"""Tests for --subprocesses subprocess profiling support."""

import argparse
import io
import os
import signal
import subprocess
import sys
import tempfile
import threading
import time
import unittest
from unittest.mock import MagicMock, patch

from test.support import (
    SHORT_TIMEOUT,
    reap_children,
    requires_remote_subprocess_debugging,
)

# Guard imports that require _remote_debugging module.
# This module is not available on all platforms (e.g., WASI).
try:
    from profiling.sampling._child_monitor import (
        get_child_pids,
        ChildProcessMonitor,
        is_python_process,
        _MAX_CHILD_PROFILERS,
        _CLEANUP_INTERVAL_CYCLES,
    )
except ImportError:
    # Module will be skipped via @requires_remote_subprocess_debugging decorators
    get_child_pids = None
    ChildProcessMonitor = None
    is_python_process = None
    _MAX_CHILD_PROFILERS = None
    _CLEANUP_INTERVAL_CYCLES = None

try:
    from profiling.sampling.cli import (
        _add_sampling_options,
        _validate_args,
        _build_child_profiler_args,
        _build_output_pattern,
        _setup_child_monitor,
    )
except ImportError:
    # cli module imports sample module which requires _remote_debugging
    _add_sampling_options = None
    _validate_args = None
    _build_child_profiler_args = None
    _build_output_pattern = None
    _setup_child_monitor = None

from .helpers import _cleanup_process

# String to check for in stderr when profiler lacks permissions (e.g., macOS)
_PERMISSION_ERROR_MSG = "Permission Error"


def _readline_with_timeout(file_obj, timeout):
    # Thread-based readline with timeout - works across all platforms
    # including Windows where select() doesn't work with pipes.
    # Returns the line read, or None if timeout occurred.
    result = [None]
    exception = [None]

    def reader():
        try:
            result[0] = file_obj.readline()
        except Exception as e:
            exception[0] = e

    thread = threading.Thread(target=reader, daemon=True)
    thread.start()
    thread.join(timeout=timeout)

    if thread.is_alive():
        return None

    if exception[0] is not None:
        raise exception[0]

    return result[0]


def _wait_for_process_ready(proc, timeout):
    # Wait for a subprocess to be ready using polling instead of fixed sleep.
    # Returns True if process is ready, False if it exited or timeout.
    deadline = time.time() + timeout
    poll_interval = 0.01

    while time.time() < deadline:
        if proc.poll() is not None:
            return False

        try:
            if sys.platform == "linux":
                if os.path.exists(f"/proc/{proc.pid}/exe"):
                    return True
            else:
                return True
        except OSError:
            pass

        time.sleep(poll_interval)
        poll_interval = min(poll_interval * 2, 0.1)

    return proc.poll() is None


@unittest.skipIf(
    _build_child_profiler_args is None,
    "profiling.sampling.cli unavailable",
)
class TestChildProfilerArgBuilder(unittest.TestCase):
    """Tests for child profiler CLI argument construction."""

    def test_build_child_profiler_args_diff_flamegraph(self):
        """Test child args use the real --diff-flamegraph flag."""
        args = argparse.Namespace(
            sample_interval_usec=1000,
            duration=None,
            all_threads=False,
            realtime_stats=False,
            native=False,
            gc=True,
            opcodes=False,
            async_aware=False,
            mode="wall",
            format="diff_flamegraph",
            diff_baseline="baseline.bin",
        )

        child_args = _build_child_profiler_args(args)

        self.assertIn("--diff-flamegraph", child_args)
        self.assertNotIn("--diff_flamegraph", child_args)

        flag_index = child_args.index("--diff-flamegraph")
        self.assertGreater(len(child_args), flag_index + 1)
        self.assertEqual(child_args[flag_index + 1], "baseline.bin")


@requires_remote_subprocess_debugging()
class TestGetChildPids(unittest.TestCase):
    """Tests for the get_child_pids function."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_get_child_pids_from_remote_debugging(self):
        """Test get_child_pids from _remote_debugging module."""
        try:
            import _remote_debugging

