"""
Deterministic compiler: validated Scene -> clean, standalone Three.js HTML.

The SAME html string is used for both the live preview (wrapped in an iframe)
and the "copy code" tab, so what the user sees is exactly what they copy.
"""
from __future__ import annotations

import base64
import json
from typing import Any, Dict

from scene import (Animation, ExtrudeNode, GroupNode, LayoutGrid, LayoutRow,
                   LayoutStack, Obj, Scene, Text3DNode, _shape_extent)

FONT_URL = "https://unpkg.com/three@0.160.0/examples/fonts/helvetiker_regular.typeface.json"


class _Ctx:
    """Mutable compilation context threaded through recursive scene-graph traversal."""
    __slots__ = ("style", "_idx", "text_jobs")

    def __init__(self, style: str) -> None:
        self.style = style
        self._idx = 0
        # Each entry: (Text3DNode, js_var_name, js_parent_var)
        self.text_jobs: list = []

    def nxt(self) -> int:
        i = self._idx
        self._idx += 1
        return i


def _col_str(color: str) -> str:
    """Wrap a sanitized color value for JS: 'new THREE.Color("<value>")'."""
    return f'new THREE.Color("{color}")'


def geometry_js(o: Obj) -> str:
    p = o.params or {}
    def g(k: str, d: float) -> float:
        return float(p.get(k, d))

    s = o.shape
    if s == "box":
        return f"new THREE.BoxGeometry({g('width', 1)}, {g('height', 1)}, {g('depth', 1)})"
    if s == "sphere":
        return f"new THREE.SphereGeometry({g('radius', 0.6)}, 32, 16)"
    if s == "cylinder":
        return (f"new THREE.CylinderGeometry({g('radiusTop', 0.5)}, "
                f"{g('radiusBottom', 0.5)}, {g('height', 1)}, 32)")
    if s == "cone":
        return f"new THREE.ConeGeometry({g('radius', 0.5)}, {g('height', 1)}, 32)"
    if s == "torus":
        return f"new THREE.TorusGeometry({g('radius', 0.5)}, {g('tube', 0.2)}, 16, 48)"
    if s == "torusKnot":
        return f"new THREE.TorusKnotGeometry({g('radius', 0.5)}, {g('tube', 0.15)}, 100, 16)"
    if s == "plane":
        return f"new THREE.PlaneGeometry({g('width', 5)}, {g('height', 5)})"
    poly = {
        "tetrahedron": "TetrahedronGeometry",
        "icosahedron": "IcosahedronGeometry",
        "dodecahedron": "DodecahedronGeometry",
        "octahedron": "OctahedronGeometry",
    }
    if s in poly:
        return f"new THREE.{poly[s]}({g('radius', 0.6)}, 0)"
    if s == "capsule":
        return f"new THREE.CapsuleGeometry({g('radius', 0.4)}, {g('length', 1.0)}, 8, 16)"
    if s == "ring":
        return f"new THREE.RingGeometry({g('innerRadius', 0.3)}, {g('outerRadius', 0.6)}, 32)"
    if s == "circle":
        return f"new THREE.CircleGeometry({g('radius', 0.6)}, 32)"
    if s == "tube":
        r = g('radius', 0.1)
        return (
            f"(()=>{{ const _c=new THREE.CatmullRomCurve3(["
            f"new THREE.Vector3(-0.4,-0.6,0),"
            f"new THREE.Vector3(0.4,-0.2,0),"
            f"new THREE.Vector3(-0.4,0.2,0),"
            f"new THREE.Vector3(0.4,0.6,0)"
            f"]); return new THREE.TubeGeometry(_c,64,{r},12,false); }})()"
        )
    if s == "roundedBox":
        return (f"new RoundedBoxGeometry({g('width', 1.0)}, {g('height', 1.0)}, "
                f"{g('depth', 1.0)}, 4, {g('radius', 0.1)})")
    return "new THREE.BoxGeometry(1, 1, 1)"


def _preset_mat_js(node) -> str | None:
    """Return a JS material string for a named preset, or None if no preset is set.

