"""PowerPoint (.pptx) → Markdown。每張投影片一節，含表格、圖片佔位與講者備註。

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

from pptx import Presentation
from pptx.enum.shapes import MSO_SHAPE_TYPE


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


def convert(src, assets_dir=None, md_dir=None):
    """回傳 (markdown, status)。status 恆為 'ok'。"""
    src = pathlib.Path(src)
    md_dir = pathlib.Path(md_dir) if md_dir else src.parent
    prs = Presentation(str(src))
    counter = 0
    sections = []
    for i, slide in enumerate(prs.slides, 1):
        blocks = [f"## Slide {i}"]
        for shape in slide.shapes:
            if shape.has_text_frame and shape.text_frame.text.strip():
                blocks.append(shape.text_frame.text.strip())
            elif shape.has_table:
                blocks.append(_table_md(shape.table))
            elif shape.shape_type == MSO_SHAPE_TYPE.PICTURE:
                counter += 1
                name = f"img{counter}.{shape.image.ext}"
                if assets_dir is not None:
                    assets_dir.mkdir(parents=True, exist_ok=True)
                    (assets_dir / name).write_bytes(shape.image.blob)
                    rel = (assets_dir / name).relative_to(md_dir).as_posix()
                else:
                    rel = name
                # <> 包住：檔名含空格或不平衡括號時，未包住的連結會失效
                blocks.append(f"![{name}](<{rel}>)")
        if slide.has_notes_slide:
            notes = slide.notes_slide.notes_text_frame.text.strip()
            if notes:
                blocks.append(f"### 講者備註\n\n{notes}")
        sections.append("\n\n".join(blocks))
    return "\n\n".join(sections), "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")
        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()