/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2010 Apple Inc. All rights reserved.
 *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "core/html/HTMLLabelElement.h"

#include "core/HTMLNames.h"
#include "core/dom/Document.h"
#include "core/dom/ElementTraversal.h"
#include "core/editing/FrameSelection.h"
#include "core/events/MouseEvent.h"
#include "core/frame/LocalFrame.h"
#include "core/html/FormAssociatedElement.h"
#include "core/page/EventHandler.h"

namespace blink {

using namespace HTMLNames;

inline HTMLLabelElement::HTMLLabelElement(Document& document, HTMLFormElement* form)
    : HTMLElement(labelTag, document)
    , m_processingClick(false)
{
    FormAssociatedElement::associateByParser(form);
}

PassRefPtrWillBeRawPtr<HTMLLabelElement> HTMLLabelElement::create(Document& document, HTMLFormElement* form)
{
    RefPtrWillBeRawPtr<HTMLLabelElement> labelElement = adoptRefWillBeNoop(new HTMLLabelElement(document, form));
    return labelElement.release();
}

bool HTMLLabelElement::rendererIsFocusable() const
{
    HTMLLabelElement* that = const_cast<HTMLLabelElement*>(this);
    return that->isContentEditable();
}

LabelableElement* HTMLLabelElement::control() const
{
    const AtomicString& controlId = getAttribute(forAttr);
    if (controlId.isNull()) {
        // Search the children and descendants of the label element for a form element.
        // per http://dev.w3.org/html5/spec/Overview.html#the-label-element
        // the form element must be "labelable form-associated element".
        for (LabelableElement& element : Traversal<LabelableElement>::descendantsOf(*this)) {
            if (element.supportLabels())
                return &element;
        }
        return nullptr;
    }

    if (Element* element = treeScope().getElementById(controlId)) {
        if (isLabelableElement(*element) && toLabelableElement(*element).supportLabels())
            return toLabelableElement(element);
    }

    return nullptr;
}

HTMLFormElement* HTMLLabelElement::formOwner() const
{
    return FormAssociatedElement::form();
}

void HTMLLabelElement::setActive(bool down)
{
    if (down == active())
        return;

    // Update our status first.
    HTMLElement::setActive(down);

    // Also update our corresponding control.
    if (HTMLElement* element = control())
        element->setActive(down);
}

void HTMLLabelElement::setHovered(bool over)
{
    if (over == hovered())
        return;

    // Update our status first.
    HTMLElement::setHovered(over);

    // Also update our corresponding control.
    if (HTMLElement* element = control())
        element->setHovered(over);
}

bool HTMLLabelElement::isInteractiveContent() const
{
    return true;
}

bool HTMLLabelElement::isInInteractiveContent(Node* node) const
{
    if (!containsIncludingShadowDOM(node))
        return false;
    while (node && this != node) {
        if (node->isHTMLElement() && toHTMLElement(node)->isInteractiveContent())
            return true;
        node = node->parentOrShadowHostNode();
    }
    return false;
}

void HTMLLabelElement::defaultEventHandler(Event* evt)
{
    if (evt->type() == EventTypeNames::click && !m_processingClick) {
        RefPtrWillBeRawPtr<HTMLElement> element = control();

        // If we can't find a control or if the control received the click
        // event, then there's no need for us to do anything.
        if (!element || (evt->target() && element->containsIncludingShadowDOM(evt->target()->toNode())))
            return;

        if (evt->target() && isInInteractiveContent(evt->target()->toNode()))
            return;

        //   Behaviour of label element is as follows:
        //     - If there is double click, two clicks will be passed to control
        //       element. Control element will *not* be focused.
        //     - If there is selection of label element by dragging, no click
        //       event is passed. Also, no focus on control element.
        //     - If there is already a selection on label element and then label
        //       is clicked, then click event is passed to control element and
        //       control element is focused.

        bool isLabelTextSelected = false;