            # Test that the function exists
            self.assertTrue(hasattr(_remote_debugging, "get_child_pids"))

            # Test with current process (should return empty or have children if any)
            result = _remote_debugging.get_child_pids(os.getpid())
            self.assertIsInstance(result, list)
        except (ImportError, AttributeError):
            self.skipTest("_remote_debugging.get_child_pids not available")

    def test_get_child_pids_fallback(self):
        """Test the fallback implementation for get_child_pids."""
        # Test with current process
        result = get_child_pids(os.getpid())
        self.assertIsInstance(result, list)

    @unittest.skipUnless(sys.platform == "linux", "Linux only")
    def test_discover_child_process_linux(self):
        """Test that we can discover child processes on Linux."""
        # Create a child process
        proc = subprocess.Popen(
            [sys.executable, "-c", "import time; time.sleep(10)"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        try:
            # Poll until child appears
            deadline = time.time() + SHORT_TIMEOUT
            children = []
            while time.time() < deadline:
                children = get_child_pids(os.getpid())
                if proc.pid in children:
                    break
                time.sleep(0.05)

            self.assertIn(
                proc.pid,
                children,
                f"Child PID {proc.pid} not discovered within {SHORT_TIMEOUT}s. "
                f"Found PIDs: {children}",
            )
        finally:
            _cleanup_process(proc)

    def test_recursive_child_discovery(self):
        """Test that recursive=True finds grandchildren."""
        # Create a child that spawns a grandchild and keeps a reference to it
        # so we can clean it up via the child process
        code = """
import subprocess
import sys
import threading
grandchild = subprocess.Popen([sys.executable, '-c', 'import time; time.sleep(60)'])
print(grandchild.pid, flush=True)
# Wait for parent to send signal byte (cross-platform)
# Using threading with timeout so test doesn't hang if something goes wrong
# Timeout is 60s (2x test timeout) to ensure child outlives test in worst case
def wait_for_signal():
    try:
        sys.stdin.buffer.read(1)
    except:
        pass
t = threading.Thread(target=wait_for_signal, daemon=True)
t.start()
t.join(timeout=60)
# Clean up grandchild before exiting
if grandchild.poll() is None:
    grandchild.terminate()
    try:
        grandchild.wait(timeout=2)
    except subprocess.TimeoutExpired:
        grandchild.kill()
        try:
            grandchild.wait(timeout=2)
        except subprocess.TimeoutExpired:
            grandchild.wait()
"""
        proc = subprocess.Popen(
            [sys.executable, "-c", code],
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.DEVNULL,
        )

        grandchild_pid = None
        try:
            # Read grandchild PID with thread-based timeout
            # This prevents indefinite blocking on all platforms
            grandchild_pid_line = _readline_with_timeout(
                proc.stdout, SHORT_TIMEOUT
            )
            if grandchild_pid_line is None:
                self.fail(
                    f"Timeout waiting for grandchild PID from child process "
                    f"(child PID: {proc.pid})"
                )
            if not grandchild_pid_line:
                self.fail(
                    f"Child process {proc.pid} closed stdout without printing "
                    f"grandchild PID"
                )
            grandchild_pid = int(grandchild_pid_line.strip())

            # Poll until grandchild is visible
            deadline = time.time() + SHORT_TIMEOUT
            pids_recursive = []
            while time.time() < deadline:
                pids_recursive = get_child_pids(os.getpid(), recursive=True)
                if grandchild_pid in pids_recursive:
                    break
                time.sleep(0.05)

            self.assertIn(
                proc.pid,
                pids_recursive,
                f"Child PID {proc.pid} not found in recursive discovery. "
                f"Found: {pids_recursive}",
            )
            self.assertIn(
                grandchild_pid,
                pids_recursive,
                f"Grandchild PID {grandchild_pid} not found in recursive discovery. "
                f"Found: {pids_recursive}",
            )

            # Non-recursive should find only direct child
            pids_direct = get_child_pids(os.getpid(), recursive=False)
            self.assertIn(
                proc.pid,
                pids_direct,
                f"Child PID {proc.pid} not found in non-recursive discovery. "
                f"Found: {pids_direct}",
            )
            self.assertNotIn(
                grandchild_pid,
                pids_direct,
                f"Grandchild PID {grandchild_pid} should NOT be in non-recursive "
                f"discovery. Found: {pids_direct}",
            )
        finally:
            # Send signal byte to child to trigger cleanup, then close stdin
            try:
                proc.stdin.write(b"x")
                proc.stdin.flush()
                proc.stdin.close()
            except OSError:
                pass
            proc.stdout.close()
            _cleanup_process(proc)
            # The grandchild may not have been cleaned up by the child process
            # (e.g., if the child was killed). Explicitly terminate the
            # grandchild to prevent PermissionError on Windows when removing
            # temp directories.
            if grandchild_pid is not None:
                try:
                    os.kill(grandchild_pid, signal.SIGTERM)
                except (OSError, ProcessLookupError):
                    pass  # Process already exited

