/*
 * Copyright (c) 2021, Tim Flynn <trflynn89@serenityos.org>
 * Copyright (c) 2023, Luke Wilde <lukew@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibWeb/Bindings/AttrPrototype.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/DOM/Attr.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/DOM/MutationType.h>
#include <LibWeb/DOM/StaticNodeList.h>
#include <LibWeb/HTML/CustomElements/CustomElementReactionNames.h>

namespace Web::DOM {

GC_DEFINE_ALLOCATOR(Attr);

GC::Ref<Attr> Attr::create(Document& document, FlyString local_name, String value, Element* owner_element)
{
    return document.realm().create<Attr>(document, QualifiedName(move(local_name), Optional<FlyString> {}, Optional<FlyString> {}), move(value), owner_element);
}

GC::Ref<Attr> Attr::create(Document& document, QualifiedName qualified_name, String value, Element* owner_element)
{
    return document.realm().create<Attr>(document, move(qualified_name), move(value), owner_element);
}

GC::Ref<Attr> Attr::clone(Document& document) const
{
    return realm().create<Attr>(document, m_qualified_name, m_value, nullptr);
}

Attr::Attr(Document& document, QualifiedName qualified_name, String value, Element* owner_element)
    : Node(document, NodeType::ATTRIBUTE_NODE)
    , m_qualified_name(move(qualified_name))
    , m_lowercase_name(MUST(String(m_qualified_name.as_string()).to_lowercase()))
    , m_value(move(value))
    , m_owner_element(owner_element)
{
}

void Attr::initialize(JS::Realm& realm)
{
    Base::initialize(realm);
    WEB_SET_PROTOTYPE_FOR_INTERFACE(Attr);
}

void Attr::visit_edges(Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_owner_element);
}

Element* Attr::owner_element()
{
    return m_owner_element.ptr();
}

Element const* Attr::owner_element() const
{
    return m_owner_element.ptr();
}

void Attr::set_owner_element(Element* owner_element)
{
    m_owner_element = owner_element;
}

// https://dom.spec.whatwg.org/#set-an-existing-attribute-value
void Attr::set_value(String value)
{
    // 1. If attribute’s element is null, then set attribute’s value to value.
    if (!owner_element()) {
        m_value = move(value);
    }
    // 2. Otherwise, change attribute to value.
    else {
        change_attribute(move(value));
    }
}

// https://dom.spec.whatwg.org/#concept-element-attributes-change
void Attr::change_attribute(String value)
{
    // 1. Let oldValue be attribute’s value.
    auto old_value = move(m_value);

    // 2. Set attribute’s value to value.
    m_value = move(value);

    // 3. Handle attribute changes for attribute with attribute’s element, oldValue, and value.
    handle_attribute_changes(*owner_element(), old_value, m_value);
}

// https://dom.spec.whatwg.org/#handle-attribute-changes
void Attr::handle_attribute_changes(Element& element, Optional<String> const& old_value, Optional<String> const& new_value)
{
    // 1. Queue a mutation record of "attributes" for element with attribute’s local name, attribute’s namespace, oldValue, « », « », null, and null.
    element.queue_mutation_record(MutationType::attributes, local_name(), namespace_uri(), old_value, {}, {}, nullptr, nullptr);

    // 2. If element is custom, then enqueue a custom element callback reaction with element, callback name "attributeChangedCallback",
    //    and « attribute’s local name, oldValue, newValue, attribute’s namespace ».
    if (element.is_custom()) {
        auto& vm = this->vm();

        GC::RootVector<JS::Value> arguments { vm.heap() };
        arguments.append(JS::PrimitiveString::create(vm, local_name()));
        arguments.append(!old_value.has_value() ? JS::js_null() : JS::PrimitiveString::create(vm, old_value.value()));
        arguments.append(!new_value.has_value() ? JS::js_null() : JS::PrimitiveString::create(vm, new_value.value()));
        arguments.append(!namespace_uri().has_value() ? JS::js_null() : JS::PrimitiveString::create(vm, namespace_uri().value()));

        element.enqueue_a_custom_element_callback_reaction(HTML::CustomElementReactionNames::attributeChangedCallback, move(arguments));
    }

    // 3. Run the attribute change steps with element, attribute’s local name, oldValue, newValue, and attribute’s namespace.
    element.run_attribute_change_steps(local_name(), old_value, new_value, namespace_uri());
}

}
