/*
 * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Format.h>
#include <LibCore/EventLoop.h>
#include <LibCore/LocalServer.h>
#include <LibCore/LocalSocket.h>
#include <LibCore/Stream.h>
#include <LibCore/TCPServer.h>
#include <LibCore/TCPSocket.h>
#include <LibCore/Timer.h>
#include <LibCore/UDPServer.h>
#include <LibCore/UDPSocket.h>
#include <LibTest/TestCase.h>
#include <LibThreading/BackgroundAction.h>
#include <fcntl.h>
#include <unistd.h>

// File tests

TEST_CASE(file_open)
{
    auto maybe_file = Core::Stream::File::open("/tmp/file-open-test.txt", Core::Stream::OpenMode::Write);
    if (maybe_file.is_error()) {
        warnln("Failed to open the file: {}", strerror(maybe_file.error().code()));
        VERIFY_NOT_REACHED();
    }

    // Testing out some basic file properties.
    auto file = maybe_file.release_value();
    EXPECT(file.is_open());
    EXPECT(!file.is_readable());
    EXPECT(file.is_writable());
    EXPECT(!file.is_eof());

    auto maybe_size = file.size();
    EXPECT(!maybe_size.is_error());
    EXPECT_EQ(maybe_size.value(), 0);
}

TEST_CASE(file_write_bytes)
{
    auto maybe_file = Core::Stream::File::open("/tmp/file-write-bytes-test.txt", Core::Stream::OpenMode::Write);
    auto file = maybe_file.release_value();

    constexpr auto some_words = "These are some words"sv;
    ReadonlyBytes buffer { some_words.characters_without_null_termination(), some_words.length() };
    auto result = file.write(buffer);
    EXPECT(!result.is_error());
}

constexpr auto expected_buffer_contents = "&lt;small&gt;(Please consider translating this message for the benefit of your fellow Wikimedians. Please also consider translating"sv;

TEST_CASE(file_read_bytes)
{
    auto maybe_file = Core::Stream::File::open("/usr/Tests/LibCore/long_lines.txt", Core::Stream::OpenMode::Read);
    EXPECT(!maybe_file.is_error());
    auto file = maybe_file.release_value();

    auto maybe_buffer = ByteBuffer::create_uninitialized(131);
    EXPECT(maybe_buffer.has_value());
    auto buffer = maybe_buffer.release_value();

    auto result = file.read(buffer);
    EXPECT(!result.is_error());
    EXPECT_EQ(result.value(), 131ul);

    StringView buffer_contents { buffer.bytes() };
    EXPECT_EQ(buffer_contents, expected_buffer_contents);
}

constexpr auto expected_seek_contents1 = "|Lleer esti mens"sv;
constexpr auto expected_seek_contents2 = "s of advanced ad"sv;
constexpr auto expected_seek_contents3 = "levels of advanc"sv;

TEST_CASE(file_seeking_around)
{
    auto maybe_file = Core::Stream::File::open("/usr/Tests/LibCore/long_lines.txt", Core::Stream::OpenMode::Read);
    EXPECT(!maybe_file.is_error());
    auto file = maybe_file.release_value();

    EXPECT_EQ(file.size().release_value(), 8702);

    auto maybe_buffer = ByteBuffer::create_uninitialized(16);
    EXPECT(maybe_buffer.has_value());
    auto buffer = maybe_buffer.release_value();

    StringView buffer_contents { buffer.bytes() };

    EXPECT(!file.seek(500, Core::Stream::SeekMode::SetPosition).is_error());
    EXPECT_EQ(file.tell().release_value(), 500);
    EXPECT(file.read_or_error(buffer));
    EXPECT_EQ(buffer_contents, expected_seek_contents1);

    EXPECT(!file.seek(234, Core::Stream::SeekMode::FromCurrentPosition).is_error());
    EXPECT_EQ(file.tell().release_value(), 750);
    EXPECT(file.read_or_error(buffer));
    EXPECT_EQ(buffer_contents, expected_seek_contents2);

