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

// Discovery across processes: an app's Registration writes its record
// (readable by its user only) and holds the lock while it lives, and
// ListInstances lists it. An app killed with SIGKILL, which never runs its
// destructor, leaves its files behind with the lock free, and the next
// listing removes them instead of offering a dead instance; one that ends
// normally removes its own. Pids cannot tell this apart: every `flatpak run`
// sandbox has its own pid namespace. Also checks the generated build info.
#include <signal.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
import std;
import Crafter.Debug.Core;
using namespace Crafter::Debug;
namespace fs = std::filesystem;

namespace {
    std::int32_t failures = 0;

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

    std::uint32_t Mode(const fs::path& path) {
        struct stat info {};
        ::stat(path.c_str(), &info);
        return info.st_mode & 0777;
    }
}

int main() {
    const fs::path dir = fs::temp_directory_path() / "crafter-debug-ShouldDiscoverLiveInstances";
    fs::remove_all(dir);
    ::setenv("CRAFTER_DEBUG_DIR", dir.c_str(), 1);

    std::optional<Registration> one;
    one.emplace(InstanceRecord{ .name = "one", .port = 4100, .token = "secret", .protocol = protocolVersion });
    const std::vector<Instance> first = ListInstances();
    Check(first.size() == 1 && first[0].record.name == "one" && first[0].record.port == 4100 && first[0].record.token == "secret", "a registered instance is listed");
    Check(first.size() == 1 && first[0].record.pid == ::getpid() && !first[0].record.instanceId.empty() && first[0].record.exe.ends_with("ShouldDiscoverLiveInstances"),
          "the record carries the pid, an instance id and the executable");
    Check(Mode(dir) == 0700 && first.size() == 1 && Mode(first[0].recordPath) == 0600, "the directory and record are its user's only");
    if (fs::exists("/.flatpak-info")) {
        Check(!one->Record().flatpakInstance.empty() && one->Record().hostInitPid > 0, "inside a Flatpak, the sandbox's instance id and host init pid are recorded");
    }

    std::array<std::int32_t, 2> ready{};
    ::pipe(ready.data());
    const ::pid_t child = ::fork();
    if (child == 0) {
        ::close(ready[0]);
        Registration two(InstanceRecord{ .name = "two" });
        const char signal = 'r';
        (void)::write(ready[1], &signal, 1);
        while (true) ::pause();
    }
    ::close(ready[1]);
    char signal = 0;
    (void)::read(ready[0], &signal, 1);
    const std::vector<Instance> both = ListInstances();
    Check(both.size() == 2, std::format("two live instances are listed ({})", both.size()));
    fs::path twoRecord;
    for (const Instance& instance : both) {
        if (instance.record.name == "two") twoRecord = instance.recordPath;
    }

    ::kill(child, SIGKILL);
    ::waitpid(child, nullptr, 0);
    Check(fs::exists(twoRecord), "a killed instance leaves its record behind");
    const std::vector<Instance> afterKill = ListInstances();
    Check(afterKill.size() == 1 && afterKill[0].record.name == "one", "the next listing leaves out the killed instance");
    Check(!fs::exists(twoRecord) && !fs::exists(fs::path(twoRecord).replace_extension(".lock")), "and removes its files");

    one.reset();
    Check(ListInstances().empty() && fs::is_empty(dir), "an instance that ends removes its own files");

    Check(Detail::SourceId().size() == 16, std::format("the build has a source id ({})", Detail::SourceId()));
    Check(Detail::ClientPath().ends_with("/crafter-debug"), std::format("the build knows its client ({})", Detail::ClientPath()));

    fs::remove_all(dir);
    return failures == 0 ? 0 : 1;
}