    def test_nonexistent_pid_returns_empty(self):
        """Test that nonexistent PID returns empty list."""
        # Use a very high PID that's unlikely to exist
        result = get_child_pids(999999999)
        self.assertEqual(result, [])


@requires_remote_subprocess_debugging()
class TestChildProcessMonitor(unittest.TestCase):
    """Tests for the ChildProcessMonitor class."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_monitor_creation(self):
        """Test that ChildProcessMonitor can be created."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(),
            cli_args=["-r", "10khz", "-d", "5"],
            output_pattern="test_{pid}.pstats",
        )
        self.assertEqual(monitor.parent_pid, os.getpid())
        self.assertEqual(monitor.cli_args, ["-r", "10khz", "-d", "5"])
        self.assertEqual(monitor.output_pattern, "test_{pid}.pstats")

    def test_monitor_lifecycle(self):
        """Test monitor lifecycle via context manager."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        )

        # Before entering context, thread should not exist
        self.assertIsNone(monitor._monitor_thread)

        with monitor:
            # Inside context, thread should be running
            self.assertIsNotNone(monitor._monitor_thread)
            self.assertTrue(monitor._monitor_thread.is_alive())

        # After exiting context, thread should be stopped
        self.assertFalse(monitor._monitor_thread.is_alive())

    def test_spawned_profilers_property(self):
        """Test that spawned_profilers returns a copy of the list."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        )

        # Should return empty list initially
        profilers = monitor.spawned_profilers
        self.assertEqual(profilers, [])
        self.assertIsNot(profilers, monitor._spawned_profilers)

    def test_context_manager(self):
        """Test that ChildProcessMonitor works as a context manager."""
        with ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        ) as monitor:
            self.assertIsNotNone(monitor._monitor_thread)
            self.assertTrue(monitor._monitor_thread.is_alive())

        # After exiting context, thread should be stopped
        self.assertFalse(monitor._monitor_thread.is_alive())


@requires_remote_subprocess_debugging()
class TestCLIChildrenFlag(unittest.TestCase):
    """Tests for the --subprocesses CLI flag."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_subprocesses_flag_parsed(self):
        """Test that --subprocesses flag is recognized."""
        parser = argparse.ArgumentParser()
        _add_sampling_options(parser)

        # Parse with --subprocesses
        args = parser.parse_args(["--subprocesses"])
        self.assertTrue(args.subprocesses)

        # Parse without --subprocesses
        args = parser.parse_args([])
        self.assertFalse(args.subprocesses)

    def test_subprocesses_incompatible_with_live(self):
        """Test that --subprocesses is incompatible with --live."""
        # Create mock args with both subprocesses and live
        args = argparse.Namespace(
            subprocesses=True,
            live=True,
            async_aware=False,
            format="pstats",
            mode="wall",
            sort=None,
            limit=None,
            no_summary=False,
            opcodes=False,
            blocking=False,
            interval=1000,
        )

        parser = argparse.ArgumentParser()

        with self.assertRaises(SystemExit):
            _validate_args(args, parser)

    def test_build_child_profiler_args(self):
        """Test building CLI args for child profilers."""
        args = argparse.Namespace(
            sample_interval_usec=200,
            duration=15,
            all_threads=True,
            realtime_stats=False,
            native=True,
            gc=True,
            opcodes=False,
            async_aware=False,
            mode="cpu",
            format="flamegraph",
        )

        child_args = _build_child_profiler_args(args)

        # Verify flag-value pairs are correctly paired (flag followed by value)
        def assert_flag_value_pair(flag, value):
            self.assertIn(
                flag,
                child_args,
                f"Flag '{flag}' not found in args: {child_args}",
            )
            flag_index = child_args.index(flag)
            self.assertGreater(
                len(child_args),
                flag_index + 1,
                f"No value after flag '{flag}' in args: {child_args}",
            )
            self.assertEqual(
                child_args[flag_index + 1],
                str(value),
                f"Flag '{flag}' should be followed by '{value}', got "
                f"'{child_args[flag_index + 1]}' in args: {child_args}",
            )

        assert_flag_value_pair("-r", 5000)
        assert_flag_value_pair("-d", 15)
        assert_flag_value_pair("--mode", "cpu")

