/*
 * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
 * Copyright (c) 2022, Tobias Christiansen <tobyase@serenityos.org>
 * Copyright (c) 2022, Timothy Slater <tslater2006@gmail.com>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "Layer.h"
#include "Image.h"
#include "Selection.h"
#include <AK/RefPtr.h>
#include <AK/Try.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/Painter.h>

namespace PixelPaint {

ErrorOr<NonnullRefPtr<Layer>> Layer::try_create_with_size(Image& image, Gfx::IntSize const& size, String name)
{
    VERIFY(!size.is_empty());

    if (size.width() > 16384 || size.height() > 16384)
        return Error::from_string_literal("Layer size too large");

    auto bitmap = TRY(Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, size));
    return adopt_nonnull_ref_or_enomem(new (nothrow) Layer(image, move(bitmap), move(name)));
}

ErrorOr<NonnullRefPtr<Layer>> Layer::try_create_with_bitmap(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, String name)
{
    VERIFY(!bitmap->size().is_empty());

    if (bitmap->size().width() > 16384 || bitmap->size().height() > 16384)
        return Error::from_string_literal("Layer size too large");

    return adopt_nonnull_ref_or_enomem(new (nothrow) Layer(image, bitmap, move(name)));
}

ErrorOr<NonnullRefPtr<Layer>> Layer::try_create_snapshot(Image& image, Layer const& layer)
{
    auto bitmap = TRY(layer.content_bitmap().clone());
    auto snapshot = TRY(try_create_with_bitmap(image, move(bitmap), layer.name()));

    /*
        We set these properties directly because calling the setters might
        notify the image of an update on the newly created layer, but this
        layer has not yet been added to the image.
    */
    snapshot->m_opacity_percent = layer.opacity_percent();
    snapshot->m_visible = layer.is_visible();

    snapshot->set_selected(layer.is_selected());
    snapshot->set_location(layer.location());

    return snapshot;
}

Layer::Layer(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, String name)
    : m_image(image)
    , m_name(move(name))
    , m_content_bitmap(move(bitmap))
    , m_cached_display_bitmap(m_content_bitmap)
{
}

void Layer::did_modify_bitmap(Gfx::IntRect const& rect)
{
    if (!m_scratch_edited_bitmap.is_null()) {
        for (int y = 0; y < rect.height(); ++y) {
            for (int x = 0; x < rect.width(); ++x) {
                Gfx::IntPoint next_point = { rect.left() + x, rect.top() + y };
                if (!m_scratch_edited_bitmap->rect().contains(next_point))
                    continue;

                if (this->image().selection().is_selected(next_point.translated(this->location())))
                    currently_edited_bitmap().set_pixel(next_point, m_scratch_edited_bitmap->get_pixel(next_point));
                else
                    m_scratch_edited_bitmap->set_pixel(next_point, currently_edited_bitmap().get_pixel(next_point));
            }
        }
    }

    m_image.layer_did_modify_bitmap({}, *this, rect);
    update_cached_bitmap();
}

void Layer::set_visible(bool visible)
{
    if (m_visible == visible)
        return;
    m_visible = visible;
    m_image.layer_did_modify_properties({}, *this);
}

void Layer::set_opacity_percent(int opacity_percent)
{
    if (m_opacity_percent == opacity_percent)
        return;
    m_opacity_percent = opacity_percent;
    m_image.layer_did_modify_properties({}, *this);
}

void Layer::set_name(String name)
{
    if (m_name == name)
        return;
    m_name = move(name);
    m_image.layer_did_modify_properties({}, *this);
}

Gfx::Bitmap& Layer::get_scratch_edited_bitmap()
{
    if (this->image().selection().is_empty()) {
        m_scratch_edited_bitmap = nullptr;
        return currently_edited_bitmap();
    }

    if (!m_scratch_edited_bitmap.is_null())
        return *m_scratch_edited_bitmap;

    m_scratch_edited_bitmap = MUST(currently_edited_bitmap().clone());

    return *m_scratch_edited_bitmap;
}

RefPtr<Gfx::Bitmap> Layer::try_copy_bitmap(Selection const& selection) const
{
    if (selection.is_empty()) {
        return {};
    }
    auto selection_rect = selection.bounding_rect();

    auto bitmap_or_error = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, selection_rect.size());
    if (bitmap_or_error.is_error())
        return nullptr;
    auto result = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
    VERIFY(result->has_alpha_channel());

    for (int y = selection_rect.top(); y <= selection_rect.bottom(); y++) {
        for (int x = selection_rect.left(); x <= selection_rect.right(); x++) {

