main.cpp

#define SDL_MAIN_USE_CALLBACKS 1 // USE CALLBACKS INSTEAD OF THE "main()" FUNCTION

#include <stdlib.h>
#include <time.h>
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include <imgui.h>
#include <imgui_impl_sdl3.h>
#include <imgui_impl_sdlrenderer3.h>

extern "C" {
    #include <Grid.h>
    #include <WilsonMazeGeneration.h>
    #include <AStarPathfinding.h>
}

#define WINDOW_WIDTH 800 + (GRID_PADDING_SIZE * 2)
#define WINDOW_HEIGHT 800 + (GRID_PADDING_SIZE * 2)

typedef struct AppContext {
    SDL_Window* window;
    SDL_Renderer* renderer;
    ImDrawData *data;

    bool isRunning;
    bool hasMaze;
    MazeContext* mazeContext;

    bool showPath;
    bool showGradient;
    PathContext* pathContext;  
    cell* cells;
} AppContext;

// THIS FUNCTION RUNS ONCE AT STARTUP
SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
{
    srand(time(NULL));

    if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS)) {
        SDL_LogError(SDL_LOG_CATEGORY_CUSTOM, "Error %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    // SETUP APP STATE
    AppContext* appContext = (AppContext*) SDL_malloc(sizeof(AppContext));
    appContext->cells = (cell*) malloc(GRID_ARRAY_SIZE * sizeof(cell));
    appContext->isRunning = false;
    appContext->hasMaze = false;
    appContext->showPath = true;
    appContext->showGradient = false;
    if (appContext == NULL) {
        SDL_LogError(SDL_LOG_CATEGORY_CUSTOM, "Error %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }
    *appstate = appContext;

    if (!SDL_CreateWindowAndRenderer("Maze Generation", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &appContext->window, &appContext->renderer)) {
        SDL_LogError(SDL_LOG_CATEGORY_CUSTOM, "Error %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    // SETUP IMGUI
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO &io = ImGui::GetIO();
    io.IniFilename = NULL;
    io.LogFilename = NULL;
    ImGui::StyleColorsDark();

    ImGui_ImplSDL3_InitForSDLRenderer(appContext->window, appContext->renderer);
    ImGui_ImplSDLRenderer3_Init(appContext->renderer);

    // CREATE/DRAW GRID
    CreateGrid(appContext->renderer, appContext->cells);
    
    return SDL_APP_CONTINUE;
}

// THIS FUNCTION RUNS WHEN A NEW EVENT OCCURS (MOUSE INPUT, KEY PRESS, ETC.)
SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event* event) {
    AppContext* appContext = (AppContext*) appstate;
    
    switch (event->type) {
        case SDL_EVENT_QUIT:
            return SDL_APP_SUCCESS;
        case SDL_EVENT_KEY_DOWN:
            switch(event->key.key) {
                case SDLK_ESCAPE:
                    return SDL_APP_SUCCESS;
                case SDLK_KP_BACKSPACE:
                case SDLK_BACKSPACE:
                    appContext->mazeContext = Init_WilsonMaze(appContext->cells);
                    appContext->isRunning = true;
                case SDLK_KP_ENTER:
                case SDLK_RETURN:
                    if(appContext->hasMaze && !appContext->isRunning) {
                        appContext->pathContext = Init_AStarPathfinding(0, (GRID_ARRAY_SIZE - 1), appContext->cells);
                    }
            }
    }

    ImGui_ImplSDL3_ProcessEvent(event);

    return SDL_APP_CONTINUE;
}

// THIS FUNCTION RUNS ONCE PER FRAME
SDL_AppResult SDL_AppIterate(void *appstate) {
    AppContext* appContext = (AppContext*) appstate;

    ImGui_ImplSDLRenderer3_NewFrame();
    ImGui_ImplSDL3_NewFrame();
    ImGui::NewFrame();

    ImGui::SetNextWindowSize(ImVec2(136, 0));
    ImGui::Begin("Control Panel", NULL, ImGuiWindowFlags_NoCollapse);
    if (ImGui::Button("Generate", ImVec2(120, 20))) {
        if(!appContext->isRunning) {
            appContext->mazeContext = Init_WilsonMaze(appContext->cells);
            appContext->isRunning = true;
        }
    }
    if (ImGui::Button("Solve", ImVec2(120, 20))) {
        if(appContext->hasMaze && !appContext->isRunning) {
            appContext->pathContext = Init_AStarPathfinding(0, (GRID_ARRAY_SIZE - 1), appContext->cells);
        }
    }

    ImGui::Checkbox("Path", &appContext->showPath);
    ImGui::Checkbox("Gradient", &appContext->showGradient);

    ImGui::End();

    // RENDERING EACH WILSON'S ALGORITHM WALK ITERATION
    if(appContext->isRunning) {
        if(!Continue_WilsonMaze(appContext->mazeContext, appContext->cells)) {
            appContext->isRunning = false;
            appContext->hasMaze = true;
        }
    }

    // RENDERING
    ImGui::Render();
    DrawGrid(appContext->renderer, appContext->cells, appContext->showPath, appContext->showGradient);
    appContext->data = ImGui::GetDrawData();
    ImGui_ImplSDLRenderer3_RenderDrawData(appContext->data, appContext->renderer);
    SDL_RenderPresent(appContext->renderer);
    
    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void* appstate, SDL_AppResult result) {
    AppContext* appContext = (AppContext*) appstate;

    ImGui_ImplSDLRenderer3_Shutdown();
    ImGui_ImplSDL3_Shutdown();
    ImGui::DestroyContext();

    SDL_DestroyRenderer(appContext->renderer);
    SDL_DestroyWindow(appContext->window);
    SDL_Quit();

    SDL_free(appContext);
}