        # Verify standalone flags are present
        self.assertIn(
            "-a", child_args, f"Flag '-a' not found in args: {child_args}"
        )
        self.assertIn(
            "--native",
            child_args,
            f"Flag '--native' not found in args: {child_args}",
        )
        self.assertIn(
            "--flamegraph",
            child_args,
            f"Flag '--flamegraph' not found in args: {child_args}",
        )
        self.assertNotIn(
            "--browser",
            child_args,
            f"Flag '--browser' should not be in child args: {child_args}",
        )

    def test_build_child_profiler_args_no_gc(self):
        """Test building CLI args with --no-gc."""
        args = argparse.Namespace(
            sample_interval_usec=100,
            duration=5,
            all_threads=False,
            realtime_stats=False,
            native=False,
            gc=False,  # Explicitly disabled
            opcodes=False,
            async_aware=False,
            mode="wall",
            format="pstats",
        )

        child_args = _build_child_profiler_args(args)

        self.assertIn(
            "--no-gc",
            child_args,
            f"Flag '--no-gc' not found when gc=False. Args: {child_args}",
        )

    def test_build_output_pattern_with_outfile(self):
        """Test output pattern generation with user-specified output."""
        # With extension
        args = argparse.Namespace(outfile="output.html", format="flamegraph")
        pattern = _build_output_pattern(args)
        self.assertEqual(pattern, "output_{pid}.html")

        # Without extension
        args = argparse.Namespace(outfile="output", format="pstats")
        pattern = _build_output_pattern(args)
        self.assertEqual(pattern, "output_{pid}")

    def test_build_output_pattern_default(self):
        """Test output pattern generation with default output."""
        # Flamegraph format
        args = argparse.Namespace(outfile=None, format="flamegraph")
        pattern = _build_output_pattern(args)
        self.assertIn("{pid}", pattern)
        self.assertIn("flamegraph", pattern)
        self.assertTrue(pattern.endswith(".html"))

        # Heatmap format
        args = argparse.Namespace(outfile=None, format="heatmap")
        pattern = _build_output_pattern(args)
        self.assertEqual(pattern, "heatmap_{pid}")


@requires_remote_subprocess_debugging()
class TestChildrenIntegration(unittest.TestCase):
    """Integration tests for --subprocesses functionality."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_setup_child_monitor(self):
        """Test setting up a child monitor from args."""
        args = argparse.Namespace(
            sample_interval_usec=100,
            duration=5,
            all_threads=False,
            realtime_stats=False,
            native=False,
            gc=True,
            opcodes=False,
            async_aware=False,
            mode="wall",
            format="pstats",
            outfile=None,
        )

        monitor = _setup_child_monitor(args, os.getpid())
        # Use addCleanup to ensure monitor is properly cleaned up even if
        # assertions fail
        self.addCleanup(monitor.__exit__, None, None, None)

        self.assertIsNotNone(monitor)
        self.assertEqual(
            monitor.parent_pid,
            os.getpid(),
            f"Monitor parent_pid should be {os.getpid()}, got {monitor.parent_pid}",
        )


@requires_remote_subprocess_debugging()
class TestIsPythonProcess(unittest.TestCase):
    """Tests for the is_python_process function."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_is_python_process_current_process(self):
        """Test that current process is detected as Python."""
        # Current process should be Python
        result = is_python_process(os.getpid())
        self.assertTrue(
            result,
            f"Current process (PID {os.getpid()}) should be detected as Python",
        )

    def test_is_python_process_python_subprocess(self):
        """Test that a Python subprocess is detected as Python."""
        # Start a Python subprocess
        proc = subprocess.Popen(
            [sys.executable, "-c", "import time; time.sleep(10)"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        try:
            # Poll until Python runtime structures are initialized
            # (is_python_process probes for runtime structures which take
            # time to initialize after process start)
            deadline = time.time() + SHORT_TIMEOUT
            detected = False
            while time.time() < deadline:
                if proc.poll() is not None:
                    self.fail(f"Process {proc.pid} exited unexpectedly")
                if is_python_process(proc.pid):
                    detected = True
                    break
                time.sleep(0.05)

            self.assertTrue(
                detected,
                f"Python subprocess (PID {proc.pid}) should be detected as Python "
                f"within {SHORT_TIMEOUT}s",
            )
        finally:
            _cleanup_process(proc)

