErr() requires(!std::is_copy_constructible_v<error_type>) {
            return std::move(std::get<error_type>(m_value));
        }

        explicit operator bool() const
            requires(!std::is_same_v<T, bool> && !std::is_same_v<E, bool>) {
            return this->isOk();
        }
    };

    template <class T>
    class [[nodiscard]] Result<T, T> {
    public:
        using value_type = std::remove_reference_t<T>;
        using error_type = std::remove_reference_t<T>;

        // for some reason doing requires causes errors with pch...
        static_assert(
            std::is_copy_constructible_v<value_type> || 
            std::is_move_constructible_v<value_type>,
            "T must be copiable or movable!"
        );

    protected:
        bool m_success;
        value_type m_value;

    public:
        bool isOk() const {
            return m_success;
        }

        bool isErr() const {
            return !m_success;
        }

        template<class ... Args>
        Result<T, std::string> expect(const char* str, Args&&... args) {
            if (isErr()) {
                return Result(fmt::format(str, std::forward<Args>(args)...), false);
            } else {
                return *this;
            }
        }

        explicit Result(value_type const& value, bool success) requires
            std::is_copy_constructible_v<value_type> :
            m_value(value),
            m_success(success) {}

        explicit Result(value_type&& value, bool success) requires
            std::is_move_constructible_v<value_type> :
            m_value(std::forward<value_type>(value)),
            m_success(success) {}

        Result(Result<T, T> const& other) requires std::is_copy_constructible_v<value_type>
        = default;

        Result(Result<T, T>&& other
        ) requires(!std::is_copy_constructible_v<value_type>) = default;

        template <class T2, class E2>
        requires ConvertibleToResult<T2, T> && ConvertibleToResult<E2, T> Result(
            Result<T2, E2> const& other
        )

        requires std::is_copy_constructible_v<value_type> :
            m_value(other.isOk() ? other.unwrap() : other.unwrapErr()),
            m_success(other.isOk()) {}

        template <class T2, class E2>
        requires ConvertibleToResult<T2, T> && ConvertibleToResult<E2, T> Result(
            Result<T2, E2>&& other
        )

        requires(!std::is_copy_constructible_v<value_type>) :
            m_value(other.isOk() ? other.unwrap() : other.unwrapErr()), m_success(other.isOk()) {}

        template <class T2>
        requires ConvertibleToResult<T2, T> Result(Result<T2, AnyType> const& other)

        requires std::is_copy_constructible_v<value_type> :
            Result(value_type(other.unwrap()), true) {}

        template <class T2>
        requires ConvertibleToResult<T2, T> Result(Result<T2, AnyType>&& other)

        requires(!std::is_copy_constructible_v<value_type>) :
            Result(std::forward<value_type>(other.unwrap()), true) {}

        template <class E2>
        requires ConvertibleToResult<E2, T> Result(Result<AnyType, E2> const& other)

        requires std::is_copy_constructible_v<value_type> :
            Result(error_type(other.unwrapErr()), false) {}

        template <class E2>
        requires ConvertibleToResult<E2, T> Result(Result<AnyType, E2>&& other)

        requires(!std::is_copy_constructible_v<value_type>) :
            Result(std::forward<error_type>(other.unwrapErr()), false) {}

        value_type unwrap() const requires std::is_copy_constructible_v<value_type> {
            return m_value;
        }

        value_type&& unwrap() requires(!std::is_copy_constructible_v<value_type>) {
            return std::move(m_value);
        }

        error_type unwrapErr() const requires std::is_copy_constructible_v<error_type> {
            return m_value;
        }

        error_type&& unwrapErr() requires(!std::is_copy_constructible_v<error_type>) {
            return std::move(m_value);
        }

        explicit operator bool() const requires(!std::is_same_v<T, bool>) {
            return this->isOk();
        }
    };

    template <class T = DefaultValue, class E = AnyType>

    requires std::is_copy_constructible_v<T> Result<T, E> Ok(T value = T()) {
        return Result<T, E>(value);
    }

    template <class T = DefaultValue, class E = AnyType>

    requires(!std::is_copy_constructible_v<T>) Result<T, E> Ok(T&& value) {
        return Result<T, E>(std::forward<T>(value));
    }

    template <class E = DefaultError, class T = AnyType>

    requires std::is_copy_constructible_v<E> Result<T, E> Err(E error = E()) {
        return Result<T, E>(error);
    }

    template <class E = DefaultError, class T = AnyType>

    requires(!std::is_copy_constructible_v<E>) Result<T, E> Err(E&& error) {
        return Result<T, E>(std::forward<E>(error));
    }

#define GEODE_UNWRAP_INTO(into, ...)                                            \
    auto GEODE_CONCAT(unwrap_res_, __LINE__) = (__VA_ARGS__);                   \
    if (GEODE_CONCAT(unwrap_res_, __LINE__).isErr()) {                          \
        return Err(std::move(GEODE_CONCAT(unwrap_res_, __LINE__).unwrapErr())); \
    }                                                                           \
    into = std::move(GEODE_CONCAT(unwrap_res_, __LINE__).unwrap())

#define GEODE_UNWRAP(...)                                                           \
    {                                                                               \
        auto GEODE_CONCAT(unwrap_res_, __LINE__) = (__VA_ARGS__);                   \
        if (GEODE_CONCAT(unwrap_res_, __LINE__).isErr()) {                          \
            return Err(std::move(GEODE_CONCAT(unwrap_res_, __LINE__).unwrapErr())); \
        }                                                                           \
    }
}