import socket
import urllib.parse
import validators
from typing import Union, Sequence, Iterator

from langchain_community.document_loaders import (
    WebBaseLoader,
)
from langchain_core.documents import Document


from open_webui.constants import ERROR_MESSAGES
from open_webui.config import ENABLE_RAG_LOCAL_WEB_FETCH
from open_webui.env import SRC_LOG_LEVELS

import logging

log = logging.getLogger(__name__)
log.setLevel(SRC_LOG_LEVELS["RAG"])


def validate_url(url: Union[str, Sequence[str]]):
    if isinstance(url, str):
        if isinstance(validators.url(url), validators.ValidationError):
            raise ValueError(ERROR_MESSAGES.INVALID_URL)
        if not ENABLE_RAG_LOCAL_WEB_FETCH:
            # Local web fetch is disabled, filter out any URLs that resolve to private IP addresses
            parsed_url = urllib.parse.urlparse(url)
            # Get IPv4 and IPv6 addresses
            ipv4_addresses, ipv6_addresses = resolve_hostname(parsed_url.hostname)
            # Check if any of the resolved addresses are private
            # This is technically still vulnerable to DNS rebinding attacks, as we don't control WebBaseLoader
            for ip in ipv4_addresses:
                if validators.ipv4(ip, private=True):
                    raise ValueError(ERROR_MESSAGES.INVALID_URL)
            for ip in ipv6_addresses:
                if validators.ipv6(ip, private=True):
                    raise ValueError(ERROR_MESSAGES.INVALID_URL)
        return True
    elif isinstance(url, Sequence):
        return all(validate_url(u) for u in url)
    else:
        return False


def resolve_hostname(hostname):
    # Get address information
    addr_info = socket.getaddrinfo(hostname, None)

    # Extract IP addresses from address information
    ipv4_addresses = [info[4][0] for info in addr_info if info[0] == socket.AF_INET]
    ipv6_addresses = [info[4][0] for info in addr_info if info[0] == socket.AF_INET6]

    return ipv4_addresses, ipv6_addresses


class SafeWebBaseLoader(WebBaseLoader):
    """WebBaseLoader with enhanced error handling for URLs."""

    def lazy_load(self) -> Iterator[Document]:
        """Lazy load text from the url(s) in web_path with error handling."""
        for path in self.web_paths:
            try:
                soup = self._scrape(path, bs_kwargs=self.bs_kwargs)
                text = soup.get_text(**self.bs_get_text_kwargs)

                # Build metadata
                metadata = {"source": path}
                if title := soup.find("title"):
                    metadata["title"] = title.get_text()
                if description := soup.find("meta", attrs={"name": "description"}):
                    metadata["description"] = description.get(
                        "content", "No description found."
                    )
                if html := soup.find("html"):
                    metadata["language"] = html.get("lang", "No language found.")

                yield Document(page_content=text, metadata=metadata)
            except Exception as e:
                # Log the error and continue with the next URL
                log.error(f"Error loading {path}: {e}")


def get_web_loader(
    url: Union[str, Sequence[str]],
    verify_ssl: bool = True,
    requests_per_second: int = 2,
):
    # Check if the URL is valid
    if not validate_url(url):
        raise ValueError(ERROR_MESSAGES.INVALID_URL)
    return SafeWebBaseLoader(
        url,
        verify_ssl=verify_ssl,
        requests_per_second=requests_per_second,
        continue_on_failure=True,
    )