    @unittest.skipUnless(sys.platform == "linux", "Linux only test")
    def test_is_python_process_non_python_subprocess(self):
        """Test that a non-Python subprocess is not detected as Python."""
        # Start a non-Python subprocess (sleep command)
        proc = subprocess.Popen(
            ["sleep", "10"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        try:
            # Wait for process to be ready using polling
            self.assertTrue(
                _wait_for_process_ready(proc, SHORT_TIMEOUT),
                f"Process {proc.pid} should be ready within {SHORT_TIMEOUT}s",
            )

            self.assertFalse(
                is_python_process(proc.pid),
                f"Non-Python subprocess 'sleep' (PID {proc.pid}) should NOT be "
                f"detected as Python",
            )
        finally:
            _cleanup_process(proc)

    def test_is_python_process_nonexistent_pid(self):
        """Test that nonexistent PID returns False."""
        # Use a very high PID that's unlikely to exist
        result = is_python_process(999999999)
        self.assertFalse(
            result,
            "Nonexistent PID 999999999 should return False",
        )

    def test_is_python_process_exited_process(self):
        """Test handling of a process that exits quickly."""
        # Start a process that exits immediately
        proc = subprocess.Popen(
            [sys.executable, "-c", "pass"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        # Wait for it to exit
        proc.wait(timeout=SHORT_TIMEOUT)

        # Should return False for exited process (not raise)
        result = is_python_process(proc.pid)
        self.assertFalse(
            result, f"Exited process (PID {proc.pid}) should return False"
        )


@requires_remote_subprocess_debugging()
class TestMaxChildProfilersLimit(unittest.TestCase):
    """Tests for the _MAX_CHILD_PROFILERS limit."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_max_profilers_constant_exists(self):
        """Test that _MAX_CHILD_PROFILERS constant is defined."""
        self.assertEqual(
            _MAX_CHILD_PROFILERS,
            100,
            f"_MAX_CHILD_PROFILERS should be 100, got {_MAX_CHILD_PROFILERS}",
        )

    def test_cleanup_interval_constant_exists(self):
        """Test that _CLEANUP_INTERVAL_CYCLES constant is defined."""
        self.assertEqual(
            _CLEANUP_INTERVAL_CYCLES,
            10,
            f"_CLEANUP_INTERVAL_CYCLES should be 10, got {_CLEANUP_INTERVAL_CYCLES}",
        )

    def test_monitor_respects_max_limit(self):
        """Test that monitor refuses to spawn more than _MAX_CHILD_PROFILERS."""
        # Create a monitor
        monitor = ChildProcessMonitor(
            pid=os.getpid(),
            cli_args=["-r", "10khz", "-d", "5"],
            output_pattern="test_{pid}.pstats",
        )

        # Manually fill up the profilers list to the limit
        mock_profilers = [MagicMock() for _ in range(_MAX_CHILD_PROFILERS)]
        for mock_proc in mock_profilers:
            mock_proc.poll.return_value = None  # Simulate running process
        monitor._spawned_profilers = mock_profilers

        # Try to spawn another profiler - should be rejected
        stderr_capture = io.StringIO()
        with patch("sys.stderr", stderr_capture):
            monitor._spawn_profiler_for_child(99999)

        # Verify warning was printed
        stderr_output = stderr_capture.getvalue()
        self.assertIn(
            "Max child profilers",
            stderr_output,
            f"Expected warning about max profilers, got: {stderr_output}",
        )
        self.assertIn(
            str(_MAX_CHILD_PROFILERS),
            stderr_output,
            f"Warning should mention limit ({_MAX_CHILD_PROFILERS}): {stderr_output}",
        )

        # Verify no new profiler was added
        self.assertEqual(
            len(monitor._spawned_profilers),
            _MAX_CHILD_PROFILERS,
            f"Should still have {_MAX_CHILD_PROFILERS} profilers, got "
            f"{len(monitor._spawned_profilers)}",
        )


