// SPDX-FileCopyrightText: Copyright 2024 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "common/settings.h"
#include "video_core/host_shaders/opengl_present_vert.h"
#include "video_core/renderer_opengl/gl_device.h"
#include "video_core/renderer_opengl/gl_shader_manager.h"
#include "video_core/renderer_opengl/gl_shader_util.h"
#include "video_core/renderer_opengl/present/window_adapt_pass.h"

namespace OpenGL {

namespace {
constexpr GLint PositionLocation = 0;
constexpr GLint TexCoordLocation = 1;
constexpr GLint ModelViewMatrixLocation = 0;

struct ScreenRectVertex {
    constexpr ScreenRectVertex(u32 x, u32 y, GLfloat u, GLfloat v)
        : position{{static_cast<GLfloat>(x), static_cast<GLfloat>(y)}}, tex_coord{{u, v}} {}

    std::array<GLfloat, 2> position;
    std::array<GLfloat, 2> tex_coord;
};

/**
 * Defines a 1:1 pixel orthographic projection matrix with (0,0) on the top-left
 * corner and (width, height) on the lower-bottom.
 *
 * The projection part of the matrix is trivial, hence these operations are represented
 * by a 3x2 matrix.
 */
std::array<GLfloat, 3 * 2> MakeOrthographicMatrix(float width, float height) {
    std::array<GLfloat, 3 * 2> matrix; // Laid out in column-major order

    // clang-format off
    matrix[0] = 2.f / width; matrix[2] =  0.f;          matrix[4] = -1.f;
    matrix[1] = 0.f;         matrix[3] = -2.f / height; matrix[5] =  1.f;
    // Last matrix row is implicitly assumed to be [0, 0, 1].
    // clang-format on

    return matrix;
}
} // namespace

WindowAdaptPass::WindowAdaptPass(const Device& device_, OGLSampler&& sampler_,
                                 std::string_view frag_source)
    : device(device_), sampler(std::move(sampler_)) {
    vert = CreateProgram(HostShaders::OPENGL_PRESENT_VERT, GL_VERTEX_SHADER);
    frag = CreateProgram(frag_source, GL_FRAGMENT_SHADER);

    // Generate VBO handle for drawing
    vertex_buffer.Create();

    // Attach vertex data to VAO
    glNamedBufferData(vertex_buffer.handle, sizeof(ScreenRectVertex) * 4, nullptr, GL_STREAM_DRAW);

    // Query vertex buffer address when the driver supports unified vertex attributes
    if (device.HasVertexBufferUnifiedMemory()) {
        glMakeNamedBufferResidentNV(vertex_buffer.handle, GL_READ_ONLY);
        glGetNamedBufferParameterui64vNV(vertex_buffer.handle, GL_BUFFER_GPU_ADDRESS_NV,
                                         &vertex_buffer_address);
    }
}

WindowAdaptPass::~WindowAdaptPass() = default;

void WindowAdaptPass::DrawToFramebuffer(ProgramManager& program_manager, GLuint texture,
                                        const Layout::FramebufferLayout& layout,
                                        const Common::Rectangle<f32>& crop) {
    glBindTextureUnit(0, texture);

    const std::array ortho_matrix =
        MakeOrthographicMatrix(static_cast<float>(layout.width), static_cast<float>(layout.height));

    program_manager.BindPresentPrograms(vert.handle, frag.handle);
    glProgramUniformMatrix3x2fv(vert.handle, ModelViewMatrixLocation, 1, GL_FALSE,
                                ortho_matrix.data());

    // Map the coordinates to the screen.
    const auto& screen = layout.screen;
    const auto x = screen.left;
    const auto y = screen.top;
    const auto w = screen.GetWidth();
    const auto h = screen.GetHeight();

    const std::array vertices = {
        ScreenRectVertex(x, y, crop.left, crop.top),
        ScreenRectVertex(x + w, y, crop.right, crop.top),
        ScreenRectVertex(x, y + h, crop.left, crop.bottom),
        ScreenRectVertex(x + w, y + h, crop.right, crop.bottom),
    };
    glNamedBufferSubData(vertex_buffer.handle, 0, sizeof(vertices), std::data(vertices));

    glDisable(GL_FRAMEBUFFER_SRGB);
    glViewportIndexedf(0, 0.0f, 0.0f, static_cast<GLfloat>(layout.width),
                       static_cast<GLfloat>(layout.height));

    glEnableVertexAttribArray(PositionLocation);
    glEnableVertexAttribArray(TexCoordLocation);
    glVertexAttribDivisor(PositionLocation, 0);
    glVertexAttribDivisor(TexCoordLocation, 0);
    glVertexAttribFormat(PositionLocation, 2, GL_FLOAT, GL_FALSE,
                         offsetof(ScreenRectVertex, position));
    glVertexAttribFormat(TexCoordLocation, 2, GL_FLOAT, GL_FALSE,
                         offsetof(ScreenRectVertex, tex_coord));
    glVertexAttribBinding(PositionLocation, 0);
    glVertexAttribBinding(TexCoordLocation, 0);
    if (device.HasVertexBufferUnifiedMemory()) {
        glBindVertexBuffer(0, 0, 0, sizeof(ScreenRectVertex));
        glBufferAddressRangeNV(GL_VERTEX_ATTRIB_ARRAY_ADDRESS_NV, 0, vertex_buffer_address,
                               sizeof(vertices));
    } else {
        glBindVertexBuffer(0, vertex_buffer.handle, 0, sizeof(ScreenRectVertex));
    }

    glBindSampler(0, sampler.handle);

    // Update background color before drawing
    glClearColor(Settings::values.bg_red.GetValue() / 255.0f,
                 Settings::values.bg_green.GetValue() / 255.0f,
                 Settings::values.bg_blue.GetValue() / 255.0f, 1.0f);

    glClear(GL_COLOR_BUFFER_BIT);
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}

} // namespace OpenGL