"""FBX 减面 CLI：减到指定三角面数并重展 UV（seam 展开 + UVPM4 排布），输出 <名>_low.fbx。
用法：python model_decimate.py src/well1500.fbx --tris 5000 [-o dir]
     [--unwrap seam|smart] [--blender exe]"""
import argparse
import os

from mt_run import find_blender, run_blender_script


def main():
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("input", help="FBX 文件")
    ap.add_argument("--tris", type=int, required=True, help="目标三角面数")
    ap.add_argument("-o", "--out", default=None, help="输出目录（默认源文件同目录）")
    ap.add_argument("--unwrap", choices=("seam", "smart"), default="seam",
                    help="UV 展开：seam=锐边接缝整岛展开（默认），smart=Smart UV Project")
    ap.add_argument("--max-overlap", type=float, default=None,
                    help="UV 重叠容忍上限（0-1，默认内置 0.08）；调高可让更高 seam 角度过门、减少碎岛")
    ap.add_argument("--blender", default=None)
    args = ap.parse_args()
    if args.tris <= 0:
        ap.error("--tris 必须为正整数")
    if args.max_overlap is not None and not (0.0 < args.max_overlap <= 1.0):
        ap.error("--max-overlap 必须在 (0, 1] 内")

    blender = find_blender(args.blender)
    name = os.path.splitext(os.path.basename(args.input))[0]
    outdir = args.out or os.path.dirname(os.path.abspath(args.input))
    out_fbx = os.path.join(outdir, name + "_low.fbx")

    s = run_blender_script(blender, "bl_decimate.py",
                           [args.input, out_fbx, str(args.tris), args.unwrap,
                            "" if args.max_overlap is None else str(args.max_overlap)])

    print("== %s: %d -> %d 面（目标 %d）-> %s" %
          (s["src"], s["tris_before"], s["tris_after"], s["target"], out_fbx))
    u = s["uv"]
    overlap = "%.1f%%" % (u["overlap"] * 100) if u["overlap"] is not None else "n/a"
    print("  UV: 模式=%s 岛数=%d 利用率=%.1f%% 翻转=%.1f%% 重叠=%s" %
          (u["mode"], u["islands"], u["fill"] * 100, u["flipped"] * 100, overlap))
    if s.get("uv_polys"):
        try:
            import json as _json
            from uv_preview import render_uv_png
            with open(s["uv_polys"], encoding="utf-8") as fp:
                polys = _json.load(fp)
            render_uv_png(polys, s["uv_preview"])
            print("  UV 观察图: %s" % s["uv_preview"])
        except Exception as e:
            print("  [警告] UV 观察图渲染失败：%s" % e)
        finally:  # sidecar 是内部临时文件，无论渲染成败都清掉
            if os.path.exists(s["uv_polys"]):
                os.remove(s["uv_polys"])
    for w in s["warnings"]:
        print("  [警告] %s" % w)


if __name__ == "__main__":
    main()