#include "capture_file_writer.h"
#include "channel_bundle_support.hpp"
#include "locator/tcp_server.hpp"
#include "processing_live_config.hpp"
#include "runtime_wait.hpp"
#include "shm_ring.hpp"
#include "sweep_orchestrator.hpp"
#include "tty_protocol_writer.h"

#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>

#include <array>
#include <atomic>
#include <chrono>
#include <cstring>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <limits>
#include <random>
#include <stdexcept>
#include <thread>

#include <nlohmann/json.hpp>

namespace {
using namespace radar;
using Json = nlohmann::json;

void require(bool condition, const char* message) {
    if (!condition) {
        throw std::runtime_error(message);
    }
}

template <typename Callable>
void expect_error(Callable operation) {
    try {
        operation();
    } catch (const std::bad_alloc&) {
        throw;  // A malformed count must be rejected before allocating.
    } catch (const std::exception&) {
        return;
    }
    throw std::runtime_error("Expected operation to reject malformed input");
}

struct Workspace {
    std::filesystem::path path;
    Workspace() {
        char pattern[] = "/tmp/radar-native-XXXXXX";
        const auto* created = ::mkdtemp(pattern);
        require(created != nullptr, "mkdtemp failed");
        path = created;
    }
    ~Workspace() { std::filesystem::remove_all(path); }
};

struct RingName {
    std::string name = "/radar_native_test_" + std::to_string(::getpid());
    RingName() { ipc::ShmRing::unlink_ring(name); }
    ~RingName() { ipc::ShmRing::unlink_ring(name); }
};

void write_u32(std::vector<std::uint8_t>& bytes, std::size_t offset, std::uint32_t value) {
    require(offset + sizeof(value) <= bytes.size(), "invalid test offset");
    std::memcpy(bytes.data() + offset, &value, sizeof(value));
}

void test_wire_decoders() {
    ipc::RawSweepCollection raw{.collection_id = 7, .monotonic_ns = 42,
        .capture_start_ns = 21, .capture_end_ns = 40,
        .traces = {{.combo = {1, 2}, .frequency_hz = {1, 2},
            .s11 = {{1, 2}, {3, 4}}, .s21 = {{5, 6}, {7, 8}},
            .capture_start_ns = 25, .capture_end_ns = 39}}};
    ipc::ResultCollection results{.collection_id = 7, .processing_duration_ns = 17,
        .collection_payloads = {
            {.kind = ipc::ResultKind::TraceComplex, .frequency_hz = {1}, .trace = {{2, 3}}},
            {.kind = ipc::ResultKind::ScalarF32, .scalar_value = 4},
            {.kind = ipc::ResultKind::ImageF32, .image_x_axis = {1, 2},
                .image_y_axis = {3}, .image_values = {4, 5}},
            {.kind = ipc::ResultKind::TableF32, .table_columns = 2, .table_values = {6, 7}},
            {.kind = ipc::ResultKind::ImageF32, .image_y_axis = {1}},
            {.kind = ipc::ResultKind::TableF32, .table_columns = 3}},
        .blocks = {{.combo = {1, 2}, .payloads = {{.kind = ipc::ResultKind::ScalarF32}}}}};
    const auto raw_bytes = ipc::serialize_raw_collection(raw);
    const auto pre_bytes = ipc::serialize_preprocessed_collection(raw);
    const auto result_bytes = ipc::serialize_result_collection(results);
    require(ipc::serialize_raw_collection(ipc::deserialize_raw_collection(raw_bytes)) == raw_bytes,
        "raw roundtrip changed data");
    require(ipc::serialize_preprocessed_collection(ipc::deserialize_preprocessed_collection(pre_bytes)) == pre_bytes,
        "preprocessed roundtrip changed data");
    require(ipc::serialize_result_collection(ipc::deserialize_result_collection(result_bytes)) == result_bytes,
        "result roundtrip changed data or empty shape");

