from __future__ import annotations

from typing import Any
import urllib.request
import urllib.parse
import re

from core.tools.base import BaseTool, ToolContext
from core.tools.registry import registry
from core.events import bus


class SearchTool(BaseTool):
    """
    Lightweight web search tool using DuckDuckGo HTML endpoint.

    Designed for:
    - query → results
    - agent retrieval step before crawling
    """

    name = "search"
    description = "Web search (DuckDuckGo HTML scraping)"

    # =========================
    # EXECUTE
    # =========================

    def execute(self, payload: dict[str, Any], ctx: ToolContext):
        action = str(payload.get("action", "search")).strip()

        bus.log(
            "SEARCH",
            "search_execute",
            "INFO",
            {"action": action}
        )

        match action:
            case "search":
                return self.search(payload)

            case _:
                raise ValueError(f"Unknown search action: {action}")

    # =========================
    # SEARCH
    # =========================

    def search(self, payload: dict[str, Any]):
        query = payload.get("query")
        limit = payload.get("limit", 5)

        if not isinstance(query, str):
            raise ValueError("query must be string")
        if not isinstance(limit, int):
            limit = 5

        encoded = urllib.parse.quote(query)

        url = f"https://duckduckgo.com/html/?q={encoded}"

        req = urllib.request.Request(
            url,
            headers={
                "User-Agent": "MCP-Search/1.0"
            }
        )

        try:
            with urllib.request.urlopen(req, timeout=6) as resp:
                html = resp.read().decode("utf-8", errors="ignore")

            results = self._parse_results(html)

            return {
                "query": query,
                "results": results[:limit],
                "count": len(results)
            }

        except Exception as e:
            return {
                "query": query,
                "error": str(e)
            }

    # =========================
    # PARSER
    # =========================

    def _parse_results(self, html: str) -> list[dict[str, Any]]:
        """
        DuckDuckGo HTML parsing (lightweight heuristic).
        """

        results = []

        # Extract result blocks
        links = re.findall(r'<a rel="nofollow" class="result__a" href="(.*?)".*?>(.*?)</a>', html)

        for url, title in links:
            clean_title = re.sub("<.*?>", "", title)

            results.append({
                "title": clean_title,
                "url": url,
            })

        return results


# =========================
# REGISTER
# =========================

registry.register(SearchTool())