// Copyright 2019 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>
#include <array>
#include <cstddef>
#include <cstring>
#include <optional>
#include <vector>

#include <glad/glad.h>

#include "common/logging/log.h"
#include "common/scope_exit.h"
#include "video_core/renderer_opengl/gl_device.h"
#include "video_core/renderer_opengl/gl_resource_manager.h"

namespace OpenGL {

namespace {

// One uniform block is reserved for emulation purposes
constexpr u32 ReservedUniformBlocks = 1;

constexpr u32 NumStages = 5;

constexpr std::array LimitUBOs = {GL_MAX_VERTEX_UNIFORM_BLOCKS, GL_MAX_TESS_CONTROL_UNIFORM_BLOCKS,
                                  GL_MAX_TESS_EVALUATION_UNIFORM_BLOCKS,
                                  GL_MAX_GEOMETRY_UNIFORM_BLOCKS, GL_MAX_FRAGMENT_UNIFORM_BLOCKS};

constexpr std::array LimitSSBOs = {
    GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS, GL_MAX_TESS_CONTROL_SHADER_STORAGE_BLOCKS,
    GL_MAX_TESS_EVALUATION_SHADER_STORAGE_BLOCKS, GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS,
    GL_MAX_FRAGMENT_SHADER_STORAGE_BLOCKS};

constexpr std::array LimitSamplers = {
    GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS, GL_MAX_TESS_CONTROL_TEXTURE_IMAGE_UNITS,
    GL_MAX_TESS_EVALUATION_TEXTURE_IMAGE_UNITS, GL_MAX_GEOMETRY_TEXTURE_IMAGE_UNITS,
    GL_MAX_TEXTURE_IMAGE_UNITS};

constexpr std::array LimitImages = {GL_MAX_VERTEX_IMAGE_UNIFORMS,
                                    GL_MAX_TESS_CONTROL_IMAGE_UNIFORMS,
                                    GL_MAX_TESS_EVALUATION_IMAGE_UNIFORMS,
                                    GL_MAX_GEOMETRY_IMAGE_UNIFORMS, GL_MAX_FRAGMENT_IMAGE_UNIFORMS};

template <typename T>
T GetInteger(GLenum pname) {
    GLint temporary;
    glGetIntegerv(pname, &temporary);
    return static_cast<T>(temporary);
}

bool TestProgram(const GLchar* glsl) {
    const GLuint shader{glCreateShaderProgramv(GL_VERTEX_SHADER, 1, &glsl)};
    GLint link_status;
    glGetProgramiv(shader, GL_LINK_STATUS, &link_status);
    glDeleteProgram(shader);
    return link_status == GL_TRUE;
}

std::vector<std::string_view> GetExtensions() {
    GLint num_extensions;
    glGetIntegerv(GL_NUM_EXTENSIONS, &num_extensions);
    std::vector<std::string_view> extensions;
    extensions.reserve(num_extensions);
    for (GLint index = 0; index < num_extensions; ++index) {
        extensions.push_back(
            reinterpret_cast<const char*>(glGetStringi(GL_EXTENSIONS, static_cast<GLuint>(index))));
    }
    return extensions;
}

bool HasExtension(const std::vector<std::string_view>& images, std::string_view extension) {
    return std::find(images.begin(), images.end(), extension) != images.end();
}

u32 Extract(u32& base, u32& num, u32 amount, std::optional<GLenum> limit = {}) {
    ASSERT(num >= amount);
    if (limit) {
        amount = std::min(amount, GetInteger<u32>(*limit));
    }
    num -= amount;
    return std::exchange(base, base + amount);
}

std::array<Device::BaseBindings, Tegra::Engines::MaxShaderTypes> BuildBaseBindings() noexcept {
    std::array<Device::BaseBindings, Tegra::Engines::MaxShaderTypes> bindings;

    static std::array<std::size_t, 5> stage_swizzle = {0, 1, 2, 3, 4};
    const u32 total_ubos = GetInteger<u32>(GL_MAX_UNIFORM_BUFFER_BINDINGS);
    const u32 total_ssbos = GetInteger<u32>(GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS);
    const u32 total_samplers = GetInteger<u32>(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS);

    u32 num_ubos = total_ubos - ReservedUniformBlocks;
    u32 num_ssbos = total_ssbos;
    u32 num_samplers = total_samplers;

    u32 base_ubo = ReservedUniformBlocks;
    u32 base_ssbo = 0;
    u32 base_samplers = 0;

    for (std::size_t i = 0; i < NumStages; ++i) {
        const std::size_t stage = stage_swizzle[i];
        bindings[stage] = {
            Extract(base_ubo, num_ubos, total_ubos / NumStages, LimitUBOs[stage]),
            Extract(base_ssbo, num_ssbos, total_ssbos / NumStages, LimitSSBOs[stage]),
            Extract(base_samplers, num_samplers, total_samplers / NumStages, LimitSamplers[stage])};
    }

    u32 num_images = GetInteger<u32>(GL_MAX_IMAGE_UNITS);
    u32 base_images = 0;