    for (std::size_t size = 0; size < result_bytes.size(); ++size) {
        expect_error([&] { (void)ipc::deserialize_result_collection(std::span(result_bytes).first(size)); });
    }
    for (std::size_t count_offset : {28U, 32U, 39U}) {
        auto corrupt = result_bytes;
        write_u32(corrupt, count_offset, std::numeric_limits<std::uint32_t>::max());
        expect_error([&] { (void)ipc::deserialize_result_collection(corrupt); });
    }
    for (auto kind : {ipc::ResultKind::ImageF32, ipc::ResultKind::TableF32}) {
        ipc::ResultCollection empty{.collection_payloads = {{.kind = kind}}};
        auto corrupt = ipc::serialize_result_collection(empty);
        write_u32(corrupt, 39, std::numeric_limits<std::uint32_t>::max());
        write_u32(corrupt, 43, std::numeric_limits<std::uint32_t>::max());
        expect_error([&] { (void)ipc::deserialize_result_collection(corrupt); });
    }
    // Deterministic random mutations include wire-compatible valid frames as seeds.
    std::mt19937 random(0x52414452U);
    for (unsigned iteration = 0; iteration < 10'000U; ++iteration) {
        auto bytes = iteration % 3U == 0U ? raw_bytes : iteration % 3U == 1U ? pre_bytes : result_bytes;
        for (unsigned edit = 0; edit < 1U + random() % 5U; ++edit) {
            bytes[random() % bytes.size()] = static_cast<std::uint8_t>(random());
        }
        if (iteration % 4U == 0U) {
            bytes.resize(random() % bytes.size());
        }
        try {
            if (iteration % 3U == 0U) { (void)ipc::deserialize_raw_collection(bytes); }
            else if (iteration % 3U == 1U) { (void)ipc::deserialize_preprocessed_collection(bytes); }
            else { (void)ipc::deserialize_result_collection(bytes); }
        } catch (const std::bad_alloc&) { throw; }
        catch (const std::runtime_error&) {}
    }
}

void test_configuration(const std::string& seed_path, const Workspace& workspace) {
    std::ifstream input(seed_path);
    const auto seed = Json::parse(input);
    const auto config_path = workspace.path / "config.json";
    const auto save = [&](const Json& config) { std::ofstream(config_path) << config; };
    save(seed);
    const auto config = config::load_run_config(config_path.string());
    for (const auto& [pointer, value] : std::array<std::pair<const char*, double>, 8>{{
        {"/radar/sweep/start_hz", -1}, {"/radar/sweep/stop_hz", 1e100},
        {"/radar/sweep/if_bandwidth_hz", 0}, {"/radar/sweep/points", 0},
        {"/radar/sweep/points", 4294967296.0}, {"/run/combos/0/input", 0.0000001},
        {"/rings/raw/slot_size_bytes", 65}, {"/gpr/rx_geometry/0/x_m", 1e100}}}) {
        auto invalid = seed;
        invalid[Json::json_pointer(pointer)] = value;
        save(invalid);
        expect_error([&] { (void)config::load_run_config(config_path.string()); });
    }
    const auto live_path = workspace.path / "live.json";
    std::ofstream(live_path) << Json{{"bscan_gain", 2}, {"settings_revision", 11}};
    processing::ProcessingLiveConfigLoader loader(live_path.string(), config);
    require(loader.refresh_if_needed().bscan_gain == 2, "valid live config did not load");
    const auto revision = loader.revision();
    for (const auto& invalid : {Json{{"bscan_gain", 1e100}},
             Json{{"gpr_input_positions", {0.0000001}}}, Json{{"bscan_gain", true}}}) {
        std::ofstream(live_path) << invalid;
        std::this_thread::sleep_for(std::chrono::milliseconds(110));
        const auto current = loader.refresh_if_needed();
        require(current.bscan_gain == 2 && loader.revision() == revision,
            "invalid live config replaced the last valid settings");
    }
    const std::array<float, 1> nan_axis{std::numeric_limits<float>::quiet_NaN()};
    require(!preprocessing::frequency_axes_match(nan_axis, nan_axis), "NaN frequency axes matched");
    preprocessing::ChannelTrace invalid_trace{.frequency_hz = {1},
        .samples = {{std::numeric_limits<float>::infinity(), 0}}};
    expect_error([&] { preprocessing::validate_channel_trace_layout(invalid_trace, "test", {}); });
}

void test_ring() {
    RingName name;
    expect_error([&] { (void)ipc::ShmRing::open_or_create(name.name, 2, 65); });
    expect_error([&] { (void)ipc::ShmRing::open_or_create(name.name, 0xffffffffU, 0xfffffff8U); });
    auto ring = ipc::ShmRing::open_or_create(name.name, 2, 4096);
    const auto child = ::fork();
    require(child >= 0, "fork failed");
    if (child == 0) {
        std::array<std::uint64_t, 512> words{};
        for (std::uint64_t sequence = 1; sequence <= 20'000U; ++sequence) {
            words.fill(sequence);
            if (!ring.push({reinterpret_cast<const std::uint8_t*>(words.data()), sizeof(words)})) {
                ::_exit(2);
            }
        }
        ::_exit(0);
    }
    std::uint64_t previous = 0;
    std::vector<std::uint8_t> payload;
    int status = 0;
    bool finished = false;
    const auto deadline = std::chrono::steady_clock::now() + std::chrono::seconds(10);
    try {
        while (true) {
            if (ring.pop(payload)) {
                require(payload.size() == 4096, "stress payload changed size");
                std::uint64_t sequence = 0;
                std::memcpy(&sequence, payload.data(), sizeof(sequence));
                require(sequence > previous, "stress ring yielded duplicate or older data");
                for (std::size_t offset = 0; offset < payload.size(); offset += sizeof(sequence)) {
                    std::uint64_t word = 0;
                    std::memcpy(&word, payload.data() + offset, sizeof(word));
                    require(word == sequence, "stress ring accepted a torn payload");
                }
                previous = sequence;
            } else if (finished) { break; }
            finished = finished || ::waitpid(child, &status, WNOHANG) == child;
            require(std::chrono::steady_clock::now() < deadline, "ring stress timed out");
        }
        require(WIFEXITED(status) && WEXITSTATUS(status) == 0 && previous != 0,
            "ring stress writer failed");
    } catch (...) {
        ::kill(child, SIGKILL);
        if (!finished) { (void)::waitpid(child, &status, 0); }
        throw;
    }
}

