/*
 * Copyright (c) 2022-2023, Linus Groh <linusg@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Debug.h>
#include <AK/TypeCasts.h>
#include <LibJS/Heap/Heap.h>
#include <LibJS/Runtime/Completion.h>
#include <LibJS/Runtime/VM.h>
#include <LibWeb/Bindings/MainThreadVM.h>
#include <LibWeb/Fetch/Infrastructure/FetchParams.h>
#include <LibWeb/Fetch/Infrastructure/HTTP/Bodies.h>
#include <LibWeb/Fetch/Infrastructure/HTTP/Responses.h>
#include <LibWeb/URL/URL.h>

namespace Web::Fetch::Infrastructure {

Response::Response(JS::NonnullGCPtr<HeaderList> header_list)
    : m_header_list(header_list)
{
}

void Response::visit_edges(JS::Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_header_list);
    visitor.visit(m_body);
}

JS::NonnullGCPtr<Response> Response::create(JS::VM& vm)
{
    return vm.heap().allocate_without_realm<Response>(HeaderList::create(vm));
}

// https://fetch.spec.whatwg.org/#ref-for-concept-network-error%E2%91%A3
// A network error is a response whose status is always 0, status message is always
// the empty byte sequence, header list is always empty, and body is always null.

JS::NonnullGCPtr<Response> Response::aborted_network_error(JS::VM& vm)
{
    auto response = network_error(vm, "Fetch has been aborted"sv);
    response->set_aborted(true);
    return response;
}

JS::NonnullGCPtr<Response> Response::network_error(JS::VM& vm, Variant<String, StringView> message)
{
    dbgln_if(WEB_FETCH_DEBUG, "Fetch: Creating network error response with message: {}", message.visit([](auto const& s) -> StringView { return s; }));
    auto response = Response::create(vm);
    response->set_status(0);
    response->set_type(Type::Error);
    VERIFY(!response->body());
    response->m_network_error_message = move(message);
    return response;
}

// https://fetch.spec.whatwg.org/#appropriate-network-error
JS::NonnullGCPtr<Response> Response::appropriate_network_error(JS::VM& vm, FetchParams const& fetch_params)
{
    // 1. Assert: fetchParams is canceled.
    VERIFY(fetch_params.is_canceled());

    // 2. Return an aborted network error if fetchParams is aborted; otherwise return a network error.
    return fetch_params.is_aborted()
        ? aborted_network_error(vm)
        : network_error(vm, "Fetch has been terminated"sv);
}

// https://fetch.spec.whatwg.org/#concept-aborted-network-error
bool Response::is_aborted_network_error() const
{
    // A response whose type is "error" and aborted flag is set is known as an aborted network error.
    // NOTE: We have to use the virtual getter here to not bypass filtered responses.
    return type() == Type::Error && aborted();
}

// https://fetch.spec.whatwg.org/#concept-network-error
bool Response::is_network_error() const
{
    // A response whose type is "error" is known as a network error.
    // NOTE: We have to use the virtual getter here to not bypass filtered responses.
    return type() == Type::Error;
}

// https://fetch.spec.whatwg.org/#concept-response-url
Optional<AK::URL const&> Response::url() const
{
    // A response has an associated URL. It is a pointer to the last URL in response’s URL list and null if response’s URL list is empty.
    // NOTE: We have to use the virtual getter here to not bypass filtered responses.
    if (url_list().is_empty())
        return {};
    return url_list().last();
}

// https://fetch.spec.whatwg.org/#concept-response-location-url
ErrorOr<Optional<AK::URL>> Response::location_url(Optional<String> const& request_fragment) const
{
    // The location URL of a response response, given null or an ASCII string requestFragment, is the value returned by the following steps. They return null, failure, or a URL.