    EXPECT(!file.seek(-105, Core::Stream::SeekMode::FromEndPosition).is_error());
    EXPECT_EQ(file.tell().release_value(), 8597);
    EXPECT(file.read_or_error(buffer));
    EXPECT_EQ(buffer_contents, expected_seek_contents3);
}

TEST_CASE(file_adopt_fd)
{
    int rc = ::open("/usr/Tests/LibCore/long_lines.txt", O_RDONLY);
    EXPECT(rc >= 0);

    auto maybe_file = Core::Stream::File::adopt_fd(rc, Core::Stream::OpenMode::Read);
    EXPECT(!maybe_file.is_error());
    auto file = maybe_file.release_value();

    EXPECT_EQ(file.size().release_value(), 8702);

    auto maybe_buffer = ByteBuffer::create_uninitialized(16);
    EXPECT(maybe_buffer.has_value());
    auto buffer = maybe_buffer.release_value();

    StringView buffer_contents { buffer.bytes() };

    EXPECT(!file.seek(500, Core::Stream::SeekMode::SetPosition).is_error());
    EXPECT_EQ(file.tell().release_value(), 500);
    EXPECT(file.read_or_error(buffer));
    EXPECT_EQ(buffer_contents, expected_seek_contents1);

    // A single seek & read test should be fine for now.
}

TEST_CASE(file_adopt_invalid_fd)
{
    auto maybe_file = Core::Stream::File::adopt_fd(-1, Core::Stream::OpenMode::Read);
    EXPECT(maybe_file.is_error());
    EXPECT_EQ(maybe_file.error().code(), EBADF);
}

// TCPSocket tests

constexpr auto sent_data = "Mr. Watson, come here. I want to see you."sv;

TEST_CASE(tcp_socket_read)
{
    // NOTE: This is required here because Core::TCPServer requires
    //       Core::EventLoop through Core::Notifier.
    Core::EventLoop event_loop;

    auto maybe_tcp_server = Core::TCPServer::try_create();
    EXPECT(!maybe_tcp_server.is_error());
    auto tcp_server = maybe_tcp_server.release_value();
    EXPECT(!tcp_server->listen({ 127, 0, 0, 1 }, 9090).is_error());
    EXPECT(!tcp_server->set_blocking(true).is_error());

    auto maybe_client_socket = Core::Stream::TCPSocket::connect({ { 127, 0, 0, 1 }, 9090 });
    EXPECT(!maybe_client_socket.is_error());
    auto client_socket = maybe_client_socket.release_value();

    EXPECT(client_socket.is_open());

    auto maybe_server_socket = tcp_server->accept();
    EXPECT(!maybe_server_socket.is_error());
    auto server_socket = maybe_server_socket.release_value();
    EXPECT(!server_socket.write({ sent_data.characters_without_null_termination(), sent_data.length() }).is_error());
    server_socket.close();

    EXPECT(client_socket.can_read_without_blocking(100).release_value());
    EXPECT_EQ(client_socket.pending_bytes().release_value(), sent_data.length());

    auto maybe_receive_buffer = ByteBuffer::create_uninitialized(64);
    auto receive_buffer = maybe_receive_buffer.release_value();
    auto maybe_nread = client_socket.read(receive_buffer);
    EXPECT(!maybe_nread.is_error());
    auto nread = maybe_nread.release_value();

    StringView received_data { receive_buffer.data(), nread };
    EXPECT_EQ(sent_data, received_data);
}

TEST_CASE(tcp_socket_write)
{
    Core::EventLoop event_loop;

    auto maybe_tcp_server = Core::TCPServer::try_create();
    EXPECT(!maybe_tcp_server.is_error());
    auto tcp_server = maybe_tcp_server.release_value();
    EXPECT(!tcp_server->listen({ 127, 0, 0, 1 }, 9090).is_error());
    EXPECT(!tcp_server->set_blocking(true).is_error());

    auto maybe_client_socket = Core::Stream::TCPSocket::connect({ { 127, 0, 0, 1 }, 9090 });
    EXPECT(!maybe_client_socket.is_error());
    auto client_socket = maybe_client_socket.release_value();

    auto maybe_server_socket = tcp_server->accept();
    EXPECT(!maybe_server_socket.is_error());
    auto server_socket = maybe_server_socket.release_value();
    EXPECT(!server_socket.set_blocking(true).is_error());

