#include <mln/storage/network_status.hpp>
#include <mln/storage/online_file_source.hpp>
#include <mln/storage/resource.hpp>
#include <mln/storage/resource_options.hpp>
#include <mln/test/util.hpp>
#include <mln/util/chrono.hpp>
#include <mln/util/constants.hpp>
#include <mln/util/run_loop.hpp>
#include <mln/util/string.hpp>
#include <mln/util/timer.hpp>

#include <gtest/gtest.h>

using namespace mln;

#ifdef WIN32
// Windows doesn't fail immediately like other OS
constexpr double connectionTimeout = 2.0;
#else
constexpr double connectionTimeout = 0;
#endif

TEST(OnlineFileSource, Cancel) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    fs->request({Resource::Unknown, "http://127.0.0.1:3000/test"},
                [&](Response) { ADD_FAILURE() << "Callback should not be called"; });

    loop.runOnce();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(CancelMultiple)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3000/test"};

    std::unique_ptr<AsyncRequest> req2 = fs->request(
        resource, [&](Response) { ADD_FAILURE() << "Callback should not be called"; });
    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response res) {
        req.reset();
        EXPECT_EQ(nullptr, res.error);
        ASSERT_TRUE(res.data.get());
        EXPECT_EQ("Hello World!", *res.data);
        EXPECT_FALSE(bool(res.expires));
        EXPECT_FALSE(res.mustRevalidate);
        EXPECT_FALSE(bool(res.modified));
        EXPECT_FALSE(bool(res.etag));
        loop.stop();
    });
    req2.reset();

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(TemporaryError)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    const auto start = Clock::now();
    int counter = 0;

    auto req = fs->request({Resource::Unknown, "http://127.0.0.1:3000/temporary-error"}, [&](Response res) {
        switch (counter++) {
            case 0: {
                const auto duration = std::chrono::duration<const double>(Clock::now() - start).count();
                EXPECT_GT(0.2, duration) << "Initial error request took too long";
                ASSERT_NE(nullptr, res.error);
                EXPECT_EQ(Response::Error::Reason::Server, res.error->reason);
                EXPECT_EQ("HTTP status code 500", res.error->message);
                ASSERT_FALSE(bool(res.data));
                EXPECT_FALSE(bool(res.expires));
                EXPECT_FALSE(res.mustRevalidate);
                EXPECT_FALSE(bool(res.modified));
                EXPECT_FALSE(bool(res.etag));
            } break;
            case 1: {
                const auto duration = std::chrono::duration<const double>(Clock::now() - start).count();
                EXPECT_LT(0.99, duration) << "Backoff timer didn't wait 1 second";
                EXPECT_GT(1.2, duration) << "Backoff timer fired too late";
                EXPECT_EQ(nullptr, res.error);
                ASSERT_TRUE(res.data.get());
                EXPECT_EQ("Hello World!", *res.data);
                EXPECT_FALSE(bool(res.expires));
                EXPECT_FALSE(res.mustRevalidate);
                EXPECT_FALSE(bool(res.modified));
                EXPECT_FALSE(bool(res.etag));
                loop.stop();
            } break;
        }
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(ConnectionError)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    const auto start = Clock::now();
    int counter = 0;
    double wait = connectionTimeout;

    std::unique_ptr<AsyncRequest> req = fs->request({Resource::Unknown, "http://127.0.0.1:3001/"}, [&](Response res) {
        const auto duration = std::chrono::duration<const double>(Clock::now() - start).count();
        EXPECT_LT(wait - 0.01, duration) << "Backoff timer didn't wait 1 second";
        EXPECT_GT(wait + 0.3, duration) << "Backoff timer fired too late";
        ASSERT_NE(nullptr, res.error);
        EXPECT_EQ(Response::Error::Reason::Connection, res.error->reason);
        ASSERT_FALSE(res.data.get());
        EXPECT_FALSE(bool(res.expires));
        EXPECT_FALSE(res.mustRevalidate);
        EXPECT_FALSE(bool(res.modified));
        EXPECT_FALSE(bool(res.etag));

        if (counter == 2) {
            req.reset();
            loop.stop();
        }
        wait += (1 << counter) + connectionTimeout;
        counter++;
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(Timeout)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    int counter = 0;

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3000/test?cachecontrol=max-age=1"};
    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response res) {
        counter++;
        EXPECT_EQ(nullptr, res.error);
        ASSERT_TRUE(res.data.get());
        EXPECT_EQ("Hello World!", *res.data);
        EXPECT_TRUE(bool(res.expires));
        EXPECT_FALSE(res.mustRevalidate);
        EXPECT_FALSE(bool(res.modified));
        EXPECT_FALSE(bool(res.etag));
        if (counter == 4) {
            req.reset();
            loop.stop();
        }
    });

    loop.run();

