/**
 * @file gui.cpp
 * @brief Contains code for GUI-related logic.
 *
 * Copyright (C) 2021 Clyne Sullivan
 *
 * Distributed under the GNU GPL v3 or later. You should have received a copy of
 * the GNU General Public License along with this program.
 * If not, see <https://www.gnu.org/licenses/>.
 */

#include "imgui.h"
#include "backends/imgui_impl_sdl.h"
#include "backends/imgui_impl_opengl2.h"

#include "config.h"

#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>

ImFont *font = nullptr;
static ImGuiIO *io = nullptr;
static SDL_Window *window = nullptr;
static decltype(SDL_GL_CreateContext(nullptr)) gl_context;

bool guiInitialize()
{
    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        printf("Error: %s\n", SDL_GetError());
        return false;
    }

    // Setup window
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
    SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
    window = SDL_CreateWindow("stmdsp gui",
        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
        WINDOW_WIDTH, WINDOW_HEIGHT,
        SDL_WINDOW_OPENGL /*| SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI*/);
    gl_context = SDL_GL_CreateContext(window);
    SDL_GL_MakeCurrent(window, gl_context);
    SDL_GL_SetSwapInterval(1); // Enable vsync

    // Setup Dear ImGui context
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    io = &ImGui::GetIO();
    io->ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
    font = io->Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf", 20);
    ImGui::StyleColorsLight();

    ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
    ImGui_ImplOpenGL2_Init();

    return true;
}

void guiRender(void (*func)())
{
   glViewport(0, 0, (int)io->DisplaySize.x, (int)io->DisplaySize.y);
   glClearColor(1, 1, 1, 1);
   glClear(GL_COLOR_BUFFER_BIT);
   func();
   SDL_GL_SwapWindow(window);
}

void guiHandleEvents(bool& done)
{
    SDL_Event event;
    for (SDL_Event event; SDL_PollEvent(&event);) {
        ImGui_ImplSDL2_ProcessEvent(&event);
        if (event.type == SDL_QUIT)
            done = true;
        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
            done = true;
    }
}

void guiShutdown()
{
    ImGui_ImplOpenGL2_Shutdown();
    ImGui_ImplSDL2_Shutdown();
    ImGui::DestroyContext();

    SDL_GL_DeleteContext(gl_context);
    SDL_DestroyWindow(window);
    SDL_Quit();
}