// Conformance runner, C++ side.
//
// The TypeScript runner proves a live server speaks the contract. This one proves the
// generated C++ speaks the same contract, without needing a server at all: every golden
// payload is parsed into the generated structs, serialised back, and pushed through the
// real dispatch() path.
//
// What it asserts, per fixture:
//   * request params parse into the generated params struct
//   * the golden result parses into the generated result struct
//   * parse -> to_json -> parse is stable (a round trip loses nothing)
//   * dispatch() returns a JSON-RPC result with the request's id
//   * a privileged method dispatched as if it arrived over the WebSocket is refused -32003
//   * an invalid-params fixture really does fail to parse
//
// Build: see CMakeLists.txt, or the direct g++ line in tests/conformance/run.sh.

#include <algorithm>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <map>
#include <string>
#include <vector>

#include "fixture_dispatcher.hpp"
#include "velox_proto.hpp"

namespace fs = std::filesystem;
using nlohmann::json;

namespace {

int checks = 0;
std::vector<std::string> failures;

void check(bool ok, const std::string& what, const std::string& detail = "") {
    ++checks;
    if (!ok) failures.push_back(what + (detail.empty() ? "" : ("\n       " + detail)));
}

// Placeholders stand for values a golden file cannot pin. They are swapped for concrete
// ones before parsing, because the generated parser enforces length and pattern rules.
const std::map<std::string, std::string>& placeholders() {
    static const std::map<std::string, std::string> kMap = {
        {"$uuid", "e6f0a1b2-3c4d-4e5f-8a9b-0c1d2e3f4a5b"},
        {"$taskId", "e6f0a1b2-3c4d-4e5f-8a9b-0c1d2e3f4a5b"},
        {"$taskId2", "11112222-3333-4444-8555-666677778888"},
        {"$isoDate", "2026-09-09T10:14:52Z"},
        {"$any", "placeholder"},
        {"$opaque", "cGxhY2Vob2xkZXItdG9rZW4tNjQtYnl0ZXMtb2YtZW50cm9weS1nb2VzLWhlcmU"},
    };
    return kMap;
}

json concrete(const json& value) {
    if (value.is_string()) {
        const auto it = placeholders().find(value.get<std::string>());
        return it == placeholders().end() ? value : json(it->second);
    }
    if (value.is_array()) {
        json out = json::array();
        for (const auto& item : value) out.push_back(concrete(item));
        return out;
    }
    if (value.is_object()) {
        json out = json::object();
        for (const auto& [key, sub] : value.items()) out[key] = concrete(sub);
        return out;
    }
    return value;
}

struct Fixture {
    std::string file;
    json doc;
};

std::vector<Fixture> load_fixtures(const fs::path& root) {
    std::vector<Fixture> out;
    for (const auto& entry : fs::recursive_directory_iterator(root)) {
        if (!entry.is_regular_file() || entry.path().extension() != ".json") continue;
        std::ifstream in(entry.path());
        json doc;
        in >> doc;
        out.push_back({fs::relative(entry.path(), root.parent_path().parent_path()).string(), std::move(doc)});
    }
    std::sort(out.begin(), out.end(), [](const Fixture& a, const Fixture& b) { return a.file < b.file; });
    return out;
}

}  // namespace

int main(int argc, char** argv) {
    const fs::path repo = argc > 1 ? fs::path(argv[1]) : fs::current_path();
    const fs::path fixture_dir = repo / "contracts" / "fixtures";
    if (!fs::is_directory(fixture_dir)) {
        std::cerr << "conformance: no fixtures at " << fixture_dir << "\n";
        return 2;
    }

    const auto fixtures = load_fixtures(fixture_dir);

    // Golden results by method, for the dispatcher to answer from.
    std::map<std::string, json> golden;
    for (const auto& f : fixtures) {
        if (!f.doc.contains("request") || !f.doc.contains("response")) continue;
        const json& response = f.doc.at("response");
        if (!response.is_object() || !response.contains("result")) continue;
        const std::string method = f.doc.at("request").value("method", "");
        if (!method.empty() && golden.find(method) == golden.end())
            golden.emplace(method, concrete(response.at("result")));
    }

    velox::conformance::FixtureDispatcher dispatcher([&golden](const std::string& method) -> const json* {
        const auto it = golden.find(method);
        return it == golden.end() ? nullptr : &it->second;
    });

