#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/un.h>
#include <sys/socket.h>

#include <sys/select.h>
#include <time.h>
#include <signal.h>
#include <dirent.h>
#include <sys/stat.h>


int initServerSockServer() {
    int server_fd = socket(AF_UNIX, SOCK_STREAM, 0);
    struct sockaddr_un addr = {0};
    addr.sun_family = AF_UNIX;
    strcpy(addr.sun_path, "/tmp/my_wallpaper.sock");
    unlink(addr.sun_path);
    if (server_fd < 0) perror("socket");
    if (bind(server_fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) perror("bind");
    if (listen(server_fd, 5) < 0) perror("listen");
    return server_fd;
}


int last_pid = -1;
void setBackgroundImage(char* path){
    printf("changing wallpaper to %s", path);
    
    int pid = fork();

    if(pid < 0){
        perror("fork error");
        return;
    }

    if(pid == 0) {
        // child
        char *args[] = {"/usr/bin/swaybg", "-m", "fit", "-i", path, "-c", "#000000", NULL};
        execvp("swaybg", args);
    }
    
    if(last_pid > 0){
        usleep(250000);
        printf("INFO: killing %d", last_pid);
        kill(last_pid, SIGTERM);
    }

    last_pid = pid;
}

int image_index = 0;
void runBgSwapNext(char** images, size_t count){
    image_index++;    
    setBackgroundImage(images[image_index%count]);
}

void runBgSwapPrevious(char** images, size_t count){
    image_index--;
    if(image_index < 0) image_index = 0;
    setBackgroundImage(images[image_index%count]);
}

int isImageFile(const char* filename) {
    const char* validExtensions[] = { ".jpg", ".jpeg", ".png", ".gif", ".bmp", ".tiff" };
    size_t numExtensions = sizeof(validExtensions) / sizeof(validExtensions[0]);    
    for (size_t i = 0; i < numExtensions; i++) {
        if (strstr(filename, validExtensions[i])) {
            return 1;
        }
    }
    return 0;
}

#define INITIAL_SIZE 10

void collectImages(const char* path, char*** images, size_t* count) {
    DIR* dir = opendir(path);
    if (dir == NULL) {
        perror("opendir failed");
        return;
    }

    struct dirent* entry;
    while ((entry = readdir(dir)) != NULL) {
        if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
            continue;
        }

        char fullPath[1024];
        snprintf(fullPath, sizeof(fullPath), "%s/%s", path, entry->d_name);

        if (entry->d_type == DT_DIR) {
            collectImages(fullPath, images, count);
        } else if (isImageFile(entry->d_name)) {
            if (*count % INITIAL_SIZE == 0) {
                *images = realloc(*images, (*count + INITIAL_SIZE) * sizeof(char*));
            }
            (*images)[*count] = malloc(strlen(fullPath) + 1);
            strcpy((*images)[*count], fullPath);
            (*count)++;
        }
    }
    closedir(dir);
}

void freeImages(char** images, size_t count) {
    for (size_t i = 0; i < count; i++) {
        free(images[i]);
    }
    free(images);
}

void shuffleImages(char** images, size_t count) {
    srand(time(NULL)); // Seed for random number generation
    for (size_t i = 0; i < count; i++) {
        size_t j = rand() % count;
        // Swap images[i] and images[j]
        char* temp = images[i];
        images[i] = images[j];
        images[j] = temp;
    }
}

int paused_wallpaper = 0;
int static_wallpaper = 0;
char* static_wallpaper_path = NULL;
int timeout_interval = 5;
void handleCommand(char *buff, int n, char** images, size_t image_count){
    if(n < 1){
        perror("ERROR: command missing");
        return;
    }
    printf("INFO: command accepted %c\n", buff[0]);
    
    switch(buff[0]){
    case 't': {
        printf("INFO: time changed to %d\n", buff[1]);
        timeout_interval = (buff[1] << 8) + buff[2];
        
    } break;
    case 'p': {
        paused_wallpaper = 1 - paused_wallpaper;
        printf("INFO: wallpaper is now %s\n", paused_wallpaper ? "paused" : "unpaused");
    } break;
    case 'c': {
        static_wallpaper = 1 - static_wallpaper;
        paused_wallpaper = static_wallpaper;
        if(static_wallpaper && static_wallpaper_path){
            setBackgroundImage(static_wallpaper_path);
        }
        printf("INFO: wallpaper is now %s\n", static_wallpaper ? "static" : "dynamic");
    } break;
    case 'n': {
        printf("INFO: wallpaper is now next");
        runBgSwapNext(images, image_count);
    } break;
    case 'b': {
        printf("INFO: wallpaper is now next");
        runBgSwapPrevious(images, image_count);
    } break;
    case 'i': {
        printf("current wallpaper is: \n%s\n", images[image_index]);
    } break;    
    }
}

int main(int argc, char** argv) {
    printf("INFO: daemon started\n");

    char** images = NULL;
    size_t image_count = 0;

    if(argc < 3){
        printf("usage: %s dirpath filepath\n", argv[0]);
        return 1;
    }

    struct stat stat_buffer;

    if(stat(argv[1], &stat_buffer) != 0){
        printf("dirpath is invalid\n");
        return 1;
    }
    
    if(stat(argv[2], &stat_buffer) != 0){
        printf("filepath is invalid\n");
        return 1;
    }
    static_wallpaper_path = argv[2];
    collectImages(argv[1], &images, &image_count);
    printf("collected %ld suitable images\n", image_count);
    shuffleImages(images, image_count);
    printf("images shuffled\n");
    
    printf("starting server\n");
    int server_fd = initServerSockServer();

    setBackgroundImage(images[0]);
    
    while(1){        
        fd_set fds;
        FD_ZERO(&fds);
        FD_SET(server_fd, &fds);

        struct timeval tv;
        tv.tv_sec = timeout_interval;   // N seconds
        tv.tv_usec = 0;
        int ret = select(server_fd + 1, &fds, NULL, NULL, &tv);

        if (ret < 0) {
            perror("select\n");
            break;
        }

        if (ret == 0) {
            if(!paused_wallpaper){
                runBgSwapNext(images, image_count);
            }
            printf("INFO: periodic task\n");
            continue;
        }
        if (FD_ISSET(server_fd, &fds)) {
            int client = accept(server_fd, NULL, NULL);
            if (client < 0) continue;

            printf("INFO: client connected\n");

            char buf[256];
            int n = read(client, buf, sizeof(buf)-1);
            if (n > 0) {
                buf[n] = 0;
                handleCommand(buf, n, images, image_count);
            }

            close(client);
            printf("INFO: client disconnected\n");
        }
    }

    
    freeImages(images, image_count);
    return 0;
}