    color override: if node.color differs from the default (#88ccff), use it;
    otherwise fall back to each preset's canonical color so it looks right out of the box.
    For neon, node.color is the emissive glow color regardless.
    """
    preset = getattr(node, "preset", None)
    if not preset:
        return None
    col = _col_str(node.color)
    has_custom = node.color != "#88ccff"

    if preset == "gold":
        c = col if has_custom else _col_str("#ffd700")
        return (f"new THREE.MeshPhysicalMaterial({{ color: {c}, "
                f"metalness: 1.0, roughness: 0.25, clearcoat: 1.0, clearcoatRoughness: 0.1 }})")

    if preset == "chrome":
        c = col if has_custom else _col_str("#ffffff")
        return (f"new THREE.MeshPhysicalMaterial({{ color: {c}, "
                f"metalness: 1.0, roughness: 0.05, clearcoat: 1.0, clearcoatRoughness: 0.05 }})")

    if preset == "glass":
        return (f"new THREE.MeshPhysicalMaterial({{ color: {col}, "
                f"metalness: 0.0, roughness: 0.05, "
                f"transmission: 1.0, thickness: 0.5, ior: 1.5, "
                f"transparent: true, opacity: 1.0 }})")

    if preset == "neon":
        return (f"new THREE.MeshStandardMaterial({{ "
                f"color: new THREE.Color('#000000'), "
                f"emissive: {col}, emissiveIntensity: 2.0 }})")

    if preset == "matte":
        return (f"new THREE.MeshStandardMaterial({{ color: {col}, "
                f"metalness: 0.0, roughness: 0.9 }})")

    if preset == "plastic":
        return (f"new THREE.MeshPhysicalMaterial({{ color: {col}, "
                f"metalness: 0.0, roughness: 0.4, clearcoat: 0.5, clearcoatRoughness: 0.3 }})")

    return None


def material_js(o: Obj, style: str = "realistic") -> str:
    col = _col_str(o.color)
    emi = _col_str(o.emissive)
    if style == "wireframe":
        return f"new THREE.MeshStandardMaterial({{ color: {col}, wireframe: true }})"
    if style == "toon":
        return f"new THREE.MeshToonMaterial({{ color: {col}, emissive: {emi} }})"
    if style == "flat":
        return (f"new THREE.MeshStandardMaterial({{ color: {col}, emissive: {emi}, "
                f"metalness: {o.metalness}, roughness: {o.roughness}, flatShading: true }})")
    # Preset overrides per-object material field in realistic mode
    preset_mat = _preset_mat_js(o)
    if preset_mat:
        return preset_mat
    # realistic — honour per-object material field
    if o.material == "basic":
        return f"new THREE.MeshBasicMaterial({{ color: {col} }})"
    if o.material == "phong":
        return f"new THREE.MeshPhongMaterial({{ color: {col}, emissive: {emi}, shininess: 80 }})"
    if o.material == "wireframe":
        return f"new THREE.MeshStandardMaterial({{ color: {col}, wireframe: true }})"
    return (f"new THREE.MeshStandardMaterial({{ color: {col}, emissive: {emi}, "
            f"metalness: {o.metalness}, roughness: {o.roughness} }})")


def _text_jobs_js(jobs: list, style: str = "realistic") -> str:
    """Emit async font-load block for text3d nodes collected during compilation.

    jobs: [(Text3DNode, js_var_name, js_parent_var), ...]
    r160 TextGeometry uses 'height' for extrusion depth (renamed 'depth' at r163).
    Returns empty string when no text nodes exist (no await, no font fetch).
    """
    if not jobs:
        return ""
    lines = [
        f"    const _font = await new FontLoader().loadAsync(",
        f"      '{FONT_URL}'",
        f"    );",
    ]
    for node, var, par in jobs:
        mat = material_js(node, style)
        txt = json.dumps(node.text)
        bevel = "true" if node.bevel else "false"
        px, py, pz = node.position
        rx, ry, rz = node.rotation
        sx, sy, sz = node.scale
        lines += [
            f"    {{  // text3d: {node.text!r}",
            f"      const _geo = new TextGeometry({txt}, {{",
            f"        font: _font, size: {node.size}, height: {node.depth},",
            f"        curveSegments: 12, bevelEnabled: {bevel},",
            f"        bevelThickness: 0.02, bevelSize: 0.02, bevelSegments: 3",
            f"      }});",
            f"      _geo.center();",
            f"      const {var} = new THREE.Mesh(_geo, {mat});",
            f"      {var}.position.set({px}, {py}, {pz});",
            f"      {var}.rotation.set({rx}, {ry}, {rz});",
            f"      {var}.scale.set({sx}, {sy}, {sz});",
            f"      {par}.add({var});",
            f"    }}",
        ]
    return "\n".join(lines)


