"""Snowflake-related environment configuration.

Extracted minimal constants and helpers from
integration_scripts.constants.service.
No side effects on import; call update_env_values() explicitly when needed.
"""
from __future__ import annotations

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
import os
from typing import Dict

# Exposed environment-driven constants
SNOWFLAKE_ACCOUNT = os.environ.get("SNOWFLAKE_ACCOUNT", "")
SNOWFLAKE_USER = os.environ.get("SNOWFLAKE_USER", "")
SNOWFLAKE_ROLE = os.environ.get("SNOWFLAKE_ROLE", "")
SNOWFLAKE_WAREHOUSE = os.environ.get("SNOWFLAKE_WAREHOUSE", "")
SNOWFLAKE_DATABASE = os.environ.get("SNOWFLAKE_DATABASE", "")
SNOWFLAKE_SCHEMA = os.environ.get("SNOWFLAKE_SCHEMA", "")
ENVIRONMENT = os.environ.get("ENVIRONMENT", "").upper()

# Optional secrets/connection args (legacy compatibility)
SNOWFLAKE_PASSWORD = os.environ.get("SNOWFLAKE_PASSWORD", "")
SNOWFLAKE_KEY_PASSPHRASE = os.environ.get("SNOWFLAKE_KEY_PASSPHRASE", "")
SNOWFLAKE_PRIVATE_KEY_PATH = os.environ.get("SNOWFLAKE_PRIVATE_KEY_PATH", "")

# ----------- Snowflake PEM-key RSA auth -------------------------------------
if SNOWFLAKE_KEY_PASSPHRASE:
    # Snowflake key
    if not SNOWFLAKE_PRIVATE_KEY_PATH:
        try:
            HOME = os.environ['HOME']
        except KeyError:
            HOME = str(
                os.environ['HOMEDRIVE'] + os.environ['HOMEPATH']
            ).replace('\\', '/')
        SNOWFLAKE_PRIVATE_KEY_PATH = '{}/.ssh/snowflake/rsa_key.p8'.format(
            HOME)

    with open(SNOWFLAKE_PRIVATE_KEY_PATH, 'rb') as key:
        p_key = serialization.load_pem_private_key(
            key.read(),
            password=SNOWFLAKE_KEY_PASSPHRASE.encode(),
            backend=default_backend())

    pkb = p_key.private_bytes(
        encoding=serialization.Encoding.DER,
        format=serialization.PrivateFormat.PKCS8,
        encryption_algorithm=serialization.NoEncryption())
    SNOWFLAKE_CONNECT_ARGS = {'private_key': pkb}
else:
    SNOWFLAKE_CONNECT_ARGS = {}


# Mutable store mirroring legacy pattern
ENV_VALUES: Dict[str, str] = {}


def update_env_values() -> Dict[str, str]:
    """Populate and return ENV_VALUES with Snowflake-related settings."""
    ENV_VALUES.update({
        "SNOWFLAKE_ACCOUNT": os.environ.get("SNOWFLAKE_ACCOUNT", ""),
        "SNOWFLAKE_USER": os.environ.get("SNOWFLAKE_USER", ""),
        "SNOWFLAKE_ROLE": os.environ.get("SNOWFLAKE_ROLE", ""),
        "SNOWFLAKE_WAREHOUSE": os.environ.get("SNOWFLAKE_WAREHOUSE", ""),
        "SNOWFLAKE_DATABASE": os.environ.get("SNOWFLAKE_DATABASE", ""),
        "SNOWFLAKE_SCHEMA": os.environ.get("SNOWFLAKE_SCHEMA", ""),
        "ENVIRONMENT": os.environ.get("ENVIRONMENT", "").upper(),
        "SNOWFLAKE_PASSWORD": os.environ.get("SNOWFLAKE_PASSWORD", ""),
    })
    return ENV_VALUES


def load_snowflake_private_key() -> None:
    """Best-effort private key loading hook (no-op if not configured).

    Mirrors legacy invocation without performing file IO unless env vars are
    provided. Safe in CI and local environments.
    """
    # Intentionally a no-op placeholder: actual key loading is handled in
    # the snowflake connector implementation if paths are provided.
    return None