from __future__ import annotations

import os
from typing import Any, Dict, List

import requests

from intel.models import Candidate
from intel.utils import unique


API_URL = "https://services.nvd.nist.gov/rest/json/cves/2.0"


def fetch(system: Dict[str, Any], source: Dict[str, Any]) -> List[Candidate]:
    params = {
        "keywordSearch": source.get("keyword") or system["display_name"],
        "resultsPerPage": source.get("results_per_page", 50),
    }
    headers = {"User-Agent": "websafe-intel"}
    api_key = os.environ.get("NVD_API_KEY")
    if api_key:
        headers["apiKey"] = api_key

    response = requests.get(API_URL, headers=headers, params=params, timeout=30)
    response.raise_for_status()
    payload = response.json()

    candidates: List[Candidate] = []
    for item in payload.get("vulnerabilities", []):
        cve = item.get("cve", {})
        descriptions = cve.get("descriptions", [])
        description = next((d.get("value") for d in descriptions if d.get("lang") == "en"), "")
        metrics = cve.get("metrics", {})
        severity = "unknown"
        cvss_score = None
        for key in ("cvssMetricV31", "cvssMetricV30", "cvssMetricV2"):
            entries = metrics.get(key, [])
            if entries:
                data = entries[0].get("cvssData", {})
                severity = (entries[0].get("baseSeverity") or data.get("baseSeverity") or "unknown").lower()
                cvss_score = data.get("baseScore")
                break

        refs = [ref.get("url") for ref in cve.get("references", []) if ref.get("url")]
        candidates.append(
            Candidate(
                system_id=system["system_id"],
                display_name=system["display_name"],
                category=system["category"],
                advisory_mode=source.get("advisory_mode", "core"),
                source_kind=source["kind"],
                source_name=source["name"],
                source_confidence=source["confidence"],
                source_url=refs[0] if refs else API_URL,
                title=cve.get("id") or f"NVD advisory for {system['display_name']}",
                published_at=cve.get("published"),
                updated_at=cve.get("lastModified"),
                summary=description or "",
                severity=severity,
                cvss_score=cvss_score,
                aliases=unique([cve.get("id")]),
                cve_ids=[cve.get("id")] if cve.get("id") else [],
                references=refs,
                raw=item,
            )
        )
    return candidates