    // 1. If response’s status is not a redirect status, then return null.
    // NOTE: We have to use the virtual getter here to not bypass filtered responses.
    if (!is_redirect_status(status()))
        return Optional<AK::URL> {};

    // 2. Let location be the result of extracting header list values given `Location` and response’s header list.
    auto location_values_or_failure = TRY(extract_header_list_values("Location"sv.bytes(), m_header_list));
    if (location_values_or_failure.has<Infrastructure::ExtractHeaderParseFailure>() || location_values_or_failure.has<Empty>())
        return Optional<AK::URL> {};

    auto const& location_values = location_values_or_failure.get<Vector<ByteBuffer>>();
    if (location_values.size() != 1)
        return Optional<AK::URL> {};

    // 3. If location is a header value, then set location to the result of parsing location with response’s URL.
    auto location = URL::parse(location_values.first(), url());
    if (!location.is_valid())
        return Error::from_string_view("Invalid 'Location' header URL"sv);

    // 4. If location is a URL whose fragment is null, then set location’s fragment to requestFragment.
    if (!location.fragment().has_value())
        location.set_fragment(request_fragment);

    // 5. Return location.
    return location;
}

// https://fetch.spec.whatwg.org/#concept-response-clone
WebIDL::ExceptionOr<JS::NonnullGCPtr<Response>> Response::clone(JS::Realm& realm) const
{
    // To clone a response response, run these steps:
    auto& vm = realm.vm();

    // 1. If response is a filtered response, then return a new identical filtered response whose internal response is a clone of response’s internal response.
    if (is<FilteredResponse>(*this)) {
        auto internal_response = TRY(static_cast<FilteredResponse const&>(*this).internal_response()->clone(realm));
        if (is<BasicFilteredResponse>(*this))
            return TRY_OR_THROW_OOM(vm, BasicFilteredResponse::create(vm, internal_response));
        if (is<CORSFilteredResponse>(*this))
            return TRY_OR_THROW_OOM(vm, CORSFilteredResponse::create(vm, internal_response));
        if (is<OpaqueFilteredResponse>(*this))
            return OpaqueFilteredResponse::create(vm, internal_response);
        if (is<OpaqueRedirectFilteredResponse>(*this))
            return OpaqueRedirectFilteredResponse::create(vm, internal_response);
        VERIFY_NOT_REACHED();
    }

    // 2. Let newResponse be a copy of response, except for its body.
    auto new_response = Infrastructure::Response::create(vm);
    new_response->set_type(m_type);
    new_response->set_aborted(m_aborted);
    new_response->set_url_list(m_url_list);
    new_response->set_status(m_status);
    new_response->set_status_message(m_status_message);
    for (auto const& header : *m_header_list)
        MUST(new_response->header_list()->append(header));
    new_response->set_cache_state(m_cache_state);
    new_response->set_cors_exposed_header_name_list(m_cors_exposed_header_name_list);
    new_response->set_range_requested(m_range_requested);
    new_response->set_request_includes_credentials(m_request_includes_credentials);
    new_response->set_timing_allow_passed(m_timing_allow_passed);
    new_response->set_body_info(m_body_info);
    // FIXME: service worker timing info

    // 3. If response’s body is non-null, then set newResponse’s body to the result of cloning response’s body.
    if (m_body)
        new_response->set_body(m_body->clone(realm));

    // 4. Return newResponse.
    return new_response;
}

// https://html.spec.whatwg.org/multipage/urls-and-fetching.html#unsafe-response
JS::NonnullGCPtr<Response> Response::unsafe_response()
{
    // A response's unsafe response is its internal response if it has one, and the response itself otherwise.
    if (is<FilteredResponse>(this))
        return static_cast<FilteredResponse&>(*this).internal_response();

    return *this;
}

// https://html.spec.whatwg.org/multipage/urls-and-fetching.html#cors-cross-origin
bool Response::is_cors_cross_origin() const
{
    // A response whose type is "opaque" or "opaqueredirect" is CORS-cross-origin.
    return type() == Type::Opaque || type() == Type::OpaqueRedirect;
}

// Non-standard
Optional<StringView> Response::network_error_message() const
{
    if (!m_network_error_message.has_value())
        return {};
    return m_network_error_message->visit([](auto const& s) -> StringView { return s; });
}

FilteredResponse::FilteredResponse(JS::NonnullGCPtr<Response> internal_response, JS::NonnullGCPtr<HeaderList> header_list)
    : Response(header_list)
    , m_internal_response(internal_response)
{
}