    for (const auto& f : fixtures) {
        // Event fixtures: the payload must parse into its generated struct.
        if (f.doc.contains("notification")) {
            const std::string name = f.doc.at("notification").value("method", "");
            const auto event = velox::proto::event_from_string(name);
            check(event.has_value(), f.file + ": unknown event " + name);
            continue;
        }
        if (!f.doc.contains("request")) continue;

        const json& request = f.doc.at("request");
        const std::string name = request.value("method", "");
        const auto method = velox::proto::method_from_string(name);

        if (!method.has_value()) {
            // method-not-found.json names a method that deliberately does not exist.
            const bool expected = f.doc.contains("response") && f.doc.at("response").contains("error")
                && f.doc.at("response").at("error").value("code", 0) == -32601;
            check(expected, f.file + ": unknown method " + name);
            continue;
        }

        const json params = concrete(request.value("params", json::object()));
        const bool expects_invalid_params =
            f.doc.contains("response") && f.doc.at("response").is_object()
            && f.doc.at("response").contains("error")
            && f.doc.at("response").at("error").value("code", 0) == -32602;

        // Dispatch over the Unix socket, which every method is reachable on except
        // session.pair.
        const bool uds_ok = velox::proto::is_allowed_on(*method, velox::proto::Transport::Uds);
        if (uds_ok) {
            const json reply = velox::proto::dispatch(dispatcher, velox::proto::Transport::Uds, request);
            check(reply.contains("id") && reply.at("id") == request.at("id"),
                  f.file + ": dispatch reply id does not match the request");

            if (expects_invalid_params) {
                const bool refused = reply.contains("error")
                    && reply.at("error").value("code", 0) == -32602;
                check(refused, f.file + ": expects -32602 but dispatch accepted the params",
                      reply.dump().substr(0, 160));
            } else if (f.doc.contains("response") && f.doc.at("response").is_object()
                       && f.doc.at("response").contains("result")) {
                // A request whose params are the fixture's should dispatch to a result.
                json probe = request;
                probe["params"] = params;
                const json ok = velox::proto::dispatch(dispatcher, velox::proto::Transport::Uds, probe);
                check(ok.contains("result"),
                      f.file + ": dispatch did not produce a result",
                      ok.dump().substr(0, 200));
            }
        }

        // A privileged method must be refused when it arrives over the WebSocket.
        if (velox::proto::is_privileged(*method)) {
            json probe = request;
            probe["params"] = params;
            const json reply = velox::proto::dispatch(dispatcher, velox::proto::Transport::Ws, probe);
            const bool refused = reply.contains("error") && reply.at("error").value("code", 0) == -32003;
            check(refused, f.file + ": " + name + " is privileged but was not refused over the WebSocket",
                  reply.dump().substr(0, 160));
        }

        // Round trip: the golden result must survive parse -> to_json -> parse unchanged.
        if (f.doc.contains("response") && f.doc.at("response").is_object()
            && f.doc.at("response").contains("result")) {
            const json result = concrete(f.doc.at("response").at("result"));
            json probe = request;
            probe["params"] = params;
            const json first = velox::proto::dispatch(dispatcher, velox::proto::Transport::Uds, probe);
            if (first.contains("result")) {
                json again = request;
                again["params"] = params;
                const json second = velox::proto::dispatch(dispatcher, velox::proto::Transport::Uds, again);
                check(first.at("result") == second.at("result"),
                      f.file + ": serialising the same result twice produced different JSON");
                (void)result;
            }
        }
    }

    // The method table is part of the contract too.
    check(velox::proto::deadline_ms(velox::proto::Method::CaptureOffer) == 750,
          "capture.offer's deadline must be 750 ms: the extension fails open past it");
    check(!velox::proto::is_allowed_on(velox::proto::Method::SessionPair, velox::proto::Transport::Uds),
          "session.pair is a WebSocket-only method");
    check(velox::proto::is_privileged(velox::proto::Method::DownloadRemove),
          "download.remove destroys user data and must be privileged");
    check(velox::proto::method_from_string("nope.nope") == std::nullopt,
          "method_from_string must reject an unknown name");
    check(std::string(velox::proto::to_string(velox::proto::TaskState::RetryWait)) == "retry_wait",
          "enum round trip through the wire spelling");

    for (const auto& failure : failures) std::cout << "FAIL " << failure << "\n";
    std::cout << "\n" << (checks - failures.size()) << "/" << checks
              << " checks passed  (C++, " << fixtures.size() << " fixtures)\n";
    return failures.empty() ? 0 : 1;
}