/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
                2020, 2021, 2022 Vladimír Vondruš <mosra@centrum.cz>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/

#include <sstream>
#include <Corrade/Containers/Array.h>
#include <Corrade/Containers/StringStl.h> /** @todo remove once Debug is stream-free */
#include <Corrade/Containers/StridedArrayView.h>
#include <Corrade/TestSuite/Tester.h>
#include <Corrade/TestSuite/Compare/Container.h>
#include <Corrade/Utility/DebugStl.h>
#include <Corrade/Utility/FormatStl.h>

#include "Magnum/Math/Matrix4.h"
#include "Magnum/MeshTools/GenerateIndices.h"
#include "Magnum/Trade/MeshData.h"

namespace Magnum { namespace MeshTools { namespace Test { namespace {

struct GenerateIndicesTest: TestSuite::Tester {
    explicit GenerateIndicesTest();

    void primitiveCount();
    void primitiveCountInvalidVertexCount();
    void primitiveCountInvalidPrimitive();

    void generateLineStripIndices();
    template<class T> void generateLineStripIndicesIndexed();
    void generateLineStripIndicesWrongVertexCount();
    void generateLineStripIndicesIntoWrongSize();

    void generateLineLoopIndices();
    template<class T> void generateLineLoopIndicesIndexed();
    void generateLineLoopIndicesWrongVertexCount();
    void generateLineLoopIndicesIntoWrongSize();

    void generateTriangleStripIndices();
    template<class T> void generateTriangleStripIndicesIndexed();
    void generateTriangleStripIndicesWrongVertexCount();
    void generateTriangleStripIndicesIntoWrongSize();

    void generateTriangleFanIndices();
    template<class T> void generateTriangleFanIndicesIndexed();
    void generateTriangleFanIndicesWrongVertexCount();
    void generateTriangleFanIndicesIntoWrongSize();

    template<class T> void generateQuadIndices();
    template<class T> void generateQuadIndicesInto();
    void generateQuadIndicesWrongIndexCount();
    void generateQuadIndicesIndexOutOfBounds();
    void generateQuadIndicesIntoWrongSize();

    void generateIndicesMeshData();
    void generateIndicesMeshDataEmpty();
    void generateIndicesMeshDataMove();
    void generateIndicesMeshDataNoAttributes();
    void generateIndicesMeshDataIndexed();
    void generateIndicesMeshDataInvalidPrimitive();
    void generateIndicesMeshDataInvalidVertexCount();
};

using namespace Math::Literals;

const struct {
    const char* name;
    Matrix4 transformation;
    UnsignedInt remap[4];
    UnsignedInt expected[6*5];
} QuadData[] {
    {"", {}, {0, 1, 2, 3}, {
        0, 2, 3, 0, 3, 4,           // ABC ACD
        9, 5, 6, 9, 6, 7,           // DAB DBC
        10, 11, 14, 10, 14, 15,     // ABC ACD
        19, 16, 17, 19, 17, 18,     // DAB DBC
        20, 21, 22, 20, 22, 23      // ABC ACD
    }},
    {"rotated indices 1", {}, {1, 2, 3, 0}, {
        2, 3, 4, 2, 4, 0,           // BCD BDA (both splits are fine)
        6, 7, 9, 6, 9, 5,           // BCD BDA
        10, 11, 14, 10, 14, 15,     // ABC ACD
        17, 18, 19, 17, 19, 16,     // BCD BDA
        20, 21, 22, 20, 22, 23      // ABC ACD
    }},
    {"rotated indices 2", {}, {2, 3, 0, 1}, {
        3, 4, 0, 3, 0, 2,           // CDA CAB
        6, 7, 9, 6, 9, 5,           // BCD BDA
        14, 15, 10, 14, 10, 11,     // CDA CAB
        17, 18, 19, 17, 19, 16,     // BCD BDA
        22, 23, 20, 22, 20, 21      // CDA CAB
    }},
    {"rotated indices 3", {}, {3, 0, 1, 2}, {
        4, 0, 2, 4, 2, 3,           // DAB DBC (both splits are fine)
        9, 5, 6, 9, 6, 7,           // DAB DBC
        14, 15, 10, 14, 10, 11,     // CDA CAB
        19, 16, 17, 19, 17, 18,     // DAB DBC
        22, 23, 20, 22, 20, 21      // CDA CAB
    }},
    {"reversed indices", {}, {3, 2, 1, 0}, {
        4, 3, 2, 4, 2, 0,           // DCB DBA (both splits are fine)
        9, 7, 6, 9, 6, 5,           // DCB DBA
        10, 15, 14, 10, 14, 11,     // ADC ACB
        19, 18, 17, 19, 17, 16,     // DCB DBA
        20, 23, 22, 20, 22, 21      // ADC ACB
    }},
    {"rotated positions", Matrix4::rotation(130.0_degf, Vector3{1.0f/Constants::sqrt3()}), {0, 1, 2, 3}, {
        0, 2, 3, 0, 3, 4,           // ABC ACD
        9, 5, 6, 9, 6, 7,           // DAB DBC
        10, 11, 14, 10, 14, 15,     // ABC ACD
        19, 16, 17, 19, 17, 18,     // DAB DBC
        20, 21, 22, 20, 22, 23      // ABC ACD
    }},
    {"mirrored positions", Matrix4::scaling(Vector3::xScale(-1.0f)), {0, 1, 2, 3}, {
        0, 2, 3, 0, 3, 4,           // ABC ACD
        9, 5, 6, 9, 6, 7,           // DAB DBC
        10, 11, 14, 10, 14, 15,     // ABC ACD
        19, 16, 17, 19, 17, 18,     // DAB DBC
        20, 21, 22, 20, 22, 23      // ABC ACD
    }}
};

