/*
 * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
 * Copyright (c) 2024, Jamie Mansfield <jmansfield@cadixdev.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibGC/Function.h>
#include <LibJS/Runtime/Realm.h>
#include <LibWeb/Bindings/DataTransferItemPrototype.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/FileAPI/File.h>
#include <LibWeb/HTML/DataTransfer.h>
#include <LibWeb/HTML/DataTransferItem.h>
#include <LibWeb/WebIDL/AbstractOperations.h>
#include <LibWeb/WebIDL/CallbackType.h>

namespace Web::HTML {

GC_DEFINE_ALLOCATOR(DataTransferItem);

GC::Ref<DataTransferItem> DataTransferItem::create(JS::Realm& realm, GC::Ref<DataTransfer> data_transfer, size_t item_index)
{
    return realm.create<DataTransferItem>(realm, data_transfer, item_index);
}

DataTransferItem::DataTransferItem(JS::Realm& realm, GC::Ref<DataTransfer> data_transfer, size_t item_index)
    : PlatformObject(realm)
    , m_data_transfer(data_transfer)
    , m_item_index(item_index)
{
}

DataTransferItem::~DataTransferItem() = default;

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

void DataTransferItem::visit_edges(JS::Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_data_transfer);
}

// https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransferitem-kind
String DataTransferItem::kind() const
{
    // The kind attribute must return the empty string if the DataTransferItem object is in the disabled mode; otherwise
    // it must return the string given in the cell from the second column of the following table from the row whose cell
    // in the first column contains the drag data item kind of the item represented by the DataTransferItem object:
    //
    //     Kind | String
    //     ---------------
    //     Text | "string"
    //     File | "file"
    if (!mode().has_value())
        return {};

    auto const& item = m_data_transfer->drag_data(*m_item_index);

    switch (item.kind) {
    case DragDataStoreItem::Kind::Text:
        return "string"_string;
    case DragDataStoreItem::Kind::File:
        return "file"_string;
    }

    VERIFY_NOT_REACHED();
}

// https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransferitem-type
String DataTransferItem::type() const
{
    // The type attribute must return the empty string if the DataTransferItem object is in the disabled mode; otherwise
    // it must return the drag data item type string of the item represented by the DataTransferItem object.
    if (!mode().has_value())
        return {};

    auto const& item = m_data_transfer->drag_data(*m_item_index);
    return item.type_string;
}

Optional<DragDataStore::Mode> DataTransferItem::mode() const
{
    if (!m_item_index.has_value())
        return {};
    return m_data_transfer->mode();
}

// https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransferitem-getasstring
void DataTransferItem::get_as_string(GC::Ptr<WebIDL::CallbackType> callback) const
{
    auto& realm = this->realm();
    auto& vm = realm.vm();

    // 1. If the callback is null, return.
    if (!callback)
        return;

    // 2. If the DataTransferItem object is not in the read/write mode or the read-only mode, return. The callback is
    //    never invoked.
    if (mode() != DragDataStore::Mode::ReadWrite && mode() != DragDataStore::Mode::ReadOnly)
        return;

    auto const& item = m_data_transfer->drag_data(*m_item_index);

    // 3. If the drag data item kind is not text, then return. The callback is never invoked.
    if (item.kind != DragDataStoreItem::Kind::Text)
        return;

    // 4. Otherwise, queue a task to invoke callback, passing the actual data of the item represented by the
    //    DataTransferItem object as the argument.
    auto data = JS::PrimitiveString::create(vm, MUST(String::from_utf8({ item.data })));

    HTML::queue_a_task(HTML::Task::Source::Unspecified, nullptr, nullptr,
        GC::Function<void()>::create(realm.heap(), [callback, data]() {
            (void)WebIDL::invoke_callback(*callback, {}, { { data } });
        }));
}

// https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransferitem-getasfile
GC::Ptr<FileAPI::File> DataTransferItem::get_as_file() const
{
    auto& realm = this->realm();

    // 1. If the DataTransferItem object is not in the read/write mode or the read-only mode, then return null
    if (mode() != DragDataStore::Mode::ReadWrite && mode() != DragDataStore::Mode::ReadOnly)
        return nullptr;

    auto const& item = m_data_transfer->drag_data(*m_item_index);

    // 2. If the drag data item kind is not File, then return null.
    if (item.kind != DragDataStoreItem::Kind::File)
        return nullptr;

    // 3. Return a new File object representing the actual data of the item represented by the DataTransferItem object.
    auto blob = FileAPI::Blob::create(realm, item.data, item.type_string);

    // FIXME: The FileAPI should use ByteString for file names.
    auto file_name = MUST(String::from_byte_string(item.file_name));

    // FIXME: Fill in other fields (e.g. last_modified).
    FileAPI::FilePropertyBag options {};
    options.type = item.type_string;

    return MUST(FileAPI::File::create(realm, { GC::make_root(blob) }, file_name, move(options)));
}

// https://wicg.github.io/entries-api/#dom-datatransferitem-webkitgetasentry
GC::Ptr<EntriesAPI::FileSystemEntry> DataTransferItem::webkit_get_as_entry() const
{
    auto& realm = this->realm();

    // 1. Let store be this's DataTransfer object’s drag data store.

    // 2. If store’s drag data store mode is not read/write mode or read-only mode, return null and abort these steps
    if (mode() != DragDataStore::Mode::ReadWrite && mode() != DragDataStore::Mode::ReadOnly)
        return nullptr;

    // 3. Let item be the item in store’s drag data store item list that this represents.
    auto const& item = m_data_transfer->drag_data(*m_item_index);

    // 4. If item’s kind is not File, then return null and abort these steps.
    if (item.kind != DragDataStoreItem::Kind::File)
        return nullptr;

    // 5. Return a new FileSystemEntry object representing the entry.
    return EntriesAPI::FileSystemEntry::create(realm, EntriesAPI::EntryType::File, item.file_name);
}

}