# Keep old name as alias for any callers that reference it directly
def text_section_js(nodes_with_idx: list, style: str = "realistic") -> str:
    jobs = [(n, f"mesh{i}", "group") for n, i in nodes_with_idx]
    return _text_jobs_js(jobs, style)


def _obj_js(node: Obj, idx: int, style: str, parent: str = "group") -> list:
    """Return JS lines for a single primitive mesh."""
    px, py, pz = node.position
    rx, ry, rz = node.rotation
    sx, sy, sz = node.scale
    return [
        f"const mesh{idx} = new THREE.Mesh({geometry_js(node)}, {material_js(node, style)});",
        f"mesh{idx}.position.set({px}, {py}, {pz});",
        f"mesh{idx}.rotation.set({rx}, {ry}, {rz});",
        f"mesh{idx}.scale.set({sx}, {sy}, {sz});",
        f"{parent}.add(mesh{idx});",
    ]


def _compile_node(node: Any, parent: str, ctx: _Ctx) -> list:
    """Recursively compile one scene node to JS lines, collecting text jobs in ctx."""
    if isinstance(node, GroupNode):
        return _compile_group(node, parent, ctx)
    if isinstance(node, Text3DNode):
        idx = ctx.nxt()
        ctx.text_jobs.append((node, f"mesh{idx}", parent))
        return []
    if isinstance(node, ExtrudeNode):
        return extrude_js(node, ctx.nxt(), ctx.style, parent)
    if isinstance(node, Obj):
        return _obj_js(node, ctx.nxt(), ctx.style, parent)
    # Old layout containers (LayoutStack/Row/Grid): flatten then compile children
    lines: list = []
    for n in _flatten([node]):
        lines.extend(_compile_node(n, parent, ctx))
    return lines


def _compile_group(node: GroupNode, parent: str, ctx: _Ctx) -> list:
    """Emit a THREE.Group() with children laid out and group transform applied."""
    idx = ctx.nxt()
    gvar = f"grp{idx}"
    lines: list = [f"const {gvar} = new THREE.Group();"]
    for child in _group_layout_children(node):
        lines.extend(_compile_node(child, gvar, ctx))
    px, py, pz = node.position
    rx, ry, rz = node.rotation
    sx, sy, sz = node.scale
    lines += [
        f"{gvar}.position.set({px}, {py}, {pz});",
        f"{gvar}.rotation.set({rx}, {ry}, {rz});",
        f"{gvar}.scale.set({sx}, {sy}, {sz});",
        f"{parent}.add({gvar});",
    ]
    return lines


def objects_js(scene: Scene, ctx: _Ctx) -> str:
    """Compile all scene objects using the context for index + text-job tracking."""
    lines: list = []
    for node in scene.objects:
        lines.extend(_compile_node(node, "group", ctx))
    return "\n      ".join(lines)


def lights_js(scene: Scene) -> str:
    """Kept for backwards compat / tests; compile_html uses preset lighting instead."""
    lines = []
    for l in scene.lights:
        c = f'"{l.color}"'
        x, y, z = l.position
        if l.type == "ambient":
            lines.append(f"scene.add(new THREE.AmbientLight({c}, {l.intensity}));")
        elif l.type == "point":
            lines.append(
                f"{{ const L = new THREE.PointLight({c}, {l.intensity}); "
                f"L.position.set({x}, {y}, {z}); scene.add(L); }}")
        else:
            lines.append(
                f"{{ const L = new THREE.DirectionalLight({c}, {l.intensity}); "
                f"L.position.set({x}, {y}, {z}); scene.add(L); }}")
    return "\n      ".join(lines)


def _shadow_config_js() -> str:
    return (
        "L.castShadow = true; "
        "L.shadow.mapSize.setScalar(1024); "
        "L.shadow.camera.near = 0.5; L.shadow.camera.far = 28; "
        "L.shadow.camera.left = -7; L.shadow.camera.right = 7; "
        "L.shadow.camera.top = 7; L.shadow.camera.bottom = -7; "
        "L.shadow.bias = -0.001;"
    )


def _preset_lights_js(preset: str, shadows: bool) -> str:
    """Return JS that adds preset lighting to the scene. Key light casts shadows if enabled."""
    sc = _shadow_config_js() if shadows else ""