const struct {
    MeshPrimitive primitive;
    Containers::Array<UnsignedInt> indices;
} MeshDataData[] {
    {MeshPrimitive::LineStrip, {InPlaceInit, {
        0, 1,
        1, 2,
        2, 3,
        3, 4
    }}},
    {MeshPrimitive::LineLoop, {InPlaceInit, {
        0, 1,
        1, 2,
        2, 3,
        3, 4,
        4, 0
    }}},
    {MeshPrimitive::TriangleStrip, {InPlaceInit, {
        0, 1, 2,
        2, 1, 3, /* Reversed */
        2, 3, 4
    }}},
    {MeshPrimitive::TriangleFan, {InPlaceInit, {
        0, 1, 2,
        0, 2, 3,
        0, 3, 4
    }}}
};

const struct {
    MeshPrimitive primitive;
    UnsignedInt invalidVertexCount, expectedVertexCount;
} MeshDataInvalidVertexCountData[] {
    {MeshPrimitive::LineStrip, 1, 2},
    {MeshPrimitive::LineLoop, 1, 2},
    {MeshPrimitive::TriangleStrip, 2, 3},
    {MeshPrimitive::TriangleFan, 2, 3}
};

GenerateIndicesTest::GenerateIndicesTest() {
    addTests({&GenerateIndicesTest::primitiveCount,
              &GenerateIndicesTest::primitiveCountInvalidVertexCount,
              &GenerateIndicesTest::primitiveCountInvalidPrimitive,

              &GenerateIndicesTest::generateLineStripIndices,
              &GenerateIndicesTest::generateLineStripIndicesIndexed<UnsignedInt>,
              &GenerateIndicesTest::generateLineStripIndicesIndexed<UnsignedShort>,
              &GenerateIndicesTest::generateLineStripIndicesIndexed<UnsignedByte>,
              &GenerateIndicesTest::generateLineStripIndicesWrongVertexCount,
              &GenerateIndicesTest::generateLineStripIndicesIntoWrongSize,

              &GenerateIndicesTest::generateLineLoopIndices,
              &GenerateIndicesTest::generateLineLoopIndicesIndexed<UnsignedInt>,
              &GenerateIndicesTest::generateLineLoopIndicesIndexed<UnsignedShort>,
              &GenerateIndicesTest::generateLineLoopIndicesIndexed<UnsignedByte>,
              &GenerateIndicesTest::generateLineLoopIndicesWrongVertexCount,
              &GenerateIndicesTest::generateLineLoopIndicesIntoWrongSize,

              &GenerateIndicesTest::generateTriangleStripIndices,
              &GenerateIndicesTest::generateTriangleStripIndicesIndexed<UnsignedInt>,
              &GenerateIndicesTest::generateTriangleStripIndicesIndexed<UnsignedShort>,
              &GenerateIndicesTest::generateTriangleStripIndicesIndexed<UnsignedByte>,
              &GenerateIndicesTest::generateTriangleStripIndicesWrongVertexCount,
              &GenerateIndicesTest::generateTriangleStripIndicesIntoWrongSize,

              &GenerateIndicesTest::generateTriangleFanIndices,
              &GenerateIndicesTest::generateTriangleFanIndicesIndexed<UnsignedInt>,
              &GenerateIndicesTest::generateTriangleFanIndicesIndexed<UnsignedShort>,
              &GenerateIndicesTest::generateTriangleFanIndicesIndexed<UnsignedByte>,
              &GenerateIndicesTest::generateTriangleFanIndicesWrongVertexCount,
              &GenerateIndicesTest::generateTriangleFanIndicesIntoWrongSize});

    addInstancedTests<GenerateIndicesTest>({
        &GenerateIndicesTest::generateQuadIndices<UnsignedInt>,
        &GenerateIndicesTest::generateQuadIndices<UnsignedShort>,
        &GenerateIndicesTest::generateQuadIndices<UnsignedByte>},
        Containers::arraySize(QuadData));

    addTests({&GenerateIndicesTest::generateQuadIndicesInto<UnsignedInt>,
              &GenerateIndicesTest::generateQuadIndicesInto<UnsignedShort>,
              &GenerateIndicesTest::generateQuadIndicesInto<UnsignedByte>,
              &GenerateIndicesTest::generateQuadIndicesWrongIndexCount,
              &GenerateIndicesTest::generateQuadIndicesIndexOutOfBounds,
              &GenerateIndicesTest::generateQuadIndicesIntoWrongSize});

