#include <xrpl/beast/core/CurrentThreadName.h>
#include <xrpl/beast/unit_test.h>

#include <boost/predef/os.h>

#include <thread>

namespace xrpl {
namespace test {

class CurrentThreadName_test : public beast::unit_test::suite
{
private:
    static void
    exerciseName(
        std::string myName,
        std::atomic<bool>* stop,
        std::atomic<int>* state)
    {
        // Verify that upon creation a thread has no name.
        auto const initialThreadName = beast::getCurrentThreadName();

        // Set the new name.
        beast::setCurrentThreadName(myName);

        // Indicate to caller that the name is set.
        *state = 1;

        // If there is an initial thread name then we failed.
        if (!initialThreadName.empty())
            return;

        // Wait until all threads have their names.
        while (!*stop)
            ;

        // Make sure the thread name that we set before is still there
        // (not overwritten by, for instance, another thread).
        if (beast::getCurrentThreadName() == myName)
            *state = 2;
    }
#if BOOST_OS_LINUX
    // Helper function to test a specific name.
    // It creates a thread, sets the name, and checks if the OS-level
    // name matches the expected (potentially truncated) name.
    void
    testName(std::string const& nameToSet, std::string const& expectedName)
    {
        std::thread t([&] {
            beast::setCurrentThreadName(nameToSet);

            // Initialize buffer to be safe.
            char actualName[beast::maxThreadNameLength + 1] = {};
            pthread_getname_np(pthread_self(), actualName, sizeof(actualName));

            BEAST_EXPECT(std::string(actualName) == expectedName);
        });
        t.join();
    }
#endif

public:
    void
    run() override
    {
        // Make two different threads with two different names.
        // Make sure that the expected thread names are still there
        // when the thread exits.
        {
            std::atomic<bool> stop{false};

            std::atomic<int> stateA{0};
            std::thread tA(exerciseName, "tA", &stop, &stateA);

            std::atomic<int> stateB{0};
            std::thread tB(exerciseName, "tB", &stop, &stateB);

            // Wait until both threads have set their names.
            while (stateA == 0 || stateB == 0)
                ;

            stop = true;
            tA.join();
            tB.join();

            // Both threads should still have the expected name when they exit.
            BEAST_EXPECT(stateA == 2);
            BEAST_EXPECT(stateB == 2);
        }
#if BOOST_OS_LINUX
        // On Linux, verify that thread names longer than 15 characters
        // are truncated to 15 characters (the 16th character is reserved for
        // the null terminator).
        {
            testName(
                "123456789012345",
                "123456789012345");  // 15 chars, no truncation
            testName(
                "1234567890123456", "123456789012345");  // 16 chars, truncated
            testName(
                "ThisIsAVeryLongThreadNameExceedingLimit",
                "ThisIsAVeryLong");      // 39 chars, truncated
            testName("", "");            // empty name
            testName("short", "short");  // short name, no truncation
        }
#endif
    }
};

BEAST_DEFINE_TESTSUITE(CurrentThreadName, beast, beast);

}  // namespace test
}  // namespace xrpl