            Gfx::IntPoint image_point { x, y };
            auto layer_point = image_point - m_location;
            auto result_point = image_point - selection_rect.top_left();

            if (!m_content_bitmap->physical_rect().contains(layer_point)) {
                result->set_pixel(result_point, Gfx::Color::Transparent);
                continue;
            }

            auto pixel = m_content_bitmap->get_pixel(layer_point);

            // Widen to int before multiplying to avoid overflow issues
            auto pixel_alpha = static_cast<int>(pixel.alpha());
            auto selection_alpha = static_cast<int>(selection.get_selection_alpha(image_point));
            auto new_alpha = (pixel_alpha * selection_alpha) / 0xFF;
            pixel.set_alpha(static_cast<u8>(clamp(new_alpha, 0, 0xFF)));

            result->set_pixel(result_point, pixel);
        }
    }

    return result;
}

void Layer::erase_selection(Selection const& selection)
{
    auto const image_and_selection_intersection = m_image.rect().intersected(selection.bounding_rect());
    auto const translated_to_layer_space = image_and_selection_intersection.translated(-location());

    for (int y = translated_to_layer_space.top(); y < translated_to_layer_space.top() + translated_to_layer_space.height(); ++y) {
        for (int x = translated_to_layer_space.left(); x < translated_to_layer_space.left() + translated_to_layer_space.width(); ++x) {

            // Selection is still in pre-translated coordinates, account for this by adding the layer's relative location
            if (content_bitmap().rect().contains(x, y) && selection.is_selected(x + location().x(), y + location().y())) {
                content_bitmap().set_pixel(x, y, Color::Transparent);
            }
        }
    }

    did_modify_bitmap(translated_to_layer_space);
}

ErrorOr<void> Layer::try_set_bitmaps(NonnullRefPtr<Gfx::Bitmap> content, RefPtr<Gfx::Bitmap> mask)
{
    if (mask && content->size() != mask->size())
        return Error::from_string_literal("Layer content and mask must be same size");

    m_content_bitmap = move(content);
    m_mask_bitmap = move(mask);
    m_scratch_edited_bitmap = nullptr;
    update_cached_bitmap();
    return {};
}

void Layer::flip(Gfx::Orientation orientation)
{
    m_content_bitmap = *m_content_bitmap->flipped(orientation).release_value_but_fixme_should_propagate_errors();
    if (m_mask_bitmap)
        m_mask_bitmap = *m_mask_bitmap->flipped(orientation).release_value_but_fixme_should_propagate_errors();

    did_modify_bitmap();
}

void Layer::rotate(Gfx::RotationDirection direction)
{
    m_content_bitmap = *m_content_bitmap->rotated(direction).release_value_but_fixme_should_propagate_errors();
    if (m_mask_bitmap)
        m_mask_bitmap = *m_mask_bitmap->rotated(direction).release_value_but_fixme_should_propagate_errors();

    did_modify_bitmap();
}

void Layer::crop(Gfx::IntRect const& rect)
{
    m_content_bitmap = *m_content_bitmap->cropped(rect).release_value_but_fixme_should_propagate_errors();
    if (m_mask_bitmap)
        m_mask_bitmap = *m_mask_bitmap->cropped(rect).release_value_but_fixme_should_propagate_errors();

    did_modify_bitmap();
}

void Layer::resize(Gfx::IntSize const& new_size, Gfx::IntPoint const& new_location, Gfx::Painter::ScalingMode scaling_mode)
{
    auto src_rect = Gfx::IntRect(Gfx::IntPoint(0, 0), size());
    auto dst_rect = Gfx::IntRect(Gfx::IntPoint(0, 0), new_size);

