#include "vdm/net/http_client.hpp"

#include <atomic>
#include <chrono>
#include <future>
#include <mutex>
#include <string>
#include <vector>

#include "testserver_fixture.hpp"
#include "vtest.hpp"

using namespace vdm;
using namespace vdm::net;
using vdm::testing::TestServer;

namespace {

// Collects callback output from a transfer and lets the test thread wait for the end.
struct Recorder {
    std::mutex mu;
    ResponseHead head;
    bool head_seen = false;
    std::uint64_t bytes = 0;
    std::promise<Result<TransferStats>> done;
    std::future<Result<TransferStats>> done_fut = done.get_future();

    DataAction want_on_head = DataAction::proceed;  // set before start()
    std::atomic<DataAction> want_on_data{DataAction::proceed};
    std::atomic<int> data_calls{0};

    TransferCallbacks callbacks() {
        return TransferCallbacks{
            .on_head =
                [this](const ResponseHead &h) {
                    std::lock_guard lk(mu);
                    head = h;
                    head_seen = true;
                    return want_on_head;
                },
            .on_data =
                [this](ConstByteSpan s) {
                    data_calls.fetch_add(1);
                    std::lock_guard lk(mu);
                    bytes += s.size();
                    return want_on_data.load();
                },
            .on_finished = [this](Result<TransferStats> r) { done.set_value(std::move(r)); },
        };
    }

    Result<TransferStats> wait(std::chrono::seconds to = std::chrono::seconds(20)) {
        if (done_fut.wait_for(to) != std::future_status::ready)
            return Err{Error::timeout, "test wait timed out"};
        return done_fut.get();
    }
};

// on_data needs an atomic for the cancel/pause tests to flip it from the test thread.
struct AtomicAction {
    std::atomic<DataAction> a{DataAction::proceed};
    void store(DataAction v) { a.store(v); }
    operator DataAction() const { return a.load(); }
    DataAction load() const { return a.load(); }
};

}  // namespace

VT_TEST(http_plain_full_get) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    Recorder rec;
    Request req;
    req.url = srv.url("/plain/file/64K");
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(r.has_value());
    VT_CHECK_EQ(r.value().http_status, 200);
    VT_CHECK_EQ(r.value().bytes_received, 65536u);
    VT_CHECK(rec.head_seen);
    VT_CHECK_EQ(rec.head.status, 200);
    VT_CHECK(rec.head.headers.has("Accept-Ranges"));
    VT_CHECK_EQ(rec.bytes, 65536u);
    VT_CHECK(t.id() != 0);
}

VT_TEST(http_ranged_get_is_206) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    Recorder rec;
    Request req;
    req.url = srv.url("/plain/file/64K");
    req.range = ByteRange{1000, 1999};
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(r.has_value());
    VT_CHECK_EQ(rec.head.status, 206);
    auto cr = rec.head.headers.get("Content-Range");
    VT_REQUIRE(cr.has_value());
    VT_CHECK_EQ(std::string(*cr), std::string("bytes 1000-1999/65536"));
    VT_CHECK_EQ(rec.bytes, 1000u);
    VT_CHECK_EQ(r.value().bytes_received, 1000u);
}

VT_TEST(http_follows_redirect_chain) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    Recorder rec;
    Request req;
    req.url = srv.url("/redirect-chain/file/16K");
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(r.has_value());
    VT_CHECK_EQ(rec.head.status, 200);  // on_head fires once, for the final response
    VT_CHECK_EQ(rec.bytes, 16u * 1024u);
    VT_CHECK(r.value().effective_url != srv.url("/redirect-chain/file/16K"));
    VT_CHECK(r.value().effective_url.find("_r=done") != std::string::npos);
}

VT_TEST(http_404_is_not_found_error) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    Recorder rec;
    Request req;
    req.url = srv.url("/plain/nope");
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(!r.has_value());
    VT_CHECK_EQ(r.error().code, Error::not_found);
    VT_CHECK_EQ(r.error().http_status, 404);
}

