"""Utility to reset development Postgres schema artifacts.

This script drops managed tables and enum types created by `scripts.init_db`.
It is intended for local development only; it refuses to run if CALMINER_ENV
indicates production or staging. The operation is idempotent: missing objects
are ignored. Use with caution.
"""
from __future__ import annotations

import logging
import os
from dataclasses import dataclass
from typing import Iterable

from sqlalchemy import text
from sqlalchemy.engine import Engine

from config.database import DATABASE_URL
from scripts.init_db import ENUM_DEFINITIONS, _create_engine

logger = logging.getLogger(__name__)


@dataclass(slots=True)
class ResetOptions:
    drop_tables: bool = True
    drop_enums: bool = True


MANAGED_TABLES: tuple[str, ...] = (
    "simulation_parameters",
    "financial_inputs",
    "scenarios",
    "projects",
    "pricing_impurity_settings",
    "pricing_metal_settings",
    "pricing_settings",
    "user_roles",
    "users",
    "roles",
)


FORBIDDEN_ENVIRONMENTS: set[str] = {"production", "staging", "prod", "stage"}


def _ensure_safe_environment() -> None:
    env = os.getenv("CALMINER_ENV", "development").lower()
    if env in FORBIDDEN_ENVIRONMENTS:
        raise RuntimeError(
            f"Refusing to reset database in environment '{env}'. "
            "Set CALMINER_ENV to 'development' to proceed."
        )


def _drop_tables(engine: Engine, tables: Iterable[str]) -> None:
    if not tables:
        return
    with engine.begin() as conn:
        for table in tables:
            logger.info("Dropping table if exists: %s", table)
            conn.execute(text(f"DROP TABLE IF EXISTS {table} CASCADE"))


def _drop_enums(engine: Engine, enum_names: Iterable[str]) -> None:
    if not enum_names:
        return
    with engine.begin() as conn:
        for enum_name in enum_names:
            logger.info("Dropping enum type if exists: %s", enum_name)
            conn.execute(text(f"DROP TYPE IF EXISTS {enum_name} CASCADE"))


def reset_database(*, options: ResetOptions | None = None, database_url: str | None = None) -> None:
    """Drop managed tables and enums for a clean slate."""
    _ensure_safe_environment()
    opts = options or ResetOptions()
    engine = _create_engine(database_url or DATABASE_URL)

    if opts.drop_tables:
        _drop_tables(engine, MANAGED_TABLES)

    if opts.drop_enums:
        _drop_enums(engine, ENUM_DEFINITIONS.keys())

    logger.info("Database reset complete")


if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)
    reset_database()