"""FlowDeck — URL / web clipper importer (v5.6.0, Phase 5).

Fetches a web page and turns it into a page: a bookmark card (OG metadata)
followed by the article converted to FlowDeck blocks.
"""
from __future__ import annotations

import ipaddress
import socket
from urllib.parse import urlparse

import httpx

from app.services.export import markdown_to_blocks
from app.services.http_client import shared_client
from app.services.importers.base import ImportPage, ImportResult
from app.services.importers.html_notes import _html_to_markdown

_BLOCKED_HOSTS = {"localhost", "localhost.localdomain"}
_MAX_BYTES = 3_000_000


def _is_public_host(host: str) -> bool:
    """SSRF guard: reject loopback/private/link-local/reserved addresses."""
    if not host or host.lower() in _BLOCKED_HOSTS:
        return False
    try:
        infos = socket.getaddrinfo(host, None)
    except socket.gaierror:
        return False
    for info in infos:
        address = info[4][0]
        try:
            ip = ipaddress.ip_address(address)
        except ValueError:
            return False
        if (ip.is_private or ip.is_loopback or ip.is_link_local
                or ip.is_reserved or ip.is_multicast or ip.is_unspecified):
            return False
    return True


def _validate_url(url: str) -> str:
    parsed = urlparse(url.strip())
    if parsed.scheme not in ("http", "https"):
        raise ValueError("Seules les URLs http(s) sont autorisées")
    if not parsed.hostname or not _is_public_host(parsed.hostname):
        raise ValueError("Hôte non autorisé")
    return url.strip()


def _bookmark_block(url: str, meta: dict) -> dict:
    block = {"type": "bookmark", "url": url}
    for key in ("title", "description", "image", "site_name"):
        if meta.get(key):
            block[key] = meta[key]
    return block


async def fetch_url_result(url: str, *, transport: httpx.BaseTransport | None = None) -> ImportResult:
    """Fetch ``url`` and build a single-page ImportResult (raises on bad URL)."""
    safe_url = _validate_url(url)
    result = ImportResult(source="url")
    try:
        async with shared_client(
            timeout=15, follow_redirects=True, transport=transport,
            headers={"User-Agent": "FlowDeck-Importer/1.0"},
        ) as client:
            response = await client.get(safe_url)
            response.raise_for_status()
            if response.url.host and not _is_public_host(response.url.host):
                raise ValueError("Redirection vers un hôte non autorisé")
            content_type = response.headers.get("content-type", "")
            if "html" not in content_type.lower():
                raise ValueError("La ressource n'est pas une page HTML")
            body = response.text[:_MAX_BYTES]
    except httpx.HTTPError as exc:
        result.warn(f"Échec du téléchargement : {exc}")
        return result.finalize()

    from app.services.og_fetcher import parse_og

    meta = parse_og(body, safe_url)
    title = (meta.get("title") or urlparse(safe_url).hostname or "Page").strip()
    markdown = _html_to_markdown(body)
    blocks = [_bookmark_block(safe_url, meta)]
    if markdown:
        blocks.extend(markdown_to_blocks(markdown))
    result.pages.append(ImportPage(
        title=title[:200],
        blocks=blocks,
        source_path=safe_url,
        external_id=safe_url,
    ))
    return result.finalize()