// Live PTY smoke test: drives the real nocal binary through interactive
// views and verifies the terminal state (alternate screen, cursor) is
// restored on exit. Usage: tui-pty-smoke /path/to/nocal

#include <pty.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <poll.h>
#include <unistd.h>

#include <chrono>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>
#include <string_view>

namespace {

int failures = 0;

void check(const bool condition, const std::string_view message)
{
    if (!condition) {
        ++failures;
        std::cerr << "FAIL: " << message << '\n';
    }
}

class PtySession {
public:
    PtySession(const char* binary, const char* home)
    {
        struct winsize size {};
        size.ws_col = 100;
        size.ws_row = 30;
        int master = -1;
        const pid_t child = ::forkpty(&master, nullptr, nullptr, &size);
        if (child < 0) {
            std::cerr << "forkpty failed: " << std::strerror(errno) << '\n';
            std::exit(2);
        }
        if (child == 0) {
            ::setenv("HOME", home, 1);
            ::setenv("XDG_DATA_HOME", home, 1);
            ::execl(binary, "nocal", "--demo", static_cast<char*>(nullptr));
            std::cerr << "exec failed: " << std::strerror(errno) << '\n';
            _exit(127);
        }
        master_ = master;
        child_ = child;
    }

    ~PtySession()
    {
        if (master_ >= 0) ::close(master_);
        if (child_ > 0 && !reaped_) {
            ::kill(child_, SIGKILL);
            ::waitpid(child_, nullptr, 0);
        }
    }

    [[nodiscard]] bool wait_for(const std::string_view needle,
                                const std::chrono::milliseconds timeout)
    {
        const auto deadline = std::chrono::steady_clock::now() + timeout;
        while (std::chrono::steady_clock::now() < deadline) {
            if (capture_.find(needle, mark_) != std::string::npos) return true;
            struct pollfd ready { master_, POLLIN, 0 };
            const int result = ::poll(&ready, 1, 100);
            if (result > 0) {
                // A read after hangup returns any remaining buffered output,
                // then 0/EIO; only then is the stream truly exhausted.
                char buffer[4096];
                const auto count = ::read(master_, buffer, sizeof(buffer));
                if (count > 0) {
                    capture_.append(buffer, static_cast<std::size_t>(count));
                    continue;
                }
                return capture_.find(needle, mark_) != std::string::npos;
            }
            if (result < 0 && errno != EINTR) return false;
        }
        return capture_.find(needle, mark_) != std::string::npos;
    }

    void send(const std::string_view keys)
    {
        mark_ = capture_.size();
        const auto written = ::write(master_, keys.data(), keys.size());
        check(written == static_cast<ssize_t>(keys.size()), "pty write completed");
    }

    [[nodiscard]] bool exited_cleanly(const std::chrono::milliseconds timeout)
    {
        const auto deadline = std::chrono::steady_clock::now() + timeout;
        while (std::chrono::steady_clock::now() < deadline) {
            int status = 0;
            const auto done = ::waitpid(child_, &status, WNOHANG);
            if (done == child_) {
                reaped_ = true;
                exit_status_ = status;
                // Drain whatever the child wrote while exiting.
                static_cast<void>(wait_for("\x1b[?1049l", std::chrono::milliseconds{500}));
                return WIFEXITED(status) && WEXITSTATUS(status) == 0;
            }
            ::usleep(50'000);
        }
        return false;
    }

    [[nodiscard]] const std::string& capture() const { return capture_; }

private:
    int master_{-1};
    pid_t child_{-1};
    bool reaped_{false};
    int exit_status_{0};
    std::string capture_;
    std::size_t mark_{0};
};

void test_interactive_views(const char* binary, const char* home)
{
    PtySession session{binary, home};
    check(session.wait_for("\x1b[?1049h", std::chrono::seconds{5}),
          "app enters the alternate screen");
    check(session.wait_for("Monday", std::chrono::seconds{5}),
          "month grid renders in the pty");

    session.send("?");
    check(session.wait_for("KEYBOARD SHORTCUTS", std::chrono::seconds{5}),
          "? opens the keyboard shortcut help");
    session.send("\x1b");
    check(session.wait_for("Monday", std::chrono::seconds{5}),
          "Esc returns from help to the month grid");

    session.send("g");
    check(session.wait_for("AGENDA", std::chrono::seconds{5}), "g opens the agenda");
    session.send("\x1b");
    check(session.wait_for("Monday", std::chrono::seconds{5}), "Esc closes the agenda");

    session.send("/");
    check(session.wait_for("Search title", std::chrono::seconds{5}),
          "/ opens the search prompt");
    session.send("\x1b");
    check(session.wait_for("Monday", std::chrono::seconds{5}), "Esc cancels search");

    session.send("q");
    check(session.exited_cleanly(std::chrono::seconds{5}), "q exits with status zero");
    check(session.capture().find("\x1b[?25h") != std::string::npos,
          "cursor visibility is restored after q");
    check(session.capture().find("\x1b[?1049l") != std::string::npos,
          "alternate screen is restored after q");
}

void test_ctrl_c_unwind(const char* binary, const char* home)
{
    const int before = failures;
    PtySession session{binary, home};
    check(session.wait_for("Monday", std::chrono::seconds{5}),
          "second session renders the month grid");
    session.send("\x03");
    check(session.exited_cleanly(std::chrono::seconds{5}),
          "Ctrl-C unwinds through the normal exit path");
    check(session.capture().find("\x1b[?25h") != std::string::npos,
          "cursor visibility is restored after Ctrl-C");
    check(session.capture().find("\x1b[?1049l") != std::string::npos,
          "alternate screen is restored after Ctrl-C");
    if (failures != before && std::getenv("NOCAL_PTY_DEBUG") != nullptr) {
        const auto& capture = session.capture();
        std::cerr << "--- ctrl-c capture tail ---\n"
                  << capture.substr(capture.size() > 2000 ? capture.size() - 2000 : 0)
                  << "\n--- end capture ---\n";
    }
}

} // namespace

int main(const int argc, char** argv)
{
    if (argc != 2) {
        std::cerr << "usage: tui-pty-smoke /path/to/nocal\n";
        return 2;
    }
    char home_template[] = "/tmp/nocal-pty-home.XXXXXX";
    const char* home = ::mkdtemp(home_template);
    if (home == nullptr) {
        std::cerr << "mkdtemp failed: " << std::strerror(errno) << '\n';
        return 2;
    }

    test_interactive_views(argv[1], home);
    test_ctrl_c_unwind(argv[1], home);

    if (failures != 0) {
        std::cerr << failures << " PTY smoke check(s) failed\n";
        return EXIT_FAILURE;
    }
    std::cout << "PTY smoke passed\n";
    return EXIT_SUCCESS;
}