    if preset == "soft":
        # Hemisphere gives the diffuse overcast feel; dim directional provides gentle shadows
        return (
            'scene.add(new THREE.HemisphereLight("#b1e1ff", "#4a3828", 1.2));\n'
            '      scene.add(new THREE.AmbientLight("#ffffff", 0.35));\n'
            f'      {{ const L = new THREE.DirectionalLight("#ffffff", 0.25); '
            f'L.position.set(3, 6, 3); {sc} scene.add(L); }}'
        )

    if preset == "neon":
        # Synthwave: dark ambient + cyan/magenta/purple points
        return (
            'scene.add(new THREE.AmbientLight("#06060f", 0.4));\n'
            '      { const L = new THREE.PointLight("#00ffff", 4.0); '
            'L.position.set(-3, 2, 3); scene.add(L); }\n'
            '      { const L = new THREE.PointLight("#ff00ff", 4.0); '
            'L.position.set(3, -1, -2); scene.add(L); }\n'
            '      { const L = new THREE.PointLight("#8800ff", 2.0); '
            'L.position.set(0, 5, -3); scene.add(L); }'
        )

    if preset == "dramatic":
        # Single hard key, barely-there fill, almost-black ambient
        return (
            f'{{ const L = new THREE.DirectionalLight("#fff4e8", 4.5); '
            f'L.position.set(8, 10, 3); {sc} scene.add(L); }}\n'
            '      { const L = new THREE.DirectionalLight("#1a2040", 0.15); '
            'L.position.set(-8, -2, -5); scene.add(L); }\n'
            '      scene.add(new THREE.AmbientLight("#020205", 0.08));'
        )

    # default: studio — 3-point (key + fill + rim + ambient)
    return (
        f'{{ const L = new THREE.DirectionalLight("#ffffff", 2.5); '
        f'L.position.set(5, 8, 5); {sc} scene.add(L); }}\n'
        '      { const L = new THREE.DirectionalLight("#b8d4ff", 0.4); '
        'L.position.set(-5, 2, -3); scene.add(L); }\n'
        '      { const L = new THREE.DirectionalLight("#ffeedd", 0.6); '
        'L.position.set(-2, 4, -8); scene.add(L); }\n'
        '      scene.add(new THREE.AmbientLight("#ffffff", 0.25));'
    )


def _accent_lights_js(scene: Scene) -> str:
    """Emit only model-specified point lights at 70% intensity as colour accents."""
    lines = []
    for l in scene.lights:
        if l.type == "point":
            x, y, z = l.position
            c = f'"{l.color}"'
            intensity = round(l.intensity * 0.7, 3)
            lines.append(
                f"{{ const L = new THREE.PointLight({c}, {intensity}); "
                f"L.position.set({x}, {y}, {z}); scene.add(L); }}"
            )
    return "\n      ".join(lines)


def animation_js(a: Animation) -> str:
    if a.type == "none":
        return ""
    if a.type == "rotate":
        return f"group.rotation.{a.axis} += 0.01 * {a.speed};"
    if a.type == "float":
        return f"group.position.y = Math.sin(t * {a.speed}) * 0.3;"
    if a.type == "orbit":
        return (f"group.rotation.y += 0.01 * {a.speed}; "
                f"group.position.x = Math.sin(t * {a.speed}) * 0.5;")
    return ""


# ---- Extrude shape-path library ----
# Each function returns a list of JS lines that build `const _shp = new THREE.Shape(); ...`
# All paths are defined in a unit-scale coordinate space (max extent ~2 units) so that
# bevel values (0.03) and depth (node.depth) are scale-consistent across all shapes.
# geometry.center() + uniform scale to 1.5 normalise every shape to the same apparent size.

def _shp_star() -> list:
    return [
        "const _shp = new THREE.Shape();",
        "const _outerR = 1.0, _innerR = 0.4, _pts = 5;",
        "for (let _i = 0; _i < _pts * 2; _i++) {",
        "  const _r = _i % 2 === 0 ? _outerR : _innerR;",
        "  const _a = (_i / (_pts * 2)) * Math.PI * 2 - Math.PI / 2;",
        "  _shp[_i === 0 ? 'moveTo' : 'lineTo'](Math.cos(_a) * _r, Math.sin(_a) * _r);",
        "}",
        "_shp.closePath();",
    ]