    {
        auto dst = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, new_size).release_value_but_fixme_should_propagate_errors();
        Gfx::Painter painter(dst);

        if (scaling_mode == Gfx::Painter::ScalingMode::None) {
            painter.blit(src_rect.top_left(), *m_content_bitmap, src_rect, 1.0f);
        } else {
            painter.draw_scaled_bitmap(dst_rect, *m_content_bitmap, src_rect, 1.0f, scaling_mode);
        }

        m_content_bitmap = move(dst);
    }

    if (m_mask_bitmap) {
        auto dst = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, new_size).release_value_but_fixme_should_propagate_errors();
        Gfx::Painter painter(dst);

        if (scaling_mode == Gfx::Painter::ScalingMode::None) {
            painter.blit(src_rect.top_left(), *m_content_bitmap, src_rect, 1.0f);
        } else {
            painter.draw_scaled_bitmap(dst_rect, *m_mask_bitmap, src_rect, 1.0f, scaling_mode);
        }

        m_mask_bitmap = move(dst);
    }

    set_location(new_location);
    did_modify_bitmap();
}

void Layer::resize(Gfx::IntRect const& new_rect, Gfx::Painter::ScalingMode scaling_mode)
{
    resize(new_rect.size(), new_rect.location(), scaling_mode);
}

void Layer::resize(Gfx::IntSize const& new_size, Gfx::Painter::ScalingMode scaling_mode)
{
    resize(new_size, location(), scaling_mode);
}

void Layer::update_cached_bitmap()
{
    if (!is_masked()) {
        if (m_content_bitmap.ptr() == m_cached_display_bitmap.ptr())
            return;
        m_cached_display_bitmap = m_content_bitmap;
        return;
    }

    if (m_cached_display_bitmap.ptr() == m_content_bitmap.ptr() || m_cached_display_bitmap->size() != size()) {
        m_cached_display_bitmap = MUST(Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, size()));
    }

    // FIXME: This can probably be done nicer
    m_cached_display_bitmap->fill(Color::Transparent);
    for (int y = 0; y < size().height(); ++y) {
        for (int x = 0; x < size().width(); ++x) {
            auto opacity_multiplier = (float)m_mask_bitmap->get_pixel(x, y).to_grayscale().red() / 255;
            auto content_color = m_content_bitmap->get_pixel(x, y);
            content_color.set_alpha(content_color.alpha() * opacity_multiplier);
            m_cached_display_bitmap->set_pixel(x, y, content_color);
        }
    }
}

void Layer::create_mask()
{
    m_mask_bitmap = MUST(Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRx8888, size()));
    m_mask_bitmap->fill(Gfx::Color::White);
    update_cached_bitmap();
}

Gfx::Bitmap& Layer::currently_edited_bitmap()
{
    switch (edit_mode()) {
    case EditMode::Mask:
        if (is_masked())
            return *mask_bitmap();
        [[fallthrough]];
    case EditMode::Content:
        return content_bitmap();
    }
    VERIFY_NOT_REACHED();
}

void Layer::set_edit_mode(Layer::EditMode mode)
{
    if (m_edit_mode == mode)
        return;
    m_scratch_edited_bitmap = nullptr;
    m_edit_mode = mode;
}

Optional<Gfx::IntRect> Layer::nonempty_content_bounding_rect() const
{
    Optional<int> min_content_y;
    Optional<int> min_content_x;
    Optional<int> max_content_y;
    Optional<int> max_content_x;

    for (int y = 0; y < m_content_bitmap->height(); ++y) {
        for (int x = 0; x < m_content_bitmap->width(); ++x) {
            auto color = m_content_bitmap->get_pixel(x, y);
            if (color.alpha() == 0)
                continue;
            min_content_x = min(min_content_x.value_or(x), x);
            min_content_y = min(min_content_y.value_or(y), y);
            max_content_x = max(max_content_x.value_or(x), x);
            max_content_y = max(max_content_y.value_or(y), y);
        }
    }

    if (!min_content_x.has_value())
        return {};

    return Gfx::IntRect {
        *min_content_x,
        *min_content_y,
        *max_content_x - *min_content_x + 1,
        *max_content_y - *min_content_y + 1
    };
}

}