    addInstancedTests({&GenerateIndicesTest::generateIndicesMeshData,
                       &GenerateIndicesTest::generateIndicesMeshDataEmpty},
        Containers::arraySize(MeshDataData));

    addTests({&GenerateIndicesTest::generateIndicesMeshDataMove,
              &GenerateIndicesTest::generateIndicesMeshDataNoAttributes,
              &GenerateIndicesTest::generateIndicesMeshDataIndexed,
              &GenerateIndicesTest::generateIndicesMeshDataInvalidPrimitive});

    addInstancedTests({&GenerateIndicesTest::generateIndicesMeshDataInvalidVertexCount},
        Containers::arraySize(MeshDataInvalidVertexCountData));
}

void GenerateIndicesTest::primitiveCount() {
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Points, 42), 42);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Instances, 13), 13);

    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Lines, 4), 2);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Lines, 14), 7);

    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::LineStrip, 2), 1);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::LineStrip, 4), 3);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::LineStrip, 10), 9);

    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::LineLoop, 2), 2);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::LineLoop, 9), 9);

    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Triangles, 3), 1);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Triangles, 6), 2);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::Triangles, 21), 7);

    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::TriangleStrip, 3), 1);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::TriangleFan, 3), 1);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::TriangleStrip, 7), 5);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::TriangleFan, 7), 5);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::TriangleStrip, 22), 20);
    CORRADE_COMPARE(MeshTools::primitiveCount(MeshPrimitive::TriangleFan, 22), 20);
}

void GenerateIndicesTest::primitiveCountInvalidVertexCount() {
    CORRADE_SKIP_IF_NO_ASSERT();

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::primitiveCount(MeshPrimitive::LineLoop, 1);
    MeshTools::primitiveCount(MeshPrimitive::TriangleStrip, 1);
    MeshTools::primitiveCount(MeshPrimitive::TriangleFan, 2);
    MeshTools::primitiveCount(MeshPrimitive::Lines, 7);
    MeshTools::primitiveCount(MeshPrimitive::Triangles, 14);
    CORRADE_COMPARE(out.str(),
        "MeshTools::primitiveCount(): expected either zero or at least 2 elements for MeshPrimitive::LineLoop, got 1\n"
        "MeshTools::primitiveCount(): expected either zero or at least 3 elements for MeshPrimitive::TriangleStrip, got 1\n"
        "MeshTools::primitiveCount(): expected either zero or at least 3 elements for MeshPrimitive::TriangleFan, got 2\n"
        "MeshTools::primitiveCount(): expected element count to be divisible by 2 for MeshPrimitive::Lines, got 7\n"
        "MeshTools::primitiveCount(): expected element count to be divisible by 3 for MeshPrimitive::Triangles, got 14\n");
}

void GenerateIndicesTest::primitiveCountInvalidPrimitive() {
    CORRADE_SKIP_IF_NO_ASSERT();

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::primitiveCount(MeshPrimitive(0xdead), 2);
    CORRADE_COMPARE(out.str(),
        "MeshTools::primitiveCount(): invalid primitive MeshPrimitive(0xdead)\n");
}

void GenerateIndicesTest::generateLineStripIndices() {
    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(0),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(2),
        Containers::arrayView<UnsignedInt>({
            0, 1
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(5),
        Containers::arrayView<UnsignedInt>({
            0, 1,
            1, 2,
            2, 3,
            3, 4
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(6),
        Containers::arrayView<UnsignedInt>({
            0, 1,
            1, 2,
            2, 3,
            3, 4,
            4, 5
        }), TestSuite::Compare::Container);
}

template<class T> void GenerateIndicesTest::generateLineStripIndicesIndexed() {
    setTestCaseTemplateName(Math::TypeTraits<T>::name());

    /* The second digit is 0, 1, 2, 3, 4, 5 for easier ordering. The output in
       the second digit should then be the same as in
       generateLineStripIndices() above. */
    T indexData[]{60, 21, 72, 93, 44, 85};
    auto indices = Containers::arrayView(indexData);

    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(indices.prefix(std::size_t{})),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(indices.prefix(2)),
        Containers::arrayView<UnsignedInt>({
            60, 21
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(indices.prefix(5)),
        Containers::arrayView<UnsignedInt>({
            60, 21,
            21, 72,
            72, 93,
            93, 44
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateLineStripIndices(indices),
        Containers::arrayView<UnsignedInt>({
            60, 21,
            21, 72,
            72, 93,
            93, 44,
            44, 85
        }), TestSuite::Compare::Container);
}

void GenerateIndicesTest::generateLineStripIndicesWrongVertexCount() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedShort indices[1];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateLineStripIndices(1);
    MeshTools::generateLineStripIndices(indices);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateLineStripIndicesInto(): expected either zero or at least two vertices, got 1\n"
        "MeshTools::generateLineStripIndicesInto(): expected either zero or at least two indices, got 1\n");
}