void test_partial_driver_open() {
    struct Radar final : drivers::RadarDriver {
        unsigned closes = 0;
        void open() override {}
        void close() override { ++closes; }
        auto acquire_sweep() -> drivers::SweepTrace override { return {}; }
    } radar;
    struct Switch final : drivers::SwitchDriver {
        std::atomic<bool>& stop;
        bool fail_open = false;
        bool fail_close = false;
        unsigned closes = 0;
        explicit Switch(std::atomic<bool>& stop_flag) : stop(stop_flag) {}
        void open() override {
            if (fail_open) { stop.store(true); throw std::runtime_error("open failure"); }
        }
        void close() override { ++closes; if (fail_close) { throw std::runtime_error("close failure"); } }
        auto position_count() const -> std::uint32_t override { return 1; }
        void switch_to(std::uint32_t) override {}
    };
    std::atomic<bool> stop{false};
    Switch input(stop), output(stop);
    input.fail_open = true;
    output.fail_close = true;
    config::RunConfig config;
    config.radar.sweep.points = 1;
    config.run_combos = {{0, 0}};
    RingName name;
    auto ring = ipc::ShmRing::open_or_create(name.name, 2, 256);
    acq::SweepOrchestrator(config, radar, input, output, ring).run(stop);
    require(radar.closes == 1 && input.closes == 1 && output.closes == 1,
        "partial driver startup did not close each driver exactly once");
}

void test_interruptible_wait() {
    std::atomic<bool> stop{false};
    std::jthread request_stop([&] {
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
        stop.store(true);
    });
    const auto start = std::chrono::steady_clock::now();
    require(config::wait_or_stop(0xffffffffU, stop), "large wait ignored stop");
    require(std::chrono::steady_clock::now() - start < std::chrono::seconds(1),
        "large wait delayed shutdown");
}

void test_csv_failures(const Workspace& workspace) {
    const auto csv = workspace.path / "capture.csv";
    const auto spool = workspace.path / "capture.capture_spool.bin";
    CaptureFileWriter writer(csv.string(), (workspace.path / "capture.svg").string(), "", "");
    writer.initialize_csv(2, false);
    CapturePacket packet{.ch1 = {1, 2}, .ch2 = {3, 4}, .di1 = {}};
    auto invalid_packet = packet;
    invalid_packet.ch2.pop_back();
    expect_error([&] { writer.append_csv_packet(invalid_packet); });
    require(std::filesystem::file_size(spool) == 16, "invalid packet partially changed the spool");
    writer.append_csv_packet(packet);
    std::filesystem::remove(csv);
    std::filesystem::create_symlink("/dev/full", csv);
    expect_error([&] { writer.write({packet}, 1000, 10); });
    require(std::filesystem::file_size(spool) > 16, "failed CSV write deleted the recovery spool");
    std::filesystem::remove(csv);
    writer.write({packet}, 1000, 10);
    require(!std::filesystem::exists(spool), "successful CSV export retained the spool");
    std::ifstream csv_input(csv);
    const std::string csv_text((std::istreambuf_iterator<char>(csv_input)), {});
    require(csv_text.find("1.000000000,3.000000000") != std::string::npos,
        "CSV retry lost channel samples");
    writer.initialize_csv(2, false);
    std::ofstream(spool, std::ios::binary | std::ios::app).put('x');
    expect_error([&] { writer.write({}, 1000, 10); });
    require(std::filesystem::exists(spool), "truncated packet header deleted the spool");
    writer.initialize_csv(2, false);
    const std::array<std::uint64_t, 4> corrupt_packet{0, 2, 0xffffffffffffffffULL, 0};
    std::ofstream(spool, std::ios::binary | std::ios::app).write(
        reinterpret_cast<const char*>(corrupt_packet.data()), sizeof(corrupt_packet));
    expect_error([&] { writer.write({}, 1000, 10); });
    require(std::filesystem::exists(spool), "oversized packet count deleted the spool");
}

