"""Opt-in durable startup breadcrumbs, outside evaluated episode timings."""
import faulthandler
import json
import os
from pathlib import Path
import signal
import tempfile
import time
import traceback


_states = {}
_fault_handler_installed = False


def _enable_fault_handler():
    """Let the parent request all Python stacks before terminating a hang."""
    global _fault_handler_installed
    if not _fault_handler_installed:
        faulthandler.enable(all_threads=True)
        faulthandler.register(signal.SIGUSR1, all_threads=True)
        _fault_handler_installed = True


def emit_startup(output, phase, startup_complete=False, **details):
    """Persist a startup phase for the external supervisor, when enabled."""
    if os.environ.get('EVAL_STARTUP_DIAGNOSTICS') != '1':
        return
    _enable_fault_handler()
    output = Path(output)
    state = {**details, 'phase': phase, 'startup_complete': bool(startup_complete),
             'timestamp': time.time(), 'monotonic': time.monotonic(), 'pid': os.getpid()}
    output.mkdir(parents=True, exist_ok=True)
    serialized = json.dumps(state, ensure_ascii=False, default=str) + '\n'
    # An event may survive even if the node fails before the state replacement.
    with (output / 'startup_events.jsonl').open('a') as stream:
        stream.write(serialized)
        stream.flush()
        os.fsync(stream.fileno())
    temporary = None
    try:
        with tempfile.NamedTemporaryFile(mode='w', prefix='.startup_state.',
                                         suffix='.tmp', dir=output, delete=False) as stream:
            temporary = Path(stream.name)
            stream.write(serialized)
            stream.flush()
            os.fsync(stream.fileno())
        os.replace(temporary, output / 'startup_state.json')
        temporary = None
        directory = os.open(output, os.O_RDONLY | os.O_DIRECTORY)
        try:
            os.fsync(directory)
        finally:
            os.close(directory)
    finally:
        if temporary is not None:
            temporary.unlink(missing_ok=True)
    _states[str(output.resolve())] = state
    print(json.dumps({'event': 'startup_phase', **state}, ensure_ascii=False, default=str), flush=True)


def record_startup_failure(output, error):
    """Record early import/construction failures without relabeling rollout errors."""
    if os.environ.get('EVAL_STARTUP_DIAGNOSTICS') != '1':
        return
    previous = _states.get(str(Path(output).resolve()), {})
    if previous.get('startup_complete'):
        return
    emit_startup(output, 'startup_failed', failed_phase=previous.get('phase'),
                 error_type=type(error).__name__, error=str(error),
                 traceback=traceback.format_exc())