/*

 * Copyright (c) 2021, Tim Flynn <trflynn89@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include <LibWeb/DOM/Document.h>

#include <LibWeb/DOM/Element.h>

#include <LibWeb/Layout/Label.h>

#include <LibWeb/Layout/LabelableNode.h>

#include <LibWeb/Layout/TextNode.h>

#include <LibWeb/Layout/Viewport.h>

#include <LibWeb/Painting/LabelablePaintable.h>

#include <LibWeb/UIEvents/MouseButton.h>

namespace Web::Layout {

JS_DEFINE_ALLOCATOR(Label);

Label::Label(DOM::Document& document, HTML::HTMLLabelElement* element, NonnullRefPtr<CSS::StyleProperties> style)

    : BlockContainer(document, element, move(style))

{

}

Label::~Label() = default;

void Label::handle_mousedown_on_label(Badge<Painting::TextPaintable>, CSSPixelPoint, unsigned button)

{

    if (button != UIEvents::MouseButton::Primary)

        return;

    if (auto control = dom_node().control(); control && is<Painting::LabelablePaintable>(control->paintable())) {

        auto& labelable_paintable = verify_cast<Painting::LabelablePaintable>(*control->paintable());

        labelable_paintable.handle_associated_label_mousedown({});

    }

    m_tracking_mouse = true;

}

void Label::handle_mouseup_on_label(Badge<Painting::TextPaintable>, CSSPixelPoint position, unsigned button)

{

    if (!m_tracking_mouse || button != UIEvents::MouseButton::Primary)

        return;

    if (auto control = dom_node().control(); control && is<Painting::LabelablePaintable>(control->paintable())) {

        bool is_inside_control = control->paintable_box()->absolute_rect().contains(position);

        bool is_inside_label = paintable_box()->absolute_rect().contains(position);

        if (is_inside_control || is_inside_label) {

            auto& labelable_paintable = verify_cast<Painting::LabelablePaintable>(*control->paintable());

            labelable_paintable.handle_associated_label_mouseup({});

        }

    }

    m_tracking_mouse = false;

}

void Label::handle_mousemove_on_label(Badge<Painting::TextPaintable>, CSSPixelPoint position, unsigned)

{

    if (!m_tracking_mouse)

        return;

    if (auto control = dom_node().control(); control && is<Painting::LabelablePaintable>(control->paintable())) {

        bool is_inside_control = control->paintable_box()->absolute_rect().contains(position);

        bool is_inside_label = paintable_box()->absolute_rect().contains(position);

        auto& labelable_paintable = verify_cast<Painting::LabelablePaintable>(*control->paintable());

        labelable_paintable.handle_associated_label_mousemove({}, is_inside_control || is_inside_label);

    }

}

bool Label::is_inside_associated_label(LabelableNode const& control, CSSPixelPoint position)

{

    if (auto* label = label_for_control_node(control); label)

        return label->paintable_box()->absolute_rect().contains(position);

    return false;

}

bool Label::is_associated_label_hovered(LabelableNode const& control)

{

    if (auto* label = label_for_control_node(control); label) {

        if (label->document().hovered_node() == &label->dom_node())

            return true;

        if (auto* child = label->first_child_of_type<TextNode>(); child)

            return label->document().hovered_node() == &child->dom_node();

    }

    return false;

}

// https://html.spec.whatwg.org/multipage/forms.html#labeled-control

Label const* Label::label_for_control_node(LabelableNode const& control)

{

    if (!control.document().layout_node())

        return nullptr;

    // The for attribute may be specified to indicate a form control with which the caption is to be associated.

    // If the attribute is specified, the attribute's value must be the ID of a labelable element in the

    // same tree as the label element. If the attribute is specified and there is an element in the tree

    // whose ID is equal to the value of the for attribute, and the first such element in tree order is

    // a labelable element, then that element is the label element's labeled control.

    if (auto const& id = control.dom_node().id(); id.has_value() && !id->is_empty()) {

        Label const* label = nullptr;

        control.document().layout_node()->for_each_in_inclusive_subtree_of_type<Label>([&](auto& node) {

            if (node.dom_node().for_() == id) {

                label = &node;

                return TraversalDecision::Break;

            }

            return TraversalDecision::Continue;

        });

        if (label)

            return label;

    }

    // If the for attribute is not specified, but the label element has a labelable element descendant,

    // then the first such descendant in tree order is the label element's labeled control.

    return control.first_ancestor_of_type<Label>();

}

}