@requires_remote_subprocess_debugging()
class TestWaitForProfilers(unittest.TestCase):
    """Tests for the wait_for_profilers method."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_wait_for_profilers_empty_list(self):
        """Test that wait_for_profilers returns immediately with no profilers."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        )

        # Should return immediately without printing anything
        stderr_capture = io.StringIO()
        with unittest.mock.patch("sys.stderr", stderr_capture):
            start = time.time()
            monitor.wait_for_profilers(timeout=10.0)
            elapsed = time.time() - start

        # Should complete very quickly (less than 1 second)
        self.assertLess(
            elapsed,
            1.0,
            f"wait_for_profilers with empty list took {elapsed:.2f}s, expected < 1s",
        )
        # No "Waiting for..." message should be printed
        self.assertNotIn(
            "Waiting for",
            stderr_capture.getvalue(),
            "Should not print waiting message when no profilers",
        )

    def test_wait_for_profilers_with_completed_process(self):
        """Test waiting for profilers that complete quickly."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        )

        # Start a process that exits quickly
        proc = subprocess.Popen(
            [sys.executable, "-c", "pass"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        # Add to spawned profilers
        monitor._spawned_profilers.append(proc)

        try:
            stderr_capture = io.StringIO()
            with unittest.mock.patch("sys.stderr", stderr_capture):
                start = time.time()
                monitor.wait_for_profilers(timeout=SHORT_TIMEOUT)
                elapsed = time.time() - start

            # Should complete quickly since process exits fast
            self.assertLess(
                elapsed,
                5.0,
                f"wait_for_profilers took {elapsed:.2f}s for quick process",
            )
            # Should print waiting message
            self.assertIn(
                "Waiting for 1 child profiler",
                stderr_capture.getvalue(),
                "Should print waiting message",
            )
        finally:
            _cleanup_process(proc)

    def test_wait_for_profilers_timeout(self):
        """Test that wait_for_profilers respects timeout."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        )

        # Start a process that runs for a long time
        proc = subprocess.Popen(
            [sys.executable, "-c", "import time; time.sleep(60)"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        # Add to spawned profilers
        monitor._spawned_profilers.append(proc)

        try:
            stderr_capture = io.StringIO()
            with unittest.mock.patch("sys.stderr", stderr_capture):
                start = time.time()
                # Use short timeout
                monitor.wait_for_profilers(timeout=0.5)
                elapsed = time.time() - start

            # Should timeout after approximately 0.5 seconds
            self.assertGreater(
                elapsed,
                0.4,
                f"wait_for_profilers returned too quickly ({elapsed:.2f}s)",
            )
            self.assertLess(
                elapsed,
                2.0,
                f"wait_for_profilers took too long ({elapsed:.2f}s), timeout not respected",
            )
        finally:
            _cleanup_process(proc)

    def test_wait_for_profilers_multiple(self):
        """Test waiting for multiple profilers."""
        monitor = ChildProcessMonitor(
            pid=os.getpid(), cli_args=[], output_pattern=None
        )

        # Start multiple processes
        procs = []
        for _ in range(3):
            proc = subprocess.Popen(
                [sys.executable, "-c", "import time; time.sleep(0.1)"],
                stdout=subprocess.DEVNULL,
                stderr=subprocess.DEVNULL,
            )
            procs.append(proc)
            monitor._spawned_profilers.append(proc)

        try:
            stderr_capture = io.StringIO()
            with unittest.mock.patch("sys.stderr", stderr_capture):
                monitor.wait_for_profilers(timeout=SHORT_TIMEOUT)

            # Should report correct count
            self.assertIn(
                "Waiting for 3 child profiler",
                stderr_capture.getvalue(),
                "Should report correct profiler count",
            )
        finally:
            for proc in procs:
                _cleanup_process(proc)


@requires_remote_subprocess_debugging()
class TestEndToEndChildrenCLI(unittest.TestCase):
    """End-to-end tests for --subprocesses CLI flag."""

    def setUp(self):
        reap_children()

    def tearDown(self):
        reap_children()

    def test_subprocesses_flag_spawns_child_and_creates_output(self):
        """Test that --subprocesses flag works end-to-end with actual subprocesses."""
        # Create a temporary directory for output files
        with tempfile.TemporaryDirectory() as tmpdir:
            # Create a script that spawns a child Python process
            parent_script = f"""
import subprocess
import sys
import time