void GenerateIndicesTest::generateLineStripIndicesIntoWrongSize() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedByte indices[5];
    UnsignedInt output[7];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateLineStripIndicesInto(0, output);
    MeshTools::generateLineStripIndicesInto(Containers::arrayView(indices).prefix(std::size_t{}), output);
    MeshTools::generateLineStripIndicesInto(5, output);
    MeshTools::generateLineStripIndicesInto(indices, output);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateLineStripIndicesInto(): bad output size, expected 0 but got 7\n"
        "MeshTools::generateLineStripIndicesInto(): bad output size, expected 0 but got 7\n"
        "MeshTools::generateLineStripIndicesInto(): bad output size, expected 8 but got 7\n"
        "MeshTools::generateLineStripIndicesInto(): bad output size, expected 8 but got 7\n");
}

void GenerateIndicesTest::generateLineLoopIndices() {
    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(0),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(2),
        Containers::arrayView<UnsignedInt>({
            0, 1,
            1, 0
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(5),
        Containers::arrayView<UnsignedInt>({
            0, 1,
            1, 2,
            2, 3,
            3, 4,
            4, 0
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(6),
        Containers::arrayView<UnsignedInt>({
            0, 1,
            1, 2,
            2, 3,
            3, 4,
            4, 5,
            5, 0
        }), TestSuite::Compare::Container);
}

template<class T> void GenerateIndicesTest::generateLineLoopIndicesIndexed() {
    setTestCaseTemplateName(Math::TypeTraits<T>::name());

    /* The second digit is 0, 1, 2, 3, 4, 5 for easier ordering. The output in
       the second digit should then be the same as in generateLineLoopIndices()
       above. */
    T indexData[]{60, 21, 72, 93, 44, 85};
    auto indices = Containers::arrayView(indexData);

    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(indices.prefix(std::size_t{})),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(indices.prefix(2)),
        Containers::arrayView<UnsignedInt>({
            60, 21,
            21, 60
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(indices.prefix(5)),
        Containers::arrayView<UnsignedInt>({
            60, 21,
            21, 72,
            72, 93,
            93, 44,
            44, 60
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateLineLoopIndices(indices),
        Containers::arrayView<UnsignedInt>({
            60, 21,
            21, 72,
            72, 93,
            93, 44,
            44, 85,
            85, 60
        }), TestSuite::Compare::Container);
}

void GenerateIndicesTest::generateLineLoopIndicesWrongVertexCount() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt indices[1];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateLineLoopIndices(1);
    MeshTools::generateLineLoopIndices(indices);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateLineLoopIndicesInto(): expected either zero or at least two vertices, got 1\n"
        "MeshTools::generateLineLoopIndicesInto(): expected either zero or at least two indices, got 1\n");
}

void GenerateIndicesTest::generateLineLoopIndicesIntoWrongSize() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedShort indices[5];
    UnsignedInt output[9];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateLineLoopIndicesInto(0, output);
    MeshTools::generateLineLoopIndicesInto(Containers::arrayView(indices).prefix(std::size_t{}), output);
    MeshTools::generateLineLoopIndicesInto(5, output);
    MeshTools::generateLineLoopIndicesInto(indices, output);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateLineLoopIndicesInto(): bad output size, expected 0 but got 9\n"
        "MeshTools::generateLineLoopIndicesInto(): bad output size, expected 0 but got 9\n"
        "MeshTools::generateLineLoopIndicesInto(): bad output size, expected 10 but got 9\n"
        "MeshTools::generateLineLoopIndicesInto(): bad output size, expected 10 but got 9\n");
}

void GenerateIndicesTest::generateTriangleStripIndices() {
    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(0),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(3),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(7),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2,
            2, 1, 3, /* Reversed */
            2, 3, 4,
            4, 3, 5, /* Reversed */
            4, 5, 6
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(8),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2,
            2, 1, 3, /* Reversed */
            2, 3, 4,
            4, 3, 5, /* Reversed */
            4, 5, 6,
            6, 5, 7  /* Reversed */
        }), TestSuite::Compare::Container);
}

template<class T> void GenerateIndicesTest::generateTriangleStripIndicesIndexed() {
    setTestCaseTemplateName(Math::TypeTraits<T>::name());

    /* The second digit is 0, 1, 2, 3, 4, 5, 6, 7 for easier ordering. The
       output in the second digit should then be the same as in
       generateTriangleStripIndices() above. */
    T indexData[]{60, 21, 72, 93, 44, 85, 36, 17};
    auto indices = Containers::arrayView(indexData);

