"""Bring-your-own (BYO) custom proxy provider.

Reads one or more proxy endpoints from the shared env (``PROXY_URL`` and/or the
comma-separated ``PROXY_URLS``). With a single endpoint it behaves like a static
proxy; with a pool (>1) it rotates client-side via Scrapling's thread-safe
``ProxyRotator`` (cyclic), transparently to every caller of the zero-arg getters.

No vendor-specific auth assumptions: a user who wants a specific vendor points
``PROXY_URLS`` at that vendor's ``http://user:pass@host:port`` endpoints.
"""

import logging

from scrapling.engines.toolbelt import ProxyRotator

from app.config import Config
from app.utils.proxy.base import ProxyProvider

logger = logging.getLogger(__name__)


class CustomProxyProvider(ProxyProvider):
    """BYO provider for a single endpoint or a rotating pool of endpoints."""

    name = "custom"

    def __init__(self) -> None:
        self._urls = self._load_urls()
        # Only build a rotator for an actual pool; a single endpoint stays static.
        self._rotator = ProxyRotator(self._urls) if len(self._urls) > 1 else None
        if not self._urls:
            logger.warning(
                "PROXY_PROVIDER='custom' selected but neither PROXY_URL nor "
                "PROXY_URLS is set; crawls will run without a proxy."
            )

    @staticmethod
    def _load_urls() -> list[str]:
        """Collect proxy URLs from env (pool first, then single), de-duplicated."""
        urls: list[str] = []
        pool = Config.PROXY_URLS
        if pool:
            urls.extend(part.strip() for part in pool.split(",") if part.strip())

        single = (Config.PROXY_URL or "").strip()
        if single and single not in urls:
            urls.append(single)

        return urls

    @property
    def is_pool_backed(self) -> bool:
        return self._rotator is not None

    def get_proxy_url(self) -> str | None:
        if not self._urls:
            return None
        if self._rotator is not None:
            # Advances the cyclic index on every call (thread-safe).
            return self._rotator.get_proxy()
        return self._urls[0]