"""从 Noto CJK SC 克隆出行高接近宋体 / 黑体的字体（OFL 允许修改，改名后仍按 OFL 分发）。
字形不变，只改垂直度量：ascent + descent = EM 倍数（参数 total），lineGap = 0。
用法：python -I make_fonts.py <源目录> <输出目录> <total，如 1.0>"""
import sys, pathlib
from fontTools.ttLib import TTCollection

src, dst, total = pathlib.Path(sys.argv[1]), pathlib.Path(sys.argv[2]), float(sys.argv[3])
dst.mkdir(parents=True, exist_ok=True)
plan = [("NotoSerifCJK-Regular.ttc", "BD Song", "Regular"), ("NotoSerifCJK-Bold.ttc", "BD Song", "Bold"),
        ("NotoSansCJK-Regular.ttc", "BD Hei", "Regular"), ("NotoSansCJK-Bold.ttc", "BD Hei", "Bold")]
for fname, family, style in plan:
    coll = TTCollection(str(src / fname))
    font = next(f for f in coll.fonts if "SC" in f["name"].getDebugName(1))
    upm = font["head"].unitsPerEm
    asc = round(upm * total * 0.86); desc = round(upm * total) - asc   # 与宋体相同的 0.86 / 0.14 比例
    font["hhea"].ascent, font["hhea"].descent, font["hhea"].lineGap = asc, -desc, 0
    os2 = font["OS/2"]
    os2.sTypoAscender, os2.sTypoDescender, os2.sTypoLineGap = asc, -desc, 0
    os2.usWinAscent, os2.usWinDescent = asc, desc
    name = font["name"]
    full = f"{family} {style}" if style != "Regular" else family
    for rec in list(name.names):
        if rec.nameID in (1, 3, 4, 6, 16, 17, 21, 22):
            name.removeNames(nameID=rec.nameID)
    for nid, val in ((1, family), (2, style), (3, f"{family.replace(' ', '')}-{style};{total}"),
                     (4, full), (6, f"{family.replace(' ', '')}-{style}")):
        name.setName(val, nid, 3, 1, 0x409); name.setName(val, nid, 1, 0, 0)
    out = dst / f"{family.replace(' ', '')}-{style}.otf"
    font.save(str(out))
    print(out.name, upm, asc, desc)