import base64
from queue import LifoQueue
from urllib.request import Request, urlopen


class TaosConnection:
    def __init__(self, base_url, username, password, timeout=10):
        self.base_url = base_url
        self.username = username or ""
        self.password = password or ""
        self.timeout = timeout

    def execute(self, sql):
        auth = f"{self.username}:{self.password}"
        auth_header = base64.b64encode(auth.encode("utf-8")).decode("ascii")
        req = Request(
            url=f"{self.base_url}/rest/sql",
            data=sql.encode("utf-8"),
            headers={
                "Authorization": f"Basic {auth_header}",
                "Content-Type": "text/plain",
            },
            method="POST",
        )
        with urlopen(req, timeout=self.timeout) as resp:
            body = resp.read().decode("utf-8", errors="replace")
            if resp.status != 200:
                raise RuntimeError(f"HTTP {resp.status} {body}")
            return body


class TaosConnectionPool:
    def __init__(self, base_url, username, password, pool_size=2, timeout=10):
        self.base_url = base_url
        self.username = username
        self.password = password
        self.pool_size = max(int(pool_size or 1), 1)
        self.timeout = timeout
        self._pool = LifoQueue(maxsize=self.pool_size)
        for _ in range(self.pool_size):
            self._pool.put(TaosConnection(base_url, username, password, timeout=timeout))

    def execute(self, sql):
        conn = self._pool.get()
        try:
            return conn.execute(sql)
        finally:
            self._pool.put(conn)


def create_taos_pool(config):
    if not config.enabled:
        return None
    return TaosConnectionPool(
        config.base_url,
        config.username,
        config.password,
        pool_size=config.pool_size,
        timeout=config.timeout,
    )