"""Flaky test tool — deterministic fail-once-then-succeed behavior.

Used exclusively for testing retry logic (goal: "test retry execution").

Behavior:
  Attempt 1: flag file does NOT exist → creates flag → returns FAILED
             (failure_class: execution_error → eligible for 1 retry)
  Attempt 2: flag file EXISTS → removes flag → returns DONE

The flag file is workspace/.flaky_test_flag.
It is always cleaned up on the second attempt, so repeated test runs work correctly.

Edge case: if the run is aborted between attempt 1 and attempt 2, the flag file
will persist. The next run will then succeed on attempt 1 (no retry exercised).
To reset: delete agent/workspace/.flaky_test_flag manually.
"""
from __future__ import annotations

from pathlib import Path

from core.state import PlanStep, StepResult, StepStatus

# parents: [0]=tools, [1]=runtime, [2]=agent → agent/workspace
_WORKSPACE_ROOT: Path = Path(__file__).resolve().parents[2] / "workspace"
_FLAG: Path = _WORKSPACE_ROOT / ".flaky_test_flag"


def run_flaky(step: PlanStep) -> StepResult:
    """Fail on first call, succeed on second (flag-based)."""
    _WORKSPACE_ROOT.mkdir(parents=True, exist_ok=True)

    if _FLAG.exists():
        # Second call: cleanup flag, succeed
        _FLAG.unlink()
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.DONE,
            output_text="flaky step succeeded on retry (flag removed)",
        )
    else:
        # First call: create flag, fail with execution_error prefix for classifier
        _FLAG.touch()
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.FAILED,
            error="execution_error: simulated transient failure on attempt 1",
        )