def _shp_heart() -> list:
    # Original Three.js docs heart path scaled by 1/50 → fits in ~[-0.6,1.6] × [0,1.9]
    return [
        "const _shp = new THREE.Shape();",
        "_shp.moveTo(0.5, 0.5);",
        "_shp.bezierCurveTo(0.5, 0.5, 0.4, 0, 0, 0);",
        "_shp.bezierCurveTo(-0.6, 0, -0.6, 0.7, -0.6, 0.7);",
        "_shp.bezierCurveTo(-0.6, 1.1, -0.2, 1.54, 0.5, 1.9);",
        "_shp.bezierCurveTo(1.2, 1.54, 1.6, 1.1, 1.6, 0.7);",
        "_shp.bezierCurveTo(1.6, 0.7, 1.6, 0, 1.0, 0);",
        "_shp.bezierCurveTo(0.7, 0, 0.5, 0.5, 0.5, 0.5);",
    ]


def _shp_hexagon() -> list:
    return [
        "const _shp = new THREE.Shape();",
        "for (let _i = 0; _i < 6; _i++) {",
        "  const _a = (Math.PI / 3) * _i + Math.PI / 6;",  # flat-top orientation
        "  _shp[_i === 0 ? 'moveTo' : 'lineTo'](Math.cos(_a), Math.sin(_a));",
        "}",
        "_shp.closePath();",
    ]


def _shp_badge() -> list:
    # Rounded rectangle — w=1.6, h=1.0, corner radius=0.25
    return [
        "const _shp = new THREE.Shape();",
        "const _bw = 1.6, _bh = 1.0, _br = 0.25;",
        "const _bx = -_bw / 2, _by = -_bh / 2;",
        "_shp.moveTo(_bx, _by + _br);",
        "_shp.lineTo(_bx, _by + _bh - _br);",
        "_shp.quadraticCurveTo(_bx, _by + _bh, _bx + _br, _by + _bh);",
        "_shp.lineTo(_bx + _bw - _br, _by + _bh);",
        "_shp.quadraticCurveTo(_bx + _bw, _by + _bh, _bx + _bw, _by + _bh - _br);",
        "_shp.lineTo(_bx + _bw, _by + _br);",
        "_shp.quadraticCurveTo(_bx + _bw, _by, _bx + _bw - _br, _by);",
        "_shp.lineTo(_bx + _br, _by);",
        "_shp.quadraticCurveTo(_bx, _by, _bx, _by + _br);",
    ]


def _shp_shield() -> list:
    # Heraldic heater shield: flat top, two curved sides, tapers to bottom point
    # x ∈ [-1, 1], y ∈ [-1.3, 1.0]
    return [
        "const _shp = new THREE.Shape();",
        "_shp.moveTo(-1.0, 1.0);",
        "_shp.lineTo( 1.0, 1.0);",
        "_shp.lineTo( 1.0, 0.2);",
        "_shp.quadraticCurveTo( 1.0, -0.8,  0.0, -1.3);",
        "_shp.quadraticCurveTo(-1.0, -0.8, -1.0,  0.2);",
        "_shp.lineTo(-1.0, 1.0);",
    ]


SHAPE_LIBRARY: Dict[str, Any] = {
    "star":    _shp_star,
    "heart":   _shp_heart,
    "hexagon": _shp_hexagon,
    "badge":   _shp_badge,
    "shield":  _shp_shield,
}


def extrude_js(node: ExtrudeNode, idx: int, style: str = "realistic",
               parent: str = "group") -> list:
    """Return JS lines for one extruded shape mesh, self-contained in a block scope."""
    shape_fn = SHAPE_LIBRARY.get(node.shape, _shp_badge)
    mat = material_js(node, style)  # type: ignore[arg-type]
    bevel = "true" if node.bevel else "false"
    depth = node.depth
    px, py, pz = node.position
    rx, ry, rz = node.rotation
    sx, sy, sz = node.scale

