// Copyright 2018 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "tests/DawnTest.h"

#include "utils/ComboRenderPipelineDescriptor.h"
#include "utils/WGPUHelpers.h"

constexpr uint32_t kRTSize = 4;

class DrawIndexedTest : public DawnTest {
  protected:
    void SetUp() override {
        DawnTest::SetUp();

        renderPass = utils::CreateBasicRenderPass(device, kRTSize, kRTSize);

        wgpu::ShaderModule vsModule =
            utils::CreateShaderModule(device, utils::SingleShaderStage::Vertex, R"(
                #version 450
                layout(location = 0) in vec4 pos;
                void main() {
                    gl_Position = pos;
                })");

        wgpu::ShaderModule fsModule =
            utils::CreateShaderModule(device, utils::SingleShaderStage::Fragment, R"(
                #version 450
                layout(location = 0) out vec4 fragColor;
                void main() {
                    fragColor = vec4(0.0, 1.0, 0.0, 1.0);
                })");

        utils::ComboRenderPipelineDescriptor descriptor(device);
        descriptor.vertexStage.module = vsModule;
        descriptor.cFragmentStage.module = fsModule;
        descriptor.primitiveTopology = wgpu::PrimitiveTopology::TriangleStrip;
        descriptor.cVertexState.vertexBufferCount = 1;
        descriptor.cVertexState.cVertexBuffers[0].arrayStride = 4 * sizeof(float);
        descriptor.cVertexState.cVertexBuffers[0].attributeCount = 1;
        descriptor.cVertexState.cAttributes[0].format = wgpu::VertexFormat::Float4;
        descriptor.cColorStates[0].format = renderPass.colorFormat;

        pipeline = device.CreateRenderPipeline(&descriptor);

        vertexBuffer = utils::CreateBufferFromData<float>(
            device, wgpu::BufferUsage::Vertex,
            {// First quad: the first 3 vertices represent the bottom left triangle
             -1.0f, 1.0f, 0.0f, 1.0f, 1.0f, -1.0f, 0.0f, 1.0f, -1.0f, -1.0f, 0.0f, 1.0f, 1.0f, 1.0f,
             0.0f, 1.0f,

             // Second quad: the first 3 vertices represent the top right triangle
             -1.0f, 1.0f, 0.0f, 1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, -1.0f, -1.0f,
             0.0f, 1.0f});
        indexBuffer = utils::CreateBufferFromData<uint32_t>(
            device, wgpu::BufferUsage::Index,
            {0, 1, 2, 0, 3, 1,
             // The indices below are added to test negatve baseVertex
             0 + 4, 1 + 4, 2 + 4, 0 + 4, 3 + 4, 1 + 4});
    }

    utils::BasicRenderPass renderPass;
    wgpu::RenderPipeline pipeline;
    wgpu::Buffer vertexBuffer;
    wgpu::Buffer indexBuffer;

    void Test(uint32_t indexCount,
              uint32_t instanceCount,
              uint32_t firstIndex,
              int32_t baseVertex,
              uint32_t firstInstance,
              uint64_t bufferOffset,
              RGBA8 bottomLeftExpected,
              RGBA8 topRightExpected) {
        wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
        {
            wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass.renderPassInfo);
            pass.SetPipeline(pipeline);
            pass.SetVertexBuffer(0, vertexBuffer);
            pass.SetIndexBuffer(indexBuffer, bufferOffset);
            pass.DrawIndexed(indexCount, instanceCount, firstIndex, baseVertex, firstInstance);
            pass.EndPass();
        }

        wgpu::CommandBuffer commands = encoder.Finish();
        queue.Submit(1, &commands);

        EXPECT_PIXEL_RGBA8_EQ(bottomLeftExpected, renderPass.color, 1, 3);
        EXPECT_PIXEL_RGBA8_EQ(topRightExpected, renderPass.color, 3, 1);
    }
};

// The most basic DrawIndexed triangle draw.
TEST_P(DrawIndexedTest, Uint32) {
    RGBA8 filled(0, 255, 0, 255);
    RGBA8 notFilled(0, 0, 0, 0);

    // Test a draw with no indices.
    Test(0, 0, 0, 0, 0, 0, notFilled, notFilled);
    // Test a draw with only the first 3 indices of the first quad (bottom left triangle)
    Test(3, 1, 0, 0, 0, 0, filled, notFilled);
    // Test a draw with only the last 3 indices of the first quad (top right triangle)
    Test(3, 1, 3, 0, 0, 0, notFilled, filled);
    // Test a draw with all 6 indices (both triangles).
    Test(6, 1, 0, 0, 0, 0, filled, filled);
}

// Test the parameter 'baseVertex' of DrawIndexed() works.
TEST_P(DrawIndexedTest, BaseVertex) {
    RGBA8 filled(0, 255, 0, 255);
    RGBA8 notFilled(0, 0, 0, 0);

    // Test a draw with only the first 3 indices of the second quad (top right triangle)
    Test(3, 1, 0, 4, 0, 0, notFilled, filled);
    // Test a draw with only the last 3 indices of the second quad (bottom left triangle)
    Test(3, 1, 3, 4, 0, 0, filled, notFilled);

    // Test negative baseVertex
    // Test a draw with only the first 3 indices of the first quad (bottom left triangle)
    Test(3, 1, 0, -4, 0, 6 * sizeof(uint32_t), filled, notFilled);
    // Test a draw with only the last 3 indices of the first quad (top right triangle)
    Test(3, 1, 3, -4, 0, 6 * sizeof(uint32_t), notFilled, filled);
}

DAWN_INSTANTIATE_TEST(DrawIndexedTest,
                      D3D12Backend(),
                      MetalBackend(),
                      OpenGLBackend(),
                      VulkanBackend());