"""網頁 URL → 完整 HTML 快照 + Markdown 正文萃取（trafilatura，全程本地處理）。

可獨立執行：python tools/convert/from_web.py <url> [-o out.md] [--snapshot out.html] [--dry-run]
"""
import argparse
import pathlib

import trafilatura


def fetch(url):
    """抓取 URL，回傳完整 HTML 字串。失敗時拋 RuntimeError。"""
    html = trafilatura.fetch_url(url)
    if not html:
        raise RuntimeError(f"抓取失敗：{url}")
    return html


def extract(html):
    """HTML → Markdown 正文。回傳 (markdown, status)。萃取不到正文時 status='empty'。"""
    md = trafilatura.extract(
        html, output_format="markdown", include_tables=True, include_links=True
    )
    if not md or not md.strip():
        return "", "empty"
    return md.strip(), "ok"


def main(argv=None):
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("url")
    ap.add_argument("-o", "--output")
    ap.add_argument("--snapshot", help="HTML 快照輸出路徑")
    ap.add_argument("--dry-run", action="store_true")
    a = ap.parse_args(argv)
    html = fetch(a.url)
    md, status = extract(html)
    if a.dry_run:
        print(f"[dry-run] {a.url}: status={status}, snapshot {len(html)} chars, "
              f"markdown {len(md)} chars")
        return
    if status != "ok":
        print(f"empty: {a.url} 萃取不到正文")
        raise SystemExit(2)
    if a.snapshot:
        pathlib.Path(a.snapshot).write_text(html, encoding="utf-8")
    out = pathlib.Path(a.output) if a.output else pathlib.Path("page.md")
    out.write_text(md, encoding="utf-8")
    print(out)


if __name__ == "__main__":
    main()