/*
 * libfud
 * Copyright 2024 Dominick Allen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef FUD_SPAN_HPP
#define FUD_SPAN_HPP

#include <cstdlib>

#include "fud_array.hpp"

namespace fud {

template <typename T, size_t Size>
struct Span {
    static_assert(Size > 0);
    using ValueType = T;

    static Span make(Array<T, Size>& array) {
        Span<T, Size> output{};
        output.m_data = array.data();
        return output;
    }

    template <typename U>
    static Span make(const Array<U, Size>& array) {
        static_assert(std::convertible_to<U, T>);
        Span<T, Size> output{};
        output.m_data = array.data();
        return output;
    }

    T* m_data;

    [[nodiscard]] constexpr size_t size() const
    {
        return Size;
    }

    constexpr T& front()
    {
        return m_data[0];
    }

    constexpr const T& front() const
    {
        return m_data[0];
    }

    constexpr T& back()
    {
        return m_data[Size - 1];
    }

    constexpr const T& back() const
    {
        return m_data[Size - 1];
    }

    constexpr T* data() noexcept
    {
        return m_data;
    }

    constexpr const T* data() const noexcept
    {
        return m_data;
    }

    constexpr T* begin() noexcept
    {
        return m_data;
    }

    constexpr const T* begin() const noexcept
    {
        return m_data;
    }

    constexpr T* end() noexcept
    {
        return m_data + Size;
    }

    constexpr const T* end() const noexcept
    {
        return m_data + Size;
    }

    constexpr T& operator[](size_t index)
    {
        return m_data[index];
    }

    constexpr const T& operator[](size_t index) const
    {
        return m_data[index];
    }

    constexpr bool operator==(const Span<T, Size>&) const noexcept = default;

    constexpr auto operator<=>(const Span<T, Size>& other) const noexcept = default;
};

} // namespace fud

#endif