"""Library for interacting with Control Web Panel

.. data:: cwp.HAS_CWP:

    Whether CWP is installed
    *(bool)*

.. data:: cwp.MYSQL_SOCK:

    MySQL socket path
    *(str)*
"""
import os
from pathlib import Path
import pwd
from typing import Literal, Union, overload
import pymysql
from pymysql.cursors import Cursor

HAS_CWP = (
    not Path('/usr/local/cpanel/cpsrvd').is_file()
    and Path('/usr/local/cwpsrv/bin/cwpsrv').is_file()
)
if Path('/etc/redhat-release').exists():
    MYSQL_SOCK = '/var/lib/mysql/mysql.sock'
else:
    MYSQL_SOCK = '/run/mysqld/mysqld.sock'


def all_domains(user: str) -> set[str]:
    """Get all domains for a CWP user

    Args:
        user (str): CWP username
    Raises:
        pymysql.Error: any issue querying the root_cwp database
    Returns:
        set[str]: domain names for this user (primary + domains + subdomains)
    """
    assert HAS_CWP
    sql = """SELECT `domain` FROM `user` WHERE `username`=%s
    UNION SELECT `domain` FROM `domains` WHERE `user`=%s
    UNION SELECT CONCAT(`subdomain`, '.', `domain`)
    FROM subdomains WHERE user=%s"""
    args = (user, user, user)
    with root_cwp() as conn, conn.cursor() as cur:
        cur: Cursor
        cur.execute(sql, args)
        return {x[0] for x in cur.fetchall()}


def get_docroots(user: str) -> dict[str, str]:
    """Get site document roots for a CWP user

    Args:
        user (str): CWP username
    Raises:
        pymysql.Error: any issue querying the root_cwp database
        KeyError: if the requested user does not exist
    Returns:
        dict[str, str]: domains and document root paths
    """
    assert HAS_CWP
    public_html = os.path.join(pwd.getpwnam(user).pw_dir, 'public_html')
    sql = """SELECT `domain`, NULL FROM `user` WHERE `username`=%s
    UNION SELECT `domain`, `path` FROM `domains` WHERE `user`=%s
    UNION SELECT CONCAT(`subdomain`, '.', `domain`), `path`
    FROM subdomains WHERE user=%s"""
    args = (user, user, user)
    docroots = {}
    with root_cwp() as conn, conn.cursor() as cur:
        cur: Cursor
        cur.execute(sql, args)
        rows = cur.fetchall()
    for row in rows:
        dom, path = row
        if path is None:
            # path is NOT NULL in the subdomain and domains schemas, so this
            # NULL from the primary domain in the user table
            docroots[dom] = public_html
        else:
            docroots[dom] = path
    return docroots


@overload
def all_users(owners: Literal[False] = False) -> list[str]:
    ...


@overload
def all_users(owners: Literal[True] = True) -> dict[str, str]:
    ...


def all_users(owners: bool = False) -> Union[dict[str, str], list[str]]:
    """Returns CWP users

    Args:
        owners: whether to return users as a dict with owners as the values
    Raises:
        pymysql.Error: any issue querying the root_cwp database
    Returns:
        either a list of all users, or a dict of users (keys) to owners (vals)
    """
    with root_cwp() as conn, conn.cursor() as cur:
        cur: Cursor
        cur.execute('SELECT username, reseller FROM user')
        data = dict(cur.fetchall())
        if owners:
            return {
                user: owner if owner in data else 'root'
                for user, owner in data.items()
                if user != 'root'
            }
        return [x for x in data if x != 'root']


def root_cwp(**kwargs) -> pymysql.Connection:
    """Open and return a MySQL connection to the root_cwp database

    Returns:
        pymysql.Connection: Connection to the root_cwp database
    """
    return pymysql.connect(
        database='root_cwp',
        read_default_file='/root/.my.cnf',
        unix_socket=MYSQL_SOCK,
        **kwargs,
    )


def vmail_paths(user: str, check_exists: bool = False) -> list[Path]:
    """Get /etc/vmail/{domain} paths for a user

    Args:
        user (str): CWP username
        check_exists (bool): if True, only return paths that exist. Paths are
            only created when there's at least one email account for that domain
    Raises:
        pymysql.Error: any issue querying the root_cwp database
    Returns:
        list[Path]: path objects for each vmail directory
    """
    paths = []
    for domain in all_domains(user):
        if domain.startswith('..') or domain.startswith('/'):
            # Shouldn't ever happen - .. and / are not valid in domains.
            # Check anyways in case of malicious injection.
            raise ValueError(f"{domain=}")
        path = Path('/var/vmail', domain)
        if not check_exists or path.exists():
            paths.append(path)
    return paths