import asyncio
import logging
import os
import pwd
import secrets
from datetime import datetime, timedelta
from functools import lru_cache
from pathlib import Path

from defence360agent.utils import atomic_rewrite
from defence360agent.wordpress.utils import (
    ensure_site_data_directory,
    format_php_with_embedded_json,
    write_plugin_data_file_atomically,
)

logger = logging.getLogger(__name__)

DEFAULT_TOKEN_EXPIRATION = timedelta(hours=72)
JWT_SECRET_PATH = "/etc/imunify-agent-proxy/jwt-secret"
JWT_SECRET_PATH_OLD = "/etc/imunify-agent-proxy/jwt-secret.old"
PROXY_SERVICE_NAME = "imunify-agent-proxy"
SECRET_EXPIRATION_TTL = timedelta(days=7)


def is_secret_expired():
    try:
        stat = os.stat(JWT_SECRET_PATH)
    except FileNotFoundError:
        st_mtime = 0.0
    else:
        st_mtime = stat.st_mtime
    # NOTE: timedelta(days=7).seconds == 0 (the .seconds attribute only holds
    # the sub-day component; .days holds the rest). Use .total_seconds() so
    # the 7-day TTL is honored.
    return (
        datetime.now().timestamp() - st_mtime
        > SECRET_EXPIRATION_TTL.total_seconds()
    )


async def rotate_secret():
    """Rotate the proxy JWT secret on disk: backup current to .old and
    write a fresh 32-byte secret atomically. Invalidates the in-process
    cache so subsequent generate_token() calls read the new secret.
    """
    secret_path = Path(JWT_SECRET_PATH)
    try:
        logger.info("Rotating proxy auth secret")
        stub_secret = secrets.token_bytes(32)
        secret_path.parent.mkdir(mode=0o700, parents=True, exist_ok=True)
        secret_path.touch(mode=0o600)
        atomic_rewrite(
            secret_path,
            stub_secret,
            uid=-1,
            backup=str(JWT_SECRET_PATH_OLD),
            permissions=0o600,
        )
        load_secret_from_file.cache_clear()
    except Exception as e:
        logger.error(
            "Got error while rotating the secret: %s", e, exc_info=True
        )


@lru_cache(1)
def load_secret_from_file() -> bytes:
    """Load JWT secret from the configured file path."""
    try:
        with open(JWT_SECRET_PATH, "rb") as f:
            return f.read().strip()
    except FileNotFoundError:
        logger.error("JWT secret file not found at %s", JWT_SECRET_PATH)
        raise
    except Exception as e:
        logger.error("Failed to read JWT secret: %s", e)
        raise


def generate_token(username: str, docroot: str) -> str:
    """
    Generate a JWT token for the given username and docroots.

    Args:
        username: The username for the token
        docroot: document root paths the user has access to

    Returns:
        The JWT token string
    """
    exp_time = datetime.utcnow() + DEFAULT_TOKEN_EXPIRATION

    claims = {"exp": exp_time, "username": username, "site_path": docroot}

    try:
        # jwt package is a heavy dependency (relying on native libraries)
        # that is not needed in all execution paths.
        # in order to save some RAM, jwt is only imporded when it's actually needed.
        import jwt

        token = jwt.encode(claims, load_secret_from_file(), algorithm="HS256")
        return token
    except Exception as e:
        logger.error("Failed to generate JWT token: %s", e)
        raise


async def create_auth_php_file(site, token: str, uid, gid: int) -> None:
    """
    Create the auth.php file in the site's imunify-security directory.

    Args:
        site: WPSite instance
        token: JWT token string
        uid, gid: int used for file creation
    """
    try:
        # Get user_info to pass to ensure_site_data_directory
        user_info = pwd.getpwuid(uid)

        # Ensure data directory exists with protection (this also ensures directory listing protection)
        data_dir = await ensure_site_data_directory(site, user_info)

        auth_file_path = data_dir / "auth.php"

        # Use helper function to format PHP with embedded JSON
        auth_data = {"token": token}
        php_content = format_php_with_embedded_json(auth_data)

        # Run the file write operation in a thread pool
        await asyncio.to_thread(
            write_plugin_data_file_atomically,
            auth_file_path,
            php_content,
            uid,
            gid,
        )

        logger.info(
            "Created auth.php file for site %s at %s", site, auth_file_path
        )

    except Exception as e:
        logger.error("Failed to create auth.php file for site %s: %s", site, e)
        raise


async def setup_site_authentication(
    site, user_info: pwd.struct_passwd
) -> None:
    """
    Set up authentication for a site by creating JWT token and auth.php file.

    Args:
        site: WPSite instance
        user_info: pwd.struct_passwd data
    """
    try:
        token = generate_token(user_info.pw_name, str(site.docroot))

        await create_auth_php_file(
            site, token, user_info.pw_uid, user_info.pw_gid
        )
        logger.info("Successfully set up authentication for site %s", site)
    except Exception as e:
        logger.error(
            "Failed to set up authentication for site %s: %s", site, e
        )
        raise