    EXPECT_EQ(4, counter);
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RetryDelayOnExpiredTile)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    int counter = 0;

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3000/test?expires=10000"};
    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response res) {
        counter++;
        EXPECT_EQ(nullptr, res.error);
        EXPECT_TRUE(util::now() > *res.expires);
        EXPECT_FALSE(res.mustRevalidate);
        loop.stop();
    });

    loop.run();

    EXPECT_EQ(1, counter);
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RetryOnClockSkew)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    int counter = 0;

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3000/clockskew"};
    std::unique_ptr<AsyncRequest> req1 = fs->request(resource, [&](Response res) {
        EXPECT_FALSE(res.mustRevalidate);
        switch (counter++) {
            case 0: {
                EXPECT_EQ(nullptr, res.error);
                EXPECT_TRUE(util::now() > *res.expires);
            } break;
            case 1: {
                EXPECT_EQ(nullptr, res.error);

                auto now = util::now();
                EXPECT_TRUE(now + Seconds(40) < *res.expires) << "Expiration not interpolated to 60s";
                EXPECT_TRUE(now + Seconds(80) > *res.expires) << "Expiration not interpolated to 60s";

                loop.stop();
            } break;
        }
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RespectPriorExpires)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    // Very long expiration time, should never arrive.
    Resource resource1{Resource::Unknown, "http://127.0.0.1:3000/test"};
    resource1.priorExpires = util::now() + Seconds(100000);

    std::unique_ptr<AsyncRequest> req1 = fs->request(resource1, [&](Response) { FAIL() << "Should never be called"; });

    // No expiration time, should be requested immediately.
    Resource resource2{Resource::Unknown, "http://127.0.0.1:3000/test"};

    std::unique_ptr<AsyncRequest> req2 = fs->request(resource2, [&](Response) { loop.stop(); });

    // Very long expiration time, should never arrive.
    Resource resource3{Resource::Unknown, "http://127.0.0.1:3000/test"};
    resource3.priorExpires = util::now() + Seconds(100000);

    std::unique_ptr<AsyncRequest> req3 = fs->request(resource3, [&](Response) { FAIL() << "Should never be called"; });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RespectMinimumUpdateInterval)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    auto start = util::now();
    Resource resource{Resource::Unknown, "http://127.0.0.1:3000/test"};
    resource.priorExpires = start + std::chrono::duration_cast<Seconds>(Milliseconds(100));
    resource.minimumUpdateInterval = Seconds(1);

    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response) {
        auto wait = util::now() - start;
        EXPECT_GE(wait, resource.minimumUpdateInterval);
        loop.stop();
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(Load)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    const int concurrency = 50;
    const int max = 10000;
    int number = 1;

    std::unique_ptr<AsyncRequest> reqs[concurrency];

    std::function<void(int)> req = [&](int i) {
        const auto current = number++;
        reqs[i] = fs->request({Resource::Unknown, std::string("http://127.0.0.1:3000/load/") + util::toString(current)},
                              [&, i, current](Response res) {
                                  reqs[i].reset();
                                  EXPECT_EQ(nullptr, res.error);
                                  ASSERT_TRUE(res.data.get());
                                  EXPECT_EQ(std::string("Request ") + util::toString(current), *res.data);
                                  EXPECT_FALSE(bool(res.expires));
                                  EXPECT_FALSE(res.mustRevalidate);
                                  EXPECT_FALSE(bool(res.modified));
                                  EXPECT_FALSE(bool(res.etag));

                                  if (number <= max) {
                                      req(i);
                                  } else if (current == max) {
                                      loop.stop();
                                  }
                              });
    };

    for (int i = 0; i < concurrency; i++) {
        req(i);
    }

    loop.run();
}

// Test for https://github.com/mapbox/mapbox-gl-native/issues/2123
//
// A request is made. While the request is in progress, the network status
// changes. This should trigger an immediate retry of all requests that are not
// in progress. This test makes sure that we don't accidentally double-trigger
// the request.

