"""Word (.docx) → Markdown。保留標題層級與表格結構，圖片抽出為附檔並留佔位引用。

可獨立執行：python tools/convert/from_docx.py <file.docx> [-o out.md] [--dry-run]
"""
import argparse
import pathlib
import re

import docx
from docx.oxml.ns import qn
from docx.table import Table
from docx.text.paragraph import Paragraph


def _heading_level(par):
    # ponytail: 只認 "Heading N" / "標題 N" 樣式名；其他語系的 Word 樣式名不涵蓋，
    # 升級路徑：改讀 w:outlineLvl。
    m = re.match(r"(?:Heading|標題)\s*(\d)", par.style.name or "")
    return int(m.group(1)) if m else None


def _table_md(tbl):
    rows = [
        [c.text.strip().replace("\n", " ").replace("|", "\\|") for c in row.cells]
        for row in tbl.rows
    ]
    if not rows:
        return ""
    width = max(len(r) for r in rows)
    rows = [r + [""] * (width - len(r)) for r in rows]
    out = ["| " + " | ".join(rows[0]) + " |", "|" + " --- |" * width]
    out += ["| " + " | ".join(r) + " |" for r in rows[1:]]
    return "\n".join(out)


def _par_md(par, doc, assets_dir, md_dir, counter):
    parts = []
    for run in par.runs:
        for blip in run._element.findall(".//" + qn("a:blip")):
            rid = blip.get(qn("r:embed"))
            if not rid:
                continue
            part = doc.part.related_parts[rid]
            ext = pathlib.Path(part.partname).suffix or ".png"
            counter[0] += 1
            name = f"img{counter[0]}{ext}"
            if assets_dir is not None:
                assets_dir.mkdir(parents=True, exist_ok=True)
                (assets_dir / name).write_bytes(part.blob)
                rel = (assets_dir / name).relative_to(md_dir).as_posix()
            else:
                rel = name  # dry-run：僅佔位
            # 連結目標以 <> 包住：來源檔名可能含空格或不平衡括號，兩者都會讓
            # Markdown 連結失效（圖片存在卻整行退化成純文字）
            parts.append(f"![{name}](<{rel}>)")
        parts.append(run.text)
    text = "".join(parts).strip()
    lvl = _heading_level(par)
    if lvl and text:
        return "#" * lvl + " " + text
    return text


def convert(src, assets_dir=None, md_dir=None):
    """回傳 (markdown, status)。status 恆為 'ok'（docx 必有文字層）。"""
    src = pathlib.Path(src)
    md_dir = pathlib.Path(md_dir) if md_dir else src.parent
    doc = docx.Document(str(src))
    counter = [0]
    blocks = []
    for child in doc.element.body.iterchildren():
        if child.tag == qn("w:p"):
            blocks.append(_par_md(Paragraph(child, doc), doc, assets_dir, md_dir, counter))
        elif child.tag == qn("w:tbl"):
            blocks.append(_table_md(Table(child, doc)))
    md = "\n\n".join(b for b in blocks if b)
    return md, "ok"


def main(argv=None):
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("src")
    ap.add_argument("-o", "--output")
    ap.add_argument("--dry-run", action="store_true")
    a = ap.parse_args(argv)
    if a.dry_run:
        md, status = convert(a.src)
        print(f"[dry-run] {a.src}: status={status}, {len(md)} chars, "
              f"{md.count(chr(10)) + 1} lines")
        return
    out = pathlib.Path(a.output) if a.output else pathlib.Path(a.src).with_suffix(".md")
    md, _ = convert(a.src, assets_dir=out.parent / f"{out.stem}-assets", md_dir=out.parent)
    out.write_text(md, encoding="utf-8")
    print(out)


if __name__ == "__main__":
    main()