        // If the click is not simulated and the text of the label element
        // is selected by dragging over it, then return without passing the
        // click event to control element.
        // Note: a click event may be not a mouse event if created by
        // document.createEvent().
        if (evt->isMouseEvent() && !toMouseEvent(evt)->isSimulated()) {
            if (LocalFrame* frame = document().frame()) {
                // Check if there is a selection and click is not on the
                // selection.
                if (!Position::nodeIsUserSelectNone(this) && frame->selection().isRange() && !frame->eventHandler().mouseDownWasSingleClickInSelection())
                    isLabelTextSelected = true;
                // If selection is there and is single click i.e. text is
                // selected by dragging over label text, then return.
                // Click count >=2, meaning double click or triple click,
                // should pass click event to control element.
                // Only in case of drag, *neither* we pass the click event,
                // *nor* we focus the control element.
                if (isLabelTextSelected && frame->eventHandler().clickCount() == 1)
                    return;
            }
        }

        m_processingClick = true;

        document().updateLayoutIgnorePendingStylesheets();
        if (element->isMouseFocusable()) {
            // If the label is *not* selected, or if the click happened on
            // selection of label, only then focus the control element.
            // In case of double click or triple click, selection will be there,
            // so do not focus the control element.
            if (!isLabelTextSelected)
                element->focus(true, FocusTypeMouse);
        }

        // Click the corresponding control.
        element->dispatchSimulatedClick(evt);

        m_processingClick = false;

        evt->setDefaultHandled();
    }

    HTMLElement::defaultEventHandler(evt);
}

bool HTMLLabelElement::willRespondToMouseClickEvents()
{
    if (control() && control()->willRespondToMouseClickEvents())
        return true;

    return HTMLElement::willRespondToMouseClickEvents();
}

void HTMLLabelElement::focus(bool, FocusType type)
{
    // to match other browsers, always restore previous selection
    if (HTMLElement* element = control())
        element->focus(true, type);
    if (isFocusable())
        HTMLElement::focus(true, type);
}

void HTMLLabelElement::accessKeyAction(bool sendMouseEvents)
{
    if (HTMLElement* element = control())
        element->accessKeyAction(sendMouseEvents);
    else
        HTMLElement::accessKeyAction(sendMouseEvents);
}

void HTMLLabelElement::updateLabel(TreeScope& scope, const AtomicString& oldForAttributeValue, const AtomicString& newForAttributeValue)
{
    if (!inDocument())
        return;

    if (oldForAttributeValue == newForAttributeValue)
        return;

    if (!oldForAttributeValue.isEmpty())
        scope.removeLabel(oldForAttributeValue, this);
    if (!newForAttributeValue.isEmpty())
        scope.addLabel(newForAttributeValue, this);
}

void HTMLLabelElement::attributeWillChange(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue)
{
    if (name == HTMLNames::forAttr) {
        TreeScope& scope = treeScope();
        if (scope.shouldCacheLabelsByForAttribute())
            updateLabel(scope, oldValue, newValue);
    }
    HTMLElement::attributeWillChange(name, oldValue, newValue);
}

Node::InsertionNotificationRequest HTMLLabelElement::insertedInto(ContainerNode* insertionPoint)
{
    InsertionNotificationRequest result = HTMLElement::insertedInto(insertionPoint);
    FormAssociatedElement::insertedInto(insertionPoint);
    if (insertionPoint->isInTreeScope()) {
        TreeScope& scope = insertionPoint->treeScope();
        if (scope == treeScope() && scope.shouldCacheLabelsByForAttribute())
            updateLabel(scope, nullAtom, fastGetAttribute(forAttr));
    }

    // Trigger for elements outside of forms.
    if (!formOwner() && insertionPoint->inDocument())
        document().didAssociateFormControl(this);

    return result;
}

void HTMLLabelElement::removedFrom(ContainerNode* insertionPoint)
{
    if (insertionPoint->isInTreeScope() && treeScope() == document()) {
        TreeScope& treeScope = insertionPoint->treeScope();
        if (treeScope.shouldCacheLabelsByForAttribute())
            updateLabel(treeScope, fastGetAttribute(forAttr), nullAtom);
    }
    HTMLElement::removedFrom(insertionPoint);
    FormAssociatedElement::removedFrom(insertionPoint);
    document().removeFormAssociation(this);
}

void HTMLLabelElement::trace(Visitor* visitor)
{
    HTMLElement::trace(visitor);
    FormAssociatedElement::trace(visitor);
}

void HTMLLabelElement::parseAttribute(const QualifiedName& attributeName, const AtomicString& attributeValue)
{
    if (attributeName == formAttr)
        formAttributeChanged();
    else
        HTMLElement::parseAttribute(attributeName, attributeValue);
}

} // namespace