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(NetworkStatusChange)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3000/delayed"};

    // This request takes 200 milliseconds to answer.
    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response res) {
        req.reset();
        EXPECT_EQ(nullptr, res.error);
        ASSERT_TRUE(res.data.get());
        EXPECT_EQ("Response", *res.data);
        EXPECT_FALSE(bool(res.expires));
        EXPECT_FALSE(res.mustRevalidate);
        EXPECT_FALSE(bool(res.modified));
        EXPECT_FALSE(bool(res.etag));
        loop.stop();
    });

    // After 50 milliseconds, we're going to trigger a NetworkStatus change.
    util::Timer reachableTimer;
    reachableTimer.start(Milliseconds(50), Duration::zero(), []() { mln::NetworkStatus::Reachable(); });

    loop.run();
}

// Tests that a change in network status preempts requests that failed due to
// connection or reachability issues.
TEST(OnlineFileSource, TEST_REQUIRES_SERVER(NetworkStatusChangePreempt)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());
    fs->pause();

    const auto start = Clock::now();
    int counter = 0;

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3001/test"};

    double wait = connectionTimeout;

    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response res) {
        const auto duration = std::chrono::duration<const double>(Clock::now() - start).count();
        if (counter == 0) {
            EXPECT_GT(wait + 0.2, duration) << "Response came in too late";
        } else if (counter == 1) {
            EXPECT_LT(wait + 0.39, duration) << "Preempted retry triggered too early";
            EXPECT_GT(wait + 0.6, duration) << "Preempted retry triggered too late";
        } else if (counter > 1) {
            FAIL() << "Retried too often";
        }
        ASSERT_NE(nullptr, res.error);
        EXPECT_EQ(Response::Error::Reason::Connection, res.error->reason);
        ASSERT_FALSE(res.data.get());
        EXPECT_FALSE(bool(res.expires));
        EXPECT_FALSE(res.mustRevalidate);
        EXPECT_FALSE(bool(res.modified));
        EXPECT_FALSE(bool(res.etag));

        wait += connectionTimeout;

        if (counter++ == 1) {
            req.reset();
            loop.stop();
        }
    });

    // After 400 milliseconds + connectionTimeout, we're going to trigger a NetworkStatus change.
    util::Timer reachableTimer;
    reachableTimer.start(Milliseconds(static_cast<int>(connectionTimeout * 1000) + 400), Duration::zero(), []() {
        mln::NetworkStatus::Reachable();
    });

    fs->resume();
    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(NetworkStatusOnlineOffline)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    const Resource resource{Resource::Unknown, "http://127.0.0.1:3000/test"};

    EXPECT_EQ(NetworkStatus::Get(), NetworkStatus::Status::Online) << "Default status should be Online";
    NetworkStatus::Set(NetworkStatus::Status::Offline);

    util::Timer onlineTimer;
    onlineTimer.start(
        Milliseconds(100), Duration::zero(), [&]() { NetworkStatus::Set(NetworkStatus::Status::Online); });

    std::unique_ptr<AsyncRequest> req = fs->request(resource, [&](Response res) {
        req.reset();

        EXPECT_EQ(nullptr, res.error);
        ASSERT_TRUE(res.data.get());

        EXPECT_EQ(NetworkStatus::Get(), NetworkStatus::Status::Online) << "Triggered before set back to Online";

        loop.stop();
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RateLimitStandard)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    auto req = fs->request({Resource::Unknown, "http://127.0.0.1:3000/rate-limit?std=true"}, [&](Response res) {
        ASSERT_NE(nullptr, res.error);
        EXPECT_EQ(Response::Error::Reason::RateLimit, res.error->reason);
        ASSERT_EQ(true, bool(res.error->retryAfter));
        ASSERT_TRUE(util::now() < res.error->retryAfter);
        loop.stop();
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RateLimitMBX)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    auto req = fs->request({Resource::Unknown, "http://127.0.0.1:3000/rate-limit?mbx=true"}, [&](Response res) {
        ASSERT_NE(nullptr, res.error);
        EXPECT_EQ(Response::Error::Reason::RateLimit, res.error->reason);
        ASSERT_EQ(true, bool(res.error->retryAfter));
        ASSERT_TRUE(util::now() < res.error->retryAfter);
        loop.stop();
    });

    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RateLimitDefault)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    auto req = fs->request({Resource::Unknown, "http://127.0.0.1:3000/rate-limit"}, [&](Response res) {
        ASSERT_NE(nullptr, res.error);
        EXPECT_EQ(Response::Error::Reason::RateLimit, res.error->reason);
        ASSERT_FALSE(res.error->retryAfter);
        loop.stop();
    });

    loop.run();
}

TEST(OnlineFileSource, GetBaseURLAndApiKeyWhilePaused) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    fs->pause();

    auto baseURL = "http://url";
    auto apiKey = "api_key";

    fs->setProperty(API_BASE_URL_KEY, baseURL);
    fs->setProperty(API_KEY_KEY, apiKey);

