SPipe/backend/drawing_dxf.py

"""Drawing sheets (src/drawing.ts model) -> DXF R2018 via ezdxf.

The browser sends the same item list it renders as SVG: lines, texts, circles
and solid fills in millimetres (origin bottom-left). R2018 stores text as
UTF-8, so Korean needs no code page; widths become lineweights, colours true
colours, fills solid hatches. Each item keeps its layer.
"""
from __future__ import annotations

import io
import re

import ezdxf
from ezdxf import colors
from ezdxf.enums import TextEntityAlignment

from .batch import BatchError

MAX_ITEMS = 400_000
_LINEWEIGHTS = [0, 5, 9, 13, 15, 18, 20, 25, 30, 35, 40, 50, 53, 60, 70, 80, 90, 100, 106, 120, 140, 158, 200, 211]
_FONTS = {"ulleungM": ("HY울릉도M.TTF", "HY울릉도M"), "malgun": ("malgun.ttf", "Malgun Gothic")}
_HEX = re.compile(r"^#([0-9a-fA-F]{6})$")
_ALIGN = {
    ("start", "bottom"): TextEntityAlignment.LEFT, ("middle", "bottom"): TextEntityAlignment.CENTER, ("end", "bottom"): TextEntityAlignment.RIGHT,
    ("start", "middle"): TextEntityAlignment.MIDDLE_LEFT, ("middle", "middle"): TextEntityAlignment.MIDDLE_CENTER, ("end", "middle"): TextEntityAlignment.MIDDLE_RIGHT,
    ("start", "top"): TextEntityAlignment.TOP_LEFT, ("middle", "top"): TextEntityAlignment.TOP_CENTER, ("end", "top"): TextEntityAlignment.TOP_RIGHT,
}


def _rgb(color: str | None) -> int | None:
    m = _HEX.match(color or "")
    return colors.rgb2int(tuple(int(m.group(1)[i:i + 2], 16) for i in (0, 2, 4))) if m else None


def _lineweight(width_mm: float | None) -> int:
    w = (width_mm or 0.25) * 100
    return min(_LINEWEIGHTS[1:], key=lambda v: abs(v - w))


def _pts(raw) -> list[tuple[float, float]]:
    try:
        return [(float(p[0]), float(p[1])) for p in raw]
    except (TypeError, ValueError, IndexError) as e:
        raise BatchError("도면 좌표가 올바르지 않습니다.") from e


def drawing_to_dxf(drawing: dict) -> bytes:
    items = drawing.get("items") or []
    if not isinstance(items, list) or not items:
        raise BatchError("도면이 비어 있습니다.")
    if len(items) > MAX_ITEMS:
        raise BatchError("도면 요소가 너무 많습니다.")
    doc = ezdxf.new("R2018", setup=True)  # standard linetypes incl. DASHED / DOT
    doc.units = ezdxf.units.MM
    doc.header["$LWDISPLAY"] = 1
    # Text style: the sheet's font (HY울릉도M by default) by file and family
    # name; CAD substitutes when the font is not installed on that PC.
    font_file, family = _FONTS.get(str(drawing.get("font") or ""), _FONTS["malgun"])
    style = doc.styles.add("MALGUN", font=font_file)
    style.set_extended_font_data(family=family)
    msp = doc.modelspace()
    layers: set[str] = set()

    def attrs(it: dict, color: str | None) -> dict:
        layer = str(it.get("layer") or "0")[:255]
        if layer not in layers:
            doc.layers.add(layer)
            layers.add(layer)
        a = {"layer": layer}
        m = _HEX.match(color or "")
        if m and max(int(m.group(1)[i:i + 2], 16) for i in (0, 2, 4)) < 64:
            a["color"] = 7  # near-black -> white/black by CAD background (AutoCAD model space is dark)
        elif m:
            a["true_color"] = _rgb(color)
        return a

    def is_white(color: str | None) -> bool:
        m = _HEX.match(color or "")
        return bool(m) and min(int(m.group(1)[i:i + 2], 16) for i in (0, 2, 4)) > 240

    for it in items:
        kind = it.get("kind")
        if kind == "line":
            pts = _pts(it.get("pts") or [])
            if len(pts) < 2:
                continue
            a = attrs(it, it.get("color") or "#111111")
            a["lineweight"] = _lineweight(it.get("width"))
            if it.get("dash") == "dashed":
                a["linetype"] = "DASHED"
            elif it.get("dash") == "dotted":
                a["linetype"] = "DOT"
            pl = msp.add_lwpolyline(pts, close=bool(it.get("closed")), dxfattribs=a)
            if a.get("linetype"):
                pl.dxf.ltscale = max(0.05, (it.get("width") or 0.25) * 1.2)
        elif kind == "fill":
            pts = _pts(it.get("pts") or [])
            # White boxes only mask lines behind labels on paper; in CAD they hide geometry.
            if len(pts) < 3 or is_white(it.get("fill")):
                continue
            a = attrs(it, it.get("fill"))
            h = msp.add_hatch(dxfattribs=a)
            h.paths.add_polyline_path(pts, is_closed=True)
            op = float(it.get("opacity") if it.get("opacity") is not None else 1)
            if op < 1:
                h.transparency = max(0.0, min(1.0, 1 - op))
        elif kind == "circle":
            x, y, r = float(it["x"]), float(it["y"]), float(it["r"])
            if it.get("fill") and it.get("fill") != "none":
                h = msp.add_hatch(dxfattribs=attrs(it, it.get("fill")))
                h.paths.add_edge_path().add_arc((x, y), r, 0, 360)
            a = attrs(it, it.get("color") or "#111111")
            a["lineweight"] = _lineweight(it.get("width") or 0.2)
            msp.add_circle((x, y), r, dxfattribs=a)
        elif kind == "text":
            text = str(it.get("text") or "")
            if not text:
                continue
            a = attrs(it, it.get("color") or "#111111")
            a.update(style="MALGUN", height=float(it.get("size") or 2.5) * 0.8, rotation=float(it.get("rotate") or 0))
            t = msp.add_text(text, dxfattribs=a)
            t.set_placement((float(it["x"]), float(it["y"])), align=_ALIGN.get((it.get("anchor") or "start", it.get("vAnchor") or "bottom"), TextEntityAlignment.LEFT))
    # Open zoomed to the sheet (extents + initial model-space view).
    w, h = float(drawing.get("width") or 420), float(drawing.get("height") or 297)
    doc.set_modelspace_vport(height=h * 1.05, center=(w / 2, h / 2))
    buf = io.StringIO()
    doc.write(buf)
    # R2018 text is UTF-8 and AutoCAD ignores $DWGCODEPAGE, but GDAL-based readers
    # (QGIS etc.) decode with it; ezdxf always writes ANSI_1252 on save.
    out = buf.getvalue().replace("$DWGCODEPAGE\n  3\nANSI_1252\n", "$DWGCODEPAGE\n  3\nANSI_65001\n", 1)
    # ezdxf writes "unknown" extents (+-1e20); give CAD the sheet so zoom-extents works.
    out = out.replace("$EXTMIN\n 10\n1e+20\n 20\n1e+20\n 30\n1e+20\n", "$EXTMIN\n 10\n0.0\n 20\n0.0\n 30\n0.0\n", 1)
    out = out.replace("$EXTMAX\n 10\n-1e+20\n 20\n-1e+20\n 30\n-1e+20\n", f"$EXTMAX\n 10\n{w}\n 20\n{h}\n 30\n0.0\n", 1)
    return out.encode("utf-8")