CHIP-8/src/Graphics.cpp

//
// Created by ryuuji on 6/20/25.
//

#include "Graphics.h"

#include <array>
#include <iostream>

#include "imgui.h"
#include "imgui_impl_sdl3.h"
#include "imgui_impl_sdlrenderer3.h"

void SDLWindowDestroyer::operator()(SDL_Window* window) const {
    std::cout << "Destroying window" << std::endl;
    SDL_DestroyWindow(window);
}

void SDLRendererDestroyer::operator()(SDL_Renderer* renderer) const {
    std::cout << "Destroying renderer" << std::endl;
    SDL_DestroyRenderer(renderer);
}

void SDLTextureDestroyer::operator()(SDL_Texture* texture) const {
    std::cout << "Destroying texture" << std::endl;
    SDL_DestroyTexture(texture);
}

Graphics::Graphics(std::shared_ptr<MachineState> machine_state): machine_state{std::move(machine_state)},
                                                                 window_width{1920},
                                                                 window_height{1080},
                                                                 chip8_width(64),
                                                                 chip8_height(32),
                                                                 main_scale(1.0f) {}
bool Graphics::init_sdl() {
    SDL_SetAppMetadata("CHIP-8 Emulator", "0.0.1", "fun.skrd.chip8");

    if (!SDL_Init(SDL_INIT_VIDEO)) {
        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
        return false;
    }

    SDL_Window* raw_window = nullptr;
    SDL_Renderer* raw_renderer = nullptr;

    main_scale = SDL_GetDisplayContentScale(SDL_GetPrimaryDisplay());
    SDL_WindowFlags window_flags = SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIDDEN | SDL_WINDOW_HIGH_PIXEL_DENSITY;

    if (!SDL_CreateWindowAndRenderer("CHIP-8 Emulator", window_width * main_scale, window_height * main_scale, window_flags, &raw_window, &raw_renderer)) {
        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
        return false;
    }

    this->window = std::unique_ptr<SDL_Window, SDLWindowDestroyer>(raw_window);
    this->renderer = std::unique_ptr<SDL_Renderer, SDLRendererDestroyer>(raw_renderer);

    SDL_SetRenderVSync(renderer.get(), 1);
    SDL_SetWindowPosition(window.get(), SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
    SDL_ShowWindow(window.get());

    SDL_Texture* raw_texture = SDL_CreateTexture(renderer.get(), SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_STREAMING, chip8_width, chip8_height);
    this->texture = std::unique_ptr<SDL_Texture, SDLTextureDestroyer>(raw_texture);
    SDL_SetTextureScaleMode(texture.get(), SDL_SCALEMODE_NEAREST);

    return true;
}

bool Graphics::init_imgui() {
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();

    ImGuiIO& io = ImGui::GetIO();
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;

    ImGui::StyleColorsDark();
    ImGuiStyle& style = ImGui::GetStyle();
    style.ScaleAllSizes(main_scale);
    style.FontScaleDpi = main_scale;

    ImGui_ImplSDL3_InitForSDLRenderer(window.get(), renderer.get());
    ImGui_ImplSDLRenderer3_Init(renderer.get());

    return true;
}


bool Graphics::init() {
    if (!init_sdl()) {
        return false;
    }

    if (!init_imgui()) {
        return false;
    }

    return true;
}

void Graphics::draw() {
    if (SDL_GetWindowFlags(window.get()) & SDL_WINDOW_MINIMIZED) {
        SDL_Delay(10);
    }

    build_chip8_texture();


    ImGuiIO& io = ImGui::GetIO();

    ImGui_ImplSDLRenderer3_NewFrame();
    ImGui_ImplSDL3_NewFrame();
    ImGui::NewFrame();
    ImGui::DockSpaceOverViewport(0, ImGui::GetMainViewport());

    draw_chip8_widget();

    ImGui::Render();
    SDL_SetRenderScale(renderer.get(), io.DisplayFramebufferScale.x, io.DisplayFramebufferScale.y);
    SDL_SetRenderDrawColor(renderer.get(), 0, 0, 0, 0xFF);
    SDL_RenderClear(renderer.get());

    ImGui_ImplSDLRenderer3_RenderDrawData(ImGui::GetDrawData(), renderer.get());
    SDL_RenderPresent(renderer.get());
}

void Graphics::build_chip8_texture() {
    SDL_Surface* surface = nullptr;
    auto& display = machine_state->display;

    if (SDL_LockTextureToSurface(texture.get(), nullptr, &surface)) {
        SDL_FillSurfaceRect(surface, nullptr, SDL_MapRGB(SDL_GetPixelFormatDetails(surface->format), nullptr, 0, 0, 0));

        for (int i = 0; i < display.size(); i++) {
            if (display[i]) {
                int x = (i % chip8_width);
                int y = (i / chip8_width);

                SDL_Rect rect = {x, y, 1, 1};
                Uint32 color = SDL_MapRGB(
                    SDL_GetPixelFormatDetails(surface->format),
                    nullptr,
                    0,
                    255,
                    0
                );


                SDL_FillSurfaceRect(surface, &rect, color);
            }
        }
        SDL_UnlockTexture(texture.get());
    }
}

void Graphics::draw_chip8_widget() {
    ImGui::Begin("CHIP-8");

    const ImVec2 available_size = ImGui::GetContentRegionAvail();

    int scale_x = static_cast<int>(available_size.x / chip8_width);
    int scale_y = static_cast<int>(available_size.y / chip8_height);
    int scale = std::max(1, std::min(scale_x, scale_y));
    ImVec2 scaled_size(chip8_width * scale, chip8_height * scale);

    ImVec2 cursor_pos = ImGui::GetCursorPos();
    ImVec2 center_offset((available_size.x - scaled_size.x) / 2, (available_size.y - scaled_size.y) / 2);
    ImGui::SetCursorPos(ImVec2(cursor_pos.x + center_offset.x, cursor_pos.y + center_offset.y));

    ImGui::Image((ImTextureID)(intptr_t)texture.get(), scaled_size);
    ImGui::End();
}