# imports
import os
import random
import threading

import pytest  # used for our unit tests
from sentry_sdk.metrics import MetricsAggregator


# unit tests
def test_basic_functionality():
    """Test ensuring the thread when it is not already running."""
    aggregator = MetricsAggregator(lambda x: None)
    assert aggregator._ensure_thread() is True
    assert aggregator._flusher is not None
    assert aggregator._flusher_pid == os.getpid()

def test_thread_already_running():
    """Test ensuring the thread when it is already running in the same process."""
    aggregator = MetricsAggregator(lambda x: None)
    aggregator._ensure_thread()  # Start the thread
    flusher_pid = aggregator._flusher_pid
    assert aggregator._ensure_thread() is True
    assert aggregator._flusher_pid == flusher_pid

def test_concurrent_calls():
    """Test handling concurrent calls to _ensure_thread."""
    aggregator = MetricsAggregator(lambda x: None)

    def ensure_thread():
        assert aggregator._ensure_thread() is True

    threads = [threading.Thread(target=ensure_thread) for _ in range(10)]
    for thread in threads:
        thread.start()
    for thread in threads:
        thread.join()

    assert aggregator._flusher is not None
    assert aggregator._flusher_pid == os.getpid()

def test_after_process_fork(monkeypatch):
    """Test ensuring the thread after a process fork."""
    aggregator = MetricsAggregator(lambda x: None)
    aggregator._ensure_thread()  # Start the thread
    original_pid = aggregator._flusher_pid

    # Simulate a fork by changing the PID
    new_pid = original_pid + 1
    monkeypatch.setattr(os, 'getpid', lambda: new_pid)

    assert aggregator._ensure_thread() is True
    assert aggregator._flusher_pid == new_pid

def test_runtime_error(monkeypatch):
    """Test handling RuntimeError when starting the thread."""
    aggregator = MetricsAggregator(lambda x: None)

    def mock_start():
        raise RuntimeError

    monkeypatch.setattr(threading.Thread, 'start', mock_start)

    assert aggregator._ensure_thread() is False
    assert aggregator._running is False

def test_aggregator_not_running():
    """Test ensuring the thread when the aggregator is not running."""
    aggregator = MetricsAggregator(lambda x: None)
    aggregator._running = False
    assert aggregator._ensure_thread() is False

def test_large_scale():
    """Test performance and scalability with large data samples."""
    aggregator = MetricsAggregator(lambda x: None)

    for _ in range(1000):
        assert aggregator._ensure_thread() is True

    assert aggregator._flusher is not None
    assert aggregator._flusher_pid == os.getpid()

def test_lock_usage(monkeypatch):
    """Test ensuring that the lock is properly used."""
    aggregator = MetricsAggregator(lambda x: None)
    lock_acquired = False

    def mock_acquire():
        nonlocal lock_acquired
        lock_acquired = True

    monkeypatch.setattr(aggregator._lock, 'acquire', mock_acquire)
    aggregator._ensure_thread()
    assert lock_acquired is True

def test_daemon_thread():
    """Test ensuring the thread is set as a daemon."""
    aggregator = MetricsAggregator(lambda x: None)
    aggregator._ensure_thread()
    assert aggregator._flusher.daemon is True

def test_multiple_calls_consistency():
    """Test consistency across multiple calls."""
    aggregator = MetricsAggregator(lambda x: None)
    for _ in range(10):
        assert aggregator._ensure_thread() is True

    assert aggregator._flusher is not None
    assert aggregator._flusher_pid == os.getpid()

def test_side_effects():
    """Test verifying side effects of the function."""
    aggregator = MetricsAggregator(lambda x: None)
    assert aggregator._ensure_thread() is True
    assert aggregator._flusher is not None
    assert aggregator._flusher_pid == os.getpid()
    assert aggregator._running is True

def test_integration_with_flush_loop():
    """Test integration with the _flush_loop method."""
    aggregator = MetricsAggregator(lambda x: None)
    aggregator._ensure_thread()
    assert aggregator._flusher is not None
    assert aggregator._flusher_pid == os.getpid()