/*
 * 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_VECTOR_HPP
#define FUD_VECTOR_HPP

#include "fud_allocator.hpp"
#include "fud_assert.hpp"
#include "fud_config.hpp"
#include "fud_option.hpp"
#include "fud_result.hpp"
#include "fud_span.hpp"
#include "fud_status.hpp"

#include <cstddef>
#include <functional>
#include <new> // IWYU pragma: keep (placement new)

namespace fud {

template <typename T>
class Vector {
    static constexpr size_t ElementSize = sizeof(T);
    static constexpr size_t Alignment = alignof(T);

  public:
    constexpr Vector() noexcept = default;
    constexpr explicit Vector(Allocator& allocator) noexcept : m_allocator{&allocator} {}
    constexpr Vector(const Vector<T>& rhs) = delete;
    constexpr Vector(Vector<T>&& rhs) noexcept :
        m_allocator(rhs.m_allocator), m_data(rhs.m_data), m_length{rhs.m_length}, m_capacity{rhs.m_capacity}
    {
        rhs.m_allocator = nullptr;
        rhs.m_data = nullptr;
        rhs.m_length = 0;
        rhs.m_capacity = 0;
    }

    ~Vector() noexcept
    {
        static_cast<void>(cleanup());
    }

    Vector& operator=(const Vector<T>& rhs) = delete;

    Vector& operator=(Vector<T>&& rhs) noexcept
    {
        if (&rhs == this) {
            return *this;
        }
        static_cast<void>(cleanup());
        m_allocator = rhs.m_allocator;
        m_data = rhs.m_data;
        m_length = rhs.m_length;
        m_capacity = rhs.m_length;

        rhs.m_allocator = nullptr;
        rhs.m_data = nullptr;
        rhs.m_length = 0;
        rhs.m_capacity = 0;

        return *this;
    }

    static constexpr Vector<T> NullVector() noexcept {
        Vector<T> output{};
        output.m_allocator = &globalNullAllocator;
        return output;
    }

    static Result<Vector<T>, FudStatus> withCapacity(size_t capacity, Allocator* allocator = &globalFudAllocator)
    {
        Vector<T> output{};
        auto status = initializeWithCapacity(output, capacity, allocator);
        if (status != FudStatus::Success) {
            return status;
        }
        return output;
    }

    static FudStatus initializeWithCapacity(
        Vector<T>& output,
        size_t capacity,
        Allocator* allocator = &globalFudAllocator)
    {
        if (output.m_data != nullptr) {
            return FudStatus::AlreadyInitialized;
        }

        if (allocator == nullptr) {
            return FudStatus::NullPointer;
        }

        if (capacity > SIZE_MAX / ElementSize) {
            return FudStatus::ArgumentInvalid;
        }

        size_t requestedSize = capacity * ElementSize;
        auto dataPtrResult = allocator->allocate(requestedSize, Alignment);
        if (dataPtrResult.isError()) {
            return dataPtrResult.getError();
        }

        output.m_allocator = allocator;
        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
        output.m_data = reinterpret_cast<T*>(dataPtrResult.getOkay());
        output.m_length = 0;
        output.m_capacity = capacity;
        return FudStatus::Success;
    }

    static Result<Vector<T>, FudStatus> withSize(size_t count, Allocator* allocator = &globalFudAllocator)
    {
        Vector<T> output{};
        auto status = initializeWithSize(output, count, allocator);
        if (status != FudStatus::Success) {
            return FudError{status};
        }
        return Okay<Vector<T>>{std::move(output)};
    }

    static FudStatus initializeWithSize(
        Vector<T>& output,
        size_t count,
        Allocator* allocator = &globalFudAllocator)
    {
        if (output.m_data != nullptr) {
            return FudStatus::AlreadyInitialized;
        }

        auto status = Vector::initializeWithCapacity(output, count, allocator);
        if (status != FudStatus::Success) {
            return status;
        }

        output.m_length = count;
        for (size_t index = 0; index < count; ++index) {
            const auto* ptr = new (output.m_data + index) T();
            fudAssert(ptr != nullptr);
        }

        return FudStatus::Success;
    }

    template <typename Builder>
    static Result<Vector<T>, FudStatus> withSizeFallible(
        size_t count,
        Builder&& builder,
        Allocator* allocator = &globalFudAllocator)
    {
        Vector<T> output{};
        auto status = initializeWithSizeFallible(output, count, std::forward<Builder>(builder), allocator);
        if (status != FudStatus::Success) {
            return FudError{status};
        }
        return Okay<Vector<T>>{std::move(output)};
    }

    template <typename Builder>
    static FudStatus initializeWithSizeFallible(
        Vector<T>& output,
        size_t count,
        Builder&& builder,
        Allocator* allocator = &globalFudAllocator)
    {
        // using BuilderResult = decltype(std::forward<Builder>(builder)(T{}));
        // static_assert(std::is_same_v<BuilderResult, FudStatus>);