    EXPECT(client_socket.write_or_error({ sent_data.characters_without_null_termination(), sent_data.length() }));
    client_socket.close();

    auto receive_buffer = ByteBuffer::create_uninitialized(64).release_value();
    auto maybe_nread = server_socket.read(receive_buffer);
    EXPECT(!maybe_nread.is_error());
    auto nread = maybe_nread.release_value();

    StringView received_data { receive_buffer.data(), nread };
    EXPECT_EQ(sent_data, received_data);
}

TEST_CASE(tcp_socket_eof)
{
    Core::EventLoop event_loop;

    auto maybe_tcp_server = Core::TCPServer::try_create();
    EXPECT(!maybe_tcp_server.is_error());
    auto tcp_server = maybe_tcp_server.release_value();
    EXPECT(!tcp_server->listen({ 127, 0, 0, 1 }, 9090).is_error());
    EXPECT(!tcp_server->set_blocking(true).is_error());

    auto maybe_client_socket = Core::Stream::TCPSocket::connect({ { 127, 0, 0, 1 }, 9090 });
    EXPECT(!maybe_client_socket.is_error());
    auto client_socket = maybe_client_socket.release_value();

    EXPECT(client_socket.is_open());

    auto server_socket = tcp_server->accept().release_value();
    server_socket.close();

    // NOTE: This may seem unintuitive, but poll will mark a fd which has
    //       reached EOF (i.e. in the case of the other side disconnecting) as
    //       POLLIN.
    EXPECT(client_socket.can_read_without_blocking(100).release_value());
    EXPECT_EQ(client_socket.pending_bytes().release_value(), 0ul);

    auto maybe_receive_buffer = ByteBuffer::create_uninitialized(1);
    auto receive_buffer = maybe_receive_buffer.release_value();
    EXPECT_EQ(client_socket.read(receive_buffer).release_value(), 0ul);
    EXPECT(client_socket.is_eof());
}

// UDPSocket tests

constexpr auto udp_reply_data = "Well hello friends!"sv;

TEST_CASE(udp_socket_read_write)
{
    // NOTE: This is required here because Core::UDPServer requires
    //       Core::EventLoop through Core::Notifier.
    Core::EventLoop event_loop;

    auto udp_server = Core::UDPServer::construct();
    EXPECT(udp_server->bind({ 127, 0, 0, 1 }, 9090));

    auto maybe_client_socket = Core::Stream::UDPSocket::connect({ { 127, 0, 0, 1 }, 9090 });
    EXPECT(!maybe_client_socket.is_error());
    auto client_socket = maybe_client_socket.release_value();

    EXPECT(client_socket.is_open());
    EXPECT(client_socket.write_or_error({ sent_data.characters_without_null_termination(), sent_data.length() }));

    // FIXME: UDPServer::receive sadly doesn't give us a way to block on it,
    // currently.
    usleep(100000);

    struct sockaddr_in client_address;
    auto server_receive_buffer = udp_server->receive(64, client_address);
    EXPECT(!server_receive_buffer.is_empty());

    StringView server_received_data { server_receive_buffer.bytes() };
    EXPECT_EQ(server_received_data, sent_data);

    EXPECT(!udp_server->send({ udp_reply_data.characters_without_null_termination(), udp_reply_data.length() }, client_address).is_error());

    EXPECT(client_socket.can_read_without_blocking(100).release_value());
    EXPECT_EQ(client_socket.pending_bytes().release_value(), udp_reply_data.length());

