import os
import tempfile


def _is_writable(path: str) -> bool:
    try:
        if not os.path.exists(path):
            os.makedirs(path, exist_ok=True)
        test_fd, test_path = tempfile.mkstemp(prefix='.wtest_', dir=path)
        os.close(test_fd)
        os.unlink(test_path)
        return True
    except Exception:
        return False


def _detect_data_dir() -> str:
    # 1) Respect DATA_DIR env only if writable
    env = os.getenv('DATA_DIR')
    if env and _is_writable(env):
        return env
    # 2) Prefer /data if writable (Spaces)
    if _is_writable('/data'):
        return '/data'
    # 3) Local dev fallback: /app/data if writable
    if _is_writable('/app/data'):
        return '/app/data'
    # 4) Final fallback: /tmp
    return '/tmp'


DATA_DIR = _detect_data_dir()

# Logs: prefer DATA_DIR/logs, fallback to /tmp/logs
_preferred_logs = os.getenv('LOG_DIR') or os.path.join(DATA_DIR, 'logs')
try:
    os.makedirs(_preferred_logs, exist_ok=True)
    # sanity: try to write
    if not _is_writable(_preferred_logs):
        raise PermissionError("Log dir not writable")
except Exception:
    _preferred_logs = '/tmp/logs'
    os.makedirs(_preferred_logs, exist_ok=True)

LOG_DIR = _preferred_logs

# Path for scheduler's last_run marker
def _compute_last_run_path(base_dir: str) -> str:
    candidates = [
        os.path.join(base_dir, 'deployment', 'last_run.txt'),
        os.path.join(base_dir, 'last_run.txt'),
        '/tmp/last_run.txt',
    ]
    for p in candidates:
        try:
            os.makedirs(os.path.dirname(p), exist_ok=True)
            # test write
            with open(p, 'a'):
                pass
            return p
        except Exception:
            continue
    return '/tmp/last_run.txt'


LAST_RUN_PATH = _compute_last_run_path(DATA_DIR)