/*
 * 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 "fud_result.hpp"
#include "fud_status.hpp"

#include <cstddef>
#include <cstdint>

namespace fud {

template <typename T, size_t Size>
struct Array;

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

    T* m_data;
    // NOLINTNEXTLINE(cppcoreguidelines-avoid-const-or-ref-data-members)
    const size_t m_size;

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

    static Result<Span, FudStatus> make(Array<T, Size>& array, size_t size)
    {
        if (size > Size) {
            return FudStatus::ArgumentInvalid;
        }
        return Span<T, Size>{array.data(), Size};
    }

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

    template <typename U>
    static Result<Span, FudStatus> make(const Array<U, Size>& array, size_t size)
    {
        static_assert(std::convertible_to<U, T>);
        if (size > Size) {
            return FudStatus::ArgumentInvalid;
        }
        return Span<T, Size>{array.data(), Size};
    }

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

    template <typename U>
    static Result<Span, FudStatus> make(Array<U, Size>& array, size_t size)
    {
        static_assert(std::convertible_to<U, T>);
        if (size > Size) {
            return FudStatus::ArgumentInvalid;
        }
        return Span<T, Size>{array.data(), array.size()};
    }

    template <size_t ArraySize>
    static Span makeCStringBuffer(Array<T, ArraySize>& array)
    {
        static_assert(ArraySize > Size);
        Span<T, Size> output{};
        output.m_data = array.data();
        return output;
    }

    [[nodiscard]] constexpr size_t size() const
    {
        if constexpr (Size < SIZE_MAX) {
            return Size;
        } else {
            return m_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