    lines = ["{  // extrude: " + node.shape]
    lines.extend("  " + l for l in shape_fn())
    lines += [
        f"  const _geo = new THREE.ExtrudeGeometry(_shp, {{",
        f"    depth: {depth}, bevelEnabled: {bevel},",
        f"    bevelThickness: 0.03, bevelSize: 0.03, bevelSegments: 3,",
        f"    curveSegments: 12, steps: 1",
        f"  }});",
        f"  _geo.center();",
        f"  _geo.computeBoundingBox();",
        f"  const _mxdim = Math.max(",
        f"    _geo.boundingBox.max.x - _geo.boundingBox.min.x,",
        f"    _geo.boundingBox.max.y - _geo.boundingBox.min.y,",
        f"    _geo.boundingBox.max.z - _geo.boundingBox.min.z",
        f"  ) || 1;",
        f"  const _nsc = 1.5 / _mxdim;",
        f"  _geo.scale(_nsc, _nsc, _nsc);",
        f"  const mesh{idx} = new THREE.Mesh(_geo, {mat});",
        f"  mesh{idx}.position.set({px}, {py}, {pz});",
        f"  mesh{idx}.rotation.set({rx}, {ry}, {rz});",
        f"  mesh{idx}.scale.set({sx}, {sy}, {sz});",
        f"  {parent}.add(mesh{idx});",
        "}",
    ]
    return lines


# ---- Layout resolver ----

def _offset_node(node: Any, axis: int, delta: float) -> Any:
    """Return a copy of node with position[axis] shifted by delta."""
    pos = list(node.position)
    pos[axis] += delta
    return node.model_copy(update={"position": pos})


def _node_axis_size(node: Any, axis: int) -> float:
    """Estimate the bounding-box size of a node along one axis (0=x,1=y,2=z)."""
    if isinstance(node, Obj):
        return _shape_extent(node.shape, node.params)[axis]
    if isinstance(node, ExtrudeNode):
        return 1.5  # normalised to 1.5-unit max dimension at render time
    if isinstance(node, Text3DNode):
        if axis == 0:  # x: rough width (0.6 units per char at size 1)
            return max(node.size * len(node.text) * 0.6, node.size)
        if axis == 1:  # y: cap height
            return node.size * 1.2
        return node.depth + 0.05  # z
    if isinstance(node, LayoutStack):
        ai = {"x": 0, "y": 1, "z": 2}.get(node.axis, 1)
        sizes = [_node_axis_size(c, ai) for c in node.children]
        return sum(sizes) + max(0, len(sizes) - 1) * node.gap if sizes else 1.0
    if isinstance(node, GroupNode):
        if not node.children:
            return 1.0
        sizes = [_node_axis_size(c, axis) for c in node.children]
        if node.layout == "row" and axis == 0:
            return sum(sizes) + max(0, len(node.children) - 1) * node.gap
        if node.layout in ("column", "stack") and axis == 1:
            return sum(sizes) + max(0, len(node.children) - 1) * node.gap
        return max(sizes)
    return 1.0


def _group_layout_children(node: GroupNode) -> list:
    """Return children repositioned according to node.layout."""
    children = node.children
    if not children or node.layout == "none":
        return children
    if node.layout == "row":
        return _layout_axis_children(children, axis=0, gap=node.gap)
    if node.layout in ("column", "stack"):
        return _layout_axis_children(children, axis=1, gap=node.gap)
    if node.layout == "grid":
        return _layout_grid_children(children, cols=node.cols, gap=node.gap)
    return children


def _layout_axis_children(children: list, axis: int, gap: float) -> list:
    """Center children along one axis with gap spacing between them."""
    sizes = [_node_axis_size(c, axis) for c in children]
    total = sum(sizes) + max(0, len(sizes) - 1) * gap
    cursor = -total / 2.0
    result = []
    for child, size in zip(children, sizes):
        result.append(_offset_node(child, axis, cursor + size / 2.0))
        cursor += size + gap
    return result


def _layout_grid_children(children: list, cols: int, gap: float) -> list:
    """Lay out children in a grid on the x-z plane, centered at origin."""
    cols = max(1, cols)
    rows = (len(children) + cols - 1) // cols
    result = []
    for i, child in enumerate(children):
        x = (i % cols - (cols - 1) / 2.0) * gap
        z = (i // cols - (rows - 1) / 2.0) * gap
        result.append(_offset_node(_offset_node(child, 0, x), 2, z))
    return result