        auto status = Vector::initializeWithCapacity(output, count, allocator);
        if (status != FudStatus::Success) {
            return status;
        }

        output.m_length = count;

        for (size_t index = 0; index < count; ++index) {
            auto builderStatus{std::forward<Builder>(builder)(output.m_data[index])};
            if (builderStatus != FudStatus::Success) {
                return builderStatus;
            }
        }

        return FudStatus::Success;
    }

    static Result<Vector<T>, FudStatus> from(const Vector<T>& rhs, Option<Allocator*> allocatorOption = NullOpt)
    {
        Allocator* allocator = nullptr;
        if (allocatorOption.hasValue()) {
            allocator = allocatorOption.value();
            if (allocator == nullptr) {
                return FudStatus::NullPointer;
            }
        } else {
            allocator = rhs.m_allocator;
            if (allocator == nullptr) {
                return FudStatus::ArgumentInvalid;
            }
        }

        fudAssert(rhs.m_length <= rhs.m_capacity);

        auto spanResult = rhs.span();
        if (spanResult.isError()) {
            return spanResult.takeError();
        }
        Vector<T> output{};
        auto status = Vector::initializeFromSpan(output, rhs.m_length, allocator);
        if (status != FudStatus::Success) {
            return status;
        }
        return output;
    }

    template <size_t Size>
    static Result<Vector<T>, FudStatus> from(Span<const T, Size>& rhs, Allocator* allocator)
    {
        Vector<T> output{};
        auto status = initializeFromSpan(output, rhs, allocator);
        if (status != FudStatus::Success) {
            return status;
        }
        return output;
    }

    template <size_t Size>
    static FudStatus initializeFromSpan(Vector<T>& output, Span<const T, Size>& rhs, Allocator* allocator)
    {
        auto status = Vector::initializeWithCapacity(output, rhs.size(), allocator);
        if (status != FudStatus::Success) {
            return status;
        }
        output.m_length = rhs.m_length;
        for (size_t index = 0; index < output.m_length; ++index) {
            output.m_data[index] = rhs[index];
        }
    }

    static Vector<T> move(Vector<T>&& rhs) noexcept
    {
        return Vector<T>{std::move(rhs)};
    }

    FudStatus copy(const Vector<T>& rhs);

    FudStatus take(Vector<T>&& rhs);

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

    [[nodiscard]] size_t capacity() const
    {
        return m_capacity;
    }

    Result<Span<const T>, FudStatus> span() const
    {
        using RetType = Result<Span<const T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        return RetType::okay(Span{m_data, m_length});
    }

    Result<Span<T>, FudStatus> span()
    {
        using RetType = Result<Span<T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        return RetType::okay(Span{m_data, m_length});
    }

    Result<Span<const T>, FudStatus> span(size_t count) const
    {
        using RetType = Result<Span<const T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (count > m_length) {
            return RetType::error(FudStatus::ArgumentInvalid);
        }
        return RetType::okay(Span{m_data, count});
    }

    Result<Span<T>, FudStatus> span(size_t count)
    {
        using RetType = Result<Span<T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (count > m_length) {
            return RetType::error(FudStatus::ArgumentInvalid);
        }
        return RetType::okay(Span{m_data, count});
    }

    Result<Span<const T>, FudStatus> span(size_t start, size_t count) const
    {
        using RetType = Result<Span<const T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (SIZE_MAX - start < m_length || start + count > m_length) {
            return RetType::error(FudStatus::ArgumentInvalid);
        }
        return RetType::okay(Span{m_data + start, count});
    }

    Result<Span<T>, FudStatus> span(size_t start, size_t count)
    {
        using RetType = Result<Span<T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (SIZE_MAX - start < m_length || start + count > m_length) {
            return RetType::error(FudStatus::ArgumentInvalid);
        }
        return RetType::okay(Span{m_data + start, count});
    }

    FudStatus reserve(size_t count)
    {
        if (count <= m_capacity) {
            return FudStatus::Success;
        }

        if (m_allocator == nullptr) {
            return FudStatus::ObjectInvalid;
        }

        if (count > SIZE_MAX / ElementSize) {
            return FudStatus::ArgumentInvalid;
        }

        size_t requestedSize = count * ElementSize;
        auto dataPtrResult = m_allocator->allocate(requestedSize, Alignment);
        if (dataPtrResult.isError()) {
            return dataPtrResult.takeError();
        }

