/// @file examples/protocol/stream_dpf3_smoke.cpp
/// @brief Local DPF3 eval plus trio-shaped stream edges (peer / rss_next / dealer).
#include <cstdint>
#include <cstring>
#include <iostream>
#include <thread>
#include <type_traits>
#include <vector>

#include "dpf.hpp"
#include "dpf/net/stream_array.hpp"
#include "dpf/net/stream_mesh.hpp"
#include "dpf/protocol_factory.hpp"

namespace
{

struct trio_edge_ping
{
    std::uint32_t from = 0;
    std::uint32_t to = 0;
    std::uint64_t nonce = 0;
};

struct trio_party_streams
{
    dpf::net::memory_stream_array & peer;
    dpf::net::memory_stream_array & rss_next;
    dpf::net::memory_stream_array & dealer;
};

template <typename T>
void exchange_pod(dpf::net::memory_stream_array & link, std::size_t stream,
    const T & mine, T & theirs)
{
    static_assert(std::is_trivially_copyable_v<T>, "pod");
    link.write(stream, &mine, sizeof(T));
    link.flush(stream);
    link.read(stream, &theirs, sizeof(T));
}

void ping_edge(trio_party_streams s, unsigned me, unsigned peer_id,
    std::uint64_t nonce, std::size_t stream_idx)
{
    trio_edge_ping mine{me, peer_id, nonce};
    trio_edge_ping theirs{};
    exchange_pod(s.peer, stream_idx, mine, theirs);
    if (theirs.from != peer_id || theirs.to != me)
        throw std::runtime_error("stream_dpf3_smoke: peer edge");
}

}  // namespace

int main()
{
    using Input = std::uint8_t;
    const Input alpha = 42;
    const dpf::fp61 beta{7};

    auto [k1, k2, k3] = dpf::make_dpf3(alpha, beta);
    const dpf::fp61 y1 = dpf::eval_point(k1, alpha);
    const dpf::fp61 y2 = dpf::eval_point(k2, alpha);
    const dpf::fp61 y3 = dpf::eval_point(k3, alpha);
    const dpf::fp61 opened = dpf::reconstruct(
        dpf::as_share(k1, y1), dpf::as_share(k2, y2), dpf::as_share(k3, y3));
    if (opened != beta)
    {
        std::cerr << "dpf3 local eval\n";
        return 1;
    }

    // Dealer delivers a keyed marker on stream 0 to each evaluator.
    auto dealer0 = dpf::net::make_memory_stream_pair(1);
    auto dealer1 = dpf::net::make_memory_stream_pair(1);
    struct key_delivery
    {
        std::uint32_t party = 0;
        std::uint64_t beta_raw = 0;
    };
    key_delivery m0{0, beta.raw()}, m1{1, beta.raw()};
    dealer0.first.write(0, &m0, sizeof(m0));
    dealer0.first.flush(0);
    dealer1.first.write(0, &m1, sizeof(m1));
    dealer1.first.flush(0);
    key_delivery got0{}, got1{};
    dealer0.second.read(0, &got0, sizeof(got0));
    dealer1.second.read(0, &got1, sizeof(got1));
    if (got0.beta_raw != beta.raw() || got1.beta_raw != beta.raw())
    {
        std::cerr << "dealer stream delivery\n";
        return 1;
    }

    // Trio-shaped edges on a 3-party clique (p2 = dealer): peer + rss_next + dealer.
    constexpr std::size_t k_peer = 0;
    constexpr std::size_t k_rss = 1;
    auto clique = dpf::net::make_memory_stream_clique(3, 2);
    std::exception_ptr err;
    std::thread t0([&] {
        try
        {
            trio_party_streams s{clique.end(0, 1), clique.end(0, 1), clique.end(0, 2)};
            ping_edge(s, 0, 1, 11, k_peer);
            const trio_edge_ping rss_out{0, 1, 99};
            s.rss_next.write(k_rss, &rss_out, sizeof(rss_out));
            s.rss_next.flush(k_rss);
        }
        catch (...)
        {
            err = std::current_exception();
        }
    });
    std::thread t1([&] {
        try
        {
            trio_party_streams s{clique.end(1, 0), clique.end(1, 0), clique.end(1, 2)};
            ping_edge(s, 1, 0, 22, k_peer);
            trio_edge_ping rss_in{};
            s.rss_next.read(k_rss, &rss_in, sizeof(rss_in));
            if (rss_in.from != 0u)
                throw std::runtime_error("stream_dpf3_smoke: rss_next");
            const trio_edge_ping dealer_out{1, 2, 88};
            s.dealer.write(k_rss, &dealer_out, sizeof(dealer_out));
            s.dealer.flush(k_rss);
        }
        catch (...)
        {
            err = std::current_exception();
        }
    });
    t0.join();
    t1.join();
    if (err)
        std::rethrow_exception(err);
    trio_edge_ping dealer_in{};
    clique.end(2, 1).read(k_rss, &dealer_in, sizeof(dealer_in));
    if (dealer_in.from != 1u || dealer_in.to != 2u)
    {
        std::cerr << "dealer edge\n";
        return 1;
    }

    std::cout << "stream_trio_ok\n";
    return 0;
}