#include "mesh/Mesh.h"
#include "mesh/MeshDecimator.h"

#include <catch2/catch_test_macros.hpp>
#include <catch2/matchers/catch_matchers_floating_point.hpp>

using simv::mesh::Mesh;
using Catch::Matchers::WithinAbs;

TEST_CASE("Mesh::RecalculateBounds finds AABB", "[mesh]") {
    Mesh m;
    m.positions = {
        {-1.0f, -2.0f, -3.0f},
        { 4.0f,  5.0f,  6.0f},
        { 0.5f,  0.0f,  1.0f},
    };
    m.RecalculateBounds();
    REQUIRE_THAT(m.bboxMin.x, WithinAbs(-1.0f, 1e-6f));
    REQUIRE_THAT(m.bboxMin.y, WithinAbs(-2.0f, 1e-6f));
    REQUIRE_THAT(m.bboxMin.z, WithinAbs(-3.0f, 1e-6f));
    REQUIRE_THAT(m.bboxMax.x, WithinAbs( 4.0f, 1e-6f));
    REQUIRE_THAT(m.bboxMax.y, WithinAbs( 5.0f, 1e-6f));
    REQUIRE_THAT(m.bboxMax.z, WithinAbs( 6.0f, 1e-6f));
}

TEST_CASE("WeldVertices collapses near-duplicate vertices", "[mesh][decimator]") {
    Mesh m;
    // Two triangles sharing an edge with verts placed within tolerance.
    m.positions = {
        {0.0f, 0.0f, 0.0f},
        {1.0f, 0.0f, 0.0f},
        {0.0f, 1.0f, 0.0f},
        {0.0001f, 0.0f, 0.0f},   // ≈ #0
        {1.0001f, 0.0f, 0.0f},   // ≈ #1
        {1.0f, 1.0f, 0.0f},
    };
    m.indices = { 0, 1, 2,  3, 4, 5 };

    simv::mesh::WeldVertices(m, /*tolerance=*/0.01f);

    REQUIRE(m.positions.size() == 4);
    REQUIRE(m.indices.size() == 6);          // both triangles still valid
    // Bounds should match the "real" hull regardless of welding order.
    REQUIRE_THAT(m.bboxMax.x, WithinAbs(1.0001f, 1e-3f));
}

TEST_CASE("WeldVertices drops degenerate triangles", "[mesh][decimator]") {
    Mesh m;
    // One real triangle + a degenerate one (all three verts within tolerance).
    m.positions = {
        {0.0f, 0.0f, 0.0f},
        {1.0f, 0.0f, 0.0f},
        {0.0f, 1.0f, 0.0f},
        {2.0f, 2.0f, 0.0f},
        {2.00005f, 2.0f, 0.0f},
        {2.0f, 2.00005f, 0.0f},
    };
    m.indices = { 0, 1, 2,  3, 4, 5 };

    simv::mesh::WeldVertices(m, /*tolerance=*/0.001f);

    // The degenerate triangle's three verts collapsed to one — that triangle
    // should be removed entirely.
    REQUIRE(m.indices.size() == 3);
}