#define _DEFAULT_SOURCE // usleep()
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <sys/epoll.h>
#include <sys/inotify.h>
// #include "inotify-syscalls.h"
#include "include/raylib.h"
#include "include/raymath.h"
#include "boids_game.h"

#define SCREEN_WIDTH 1300
#define SCREEN_HEIGHT 1080
#define TARGET_FPS 60

const char *GAME_LIB = "./libboids.so";
char epoll_buf[1024];

struct Game {
    void *handle;
    struct GameApi api;
    struct GameState *state;
};
#define MAX_EVENTS 1

void load_game(struct Game *game) {
    void *handle = dlopen(GAME_LIB, RTLD_NOW);

    if (handle) {
        game->handle = handle; 
        const struct GameApi *api = dlsym(game->handle, "GAME_API");
        if (api != NULL) {
            printf("Loaded API, calling init()\n");
            game->api = *api;
            game->state = game->api.init();
        } else {
            printf("Failed to load API\n");
            dlclose(game->handle);
        }
    } else {
        fprintf(stderr, "Error loading %s\n", GAME_LIB);
        fprintf(stderr, "Error was: %s\n", dlerror());
        exit(1);
    }
}

int main(void) {
    int fd = inotify_init();
    if (fd < 0) {
        fprintf(stderr, "Error initializing inotify\n");
    }
    int wd;
    wd = inotify_add_watch(fd, GAME_LIB, IN_MODIFY);

    // create epoll instance
    int epollfd = epoll_create1(0);
    if (epollfd == -1) {
        fprintf(stderr, "Error creating epoll instance\n");
    }

    struct epoll_event event;
    event.events = EPOLLIN;
    event.data.fd = fd;

    if (epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event) == -1) {
        fprintf(stderr, "Error adding inotify descriptor to epoll\n");
    }

    struct epoll_event events[MAX_EVENTS];

    struct Game game = {0};
    load_game(&game);

    while (!WindowShouldClose()) {
        int nfds = epoll_wait(epollfd, events, MAX_EVENTS, 0);
        if (nfds == -1) {
            fprintf(stderr, "epoll_wait failed\n");
            break;
        }

        for (int n = 0; n < nfds; ++n) {
            if (events[n].data.fd == fd) {
                printf("SO has been updated!\n");
                // This clears the inotify queue so we don't get any more events
                read(fd, epoll_buf, sizeof(epoll_buf));
            }
        }

        game.api.step(game.state);
    }

    inotify_rm_watch(fd, wd);
    close(fd);
    close(epollfd);
    CloseWindow();
}