    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(indices.prefix(std::size_t{})),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(indices.prefix(3)),
        Containers::arrayView<UnsignedInt>({
            60, 21, 72
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(indices.prefix(7)),
        Containers::arrayView<UnsignedInt>({
            60, 21, 72,
            72, 21, 93, /* Reversed */
            72, 93, 44,
            44, 93, 85, /* Reversed */
            44, 85, 36
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleStripIndices(indices),
        Containers::arrayView<UnsignedInt>({
            60, 21, 72,
            72, 21, 93, /* Reversed */
            72, 93, 44,
            44, 93, 85, /* Reversed */
            44, 85, 36,
            36, 85, 17  /* Reversed */
        }), TestSuite::Compare::Container);
}

void GenerateIndicesTest::generateTriangleStripIndicesWrongVertexCount() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedByte indices[2];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateTriangleStripIndices(2);
    MeshTools::generateTriangleStripIndices(indices);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateTriangleStripIndicesInto(): expected either zero or at least three vertices, got 2\n"
        "MeshTools::generateTriangleStripIndicesInto(): expected either zero or at least three indices, got 2\n");
}

void GenerateIndicesTest::generateTriangleStripIndicesIntoWrongSize() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt indices[5];
    UnsignedInt output[8];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateTriangleStripIndicesInto(0, output);
    MeshTools::generateTriangleStripIndicesInto(Containers::arrayView(indices).prefix(std::size_t{}), output);
    MeshTools::generateTriangleStripIndicesInto(5, output);
    MeshTools::generateTriangleStripIndicesInto(indices, output);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateTriangleStripIndicesInto(): bad output size, expected 0 but got 8\n"
        "MeshTools::generateTriangleStripIndicesInto(): bad output size, expected 0 but got 8\n"
        "MeshTools::generateTriangleStripIndicesInto(): bad output size, expected 9 but got 8\n"
        "MeshTools::generateTriangleStripIndicesInto(): bad output size, expected 9 but got 8\n");
}

void GenerateIndicesTest::generateTriangleFanIndices() {
    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(0),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(3),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(7),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2,
            0, 2, 3,
            0, 3, 4,
            0, 4, 5,
            0, 5, 6
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(8),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2,
            0, 2, 3,
            0, 3, 4,
            0, 4, 5,
            0, 5, 6,
            0, 6, 7
        }), TestSuite::Compare::Container);
}

template<class T> void GenerateIndicesTest::generateTriangleFanIndicesIndexed() {
    setTestCaseTemplateName(Math::TypeTraits<T>::name());

    /* The second digit is 0, 1, 2, 3, 4, 5, 6, 7 for easier ordering. The
       output in the second digit should then be the same as in
       generateTriangleFanIndices() above. */
    T indexData[]{60, 21, 72, 93, 44, 85, 36, 17};
    auto indices = Containers::arrayView(indexData);

    /* Empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(indices.prefix(std::size_t{})),
        Containers::ArrayView<const UnsignedInt>{},
        TestSuite::Compare::Container);

    /* Minimal non-empty input */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(indices.prefix(3)),
        Containers::arrayView<UnsignedInt>({
            60, 21, 72
        }), TestSuite::Compare::Container);

    /* Odd */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(indices.prefix(7)),
        Containers::arrayView<UnsignedInt>({
            60, 21, 72,
            60, 72, 93,
            60, 93, 44,
            60, 44, 85,
            60, 85, 36
        }), TestSuite::Compare::Container);

    /* Even */
    CORRADE_COMPARE_AS(MeshTools::generateTriangleFanIndices(indices),
        Containers::arrayView<UnsignedInt>({
            60, 21, 72,
            60, 72, 93,
            60, 93, 44,
            60, 44, 85,
            60, 85, 36,
            60, 36, 17
        }), TestSuite::Compare::Container);
}

void GenerateIndicesTest::generateTriangleFanIndicesWrongVertexCount() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt indices[2];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateTriangleFanIndices(2);
    MeshTools::generateTriangleFanIndices(indices);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateTriangleFanIndicesInto(): expected either zero or at least three vertices, got 2\n"
        "MeshTools::generateTriangleFanIndicesInto(): expected either zero or at least three indices, got 2\n");
}

void GenerateIndicesTest::generateTriangleFanIndicesIntoWrongSize() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt indices[5];
    UnsignedInt output[8];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateTriangleFanIndicesInto(0, output);
    MeshTools::generateTriangleFanIndicesInto(Containers::arrayView(indices).prefix(std::size_t{}), output);
    MeshTools::generateTriangleFanIndicesInto(5, output);
    MeshTools::generateTriangleFanIndicesInto(indices, output);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateTriangleFanIndicesInto(): bad output size, expected 0 but got 8\n"
        "MeshTools::generateTriangleFanIndicesInto(): bad output size, expected 0 but got 8\n"
        "MeshTools::generateTriangleFanIndicesInto(): bad output size, expected 9 but got 8\n"
        "MeshTools::generateTriangleFanIndicesInto(): bad output size, expected 9 but got 8\n");
}

constexpr Vector3 QuadPositions[] {
    /*
        D    C
                        -> ABC ACD (trivial case)
        A    B
    */
    {0.0f, 0.0f, 0.0f}, {},     // 0
    {1.0f, 0.0f, 0.0f},         // 2
    {1.0f, 1.0f, 0.0f},         // 3
    {0.0f, 1.0f, 0.0f},         // 4

