/*
 * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Checked.h>
#include <AK/ScopeGuard.h>
#include <LibCore/EventLoop.h>
#include <LibCore/File.h>
#include <LibCore/System.h>
#include <LibRequests/Request.h>
#include <LibRequests/RequestClient.h>

namespace Requests {

static Optional<Core::ImmutableBytes> map_body_file(int fd, u64 offset, u64 size)
{
    ArmedScopeGuard close_fd = [fd] {
        (void)Core::System::close(fd);
    };

    if (!AK::is_within_range<off_t>(offset) || !AK::is_within_range<size_t>(size)) {
        dbgln("Request: Received body file outside mappable range");
        return {};
    }

    close_fd.disarm();
    auto payload = Core::ImmutableBytes::map_from_fd_range_and_close(fd, "request response"sv, static_cast<off_t>(offset), static_cast<size_t>(size));
    if (payload.is_error()) {
        dbgln("Request: Failed to map body file: {}", payload.error());
        return {};
    }

    return payload.release_value();
}

ErrorOr<NonnullOwnPtr<ReadStream>> ReadStream::create(int reader_fd)
{
#if defined(AK_OS_WINDOWS)
    auto local_socket = TRY(Core::LocalSocket::adopt_fd(reader_fd));
    auto notifier = local_socket->notifier();
    VERIFY(notifier);
    return adopt_own(*new ReadStream(move(local_socket), notifier.release_nonnull()));
#else
    auto file = TRY(Core::File::adopt_fd(reader_fd, Core::File::OpenMode::Read));
    auto notifier = Core::Notifier::construct(reader_fd, Core::Notifier::Type::Read);
    return adopt_own(*new ReadStream(move(file), move(notifier)));
#endif
}

Request::Request(RequestClient& client, u64 request_id)
    : m_client(client)
    , m_request_id(request_id)
{
}

Request::~Request()
{
    if (m_fd != -1 && !m_fd_is_owned_by_read_stream)
        (void)Core::System::close(m_fd);
}

int Request::request_server_client_id() const
{
    return m_client->request_server_client_id();
}

bool Request::stop()
{
    RefPtr keep_alive = *this;
    auto had_active_request = m_client->stop_request({}, *this);
    auto on_stop = move(m_on_stop);

    defer_teardown();

    if (had_active_request && on_stop)
        on_stop();

    return had_active_request;
}

void Request::set_body_delivery_paused(bool paused)
{
    m_body_delivery_paused = paused;
    if (m_internal_stream_data && m_internal_stream_data->read_notifier)
        m_internal_stream_data->read_notifier->set_enabled(!m_body_delivery_paused);
}

void Request::resume_body_delivery()
{
    if (m_internal_stream_data)
        m_internal_stream_data->body_delivery_remaining_byte_count = {};
    set_body_delivery_paused(false);
}

void Request::resume_body_delivery_up_to(size_t byte_count)
{
    if (!m_internal_stream_data)
        return;

    m_internal_stream_data->body_delivery_remaining_byte_count = byte_count;
    set_body_delivery_paused(false);
}

void Request::release_for_transfer()
{
    if (auto client = m_client.strong_ref())
        client->release_request_for_transfer({}, *this);
}

bool Request::has_file_backed_response_body() const
{
    return m_internal_stream_data && m_internal_stream_data->file_backed_payload.has_value();
}

void Request::set_request_fd(Badge<Requests::RequestClient>, int fd)
{
    VERIFY(m_fd == -1);
    m_fd = fd;

    if (m_internal_stream_data)
        attach_read_stream();
}

void Request::attach_read_stream()
{
    VERIFY(m_internal_stream_data);
    if (m_fd == -1 || m_fd_is_owned_by_read_stream)
        return;

    auto read_stream = MUST(ReadStream::create(m_fd));
    m_fd_is_owned_by_read_stream = true;
    auto notifier = read_stream->notifier();
    notifier->on_activation = move(m_internal_stream_data->read_notifier->on_activation);
    notifier->set_enabled(!m_body_delivery_paused);
    m_internal_stream_data->read_notifier = notifier;
    m_internal_stream_data->read_stream = move(read_stream);
}

void Request::set_request_body_file(Badge<Requests::RequestClient>, int fd, u64 offset, u64 size)
{
    auto payload = map_body_file(fd, offset, size);
    if (!payload.has_value()) {
        if (m_internal_stream_data)
            m_body_delivery_error = NetworkError::CacheReadFailed;
        return;
    }