    // Testing that supplying a smaller buffer than required causes a failure.
    auto small_buffer = ByteBuffer::create_uninitialized(8).release_value();
    EXPECT_EQ(client_socket.read(small_buffer).error().code(), EMSGSIZE);

    auto maybe_client_receive_buffer = ByteBuffer::create_uninitialized(64);
    auto client_receive_buffer = maybe_client_receive_buffer.release_value();
    auto maybe_nread = client_socket.read(client_receive_buffer);
    EXPECT(!maybe_nread.is_error());
    auto nread = maybe_nread.release_value();

    StringView client_received_data { client_receive_buffer.data(), nread };
    EXPECT_EQ(udp_reply_data, client_received_data);
}

// LocalSocket tests

TEST_CASE(local_socket_read)
{
    Core::EventLoop event_loop;

    auto local_server = Core::LocalServer::construct();
    EXPECT(local_server->listen("/tmp/test-socket"));

    local_server->on_accept = [&](NonnullRefPtr<Core::LocalSocket> server_socket) {
        EXPECT(server_socket->write(sent_data));

        event_loop.quit(0);
        event_loop.pump();
    };

    // NOTE: Doing this on another thread, because otherwise we're at an
    //       impasse. LocalSocket::connect blocks because there's nobody to
    //       accept, and LocalServer::accept blocks because there's nobody
    //       connected.
    auto background_action = Threading::BackgroundAction<int>::construct(
        [](auto&) {
            auto maybe_client_socket = Core::Stream::LocalSocket::connect("/tmp/test-socket");
            EXPECT(!maybe_client_socket.is_error());
            auto client_socket = maybe_client_socket.release_value();

            EXPECT(client_socket.is_open());

            EXPECT(client_socket.can_read_without_blocking(100).release_value());
            EXPECT_EQ(client_socket.pending_bytes().release_value(), sent_data.length());

            auto maybe_receive_buffer = ByteBuffer::create_uninitialized(64);
            auto receive_buffer = maybe_receive_buffer.release_value();
            auto maybe_nread = client_socket.read(receive_buffer);
            EXPECT(!maybe_nread.is_error());
            auto nread = maybe_nread.release_value();

            StringView received_data { receive_buffer.data(), nread };
            EXPECT_EQ(sent_data, received_data);

            return 0;
        },
        nullptr);

    event_loop.exec();
    ::unlink("/tmp/test-socket");
}

TEST_CASE(local_socket_write)
{
    Core::EventLoop event_loop;

    auto local_server = Core::LocalServer::construct();
    EXPECT(local_server->listen("/tmp/test-socket"));

    local_server->on_accept = [&](NonnullRefPtr<Core::LocalSocket> server_socket) {
        // NOTE: For some reason LocalServer gives us a nonblocking socket..?
        server_socket->set_blocking(true);

        auto receive_buffer = server_socket->read_all();
        EXPECT(!server_socket->error());

        StringView received_data { receive_buffer.bytes() };
        EXPECT_EQ(sent_data, received_data);

        event_loop.quit(0);
        event_loop.pump();
    };

    // NOTE: Same reason as in the local_socket_read test.
    auto background_action = Threading::BackgroundAction<int>::construct(
        [](auto&) {
            auto maybe_client_socket = Core::Stream::LocalSocket::connect("/tmp/test-socket");
            EXPECT(!maybe_client_socket.is_error());
            auto client_socket = maybe_client_socket.release_value();

            EXPECT(client_socket.write_or_error({ sent_data.characters_without_null_termination(), sent_data.length() }));
            client_socket.close();

            return 0;
        },
        nullptr);

    event_loop.exec();
    ::unlink("/tmp/test-socket");
}

// Buffered stream tests

TEST_CASE(buffered_long_file_read)
{
    auto maybe_file = Core::Stream::File::open("/usr/Tests/LibCore/long_lines.txt", Core::Stream::OpenMode::Read);
    EXPECT(!maybe_file.is_error());
    auto maybe_buffered_file = Core::Stream::BufferedFile::create(maybe_file.release_value());
    EXPECT(!maybe_buffered_file.is_error());
    auto file = maybe_buffered_file.release_value();

    auto buffer = ByteBuffer::create_uninitialized(4096).release_value();
    EXPECT(!file.seek(255, Core::Stream::SeekMode::SetPosition).is_error());
    EXPECT(file.can_read_line().release_value());
    auto maybe_nread = file.read_line(buffer);
    EXPECT(!maybe_nread.is_error());
    EXPECT_EQ(maybe_nread.value(), 4095ul); // 4095 bytes on the third line