VT_TEST(http_connection_refused_is_connect_failed) {
    HttpClient client({.workers = 1});
    Recorder rec;
    Request req;
    req.url = "http://127.0.0.1:1/nothing";  // nothing listens on :1
    req.connect_timeout_ms = 2000;
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(!r.has_value());
    VT_CHECK_EQ(r.error().code, Error::connect_failed);
}

VT_TEST(http_head_probe_stops_after_headers) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    Recorder rec;
    rec.want_on_head = DataAction::abort;  // probe: headers only
    Request req;
    req.url = srv.url("/plain/file/1M");
    req.method = Method::head;
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(r.has_value());  // head_complete, NOT canceled
    VT_CHECK(rec.head_seen);
    VT_REQUIRE(rec.head.content_length.has_value());
    VT_CHECK_EQ(*rec.head.content_length, 1024u * 1024u);
    VT_CHECK_EQ(rec.data_calls.load(), 0);
}

VT_TEST(http_ranged_get_probe_stops_without_downloading_file) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    Recorder rec;
    rec.want_on_head = DataAction::abort;
    Request req;
    req.url = srv.url("/plain/file/8M");
    req.range = ByteRange{0, 0};  // classic HEAD-refused fallback
    auto t = client.start(std::move(req), rec.callbacks());

    auto r = rec.wait();
    VT_REQUIRE(r.has_value());
    VT_CHECK(rec.bytes <= 1u);  // at most the one probe byte, usually 0
}

VT_TEST(http_cancel_mid_transfer) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    AtomicAction data_action;
    std::promise<Result<TransferStats>> done;
    auto fut = done.get_future();
    std::atomic<int> calls{0};

    TransferCallbacks cbs{
        .on_head = [](const ResponseHead &) { return DataAction::proceed; },
        .on_data =
            [&](ConstByteSpan) {
                calls.fetch_add(1);
                return data_action.load();
            },
        .on_finished = [&](Result<TransferStats> r) { done.set_value(std::move(r)); },
    };

    Request req;
    req.url = srv.url("/throttled/file/4M");  // ~128 KiB/s => lots of chunks
    auto t = client.start(std::move(req), std::move(cbs));

    // wait for the transfer to actually start, then cancel
    for (int i = 0; i < 200 && calls.load() == 0; ++i)
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
    VT_REQUIRE(calls.load() > 0);
    t.cancel();

    VT_REQUIRE(fut.wait_for(std::chrono::seconds(10)) == std::future_status::ready);
    auto r = fut.get();
    VT_REQUIRE(!r.has_value());
    VT_CHECK_EQ(r.error().code, Error::canceled);
}

VT_TEST(http_pause_then_resume_completes) {
    TestServer srv;
    VT_REQUIRE(srv.available());
    HttpClient client({.workers = 1});

    std::atomic<int> calls{0};
    std::atomic<std::uint64_t> total{0};
    std::promise<Result<TransferStats>> done;
    auto fut = done.get_future();

    TransferCallbacks cbs{
        .on_head = [](const ResponseHead &) { return DataAction::proceed; },
        .on_data =
            [&](ConstByteSpan s) {
                calls.fetch_add(1);
                total.fetch_add(s.size());
                return DataAction::proceed;
            },
        .on_finished = [&](Result<TransferStats> r) { done.set_value(std::move(r)); },
    };

    Request req;
    req.url = srv.url("/throttled/file/1M");
    auto t = client.start(std::move(req), std::move(cbs));

    for (int i = 0; i < 200 && calls.load() == 0; ++i)
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
    VT_REQUIRE(calls.load() > 0);

    t.pause();
    int calls_at_pause = calls.load();
    std::this_thread::sleep_for(std::chrono::milliseconds(400));
    VT_CHECK(calls.load() - calls_at_pause <= 1);  // at most one in-flight chunk slips through
    t.resume();

    VT_REQUIRE(fut.wait_for(std::chrono::seconds(20)) == std::future_status::ready);
    auto r = fut.get();
    VT_REQUIRE(r.has_value());
    VT_CHECK_EQ(total.load(), 1024u * 1024u);
}