def _flatten(items: list, ox: float = 0.0, oy: float = 0.0, oz: float = 0.0) -> list:
    """Recursively resolve layout containers into a flat list of positioned leaf nodes."""
    result = []
    for item in items:
        if isinstance(item, (Obj, ExtrudeNode, Text3DNode)):
            result.append(item.model_copy(update={
                "position": [item.position[0] + ox,
                             item.position[1] + oy,
                             item.position[2] + oz]
            }))
        elif isinstance(item, LayoutStack):
            result.extend(_flatten_stack(item, ox, oy, oz))
        elif isinstance(item, LayoutRow):
            fake = LayoutStack(axis="x", gap=item.gap,
                               position=item.position, children=item.children)
            result.extend(_flatten_stack(fake, ox, oy, oz))
        elif isinstance(item, LayoutGrid):
            result.extend(_flatten_grid(item, ox, oy, oz))
        elif isinstance(item, GroupNode):
            # Flatten GroupNode: apply layout + group position offset (rotation ignored)
            gx = item.position[0] + ox
            gy = item.position[1] + oy
            gz = item.position[2] + oz
            result.extend(_flatten(_group_layout_children(item), gx, gy, gz))
    return result


def _flatten_stack(stack: LayoutStack, ox: float, oy: float, oz: float) -> list:
    ai = {"x": 0, "y": 1, "z": 2}.get(stack.axis, 1)
    base = [stack.position[0] + ox, stack.position[1] + oy, stack.position[2] + oz]
    sizes = [_node_axis_size(c, ai) for c in stack.children]
    total = sum(sizes) + max(0, len(sizes) - 1) * stack.gap
    cursor = -total / 2.0
    result = []
    for child, size in zip(stack.children, sizes):
        off = list(base)
        off[ai] += cursor + size / 2.0
        cursor += size + stack.gap
        result.extend(_flatten([child], *off))
    return result


def _flatten_grid(grid: LayoutGrid, ox: float, oy: float, oz: float) -> list:
    base = [grid.position[0] + ox, grid.position[1] + oy, grid.position[2] + oz]
    cols = max(1, grid.cols)
    rows = (len(grid.children) + cols - 1) // cols
    sx = -(cols - 1) * grid.gap_x / 2.0
    sz = -(rows - 1) * grid.gap_z / 2.0
    result = []
    for i, child in enumerate(grid.children):
        off = [base[0] + sx + (i % cols) * grid.gap_x,
               base[1],
               base[2] + sz + (i // cols) * grid.gap_z]
        result.extend(_flatten([child], *off))
    return result


TEMPLATE = """<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>ThreeGen preview</title>
<style>
  html, body { margin: 0; height: 100%; overflow: hidden; background: __BG__; }
  canvas { display: block; }
</style>
<script type="importmap">
{
  "imports": {
    "three": "https://cdn.jsdelivr.net/npm/three@0.160.0/build/three.module.js",
    "three/addons/": "https://cdn.jsdelivr.net/npm/three@0.160.0/examples/jsm/"
  }
}
</script>
</head>
<body>
<script type="module">
  import * as THREE from 'three';
  import { OrbitControls }      from 'three/addons/controls/OrbitControls.js';
  import { EffectComposer }     from 'three/addons/postprocessing/EffectComposer.js';
  import { RenderPass }         from 'three/addons/postprocessing/RenderPass.js';
  import { UnrealBloomPass }    from 'three/addons/postprocessing/UnrealBloomPass.js';
  import { OutputPass }         from 'three/addons/postprocessing/OutputPass.js';
  import { RoundedBoxGeometry } from 'three/addons/geometries/RoundedBoxGeometry.js';
  import { RoomEnvironment }    from 'three/addons/environments/RoomEnvironment.js';
  import { FontLoader }         from 'three/addons/loaders/FontLoader.js';
  import { TextGeometry }       from 'three/addons/geometries/TextGeometry.js';

  const scene = new THREE.Scene();
  scene.background = new THREE.Color('__BG__');

  const camera = new THREE.PerspectiveCamera(
    50, window.innerWidth / window.innerHeight, 0.1, 100);
  camera.position.set(3, 2, 4);

  const renderer = new THREE.WebGLRenderer({ antialias: true });
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
  renderer.toneMapping        = THREE.ACESFilmicToneMapping;
  renderer.toneMappingExposure = 1.1;
  renderer.outputColorSpace   = THREE.SRGBColorSpace;
  renderer.shadowMap.enabled  = __USE_SHADOWS__;
  renderer.shadowMap.type     = THREE.PCFSoftShadowMap;
  document.body.appendChild(renderer.domElement);

  // ---- environment map: gives metals/glass real reflections ----
  const pmrem = new THREE.PMREMGenerator(renderer);
  scene.environment = pmrem.fromScene(new RoomEnvironment(), 0.04).texture;
  pmrem.dispose();

  const controls = new OrbitControls(camera, renderer.domElement);
  controls.enableDamping = true;

  const group = new THREE.Group();
  scene.add(group);