    /*
             D
        A         C     -> DAB DBC (shorter diagonal)
             B
    */
    { 0.0f, 0.0f, 1.0f},        // 5
    { 5.0f, 0.0f, 0.0f},        // 6
    {10.0f, 0.0f, 1.0f}, {},    // 7
    { 5.0f, 0.0f, 2.0f},        // 9

    /*
                D
        A     C         -> ABC ACD (concave)
                B
    */
    {0.0f, 0.5f, 0.0f},         // 10
    {5.0f, 0.0f, 0.0f}, {}, {}, // 11
    {4.0f, 0.5f, 0.0f},         // 14
    {5.0f, 1.0f, 0.0f},         // 15

    /*
                C
        D     B         -> DAB DBC (concave, non-planar)
                A
    */
    {5.0f, 0.0f, 0.5f},         // 16
    {4.0f, 0.5f, 1.0f},         // 17
    {5.0f, 1.0f, 0.5f},         // 18
    {0.0f, 0.5f, 1.0f},         // 19

    /*
                C
        D     B         -> ABC ACD (concave, non-planar, ambiguous -> picking
                A                   shorter diagonal)
    */
    {5.0f, 0.0f, 0.5f},         // 20
    {4.0f, 0.5f, 2.0f},         // 21
    {5.0f, 1.0f, 0.5f},         // 22
    {0.0f, 0.5f, 1.0f},         // 23
};

constexpr UnsignedInt QuadIndices[] {
    0, 2, 3, 4,
    5, 6, 7, 9,
    10, 11, 14, 15,
    16, 17, 18, 19,
    20, 21, 22, 23
};

template<class T> void GenerateIndicesTest::generateQuadIndices() {
    auto&& data = QuadData[testCaseInstanceId()];
    setTestCaseTemplateName(Math::TypeTraits<T>::name());
    setTestCaseDescription(data.name);

    Vector3 transformedPositions[Containers::arraySize(QuadPositions)];
    for(std::size_t i = 0; i != Containers::arraySize(QuadPositions); ++i)
        transformedPositions[i] = data.transformation.transformPoint(QuadPositions[i]);

    T remappedIndices[Containers::arraySize(QuadIndices)];
    for(std::size_t i = 0; i != Containers::arraySize(QuadIndices)/4; ++i)
        for(std::size_t j = 0; j != 4; ++j)
            remappedIndices[i*4 + j] = QuadIndices[i*4 + data.remap[j]];

    Containers::Array<UnsignedInt> triangleIndices =
    MeshTools::generateQuadIndices(transformedPositions, remappedIndices);

    CORRADE_COMPARE_AS(Containers::arrayView(triangleIndices), Containers::arrayView(data.expected), TestSuite::Compare::Container);
}

template<class T> void GenerateIndicesTest::generateQuadIndicesInto() {
    setTestCaseTemplateName(Math::TypeTraits<T>::name());

    /* Simpler variant of the above w/o data transformations just to verify
       everything is passed through as expected */

    T indices[Containers::arraySize(QuadIndices)];
    for(std::size_t i = 0; i != Containers::arraySize(QuadIndices); ++i)
        indices[i] = QuadIndices[i];

    T triangleIndices[Containers::arraySize(QuadIndices)*6/4];
    MeshTools::generateQuadIndicesInto(QuadPositions, indices, triangleIndices);

    CORRADE_COMPARE_AS(Containers::arrayView(triangleIndices), Containers::arrayView<T>({
        0, 2, 3, 0, 3, 4,           // ABC ACD
        9, 5, 6, 9, 6, 7,           // DAB DBC
        10, 11, 14, 10, 14, 15,     // ABC ACD
        19, 16, 17, 19, 17, 18,     // DAB DBC
        20, 21, 22, 20, 22, 23      // ABC ACD
    }), TestSuite::Compare::Container);
}

void GenerateIndicesTest::generateQuadIndicesWrongIndexCount() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt quads[13];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateQuadIndices({}, quads);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateQuadIndicesInto(): quad index count 13 not divisible by 4\n");
}

void GenerateIndicesTest::generateQuadIndicesIndexOutOfBounds() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt quads[]{5, 4, 6, 7};
    Vector3 positions[7];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateQuadIndices(positions, quads);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateQuadIndicesInto(): index 7 out of bounds for 7 elements\n");
}

void GenerateIndicesTest::generateQuadIndicesIntoWrongSize() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedInt quads[12];
    UnsignedInt output[19];

    std::ostringstream out;
    Error redirectError{&out};
    MeshTools::generateQuadIndicesInto({}, quads, output);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateQuadIndicesInto(): bad output size, expected 18 but got 19\n");
}

void GenerateIndicesTest::generateIndicesMeshData() {
    auto&& data = MeshDataData[testCaseInstanceId()];
    {
        std::ostringstream out;
        Debug{&out, Debug::Flag::NoNewlineAtTheEnd} << data.primitive;
        setTestCaseDescription(out.str());
    }

    const struct Vertex {
        Vector2 position;
        Short data[2];
        Vector2 textureCoordinates;
    } vertexData[] {
        {{1.5f, 0.3f}, {28, -15}, {0.2f, 0.8f}},
        {{2.5f, 1.3f}, {29, -16}, {0.3f, 0.7f}},
        {{3.5f, 2.3f}, {30, -17}, {0.4f, 0.6f}},
        {{4.5f, 3.3f}, {40, -18}, {0.5f, 0.5f}},
        {{5.5f, 4.3f}, {41, -19}, {0.6f, 0.4f}}
    };
    Containers::StridedArrayView1D<const Vertex> vertices = vertexData;

