caexfer 0.1.0

//! Opt-in external Gmsh import gate, enabled by `CAEXFER_GMSH=gmsh`.
use crate::core::{Cell, CellKind, Dataset, Mesh, Point};
use crate::formats::{bdf, msh, stl};
use std::collections::BTreeMap;
use std::fs;
use std::process::Command;

/// Compare original element IDs and ordered original node IDs across readers.
fn cell_tags(mesh: &Mesh) -> BTreeMap<u64, (CellKind, Vec<u64>)> {
    mesh.cells
        .iter()
        .map(|cell| {
            (
                cell.id,
                (
                    cell.kind,
                    cell.connectivity
                        .iter()
                        .map(|&index| mesh.points[index].id)
                        .collect(),
                ),
            )
        })
        .collect()
}

/// Check Gmsh can import a Rust-written binary STL surface.
#[test]
fn gmsh_imports_binary_stl_surface() {
    let Ok(gmsh) = std::env::var("CAEXFER_GMSH") else {
        return;
    };
    let source = std::env::temp_dir().join(format!("caexfer-stl-{}.stl", std::process::id()));
    let resaved = std::env::temp_dir().join(format!("caexfer-stl-{}.msh", std::process::id()));
    let dataset = stl::read_projection(b"solid sample\nfacet normal 0 0 1\nouter loop\nvertex 0 0 0\nvertex 1 0 0\nvertex 0 1 0\nendloop\nendfacet\nendsolid sample\n")
        .unwrap()
        .dataset;
    let mut bytes = Vec::new();
    stl::write_data(&dataset, &mut bytes).unwrap();
    fs::write(&source, bytes).unwrap();
    let output = Command::new(gmsh)
        .arg(&source)
        .args(["-0", "-o"])
        .arg(&resaved)
        .args(["-v", "3"])
        .output()
        .expect("launch Gmsh");
    assert!(
        output.status.success(),
        "{}",
        String::from_utf8_lossy(&output.stderr)
    );
    assert!(resaved.exists());
    let _ = fs::remove_file(source);
    let _ = fs::remove_file(resaved);
}

/// Check Gmsh imports exported MSH 4.1 entities with original IDs.
#[test]
#[allow(clippy::too_many_lines)] // One fixture checks mixed cells and a nodes-only mesh.
fn gmsh_import_preserves_mixed_dimensions_and_original_ids() {
    let Ok(gmsh) = std::env::var("CAEXFER_GMSH") else {
        return;
    };
    let points = vec![
        Point {
            id: 10,
            position: [0., 0., 0.],
        },
        Point {
            id: 20,
            position: [1., 0., 0.],
        },
        Point {
            id: 30,
            position: [0., 1., 0.],
        },
        Point {
            id: 40,
            position: [0., 0., 1.],
        },
    ];
    let cases = [
        (
            "mixed",
            vec![
                Cell {
                    id: 100,
                    kind: CellKind::Line2,
                    connectivity: vec![0, 1],
                    property_id: None,
                },
                Cell {
                    id: 200,
                    kind: CellKind::Triangle3,
                    connectivity: vec![0, 1, 2],
                    property_id: None,
                },
                Cell {
                    id: 300,
                    kind: CellKind::Tet4,
                    connectivity: vec![0, 1, 2, 3],
                    property_id: None,
                },
            ],
        ),
        ("nodes-only", vec![]),
    ];
    for (name, cells) in cases {
        let dataset = Dataset {
            mesh: Mesh {
                points: points.clone(),
                cells,
                ..Mesh::default()
            },
            fields: vec![],
        };
        let directory = std::env::temp_dir();
        let prefix = format!("caexfer-gmsh-{}-{name}", std::process::id());
        let source = directory.join(format!("{prefix}.msh"));
        let resaved = directory.join(format!("{prefix}-resaved.msh"));
        let mut bytes = Vec::new();
        msh::write(&dataset, &mut bytes).unwrap();
        fs::write(&source, bytes).unwrap();
        let output = Command::new(&gmsh)
            .arg(&source)
            .args(["-0", "-o"])
            .arg(&resaved)
            .args(["-v", "3"])
            .output()
            .expect("launch Gmsh");
        assert!(
            output.status.success(),
            "Gmsh rejected {name}: {}",
            String::from_utf8_lossy(&output.stderr)
        );
        let external = fs::read_to_string(&resaved).expect("Gmsh must write ASCII MSH");
        let imported = msh::read(&external).expect("read Gmsh-resaved MSH");
        let original_points: BTreeMap<_, _> = dataset
            .mesh
            .points
            .iter()
            .map(|p| (p.id, p.position))
            .collect();
        let imported_points: BTreeMap<_, _> = imported
            .mesh
            .points
            .iter()
            .map(|p| (p.id, p.position))
            .collect();
        assert_eq!(
            imported_points, original_points,
            "Gmsh changed point IDs or coordinates"
        );
        assert_eq!(
            cell_tags(&imported.mesh),
            cell_tags(&dataset.mesh),
            "Gmsh changed element IDs or connectivity"
        );
        fs::remove_file(source).unwrap();
        fs::remove_file(resaved).unwrap();
    }
}

/// Check Gmsh imports every supported MSH 2.2 linear topology.
#[test]
fn gmsh_imports_msh22_all_linear_topologies() {
    let Ok(gmsh) = std::env::var("CAEXFER_GMSH") else {
        return;
    };
    let mut mesh = bdf::mesh::read(include_bytes!(
        "../../../../tests/fixtures/mixed-linear.bdf"
    ))
    .unwrap()
    .mesh;
    for cell in &mut mesh.cells {
        cell.property_id = None;
    }
    let dataset = Dataset {
        mesh,
        fields: vec![],
    };
    let directory = std::env::temp_dir();
    let source = directory.join(format!("caexfer-gmsh22-{}.msh", std::process::id()));
    let output = directory.join(format!("caexfer-gmsh22-{}-resaved.msh", std::process::id()));
    let mut bytes = Vec::new();
    msh::write_22(&dataset, &mut bytes).unwrap();
    fs::write(&source, bytes).unwrap();
    let result = Command::new(&gmsh)
        .arg(&source)
        .args(["-0", "-o"])
        .arg(&output)
        .args(["-v", "3"])
        .output()
        .expect("launch Gmsh");
    assert!(
        result.status.success(),
        "Gmsh rejected MSH 2.2: {}",
        String::from_utf8_lossy(&result.stderr)
    );
    let reread = msh::read(&fs::read_to_string(&output).unwrap()).unwrap();
    assert_eq!(reread.mesh.points.len(), 9);
    assert_eq!(reread.mesh.cells.len(), 7);
    fs::remove_file(source).unwrap();
    fs::remove_file(output).unwrap();
}