/*

 * Copyright (c) 2023, Matthew Olsson <mattco@serenityos.org>

 * Copyright (c) 2023, Shannon Booth <shannon@serenityos.org>

 *

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

 */

#include <LibJS/Runtime/PromiseCapability.h>

#include <LibJS/Runtime/TypedArray.h>

#include <LibWeb/Bindings/Intrinsics.h>

#include <LibWeb/Bindings/ReadableStreamBYOBReaderPrototype.h>

#include <LibWeb/Streams/AbstractOperations.h>

#include <LibWeb/Streams/ReadableStream.h>

#include <LibWeb/Streams/ReadableStreamBYOBReader.h>

#include <LibWeb/WebIDL/Buffers.h>

#include <LibWeb/WebIDL/ExceptionOr.h>

namespace Web::Streams {

JS_DEFINE_ALLOCATOR(ReadableStreamBYOBReader);

ReadableStreamBYOBReader::ReadableStreamBYOBReader(JS::Realm& realm)

    : Bindings::PlatformObject(realm)

    , ReadableStreamGenericReaderMixin(realm)

{

}

void ReadableStreamBYOBReader::initialize(JS::Realm& realm)

{

    Base::initialize(realm);

    WEB_SET_PROTOTYPE_FOR_INTERFACE(ReadableStreamBYOBReader);

}

// https://streams.spec.whatwg.org/#byob-reader-constructor

WebIDL::ExceptionOr<JS::NonnullGCPtr<ReadableStreamBYOBReader>> ReadableStreamBYOBReader::construct_impl(JS::Realm& realm, JS::NonnullGCPtr<ReadableStream> stream)

{

    auto reader = realm.heap().allocate<ReadableStreamBYOBReader>(realm, realm);

    // 1. Perform ? SetUpReadableStreamBYOBReader(this, stream).

    TRY(set_up_readable_stream_byob_reader(reader, *stream));

    return reader;

}

// https://streams.spec.whatwg.org/#byob-reader-release-lock

void ReadableStreamBYOBReader::release_lock()

{

    // 1. If this.[[stream]] is undefined, return.

    if (!m_stream)

        return;

    // 2. Perform ! ReadableStreamBYOBReaderRelease(this).

    readable_stream_byob_reader_release(*this);

}

void ReadableStreamBYOBReader::visit_edges(Cell::Visitor& visitor)

{

    Base::visit_edges(visitor);

    ReadableStreamGenericReaderMixin::visit_edges(visitor);

    visitor.visit(m_read_into_requests);

}

class BYOBReaderReadIntoRequest : public ReadIntoRequest {

    JS_CELL(BYOBReaderReadIntoRequest, ReadIntoRequest);

    JS_DECLARE_ALLOCATOR(BYOBReaderReadIntoRequest);

public:

    BYOBReaderReadIntoRequest(JS::Realm& realm, WebIDL::Promise& promise)

        : m_realm(realm)

        , m_promise(promise)

    {

    }

    // chunk steps, given chunk

    virtual void on_chunk(JS::Value chunk) override

    {

        // 1. Resolve promise with «[ "value" → chunk, "done" → false ]».

        WebIDL::resolve_promise(m_realm, m_promise, JS::create_iterator_result_object(m_realm->vm(), chunk, false));

    }

    // close steps, given chunk

    virtual void on_close(JS::Value chunk) override

    {

        // 1. Resolve promise with «[ "value" → chunk, "done" → true ]».

        WebIDL::resolve_promise(m_realm, m_promise, JS::create_iterator_result_object(m_realm->vm(), chunk, true));

    }

    // error steps, given e

    virtual void on_error(JS::Value error) override

    {

        // 1. Reject promise with e.

        WebIDL::reject_promise(m_realm, m_promise, error);

    }

private:

    virtual void visit_edges(Visitor& visitor) override

    {

        Base::visit_edges(visitor);

        visitor.visit(m_realm);

        visitor.visit(m_promise);

    }

    JS::NonnullGCPtr<JS::Realm> m_realm;

    JS::NonnullGCPtr<WebIDL::Promise> m_promise;

};

JS_DEFINE_ALLOCATOR(BYOBReaderReadIntoRequest);

// https://streams.spec.whatwg.org/#byob-reader-read

JS::NonnullGCPtr<JS::Promise> ReadableStreamBYOBReader::read(JS::Handle<WebIDL::ArrayBufferView>& view, ReadableStreamBYOBReaderReadOptions options)

{

    auto& realm = this->realm();

    // 1. If view.[[ByteLength]] is 0, return a promise rejected with a TypeError exception.

    if (view->byte_length() == 0) {

        WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::TypeError, "Cannot read in an empty buffer"sv };

        return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

    }

    // 2. If view.[[ViewedArrayBuffer]].[[ArrayBufferByteLength]] is 0, return a promise rejected with a TypeError exception.

    if (view->viewed_array_buffer()->byte_length() == 0) {

        WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::TypeError, "Cannot read in an empty buffer"sv };

        return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

    }

    // 3. If ! IsDetachedBuffer(view.[[ViewedArrayBuffer]]) is true, return a promise rejected with a TypeError exception.

    if (view->viewed_array_buffer()->is_detached()) {

        WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::TypeError, "Cannot read in a detached buffer"sv };

        return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

    }

    // 4. If options["min"] is 0, return a promise rejected with a TypeError exception.

    if (options.min == 0) {

        WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::TypeError, "options[\"min\'] cannot have a value of 0."sv };

        return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

    }

    // 5. If view has a [[TypedArrayName]] internal slot,

    if (view->is_typed_array_base()) {

        auto const& typed_array = *view->bufferable_object().get<JS::NonnullGCPtr<JS::TypedArrayBase>>();

        // 1. If options["min"] > view.[[ArrayLength]], return a promise rejected with a RangeError exception.

        if (options.min > typed_array.array_length().length()) {

            WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::RangeError, "options[\"min\"] cannot be larger than the length of the view."sv };

            return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

        }

    }

    // 6. Otherwise (i.e., it is a DataView),

    if (view->is_data_view()) {

        // 1. If options["min"] > view.[[ByteLength]], return a promise rejected with a RangeError exception.

        if (options.min > view->byte_length()) {

            WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::RangeError, "options[\"min\"] cannot be larger than the length of the view."sv };

            return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

        }

    }

    // 7. If this.[[stream]] is undefined, return a promise rejected with a TypeError exception.

    if (!m_stream) {

        WebIDL::SimpleException exception { WebIDL::SimpleExceptionType::TypeError, "Cannot read from an empty stream"sv };

        return WebIDL::create_rejected_promise_from_exception(realm, move(exception));

    }

    // 8. Let promise be a new promise.

    auto promise_capability = WebIDL::create_promise(realm);

    // 9. Let readIntoRequest be a new read-into request with the following items:

    //    chunk steps, given chunk

    //        Resolve promise with «[ "value" → chunk, "done" → false ]».

    //    close steps, given chunk

    //        Resolve promise with «[ "value" → chunk, "done" → true ]».

    //    error steps, given e

    //        Reject promise with e.

    auto read_into_request = heap().allocate_without_realm<BYOBReaderReadIntoRequest>(realm, promise_capability);

    // 10. Perform ! ReadableStreamBYOBReaderRead(this, view, options["min"], readIntoRequest).

    readable_stream_byob_reader_read(*this, *view, options.min, *read_into_request);

    // 11. Return promise.

    return JS::NonnullGCPtr { verify_cast<JS::Promise>(*promise_capability->promise()) };

}

}