FilteredResponse::~FilteredResponse()
{
}

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

ErrorOr<JS::NonnullGCPtr<BasicFilteredResponse>> BasicFilteredResponse::create(JS::VM& vm, JS::NonnullGCPtr<Response> internal_response)
{
    // A basic filtered response is a filtered response whose type is "basic" and header list excludes
    // any headers in internal response’s header list whose name is a forbidden response-header name.
    auto header_list = HeaderList::create(vm);
    for (auto const& header : *internal_response->header_list()) {
        if (!is_forbidden_response_header_name(header.name))
            TRY(header_list->append(header));
    }

    return vm.heap().allocate_without_realm<BasicFilteredResponse>(internal_response, header_list);
}

BasicFilteredResponse::BasicFilteredResponse(JS::NonnullGCPtr<Response> internal_response, JS::NonnullGCPtr<HeaderList> header_list)
    : FilteredResponse(internal_response, header_list)
    , m_header_list(header_list)
{
}

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

ErrorOr<JS::NonnullGCPtr<CORSFilteredResponse>> CORSFilteredResponse::create(JS::VM& vm, JS::NonnullGCPtr<Response> internal_response)
{
    // A CORS filtered response is a filtered response whose type is "cors" and header list excludes
    // any headers in internal response’s header list whose name is not a CORS-safelisted response-header
    // name, given internal response’s CORS-exposed header-name list.
    Vector<ReadonlyBytes> cors_exposed_header_name_list;
    for (auto const& header_name : internal_response->cors_exposed_header_name_list())
        cors_exposed_header_name_list.append(header_name.span());

    auto header_list = HeaderList::create(vm);
    for (auto const& header : *internal_response->header_list()) {
        if (is_cors_safelisted_response_header_name(header.name, cors_exposed_header_name_list))
            TRY(header_list->append(header));
    }

    return vm.heap().allocate_without_realm<CORSFilteredResponse>(internal_response, header_list);
}

CORSFilteredResponse::CORSFilteredResponse(JS::NonnullGCPtr<Response> internal_response, JS::NonnullGCPtr<HeaderList> header_list)
    : FilteredResponse(internal_response, header_list)
    , m_header_list(header_list)
{
}

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

JS::NonnullGCPtr<OpaqueFilteredResponse> OpaqueFilteredResponse::create(JS::VM& vm, JS::NonnullGCPtr<Response> internal_response)
{
    // An opaque filtered response is a filtered response whose type is "opaque", URL list is the empty list,
    // status is 0, status message is the empty byte sequence, header list is empty, and body is null.
    return vm.heap().allocate_without_realm<OpaqueFilteredResponse>(internal_response, HeaderList::create(vm));
}

OpaqueFilteredResponse::OpaqueFilteredResponse(JS::NonnullGCPtr<Response> internal_response, JS::NonnullGCPtr<HeaderList> header_list)
    : FilteredResponse(internal_response, header_list)
    , m_header_list(header_list)
{
}

void OpaqueFilteredResponse::visit_edges(JS::Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_header_list);
    visitor.visit(m_body);
}

JS::NonnullGCPtr<OpaqueRedirectFilteredResponse> OpaqueRedirectFilteredResponse::create(JS::VM& vm, JS::NonnullGCPtr<Response> internal_response)
{
    // An opaque-redirect filtered response is a filtered response whose type is "opaqueredirect",
    // status is 0, status message is the empty byte sequence, header list is empty, and body is null.
    return vm.heap().allocate_without_realm<OpaqueRedirectFilteredResponse>(internal_response, HeaderList::create(vm));
}

OpaqueRedirectFilteredResponse::OpaqueRedirectFilteredResponse(JS::NonnullGCPtr<Response> internal_response, JS::NonnullGCPtr<HeaderList> header_list)
    : FilteredResponse(internal_response, header_list)
    , m_header_list(header_list)
{
}

void OpaqueRedirectFilteredResponse::visit_edges(JS::Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_header_list);
    visitor.visit(m_body);
}

}