from __future__ import annotations
from typing import List, Optional
from urllib.parse import urljoin, urlparse
from config import config

def first_from_srcset(val: str) -> Optional[str]:
    if not val:
        return None
    first = val.split(",")[0].strip()
    parts = first.split()
    return parts[0] if parts else first

def abs_url(u: Optional[str]) -> Optional[str]:
    if not u:
        return None
    return urljoin(config()["base_url"], u) if isinstance(u, str) and u.startswith("/") else u

def collect_img_candidates(el) -> List[str]:
    urls: List[str] = []
    if not el:
        return urls
    attrs = ["src", "data-src", "data-original", "data-zoom-image", "data-thumb", "content", "href"]
    for a in attrs:
        v = el.get(a)
        if v:
            urls.append(v)
    for a in ["srcset", "data-srcset"]:
        v = el.get(a)
        if v:
            first = first_from_srcset(v)
            if first:
                urls.append(first)
    return urls

def _filename_key(u: str) -> str:
    p = urlparse(u)
    path = p.path or ""
    if path.endswith("/"):
        path = path[:-1]
    last = path.split("/")[-1]
    return f"{p.netloc}:{last}".lower()

def dedup_by_filename(urls: List[str]) -> List[str]:
    seen = set()
    out: List[str] = []
    for u in urls:
        k = _filename_key(u)
        if k in seen:
            continue
        seen.add(k)
        out.append(u)
    return out