    // Testing that buffering with seeking works properly
    EXPECT(!file.seek(365, Core::Stream::SeekMode::SetPosition).is_error());
    auto maybe_after_seek_nread = file.read_line(buffer);
    EXPECT(!maybe_after_seek_nread.is_error());
    EXPECT_EQ(maybe_after_seek_nread.value(), 3985ul); // 4095 - 110
}

TEST_CASE(buffered_small_file_read)
{
    auto maybe_file = Core::Stream::File::open("/usr/Tests/LibCore/small.txt", Core::Stream::OpenMode::Read);
    EXPECT(!maybe_file.is_error());
    auto maybe_buffered_file = Core::Stream::BufferedFile::create(maybe_file.release_value());
    EXPECT(!maybe_buffered_file.is_error());
    auto file = maybe_buffered_file.release_value();

    static constexpr StringView expected_lines[] {
        "Well"sv,
        "hello"sv,
        "friends!"sv,
        ":^)"sv
    };

    // Testing that we don't read out of bounds when the entire file fits into the buffer
    auto buffer = ByteBuffer::create_uninitialized(4096).release_value();
    for (auto const& line : expected_lines) {
        VERIFY(file.can_read_line().release_value());
        auto maybe_nread = file.read_line(buffer);
        EXPECT(!maybe_nread.is_error());
        EXPECT_EQ(maybe_nread.value(), line.length());
        EXPECT_EQ(StringView(buffer.span().trim(maybe_nread.value())), line);
    }
    EXPECT(!file.can_read_line().is_error());
    EXPECT(!file.can_read_line().value());
}

constexpr auto buffered_sent_data = "Well hello friends!\n:^)\nThis shouldn't be present. :^("sv;
constexpr auto first_line = "Well hello friends!"sv;
constexpr auto second_line = ":^)"sv;

TEST_CASE(buffered_tcp_socket_read)
{
    Core::EventLoop event_loop;

    auto maybe_tcp_server = Core::TCPServer::try_create();
    EXPECT(!maybe_tcp_server.is_error());
    auto tcp_server = maybe_tcp_server.release_value();
    EXPECT(!tcp_server->listen({ 127, 0, 0, 1 }, 9090).is_error());
    EXPECT(!tcp_server->set_blocking(true).is_error());

    auto maybe_client_socket = Core::Stream::TCPSocket::connect({ { 127, 0, 0, 1 }, 9090 });
    EXPECT(!maybe_client_socket.is_error());
    auto maybe_buffered_socket = Core::Stream::BufferedTCPSocket::create(maybe_client_socket.release_value());
    EXPECT(!maybe_buffered_socket.is_error());
    auto client_socket = maybe_buffered_socket.release_value();

    EXPECT(client_socket.is_open());

    auto maybe_server_socket = tcp_server->accept();
    EXPECT(!maybe_server_socket.is_error());
    auto server_socket = maybe_server_socket.release_value();
    EXPECT(!server_socket.write({ buffered_sent_data.characters_without_null_termination(), sent_data.length() }).is_error());

    EXPECT(client_socket.can_read_without_blocking(100).release_value());

    auto receive_buffer = ByteBuffer::create_uninitialized(64).release_value();

    auto maybe_first_nread = client_socket.read_line(receive_buffer);
    EXPECT(!maybe_first_nread.is_error());
    StringView first_received_line { receive_buffer.data(), maybe_first_nread.value() };
    EXPECT_EQ(first_received_line, first_line);

    auto maybe_second_nread = client_socket.read_line(receive_buffer);
    EXPECT(!maybe_second_nread.is_error());
    StringView second_received_line { receive_buffer.data(), maybe_second_nread.value() };
    EXPECT_EQ(second_received_line, second_line);
}