import requests
from bs4 import BeautifulSoup
from urllib.parse import urljoin
from requests.exceptions import RequestException

PDF_HEADERS = {
    "User-Agent": (
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
        "AppleWebKit/537.36 (KHTML, like Gecko) "
        "Chrome/121.0.0.0 Safari/537.36"
    ),
    "Accept": "application/pdf,application/octet-stream;q=0.9,*/*;q=0.8",
    "Accept-Language": "en-US,en;q=0.9,ar;q=0.8",
    "Referer": "https://www.google.com/",
}


def fetch_url(url: str):
    try:
        r = requests.get(
            url,
            timeout=20,
            allow_redirects=True,
            headers=PDF_HEADERS,
        )
        r.raise_for_status()
        ct = r.headers.get("Content-Type", "").lower()
        return ct, r.content, r.url
    except RequestException:
        return None, None, None


def looks_like_pdf(content: bytes) -> bool:
    return bool(content and content.startswith(b"%PDF"))


def get_pdf_bytes(source_url: str) -> bytes | None:
    ct, content, final_url = fetch_url(source_url)

    if not ct or not content:
        return None

    # -------------------------
    # 1️⃣ PDF مباشر (صريح أو كذاب)
    # -------------------------
    if (
        "application/pdf" in ct
        or final_url.lower().endswith(".pdf")
        or looks_like_pdf(content)
    ):
        return content

    # -------------------------
    # 2️⃣ HTML wrapper
    # -------------------------
    if "text/html" in ct:
        try:
            soup = BeautifulSoup(
                content.decode("utf-8", errors="ignore"),
                "html.parser",
            )

            # a[href]
            for a in soup.find_all("a", href=True):
                href = a["href"].strip()
                if ".pdf" in href.lower():
                    pdf_url = urljoin(final_url, href)
                    ct2, content2, _ = fetch_url(pdf_url)
                    if ct2 and ("application/pdf" in ct2 or looks_like_pdf(content2)):
                        return content2

            # iframe / embed
            for tag in soup.find_all(["iframe", "embed"], src=True):
                src = tag["src"]
                if ".pdf" in src.lower():
                    pdf_url = urljoin(final_url, src)
                    ct2, content2, _ = fetch_url(pdf_url)
                    if ct2 and ("application/pdf" in ct2 or looks_like_pdf(content2)):
                        return content2

        except Exception:
            return None

    return None