"""Web search via DuckDuckGo HTML endpoint (no API key, no new deps).

Used as optional grounding for chat ("use web") and the local-deals feature.
Degrades gracefully: any network/parse failure returns [].
"""

import html
import logging
import re
from urllib.parse import parse_qs, unquote, urlparse

logger = logging.getLogger(__name__)

_SEARCH_URL = "https://html.duckduckgo.com/html/"
_UA = (
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 "
    "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36"
)

# <a class="result__a" href="...">Title</a>
_RESULT_RE = re.compile(
    r'<a[^>]*class="[^"]*result__a[^"]*"[^>]*href="([^"]+)"[^>]*>(.*?)</a>',
    re.IGNORECASE | re.DOTALL,
)
# <a class="result__snippet" ...>snippet</a>  (sometimes a <td>/<div>)
_SNIPPET_RE = re.compile(
    r'<(?:a|td|div)[^>]*class="[^"]*result__snippet[^"]*"[^>]*>(.*?)</(?:a|td|div)>',
    re.IGNORECASE | re.DOTALL,
)
_TAG_RE = re.compile(r"<[^>]+>")


def _strip_html(s: str) -> str:
    return html.unescape(_TAG_RE.sub("", s)).strip()


def _clean_url(href: str) -> str:
    """Resolve DDG redirect links //duckduckgo.com/l/?uddg=<urlencoded>."""
    href = html.unescape(href)
    if href.startswith("//"):
        href = "https:" + href
    parsed = urlparse(href)
    if "duckduckgo.com" in parsed.netloc and parsed.path.startswith("/l"):
        uddg = parse_qs(parsed.query).get("uddg", [""])[0]
        if uddg:
            return unquote(uddg)
    return href


def search_web(query: str, max_results: int = 5) -> list[dict]:
    """Search DuckDuckGo. Returns [{"title", "snippet", "url"}]; [] on failure."""
    try:
        import httpx

        resp = httpx.get(
            _SEARCH_URL,
            params={"q": query},
            headers={"User-Agent": _UA},
            timeout=10.0,
            follow_redirects=True,
        )
        resp.raise_for_status()
        page = resp.text
        links = _RESULT_RE.findall(page)
        snippets = [_strip_html(s) for s in _SNIPPET_RE.findall(page)]
        results = []
        for i, (href, title_html) in enumerate(links[:max_results]):
            results.append(
                {
                    "title": _strip_html(title_html),
                    "snippet": snippets[i] if i < len(snippets) else "",
                    "url": _clean_url(href),
                }
            )
        return results
    except Exception as e:
        logger.warning("web search failed for %r: %s", query, e)
        return []


def format_results(results: list[dict]) -> str:
    """Readable text block for prompt injection."""
    if not results:
        return ""
    lines = ["WEB SEARCH RESULTS:"]
    for i, r in enumerate(results, 1):
        lines.append(f"{i}. {r.get('title', '')}")
        if r.get("snippet"):
            lines.append(f"   {r['snippet']}")
        if r.get("url"):
            lines.append(f"   Source: {r['url']}")
    return "\n".join(lines)