void test_asset_reload_preserves_data(const Workspace& workspace) {
    const auto save = [&](const char* name, float sample) {
        const auto path = workspace.path / name;
        const auto bytes = ipc::serialize_raw_collection({.traces = {
            {.frequency_hz = {1}, .s11 = {{sample, 0}}, .s21 = {{sample, 0}}}}});
        std::ofstream(path, std::ios::binary).write(
            reinterpret_cast<const char*>(bytes.data()), static_cast<std::streamsize>(bytes.size()));
        return path.string();
    };
    const auto open = save("open.bin", 1);
    const auto short_standard = save("short.bin", -1);
    const auto load = save("load.bin", 0);
    const auto nan = save("nan.bin", std::numeric_limits<float>::quiet_NaN());
    preprocessing::S21ReferenceBundle s21_reference;
    s21_reference.load(open);
    expect_error([&] { s21_reference.load(nan); });
    require(s21_reference.resolve({}).samples.front().re == 1, "failed S21 reload lost previous reference");
    preprocessing::S21CalibrationBundle s21_calibration;
    s21_calibration.load(open);
    expect_error([&] { s21_calibration.load(nan); });
    require(s21_calibration.is_enabled(), "failed S21 reload disabled previous calibration");
    preprocessing::S11ReferenceBundle s11_reference;
    s11_reference.load(open);
    expect_error([&] { s11_reference.load(nan); });
    require(s11_reference.resolve({}).samples.front().re == 1, "failed S11 reload lost previous reference");
    preprocessing::S11CalibrationBundle s11_calibration;
    s11_calibration.load(open, short_standard, load);
    expect_error([&] { s11_calibration.load(open, open, load); });
    const std::array<float, 1> axis{1};
    require(s11_calibration.apply({}, axis, {{0.5, 0}}).front().re == 0.5F,
        "failed OSL reload lost previous calibration");
}

void test_locator_packet_errors() {
    int sockets[2]{};
    require(::socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) == 0, "socketpair failed");
    std::atomic<double> speed{0};
    std::atomic<std::int64_t> at_ns{0};
    locator::ClientSession client(sockets[0], "regression", 2, 1024);
    client.start(speed, at_ns);
    const auto send_json = [&](const std::string& json) {
        std::vector<std::uint8_t> bytes(8 + json.size());
        write_u32(bytes, 4, static_cast<std::uint32_t>(json.size()));
        std::memcpy(bytes.data() + 8, json.data(), json.size());
        const auto sent = ::send(sockets[1], bytes.data(), bytes.size(), MSG_NOSIGNAL);
        if (sent != static_cast<ssize_t>(bytes.size())) {
            throw std::runtime_error(std::string("send test packet failed: ") + std::strerror(errno));
        }
    };
    send_json("{\"vlc\":1e400}");
    send_json("{\"vlc\":1e308}");
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    require(at_ns.load() == 0 && speed.load() == 0, "invalid socket speed reached the processor");
    send_json("{\"vlc\":3.5}");
    const auto deadline = std::chrono::steady_clock::now() + std::chrono::seconds(2);
    while (at_ns.load() == 0 && std::chrono::steady_clock::now() < deadline) {
        std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
    require(speed.load() == 3.5 && at_ns.load() > 0, "locator stopped after oversized JSON number");
    client.request_stop();
    client.join();
    ::close(sockets[1]);
    require(client.has_exited(), "locator session did not finish both loops");
    locator::LocatorServerConfig config{.host = "127.0.0.1", .port = 0};
    locator::TcpServer server(config);
    for (unsigned iteration = 0; iteration < 30; ++iteration) { server.start(); server.stop(); }
}

void test_unread_tty_shutdown(const Workspace& workspace) {
    TtyProtocolWriter writer((workspace.path / "tty").string(), 160'000);
    const std::vector<std::uint16_t> words(80'000, 42);
    writer.enqueue_encoded_frames(words.data(), words.size() / 4U);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    const auto start = std::chrono::steady_clock::now();
    writer.shutdown();
    require(std::chrono::steady_clock::now() - start < std::chrono::seconds(1),
        "unread tty blocked shutdown");
    writer.shutdown();
}

}  // namespace

int main(int argc, char** argv) {
    try {
        require(argc == 2, "Pass the simulator config fixture path");
        Workspace workspace;
        test_wire_decoders();
        test_configuration(argv[1], workspace);
        test_asset_reload_preserves_data(workspace);
        test_ring();
        test_partial_driver_open();
        test_interruptible_wait();
        test_csv_failures(workspace);
        test_locator_packet_errors();
        test_unread_tty_shutdown(workspace);
        std::cout << "native regressions passed (10,000 decoder mutations; 20,000 concurrent ring frames)\n";
    } catch (const std::exception& error) {
        std::cerr << "native regression failed: " << error.what() << '\n';
        return 1;
    }
}