//SPDX-License-Identifier: LGPL-3.0-only
//SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

// A QUIC stream's async calls report a closed stream to their callbacks, the
// same way on native as in the browser build, which has no exceptions:
//  - a receive on a closed stream gets an empty chunk. Natively it used to
//    let QUICClosedException escape the ThreadPool task, which ended the
//    program;
//  - RecieveUntilFullAsync on a stream that closes early gets what arrived;
//    RecieveUntilFullSync still throws, and leaves those bytes for the next
//    receive instead of dropping them;
//  - SendAsync tells its callback whether the stream took the buffer. It
//    used to call it the same way either way.
// A server answers a stream with "abc" and closes its side.

#include <cstdio>

import Crafter.Network;
import Crafter.Thread;
import std;
using namespace Crafter;

namespace {

int failures = 0;

void Check(bool ok, std::string_view what) {
    std::println("{}  {}", ok ? "PASS" : "FAIL", what);
    if (!ok) ++failures;
}

// A callback's result, shared with it so it outlives whichever thread sets it.
template <typename T>
struct Outcome {
    std::mutex mutex;
    std::condition_variable done;
    std::optional<T> value;

    void Set(T result) {
        {
            std::lock_guard lock(mutex);
            value = std::move(result);
        }
        done.notify_all();
    }
    std::optional<T> Wait() {
        std::unique_lock lock(mutex);
        done.wait_for(lock, std::chrono::seconds(5), [&] { return value.has_value(); });
        return value;
    }
};

std::string Text(const std::vector<char>& bytes) {
    return std::string(bytes.begin(), bytes.end());
}

} // namespace

int main() {
    ThreadPool::Start();
    constexpr std::uint16_t port = 9188;
    constexpr std::string_view alpn = "crafter/test-closed-stream";

    QUICServerCredentials serverCreds;
    serverCreds.selfSigned = true;
    ListenerQUIC listener(port, std::string(alpn), serverCreds, [&](ClientQUIC* peer) {
        peer->OnStream([](QUICStream stream) {
            try {
                (void)stream.RecieveSync();
                stream.SendSync("abc", 3, true);
            } catch (...) {}
        });
    });
    listener.ListenAsyncAsync();

    try {
        // ── A stream that was never opened ───────────────────────────────────
        {
            QUICStream closed;
            auto received = std::make_shared<Outcome<std::string>>();
            closed.RecieveAsync([received](std::vector<char> chunk) { received->Set(Text(chunk)); });
            const std::optional<std::string> got = received->Wait();
            Check(got && got->empty(), "a receive on a closed stream gets an empty chunk, and the program carries on");
            auto sent = std::make_shared<Outcome<bool>>();
            closed.SendAsync("x", 1, false, [sent](bool ok) { sent->Set(ok); });
            const std::optional<bool> ok = sent->Wait();
            Check(ok && !*ok, "a send on it tells its callback the stream didn't take it");
        }

        QUICClientCredentials clientCreds;
        clientCreds.insecureNoServerValidation = true;
        ClientQUIC client("localhost", port, std::string(alpn), clientCreds);

        // ── The server answers, then closes its side ─────────────────────────
        {
            QUICStream stream = client.OpenStream();
            auto sent = std::make_shared<Outcome<bool>>();
            stream.SendAsync("hi", 2, false, [sent](bool ok) { sent->Set(ok); });
            const std::optional<bool> ok = sent->Wait();
            Check(ok && *ok, "a send the stream takes tells its callback so");

            auto first = std::make_shared<Outcome<std::string>>();
            stream.RecieveUntilFullAsync(10, [first](std::vector<char> chunk) { first->Set(Text(chunk)); });
            const std::optional<std::string> got = first->Wait();
            Check(got == "abc", std::format("RecieveUntilFullAsync on a stream that closes early gets what arrived ({})", got.value_or("nothing")));

            auto after = std::make_shared<Outcome<std::string>>();
            stream.RecieveAsync([after](std::vector<char> chunk) { after->Set(Text(chunk)); });
            const std::optional<std::string> next = after->Wait();
            Check(next && next->empty(), "a receive after the close gets an empty chunk");
        }
        {
            QUICStream stream = client.OpenStream();
            stream.SendSync("hi", 2, false);
            bool threw = false;
            try {
                (void)stream.RecieveUntilFullSync(10);
            } catch (const QUICClosedException&) {
                threw = true;
            }
            const std::vector<char> left = stream.RecieveUntilCloseSync();
            Check(threw && Text(left) == "abc",
                  std::format("RecieveUntilFullSync throws on the early close and leaves the bytes for the next receive ({})", Text(left)));
        }
        std::println("{}", failures == 0 ? "all checks passed" : "check(s) failed");
        // As the other QUIC tests: skip the static teardown, which waits for
        // the accepted peer's idle timeout. _Exit doesn't flush.
        std::fflush(stdout);
        std::_Exit(failures == 0 ? 0 : 1);
    } catch (const std::exception& e) {
        std::println("FAIL  {}", e.what());
        std::fflush(stdout);
        std::_Exit(1);
    }
}