  // ---- lighting preset ----
      __PRESET_LIGHTS__

  // ---- model accent point-lights ----
      __ACCENT_LIGHTS__

  // ---- bloom + output post-processing ----
  const USE_BLOOM      = __USE_BLOOM__;
  const BLOOM_STRENGTH = __BLOOM_STRENGTH__;
  const composer = new EffectComposer(renderer);
  composer.addPass(new RenderPass(scene, camera));
  composer.addPass(new UnrealBloomPass(
    new THREE.Vector2(window.innerWidth, window.innerHeight),
    BLOOM_STRENGTH, 0.4, 0.0
  ));
  composer.addPass(new OutputPass());

  const clock = new THREE.Clock();
  function animate() {
    requestAnimationFrame(animate);
    const t = clock.getElapsedTime();
      __ANIM__
    controls.update();
    if (USE_BLOOM) composer.render();
    else renderer.render(scene, camera);
  }

  window.addEventListener('resize', () => {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(window.innerWidth, window.innerHeight);
    composer.setSize(window.innerWidth, window.innerHeight);
  });

  // ---- build scene (async so FontLoader can be awaited for text3d nodes) ----
  (async () => {
    // ---- sync objects (primitives + extrude) ----
      __OBJECTS__

__TEXT_SECTION__
    // ---- shadow casting on every mesh ----
    if (__USE_SHADOWS__) {
      group.traverse(o => { if (o.isMesh) { o.castShadow = true; o.receiveShadow = true; } });
    }

    // ---- auto-frame camera + contact-shadow ground plane ----
    const _box = new THREE.Box3().setFromObject(group);
    if (!_box.isEmpty()) {
      const _sz  = _box.getSize(new THREE.Vector3());
      const _ctr = _box.getCenter(new THREE.Vector3());
      const maxDim = Math.max(_sz.x, _sz.y, _sz.z) || 1;
      const fov  = camera.fov * (Math.PI / 180);
      const dist = (maxDim / 2) / Math.tan(fov / 2) * 1.6;
      camera.position.set(_ctr.x + dist * 0.7, _ctr.y + dist * 0.45, _ctr.z + dist);
      camera.near = dist / 100;
      camera.far  = dist * 100;
      camera.updateProjectionMatrix();
      controls.target.copy(_ctr);
      controls.update();

      if (__USE_SHADOWS__) {
        const gnd = new THREE.Mesh(
          new THREE.PlaneGeometry(maxDim * 8, maxDim * 8),
          new THREE.ShadowMaterial({ opacity: 0.35, transparent: true })
        );
        gnd.rotation.x    = -Math.PI / 2;
        gnd.position.y    = _box.min.y - 0.005;
        gnd.receiveShadow = true;
        scene.add(gnd);
      }
    }

    animate();
  })().catch(console.error);
</script>
</body>
</html>
"""


def compile_html(
    scene: Scene,
    glow: bool = True,
    glow_strength: float = 0.9,
    style: str = "realistic",
    lighting: str = "studio",
    shadows: bool = True,
) -> str:
    ctx = _Ctx(style)

    html = TEMPLATE
    html = html.replace("__BG__",             scene.background)
    html = html.replace("__PRESET_LIGHTS__",  _preset_lights_js(lighting, shadows))
    html = html.replace("__ACCENT_LIGHTS__",  _accent_lights_js(scene))
    html = html.replace("__OBJECTS__",        objects_js(scene, ctx))
    html = html.replace("__TEXT_SECTION__",   _text_jobs_js(ctx.text_jobs, style))
    html = html.replace("__ANIM__",           animation_js(scene.animation))
    html = html.replace("__USE_BLOOM__",      "true" if glow else "false")
    html = html.replace("__BLOOM_STRENGTH__", str(float(glow_strength)))
    html = html.replace("__USE_SHADOWS__",    "true" if shadows else "false")
    return html


def iframe(html: str, height: int = 460) -> str:
    """Wrap the standalone HTML as a data-URI iframe for gr.HTML preview."""
    b64 = base64.b64encode(html.encode("utf-8")).decode("ascii")
    return (
        f'<iframe src="data:text/html;base64,{b64}" '
        f'style="width:100%;height:{height}px;border:0;border-radius:12px;" '
        f'sandbox="allow-scripts allow-same-origin"></iframe>'
    )