    EXPECT_EQ(*fs->getProperty(API_BASE_URL_KEY).getString(), baseURL);
    EXPECT_EQ(*fs->getProperty(API_KEY_KEY).getString(), apiKey);
}

TEST(OnlineFileSource, ChangeAPIBaseURL) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());
    EXPECT_EQ(ResourceOptions::Default().tileServerOptions().baseURL(), *fs->getProperty(API_BASE_URL_KEY).getString());
    const std::string customURL = "test.domain";
    fs->setProperty(API_BASE_URL_KEY, customURL);
    EXPECT_EQ(customURL, *fs->getProperty(API_BASE_URL_KEY).getString());

    auto updatedTileServerOptions = fs->getResourceOptions().tileServerOptions();
    EXPECT_EQ(customURL, updatedTileServerOptions.baseURL());
}

TEST(OnlineFileSource, ChangeTileServerOptions) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    TileServerOptions tileServerOptsChanged;
    tileServerOptsChanged.withApiKeyParameterName("apiKeyChanged")
        .withBaseURL("baseURLChanged")
        .withDefaultStyle("defaultStyleChanged")
        .withGlyphsTemplate("defaultGlyphsTemplateChanged", "glyphsDomainChanged", {})
        .withSourceTemplate("sourceTemplateChanged", "sourceDomainChanged", {})
        .withSpritesTemplate("spritesTemplateChanged", "spritesDomainChanged", {})
        .withStyleTemplate("styleTemplateChanged", "styleDomainChanged", {})
        .withTileTemplate("tileTemplateChanged", "tileDomainChanged", {})
        .withUriSchemeAlias("uriSchemeAliasChanged");
    ResourceOptions resOpts;
    resOpts.withApiKey("changedAPIKey").withTileServerOptions(tileServerOptsChanged);

    fs->setResourceOptions(resOpts.clone());

    auto actualResourceOpts = fs->getResourceOptions();

    EXPECT_EQ(tileServerOptsChanged.baseURL(), *fs->getProperty(API_BASE_URL_KEY).getString());
    EXPECT_EQ(actualResourceOpts.apiKey(), *fs->getProperty(API_KEY_KEY).getString());

    EXPECT_EQ(resOpts.apiKey(), actualResourceOpts.apiKey());
    EXPECT_EQ(resOpts.tileServerOptions().defaultStyle(), tileServerOptsChanged.defaultStyle());
    EXPECT_EQ(resOpts.tileServerOptions().baseURL(), tileServerOptsChanged.baseURL());
    EXPECT_EQ(resOpts.tileServerOptions().glyphsTemplate(), tileServerOptsChanged.glyphsTemplate());
    EXPECT_EQ(resOpts.tileServerOptions().glyphsDomainName(), tileServerOptsChanged.glyphsDomainName());
    EXPECT_EQ(resOpts.tileServerOptions().glyphsVersionPrefix(), tileServerOptsChanged.glyphsVersionPrefix());
    EXPECT_EQ(resOpts.tileServerOptions().sourceTemplate(), tileServerOptsChanged.sourceTemplate());
    EXPECT_EQ(resOpts.tileServerOptions().sourceDomainName(), tileServerOptsChanged.sourceDomainName());
    EXPECT_EQ(resOpts.tileServerOptions().sourceVersionPrefix(), tileServerOptsChanged.sourceVersionPrefix());
    EXPECT_EQ(resOpts.tileServerOptions().spritesTemplate(), tileServerOptsChanged.spritesTemplate());
    EXPECT_EQ(resOpts.tileServerOptions().spritesDomainName(), tileServerOptsChanged.spritesDomainName());
    EXPECT_EQ(resOpts.tileServerOptions().spritesVersionPrefix(), tileServerOptsChanged.spritesVersionPrefix());
    EXPECT_EQ(resOpts.tileServerOptions().tileTemplate(), tileServerOptsChanged.tileTemplate());
    EXPECT_EQ(resOpts.tileServerOptions().tileDomainName(), tileServerOptsChanged.tileDomainName());
    EXPECT_EQ(resOpts.tileServerOptions().tileVersionPrefix(), tileServerOptsChanged.tileVersionPrefix());
    EXPECT_EQ(resOpts.tileServerOptions().styleTemplate(), tileServerOptsChanged.styleTemplate());
    EXPECT_EQ(resOpts.tileServerOptions().styleDomainName(), tileServerOptsChanged.styleDomainName());
    EXPECT_EQ(resOpts.tileServerOptions().styleVersionPrefix(), tileServerOptsChanged.styleVersionPrefix());
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(LowHighPriorityRequests)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());
    std::size_t response_counter = 0;
    const std::size_t NUM_REQUESTS = 3;