    // Reserve more image bindings on fragment and vertex stages.
    bindings[4].image =
        Extract(base_images, num_images, num_images / NumStages + 2, LimitImages[4]);
    bindings[0].image =
        Extract(base_images, num_images, num_images / NumStages + 1, LimitImages[0]);

    // Reserve the other image bindings.
    const u32 total_extracted_images = num_images / (NumStages - 2);
    for (std::size_t i = 2; i < NumStages; ++i) {
        const std::size_t stage = stage_swizzle[i];
        bindings[stage].image =
            Extract(base_images, num_images, total_extracted_images, LimitImages[stage]);
    }

    // Compute doesn't care about any of this.
    bindings[5] = {0, 0, 0, 0};

    return bindings;
}

} // Anonymous namespace

Device::Device() : base_bindings{BuildBaseBindings()} {
    const std::string_view vendor = reinterpret_cast<const char*>(glGetString(GL_VENDOR));
    const auto renderer = reinterpret_cast<const char*>(glGetString(GL_RENDERER));
    const std::vector extensions = GetExtensions();

    const bool is_nvidia = vendor == "NVIDIA Corporation";
    const bool is_amd = vendor == "ATI Technologies Inc.";
    const bool is_intel = vendor == "Intel";
    const bool is_intel_proprietary = is_intel && std::strstr(renderer, "Mesa") == nullptr;

    uniform_buffer_alignment = GetInteger<std::size_t>(GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT);
    shader_storage_alignment = GetInteger<std::size_t>(GL_SHADER_STORAGE_BUFFER_OFFSET_ALIGNMENT);
    max_vertex_attributes = GetInteger<u32>(GL_MAX_VERTEX_ATTRIBS);
    max_varyings = GetInteger<u32>(GL_MAX_VARYING_VECTORS);
    has_warp_intrinsics = GLAD_GL_NV_gpu_shader5 && GLAD_GL_NV_shader_thread_group &&
                          GLAD_GL_NV_shader_thread_shuffle;
    has_shader_ballot = GLAD_GL_ARB_shader_ballot;
    has_vertex_viewport_layer = GLAD_GL_ARB_shader_viewport_layer_array;
    has_image_load_formatted = HasExtension(extensions, "GL_EXT_shader_image_load_formatted");
    has_variable_aoffi = TestVariableAoffi();
    has_component_indexing_bug = is_amd;
    has_precise_bug = TestPreciseBug();
    has_broken_compute = is_intel_proprietary;
    has_fast_buffer_sub_data = is_nvidia;

    LOG_INFO(Render_OpenGL, "Renderer_VariableAOFFI: {}", has_variable_aoffi);
    LOG_INFO(Render_OpenGL, "Renderer_ComponentIndexingBug: {}", has_component_indexing_bug);
    LOG_INFO(Render_OpenGL, "Renderer_PreciseBug: {}", has_precise_bug);
}

Device::Device(std::nullptr_t) {
    uniform_buffer_alignment = 0;
    max_vertex_attributes = 16;
    max_varyings = 15;
    has_warp_intrinsics = true;
    has_shader_ballot = true;
    has_vertex_viewport_layer = true;
    has_image_load_formatted = true;
    has_variable_aoffi = true;
    has_component_indexing_bug = false;
    has_broken_compute = false;
    has_precise_bug = false;
}

bool Device::TestVariableAoffi() {
    return TestProgram(R"(#version 430 core
// This is a unit test, please ignore me on apitrace bug reports.
uniform sampler2D tex;
uniform ivec2 variable_offset;
out vec4 output_attribute;
void main() {
    output_attribute = textureOffset(tex, vec2(0), variable_offset);
})");
}

bool Device::TestPreciseBug() {
    return !TestProgram(R"(#version 430 core
in vec3 coords;
out float out_value;
uniform sampler2DShadow tex;
void main() {
    precise float tmp_value = vec4(texture(tex, coords)).x;
    out_value = tmp_value;
})");
}

} // namespace OpenGL