from __future__ import annotations

from pathlib import Path
from typing import Any


def geometry_backend_status() -> dict[str, Any]:
    status = {"ocp": False, "cascadio": False, "available": False, "detail": []}
    try:
        import OCP  # noqa: F401

        status["ocp"] = True
        status["detail"].append("OCP import OK")
    except Exception as e:  # noqa: BLE001
        status["detail"].append(f"OCP unavailable: {e}")

    try:
        import cascadio  # noqa: F401

        status["cascadio"] = True
        status["detail"].append("cascadio import OK")
    except Exception as e:  # noqa: BLE001
        status["detail"].append(f"cascadio unavailable: {e}")

    status["available"] = bool(status["ocp"] or status["cascadio"])
    return status


def export_meshes_stub(step_path: Path, meshes_dir: Path, link_names: list[str]) -> dict[str, Any]:
    """MVP mesh export.

    Full per-link tessellation needs OCP/pythonocc. Until then we record
    intended mesh filenames and leave placeholders.
    """
    meshes_dir.mkdir(parents=True, exist_ok=True)
    status = geometry_backend_status()
    created: list[str] = []
    pending: list[str] = []

    if status["cascadio"]:
        try:
            import cascadio

            # Whole-assembly export as a starting point (not per-link).
            out = meshes_dir / "assembly.glb"
            # cascadio API: step_to_glb(in, out) in recent versions
            if hasattr(cascadio, "step_to_glb"):
                cascadio.step_to_glb(str(step_path), str(out))
                created.append(str(out))
            else:
                pending.append("cascadio installed but step_to_glb API not found")
        except Exception as e:  # noqa: BLE001
            pending.append(f"cascadio export failed: {e}")

    for name in link_names:
        target = meshes_dir / f"{name}.stl"
        if not target.exists():
            # Tiny valid-ish ASCII STL placeholder so packages are non-empty.
            target.write_text(
                "solid placeholder\n"
                "  facet normal 0 0 1\n"
                "    outer loop\n"
                "      vertex 0 0 0\n"
                "      vertex 1 0 0\n"
                "      vertex 0 1 0\n"
                "    endloop\n"
                "  endfacet\n"
                "endsolid placeholder\n",
                encoding="utf-8",
            )
            created.append(str(target))
            pending.append(f"{name}.stl is a placeholder triangle (replace after OCCT tessellation)")

    return {"backend": status, "created": created, "pending": pending}