    NetworkStatus::Set(NetworkStatus::Status::Offline);
    fs->setProperty(MAX_CONCURRENT_REQUESTS_KEY, 1u);
    // After DefaultFileSource was split, OnlineFileSource lives on a separate
    // thread. Pause OnlineFileSource, so that messages are queued for processing.
    fs->pause();

    // First regular request.
    Resource regular1{Resource::Unknown, "http://127.0.0.1:3000/load/1"};
    std::unique_ptr<AsyncRequest> req_0 = fs->request(regular1, [&](Response) {
        response_counter++;
        req_0.reset();
    });

    // Low priority request that will be queued and should be requested last.
    Resource low_prio{Resource::Unknown, "http://127.0.0.1:3000/load/2"};
    low_prio.setPriority(Resource::Priority::Low);
    std::unique_ptr<AsyncRequest> req_1 = fs->request(low_prio, [&](Response) {
        response_counter++;
        req_1.reset();
        EXPECT_EQ(response_counter,
                  NUM_REQUESTS); // make sure this is responded last
        loop.stop();
    });

    // Second regular priority request that should de-preoritize low priority request.
    Resource regular2{Resource::Unknown, "http://127.0.0.1:3000/load/3"};
    std::unique_ptr<AsyncRequest> req_2 = fs->request(regular2, [&](Response) {
        response_counter++;
        req_2.reset();
    });

    fs->resume();
    NetworkStatus::Set(NetworkStatus::Status::Online);
    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(LowHighPriorityRequestsMany)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());
    int response_counter = 0;
    int correct_low = 0;
    int correct_regular = 0;

    NetworkStatus::Set(NetworkStatus::Status::Offline);
    fs->setProperty(MAX_CONCURRENT_REQUESTS_KEY, 1u);
    fs->pause();

    std::vector<std::unique_ptr<AsyncRequest>> collector;

    for (int num_reqs = 0; num_reqs < 20; num_reqs++) {
        if (num_reqs % 2 == 0) {
            std::unique_ptr<AsyncRequest> req = fs->request(
                {Resource::Unknown, "http://127.0.0.1:3000/load/" + std::to_string(num_reqs)}, [&](Response) {
                    response_counter++;

                    if (response_counter <= 10) { // count the high priority requests that arrive late correctly
                        correct_regular++;
                    }
                });
            collector.push_back(std::move(req));
        } else {
            Resource resource = {Resource::Unknown, "http://127.0.0.1:3000/load/" + std::to_string(num_reqs)};
            resource.setPriority(Resource::Priority::Low);

            std::unique_ptr<AsyncRequest> req = fs->request(std::move(resource), [&](Response) {
                response_counter++;

                if (response_counter > 10) { // count the low priority requests that arrive late correctly
                    correct_low++;
                }

                // stop and check correctness after last low priority request is responded
                if (20 == response_counter) {
                    loop.stop();
                    for (auto& collected_req : collector) {
                        collected_req.reset();
                    }
                    ASSERT_TRUE(correct_low >= 9);
                    ASSERT_TRUE(correct_regular >= 9);
                }
            });
            collector.push_back(std::move(req));
        }
    }

    fs->resume();
    NetworkStatus::Set(NetworkStatus::Status::Online);
    loop.run();
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(MaximumConcurrentRequests)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    ASSERT_EQ(*fs->getProperty(MAX_CONCURRENT_REQUESTS_KEY).getUint(), 20u);

    fs->setProperty(MAX_CONCURRENT_REQUESTS_KEY, 10u);
    ASSERT_EQ(*fs->getProperty(MAX_CONCURRENT_REQUESTS_KEY).getUint(), 10u);
}

TEST(OnlineFileSource, TEST_REQUIRES_SERVER(RequestSameUrlMultipleTimes)) {
    util::RunLoop loop;
    std::unique_ptr<FileSource> fs = std::make_unique<OnlineFileSource>(ResourceOptions::Default(), ClientOptions());

    int count = 0;
    std::vector<std::unique_ptr<AsyncRequest>> requests;

    for (int i = 0; i < 100; ++i) {
        requests.emplace_back(fs->request({Resource::Unknown, "http://127.0.0.1:3000/load"}, [&](Response) {
            if (++count == 100) {
                loop.stop();
            }
        }));
    }

    loop.run();
}