# Spawn a child that does some work
child = subprocess.Popen([
    sys.executable, '-c',
    'import time; [i**2 for i in range(1000)]; time.sleep(2)'
])
# Do some work in parent
for i in range(1000):
    _ = i ** 2
time.sleep(2)
child.wait()
"""
            script_file = os.path.join(tmpdir, "parent_script.py")
            with open(script_file, "w") as f:
                f.write(parent_script)

            output_file = os.path.join(tmpdir, "profile.pstats")

            # Run the profiler with --subprocesses flag
            result = subprocess.run(
                [
                    sys.executable,
                    "-m",
                    "profiling.sampling",
                    "run",
                    "--subprocesses",
                    "-d",
                    "3",
                    "-r",
                    "100",
                    "-o",
                    output_file,
                    script_file,
                ],
                capture_output=True,
                text=True,
                timeout=SHORT_TIMEOUT,
            )

            # Check that parent output file was created
            self.assertTrue(
                os.path.exists(output_file),
                f"Parent profile output not created. "
                f"stdout: {result.stdout}, stderr: {result.stderr}",
            )

            # Check for child profiler output files (pattern: profile_{pid}.pstats)
            output_files = os.listdir(tmpdir)
            child_profiles = [
                f
                for f in output_files
                if f.startswith("profile_") and f.endswith(".pstats")
            ]

            # Note: Child profiling is best-effort; the child may exit before
            # profiler attaches, or the process may not be detected as Python.
            # We just verify the mechanism doesn't crash.
            if result.returncode != 0:
                self.fail(
                    f"Profiler exited with code {result.returncode}. "
                    f"stdout: {result.stdout}, stderr: {result.stderr}"
                )

    def test_subprocesses_flag_with_flamegraph_output(self):
        """Test --subprocesses with flamegraph output format."""
        with tempfile.TemporaryDirectory() as tmpdir:
            # Simple parent that spawns a child
            parent_script = f"""
import subprocess
import sys
import time
child = subprocess.Popen([sys.executable, '-c', 'import time; time.sleep(1)'])
time.sleep(1)
child.wait()
"""
            script_file = os.path.join(tmpdir, "parent.py")
            with open(script_file, "w") as f:
                f.write(parent_script)

            output_file = os.path.join(tmpdir, "flame.html")

            result = subprocess.run(
                [
                    sys.executable,
                    "-m",
                    "profiling.sampling",
                    "run",
                    "--subprocesses",
                    "-d",
                    "2",
                    "-r",
                    "100",
                    "--flamegraph",
                    "-o",
                    output_file,
                    script_file,
                ],
                capture_output=True,
                text=True,
                timeout=SHORT_TIMEOUT,
            )

            self.assertTrue(
                os.path.exists(output_file),
                f"Flamegraph output not created. stderr: {result.stderr}",
            )

            # Verify it's valid HTML
            with open(output_file, "r") as f:
                content = f.read()
                self.assertIn(
                    "<html",
                    content.lower(),
                    "Flamegraph output should be HTML",
                )

    def test_subprocesses_flag_no_crash_on_quick_child(self):
        """Test that --subprocesses doesn't crash when child exits quickly."""
        with tempfile.TemporaryDirectory() as tmpdir:
            # Parent spawns a child that exits immediately
            parent_script = f"""
import subprocess
import sys
import time
# Child exits immediately
child = subprocess.Popen([sys.executable, '-c', 'pass'])
child.wait()
time.sleep(1)
"""
            script_file = os.path.join(tmpdir, "parent.py")
            with open(script_file, "w") as f:
                f.write(parent_script)

            output_file = os.path.join(tmpdir, "profile.pstats")

            result = subprocess.run(
                [
                    sys.executable,
                    "-m",
                    "profiling.sampling",
                    "run",
                    "--subprocesses",
                    "-d",
                    "2",
                    "-r",
                    "100",
                    "-o",
                    output_file,
                    script_file,
                ],
                capture_output=True,
                text=True,
                timeout=SHORT_TIMEOUT,
            )

            # Should not crash - exit code 0
            self.assertEqual(
                result.returncode,
                0,
                f"Profiler crashed with quick-exit child. "
                f"stderr: {result.stderr}",
            )


if __name__ == "__main__":
    unittest.main()