        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
        auto* dataPtr = reinterpret_cast<T*>(dataPtrResult.takeOkay());
        for (size_t index = 0; index < m_length; ++index) {
            const auto* ptr = new (dataPtr + index) T(std::move(m_data[index]));
            fudAssert(ptr != nullptr);
            m_data[index].~T();
        }

        auto status = FudStatus::Success;
        if (m_capacity > 0) {
            // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
            m_allocator->deallocate(reinterpret_cast<std::byte*>(m_data), m_capacity);
        }

        m_data = dataPtr;
        m_capacity = count;

        return status;
    }

    FudStatus resize(size_t count)
    {
        if (count == m_length) {
            return FudStatus::Success;
        }

        if (m_allocator == nullptr) {
            return FudStatus::ObjectInvalid;
        }

        if (count < m_length) {
            for (size_t index = count; index < m_length; ++index) {
                m_data[index].~T();
            }
            m_length = count;
            return FudStatus::Success;
        }

        auto reserveStatus = reserve(count);
        if (reserveStatus != FudStatus::Success) {
            return reserveStatus;
        }

        for (size_t index = m_length; index < count; ++index) {
            const auto* ptr = new (m_data + index) T();
            fudAssert(ptr != nullptr);
        }

        m_length = count;
        return FudStatus::Success;
    }

    FudStatus clear()
    {
        if (m_allocator == nullptr || m_data == nullptr) {
            if (m_length > 0) {
                return FudStatus::ObjectInvalid;
            }
            return FudStatus::Success;
        }
        for (size_t index = 0; index < m_length; ++index) {
            m_data[index].~T();
        }
        m_length = 0;
        return FudStatus::Success;
    }

    Result<std::reference_wrapper<T>, FudStatus> get(size_t index)
    {
        using RetType = Result<std::reference_wrapper<T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (index >= m_length) {
            return RetType::error(FudStatus::IndexInvalid);
        }
        return RetType::okay(std::ref(m_data[index]));
    }

    Result<const std::reference_wrapper<const T>, FudStatus> ref(size_t index) const
    {
        using RetType = Result<const std::reference_wrapper<const T>, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (index >= m_length) {
            return RetType::error(FudStatus::IndexInvalid);
        }
        return RetType::okay(std::cref(m_data[index]));
    }

    constexpr Option<T&> front()
    {
        if (m_length > 0) {
            fudAssert(m_data != nullptr);
            return m_data[0];
        }
        return NullOpt;
    }

    constexpr Option<const T&> front() const
    {
        if (m_length > 0) {
            fudAssert(m_data != nullptr);
            return m_data[0];
        }
        return NullOpt;
    }

    constexpr Option<T&> back()
    {
        if (m_length > 0) {
            fudAssert(m_data != nullptr);
            return m_data[m_length - 1];
        }
        return NullOpt;
    }

    constexpr Option<const T&> back() const
    {
        if (m_length > 0) {
            return m_data[m_length - 1];
        }
        return NullOpt;
    }

    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 + m_length;
    }

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

    constexpr T& operator[](size_t index)
    {
        if constexpr (fudBoundsChecking) {
            fudAssert(m_data != nullptr);
            fudAssert(index < m_length);
        }
        return m_data[index];
    }

    constexpr const T& operator[](size_t index) const
    {
        if constexpr (fudBoundsChecking) {
            fudAssert(m_data != nullptr);
            fudAssert(index < m_length);
        }
        return m_data[index];
    }

    FudStatus pushBack(const T& value)
    {
        if (m_length == m_capacity) {
            auto status = grow();
            if (status != FudStatus::Success) {
                return status;
            }
        }
        const auto* ptr = new (m_data + m_length) T(value);
        fudAssert(ptr != nullptr);
        m_length++;
        return FudStatus::Success;
    }

    FudStatus pushBack(T&& value)
    {
        if (m_length == m_capacity) {
            auto status = grow();
            if (status != FudStatus::Success) {
                return status;
            }
        }
        const auto* ptr = new (m_data + m_length) T(std::move(value));
        fudAssert(ptr != nullptr);
        m_length++;
        return FudStatus::Success;
    }

    Result<T, FudStatus> popBack()
    {
        using RetType = Result<T, FudStatus>;
        if (m_data == nullptr) {
            return RetType::error(FudStatus::ObjectInvalid);
        }
        if (m_length == 0) {
            return RetType::error(FudStatus::Empty);
        }
        auto result{RetType::okay({std::move(m_data[m_length - 1])})};
        m_length--;
        m_data[m_length].~T();
        return result;
    }

    FudStatus eraseBack()
    {
        if (m_data == nullptr) {
            return FudStatus::ObjectInvalid;
        }
        if (m_length == 0) {
            return FudStatus::Empty;
        }
        m_length--;
        m_data[m_length].~T();
        return FudStatus::Success;
    }