    Trade::MeshData mesh{data.primitive, {}, vertexData, {
        Trade::MeshAttributeData{Trade::MeshAttribute::Position,
            vertices.slice(&Vertex::position)},
        /* Array attribute to verify it's correctly propagated */
        Trade::MeshAttributeData{Trade::meshAttributeCustom(42),
            VertexFormat::Short, vertices.slice(&Vertex::data), 2},
        Trade::MeshAttributeData{Trade::MeshAttribute::TextureCoordinates,
            vertices.slice(&Vertex::textureCoordinates)}
    }};

    Trade::MeshData out = generateIndices(mesh);
    CORRADE_VERIFY(out.isIndexed());
    CORRADE_COMPARE(out.indexType(), MeshIndexType::UnsignedInt);
    CORRADE_COMPARE_AS(out.indices<UnsignedInt>(), data.indices,
        TestSuite::Compare::Container);

    CORRADE_COMPARE(out.attributeCount(), 3);
    CORRADE_COMPARE_AS(out.attribute<Vector2>(Trade::MeshAttribute::Position),
        Containers::arrayView<Vector2>({
            {1.5f, 0.3f}, {2.5f, 1.3f}, {3.5f, 2.3f}, {4.5f, 3.3f}, {5.5f, 4.3f}
        }), TestSuite::Compare::Container);

    CORRADE_COMPARE(out.attributeName(1), Trade::meshAttributeCustom(42));
    CORRADE_COMPARE(out.attributeFormat(1), VertexFormat::Short);
    CORRADE_COMPARE(out.attributeArraySize(1), 2);
    CORRADE_COMPARE_AS((Containers::arrayCast<1, const Vector2s>(out.attribute<Short[]>(1))),
        Containers::arrayView<Vector2s>({
            {28, -15}, {29, -16}, {30, -17}, {40, -18}, {41, -19}
        }), TestSuite::Compare::Container);

    CORRADE_COMPARE_AS(out.attribute<Vector2>(Trade::MeshAttribute::TextureCoordinates),
        Containers::arrayView<Vector2>({
            {0.2f, 0.8f}, {0.3f, 0.7f}, {0.4f, 0.6f}, {0.5f, 0.5f}, {0.6f, 0.4f}
        }), TestSuite::Compare::Container);
}

void GenerateIndicesTest::generateIndicesMeshDataEmpty() {
    auto&& data = MeshDataData[testCaseInstanceId()];
    {
        std::ostringstream out;
        Debug{&out, Debug::Flag::NoNewlineAtTheEnd} << data.primitive;
        setTestCaseDescription(out.str());
    }

    /* Similar to generateIndicesMeshData(), just with 0 vertices. Verifying it
       doesn't crash anywhere and produces an empty mesh as well. */

    struct Vertex {
        Vector2 position;
        Short data[2];
        Vector2 textureCoordinates;
    };
    Containers::StridedArrayView1D<const Vertex> vertices;

    Trade::MeshData mesh{data.primitive, {}, nullptr, {
        Trade::MeshAttributeData{Trade::MeshAttribute::Position,
            vertices.slice(&Vertex::position)},
        /* Array attribute to verify it's correctly propagated */
        Trade::MeshAttributeData{Trade::meshAttributeCustom(42),
            VertexFormat::Short,
            vertices.slice(&Vertex::data), 2},
        Trade::MeshAttributeData{Trade::MeshAttribute::TextureCoordinates,
            vertices.slice(&Vertex::textureCoordinates)}
    }};

    Trade::MeshData out = generateIndices(mesh);
    CORRADE_VERIFY(out.isIndexed());
    CORRADE_COMPARE(out.indexCount(), 0);
    CORRADE_COMPARE(out.attributeCount(), 3);
    CORRADE_COMPARE(out.vertexCount(), 0);
}

void GenerateIndicesTest::generateIndicesMeshDataMove() {
    struct Vertex {
        Vector2 position;
        Vector2 textureCoordinates;
    };

    Containers::Array<char> vertexData{5*sizeof(Vertex)};
    auto vertices = Containers::arrayCast<Vertex>(vertexData);
    vertices[0].position = {1.5f, 0.3f};
    vertices[1].position = {2.5f, 1.3f};
    vertices[2].position = {3.5f, 2.3f};
    vertices[3].position = {4.5f, 3.3f};
    vertices[4].position = {5.5f, 4.3f};
    vertices[0].textureCoordinates = {0.2f, 0.8f};
    vertices[1].textureCoordinates = {0.3f, 0.7f};
    vertices[2].textureCoordinates = {0.4f, 0.6f};
    vertices[3].textureCoordinates = {0.5f, 0.5f};
    vertices[4].textureCoordinates = {0.6f, 0.4f};

