from __future__ import annotations

import os
from collections.abc import Mapping
from dataclasses import dataclass

DEFAULT_POLL_INTERVAL_SECONDS = 0.25
DEFAULT_WAIT_TIMEOUT_SECONDS = 10.0
DEFAULT_WORKFLOW_DB_PATH = "workflows/workflows.sqlite3"

POLL_INTERVAL_ENV = "WORKFLOW_POLL_INTERVAL_SECONDS"
WAIT_TIMEOUT_ENV = "WORKFLOW_WAIT_TIMEOUT_SECONDS"
DB_PATH_ENV = "WORKFLOW_DB_PATH"


@dataclass(frozen=True)
class WorkflowConfig:
    poll_interval_seconds: float = DEFAULT_POLL_INTERVAL_SECONDS
    wait_timeout_seconds: float = DEFAULT_WAIT_TIMEOUT_SECONDS
    db_path: str = DEFAULT_WORKFLOW_DB_PATH


def load_config(env: Mapping[str, str] | None = None) -> WorkflowConfig:
    values = env or os.environ
    return WorkflowConfig(
        poll_interval_seconds=_parse_float(
            values.get(POLL_INTERVAL_ENV),
            default=DEFAULT_POLL_INTERVAL_SECONDS,
        ),
        wait_timeout_seconds=_parse_float(
            values.get(WAIT_TIMEOUT_ENV),
            default=DEFAULT_WAIT_TIMEOUT_SECONDS,
        ),
        db_path=values.get(DB_PATH_ENV) or DEFAULT_WORKFLOW_DB_PATH,
    )


def _parse_float(value: str | None, *, default: float) -> float:
    if value is None:
        return default
    try:
        parsed = float(value)
    except ValueError:
        return default
    return parsed if parsed >= 0 else default