    FudStatus insert(size_t index, const T& value)
    {
        if (index > m_length) {
            return FudStatus::IndexInvalid;
        }
        if (index == m_length) {
            return pushBack(value);
        }
        if (m_length == m_capacity) {
            auto status = grow();
            if (status != FudStatus::Success) {
                return status;
            }
        }

        const auto* ptr = new (m_data + m_length) T(std::move(m_data[m_length - 1]));
        fudAssert(ptr != nullptr);

        for (size_t backIndex = m_length - 1; backIndex > index; --backIndex) {
            m_data[backIndex] = std::move(m_data[backIndex - 1]);
        }
        m_data[index] = value;
        m_length++;
        return FudStatus::Success;
    }

    FudStatus insert(size_t index, T&& value)
    {
        if (index > m_length) {
            return FudStatus::IndexInvalid;
        }
        if (index == m_length) {
            return pushBack(std::move(value));
        }
        if (m_length == m_capacity) {
            auto status = grow();
            if (status != FudStatus::Success) {
                return status;
            }
        }

        const auto* ptr = new (m_data + m_length) T(std::move(m_data[m_length - 1]));
        fudAssert(ptr != nullptr);

        for (size_t backIndex = m_length - 1; backIndex > index; --backIndex) {
            m_data[backIndex] = std::move(m_data[backIndex - 1]);
        }
        m_data[index] = std::move(value);
        m_length++;
        return FudStatus::Success;
    }

    template <size_t Size>
    FudStatus extend(Span<const T, Size> fixedSpan)
    {
        if (fixedSpan.data() == nullptr) {
            return FudStatus::NullPointer;
        }
        if (std::numeric_limits<size_t>::max() - Size < m_length) {
            return FudStatus::Failure;
        }
        if (m_length + Size > m_capacity)
        {
            size_t currentLength = m_length;
            auto status = resize(m_length + Size);
            m_length = currentLength;
            if (status != FudStatus::Success) {
                return status;
            }
        }

        for (size_t spanIndex = 0; spanIndex < Size; ++spanIndex) {
            const auto* ptr = new (m_data + m_length) T(fixedSpan[spanIndex]);
            fudAssert(ptr != nullptr);
            m_length++;
        }

        return FudStatus::Success;
    }

    FudStatus extend(Span<const T> span)
    {
        if (span.data() == nullptr) {
            return FudStatus::NullPointer;
        }
        if (std::numeric_limits<size_t>::max() - span.size() < m_length) {
            return FudStatus::Failure;
        }
        if (m_length + span.size() > m_capacity)
        {
            size_t currentLength = m_length;
            auto status = resize(m_length + span.size());
            m_length = currentLength;
            if (status != FudStatus::Success) {
                return status;
            }
        }

        for (size_t spanIndex = 0; spanIndex < span.size(); ++spanIndex) {
            const auto* ptr = new (m_data + m_length) T(span[spanIndex]);
            fudAssert(ptr != nullptr);
            m_length++;
        }

        return FudStatus::Success;
    }

    FudStatus erase(size_t index)
    {
        if (index >= m_length) {
            return FudStatus::IndexInvalid;
        }

        m_data[index].~T();
        for (size_t fwdIndex = index; fwdIndex + 1 < m_length; fwdIndex++)
        {
            m_data[fwdIndex] = std::move(m_data[fwdIndex + 1]);
        }
        m_data[m_length - 1].~T();
        m_length--;
        return FudStatus::Success;
    }

  private:
    FudStatus grow()
    {
        // See https://github.com/facebook/folly/blob/main/folly/docs/FBVector.md
        size_t additional = m_capacity < 2 ? 1 : m_capacity / 2;
        constexpr auto maxSize = std::numeric_limits<size_t>::max();
        if (maxSize - additional * ElementSize < m_capacity * ElementSize) {
            additional = maxSize - m_capacity * ElementSize / 2;
        }
        while (additional > 0) {
            auto reserveStatus = reserve(additional + m_capacity);
            if (reserveStatus == FudStatus::Success) {
                break;
            }
            if (reserveStatus == FudStatus::AllocFailure) {
                additional /= 2;
            } else {
                return reserveStatus;
            }
        }

        if (m_length == m_capacity) {
            return FudStatus::AllocFailure;
        }

        return FudStatus::Success;
    }

    FudStatus cleanup() noexcept
    {
        auto status = clear();

        if (m_data != nullptr && m_allocator != nullptr) {
            // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
            m_allocator->deallocate(reinterpret_cast<std::byte*>(m_data), m_capacity);
        }

        m_allocator = nullptr;
        m_data = nullptr;
        m_length = 0;
        m_capacity = 0;
        return status;
    }

    Allocator* m_allocator{&globalFudAllocator};
    T* m_data{nullptr};
    size_t m_length{0};
    size_t m_capacity{0};
};

} // namespace fud

#endif