    Trade::MeshData out = generateIndices(Trade::MeshData{
        MeshPrimitive::TriangleFan, std::move(vertexData), {
            Trade::MeshAttributeData{Trade::MeshAttribute::Position,
                Containers::stridedArrayView(vertices,
                    &vertices[0].position, 5, sizeof(Vertex))},
            Trade::MeshAttributeData{Trade::MeshAttribute::TextureCoordinates,
                Containers::stridedArrayView(vertices,
                    &vertices[0].textureCoordinates, 5, sizeof(Vertex))}
        }});
    CORRADE_VERIFY(out.isIndexed());
    CORRADE_COMPARE(out.indexType(), MeshIndexType::UnsignedInt);
    CORRADE_COMPARE_AS(out.indices<UnsignedInt>(),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2,
            0, 2, 3,
            0, 3, 4
        }), TestSuite::Compare::Container);

    CORRADE_COMPARE(out.attributeCount(), 2);
    CORRADE_COMPARE_AS(out.attribute<Vector2>(Trade::MeshAttribute::Position),
        Containers::arrayView<Vector2>({
            {1.5f, 0.3f}, {2.5f, 1.3f}, {3.5f, 2.3f}, {4.5f, 3.3f}, {5.5f, 4.3f}
        }), TestSuite::Compare::Container);
    CORRADE_COMPARE_AS(out.attribute<Vector2>(Trade::MeshAttribute::TextureCoordinates),
        Containers::arrayView<Vector2>({
            {0.2f, 0.8f}, {0.3f, 0.7f}, {0.4f, 0.6f}, {0.5f, 0.5f}, {0.6f, 0.4f}
        }), TestSuite::Compare::Container);

    /* The vertex data should be moved, not copied */
    CORRADE_COMPARE(out.vertexData().data(), static_cast<void*>(vertices.data()));
}

void GenerateIndicesTest::generateIndicesMeshDataNoAttributes() {
    Trade::MeshData out = generateIndices(Trade::MeshData{MeshPrimitive::TriangleStrip, 4});
    CORRADE_VERIFY(out.isIndexed());
    CORRADE_COMPARE(out.indexType(), MeshIndexType::UnsignedInt);
    CORRADE_COMPARE_AS(out.indices<UnsignedInt>(),
        Containers::arrayView<UnsignedInt>({
            0, 1, 2,
            2, 1, 3, /* Reversed */
        }), TestSuite::Compare::Container);
    CORRADE_COMPARE(out.vertexCount(), 4);
    CORRADE_COMPARE(out.attributeCount(), 0);
}

void GenerateIndicesTest::generateIndicesMeshDataIndexed() {
    CORRADE_SKIP_IF_NO_ASSERT();

    UnsignedByte indices[]{0};
    Trade::MeshData mesh{MeshPrimitive::TriangleFan,
        {}, indices, Trade::MeshIndexData{indices}, 0};

    /* Test both r-value and l-value overload */
    std::ostringstream out;
    Error redirectError{&out};
    generateIndices(mesh);
    generateIndices(Trade::MeshData{MeshPrimitive::TriangleFan,
        {}, indices, Trade::MeshIndexData{indices}, 0});
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateIndices(): mesh data already indexed\n"
        "MeshTools::generateIndices(): mesh data already indexed\n");
}

void GenerateIndicesTest::generateIndicesMeshDataInvalidPrimitive() {
    CORRADE_SKIP_IF_NO_ASSERT();

    Trade::MeshData mesh{MeshPrimitive::Triangles, 2};

    std::ostringstream out;
    Error redirectError{&out};
    generateIndices(mesh);
    CORRADE_COMPARE(out.str(),
        "MeshTools::generateIndices(): invalid primitive MeshPrimitive::Triangles\n");
}

void GenerateIndicesTest::generateIndicesMeshDataInvalidVertexCount() {
    auto&& data = MeshDataInvalidVertexCountData[testCaseInstanceId()];
    std::ostringstream primitiveName;
    Debug{&primitiveName, Debug::Flag::NoNewlineAtTheEnd} << data.primitive;
    setTestCaseDescription(primitiveName.str());

    CORRADE_SKIP_IF_NO_ASSERT();

    Trade::MeshData mesh{data.primitive, data.invalidVertexCount};

    std::ostringstream out;
    Error redirectError{&out};
    generateIndices(mesh);
    CORRADE_COMPARE(out.str(), Utility::formatString(
        "MeshTools::generateIndices(): expected either zero or at least {} vertices for {}, got {}\n", data.expectedVertexCount, primitiveName.str(), data.invalidVertexCount));
}

}}}}

CORRADE_TEST_MAIN(Magnum::MeshTools::Test::GenerateIndicesTest)