    // If the request was stopped while this IPC was in-flight, just bail.
    if (!m_internal_stream_data)
        return;

    if (m_mode == Mode::Buffered) {
        m_internal_buffered_data->payload = payload.release_value();
        return;
    }

    m_internal_stream_data->file_backed_payload = payload.release_value();
    if (m_internal_stream_data->on_data_available) {
        m_internal_stream_data->delivered_size += m_internal_stream_data->file_backed_payload->size();
        m_internal_stream_data->on_data_available(ResponseData::from_immutable_bytes(*m_internal_stream_data->file_backed_payload));
    }
}

void Request::set_request_cached_body_file(Badge<Requests::RequestClient>, int fd, u64 offset, u64 size)
{
    auto payload = map_body_file(fd, offset, size);
    if (!payload.has_value())
        return;

    if (m_mode == Mode::Buffered) {
        m_internal_buffered_data->payload = payload.release_value();
        return;
    }

    // If the request was stopped while this IPC was in-flight, just bail.
    if (!m_internal_stream_data)
        return;

    m_internal_stream_data->cached_payload = payload.release_value();
    if (m_internal_stream_data->on_cached_body_available)
        m_internal_stream_data->on_cached_body_available(*m_internal_stream_data->cached_payload);
}

void Request::set_buffered_request_finished_callback(BufferedRequestFinished on_buffered_request_finished)
{
    VERIFY(m_mode == Mode::Unknown);
    m_mode = Mode::Buffered;

    m_internal_buffered_data = make<InternalBufferedData>();

    on_headers_received = [this](auto headers, auto response_code, auto const& reason_phrase, auto javascript_bytecode, auto javascript_bytecode_cache_vary_key) {
        m_internal_buffered_data->response_headers = move(headers);
        m_internal_buffered_data->response_code = move(response_code);
        m_internal_buffered_data->reason_phrase = reason_phrase;
        m_internal_buffered_data->javascript_bytecode = move(javascript_bytecode);
        m_internal_buffered_data->javascript_bytecode_cache_vary_key = javascript_bytecode_cache_vary_key;
    };

    on_finish = [this, on_buffered_request_finished = move(on_buffered_request_finished)](auto total_size, auto& timing_info, auto network_error) {
        auto payload = [&] {
            if (m_internal_buffered_data->payload.has_value())
                return m_internal_buffered_data->payload.release_value();

            auto output_buffer = ByteBuffer::create_uninitialized(m_internal_buffered_data->payload_stream.used_buffer_size()).release_value_but_fixme_should_propagate_errors();
            m_internal_buffered_data->payload_stream.read_until_filled(output_buffer).release_value_but_fixme_should_propagate_errors();
            return Core::ImmutableBytes::adopt(move(output_buffer));
        }();

        on_buffered_request_finished(
            total_size,
            timing_info,
            network_error,
            m_internal_buffered_data->response_headers,
            m_internal_buffered_data->response_code,
            m_internal_buffered_data->reason_phrase,
            move(m_internal_buffered_data->javascript_bytecode),
            m_internal_buffered_data->javascript_bytecode_cache_vary_key,
            move(payload));
    };

    set_up_internal_stream_data([this](auto data) {
        // FIXME: What do we do if this fails?
        m_internal_buffered_data->payload_stream.write_until_depleted(data.bytes()).release_value_but_fixme_should_propagate_errors();
    });
}

void Request::set_unbuffered_request_callbacks(HeadersReceived on_headers_received, DataReceived on_data_received, CachedBodyAvailable on_cached_body_available, RequestFinished on_finish)
{
    VERIFY(m_mode == Mode::Unknown);
    m_mode = Mode::Unbuffered;

    this->on_headers_received = move(on_headers_received);
    this->on_finish = move(on_finish);

    set_up_internal_stream_data(move(on_data_received));
    m_internal_stream_data->on_cached_body_available = move(on_cached_body_available);
}

void Request::set_stop_callback(RequestStopped on_stop)
{
    m_on_stop = move(on_stop);
}

void Request::did_finish(Badge<RequestClient>, u64 total_size, RequestTimingInfo const& timing_info, Optional<NetworkError> const& network_error)
{
    auto effective_network_error = m_body_delivery_error.has_value() ? m_body_delivery_error : network_error;
    if (on_finish)
        on_finish(total_size, timing_info, effective_network_error);
}

void Request::did_receive_headers(Badge<RequestClient>, NonnullRefPtr<HTTP::HeaderList> response_headers, Optional<u32> response_code, Optional<String> const& reason_phrase, Optional<Core::ImmutableBytes> javascript_bytecode, Optional<u64> javascript_bytecode_cache_vary_key)
{
    if (on_headers_received)
        on_headers_received(move(response_headers), response_code, reason_phrase, move(javascript_bytecode), javascript_bytecode_cache_vary_key);
}

void Request::did_request_certificates(Badge<RequestClient>)
{
    if (on_certificate_requested) {
        auto result = on_certificate_requested();
        if (!m_client->set_certificate({}, *this, result.certificate, result.key)) {
            dbgln("Request: set_certificate failed");
        }
    }
}

void Request::did_transfer(Badge<RequestClient>)
{
    auto on_stop = move(m_on_stop);

    defer_teardown();

    if (on_stop)
        on_stop();
}

void Request::defer_teardown()
{
    if (m_internal_stream_data && m_internal_stream_data->read_notifier)
        m_internal_stream_data->read_notifier->set_enabled(false);
    m_mode = Mode::Unknown;
    Core::deferred_invoke([self = NonnullRefPtr(*this)] {
        self->on_headers_received = nullptr;
        self->on_finish = nullptr;
        self->on_certificate_requested = nullptr;
        self->m_internal_buffered_data = nullptr;
        self->m_internal_stream_data = nullptr;
    });
}

void Request::set_up_internal_stream_data(DataReceived on_data_available)
{
    VERIFY(!m_internal_stream_data);

    m_internal_stream_data = make<InternalStreamData>();
    m_internal_stream_data->on_data_available = move(on_data_available);
    m_internal_stream_data->read_notifier = Core::Notifier::construct(fd(), Core::Notifier::Type::Read);
    m_internal_stream_data->read_notifier->set_enabled(!m_body_delivery_paused);
    attach_read_stream();

    auto user_on_finish = move(on_finish);
    on_finish = [this](auto total_size, auto const& timing_info, auto network_error) {
        // If the request was stopped while this IPC was in-flight, just bail.
        if (!m_internal_stream_data)
            return;

        m_internal_stream_data->total_size = total_size;
        m_internal_stream_data->network_error = network_error;
        m_internal_stream_data->timing_info = timing_info;
        m_internal_stream_data->request_done = true;
        m_internal_stream_data->on_finish();
    };

    m_internal_stream_data->on_finish = [this, user_on_finish = move(user_on_finish)]() {
        // If the request was stopped while this IPC was in-flight, just bail.
        if (!m_internal_stream_data)
            return;

        auto has_received_all_reported_bytes = m_internal_stream_data->request_done && m_internal_stream_data->delivered_size >= m_internal_stream_data->total_size;
        if (!m_internal_stream_data->user_finish_called && (!m_internal_stream_data->read_stream || m_internal_stream_data->read_stream->is_eof() || has_received_all_reported_bytes)) {
            m_internal_stream_data->user_finish_called = true;
            user_on_finish(m_internal_stream_data->total_size, m_internal_stream_data->timing_info, m_internal_stream_data->network_error);
        }
    };

    m_internal_stream_data->read_notifier->on_activation = [this]() {
        static constexpr size_t buffer_size = 256 * KiB;
        static char buffer[buffer_size];

        // If the request was stopped while this IPC was in-flight, just bail.
        if (!m_internal_stream_data)
            return;

        do {
            auto bytes_to_read = buffer_size;
            if (m_internal_stream_data->body_delivery_remaining_byte_count.has_value()) {
                if (*m_internal_stream_data->body_delivery_remaining_byte_count == 0) {
                    set_body_delivery_paused(true);
                    break;
                }
                bytes_to_read = min(bytes_to_read, *m_internal_stream_data->body_delivery_remaining_byte_count);
            }

            auto result = m_internal_stream_data->read_stream->read_some({ buffer, bytes_to_read });
            if (result.is_error() && (!result.error().is_errno() || (result.error().is_errno() && result.error().code() != EINTR)))
                break;
            if (result.is_error())
                continue;

            auto read_bytes = result.release_value();
            if (read_bytes.is_empty())
                break;

            m_internal_stream_data->delivered_size += read_bytes.size();
            m_internal_stream_data->on_data_available(ResponseData::from_bytes(read_bytes));
            if (!m_internal_stream_data)
                return;

            if (m_internal_stream_data->body_delivery_remaining_byte_count.has_value()) {
                if (read_bytes.size() >= *m_internal_stream_data->body_delivery_remaining_byte_count) {
                    m_internal_stream_data->body_delivery_remaining_byte_count = 0;
                    set_body_delivery_paused(true);
                    break;
                }
                *m_internal_stream_data->body_delivery_remaining_byte_count -= read_bytes.size();
            }
        } while (true);

        if (m_internal_stream_data->read_stream->is_eof())
            m_internal_stream_data->read_notifier->close();

        if (m_internal_stream_data->request_done)
            m_internal_stream_data->on_finish();
    };
}

Request::InternalBufferedData::InternalBufferedData()
    : response_headers(HTTP::HeaderList::create())
{
}

}