#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <libgen.h>
#include <glob.h>
#include <unistd.h>

void to_lowercase_filename(const char *path) {
    // Separate directory and filename
    char path_copy1[1024];
    char path_copy2[1024];
    strncpy(path_copy1, path, sizeof(path_copy1) - 1);
    strncpy(path_copy2, path, sizeof(path_copy2) - 1);

    char *dir = dirname(path_copy1);
    char *base = basename(path_copy2);

    // Convert only the filename part to lowercase
    char new_base[256];
    size_t i;
    for (i = 0; base[i] != '\0' && i < sizeof(new_base) - 1; i++) {
        new_base[i] = tolower((unsigned char)base[i]);
    }
    new_base[i] = '\0';

    // Construct new path
    char new_path[1024];
    if (strcmp(dir, ".") == 0) {
        snprintf(new_path, sizeof(new_path), "%s", new_base);
    } else {
        snprintf(new_path, sizeof(new_path), "%s/%s", dir, new_base);
    }

    // Skip if unchanged
    if (strcmp(path, new_path) == 0) {
        return;
    }

    // Rename file
    if (rename(path, new_path) == 0) {
        printf("Renamed: '%s' -> '%s'\n", path, new_path);
    } else {
        perror("Error renaming file");
    }
}

int main(int argc, char *argv[]) {
    if (argc < 2) {
        fprintf(stderr, "Usage: %s <pattern1> [pattern2 ...]\n", argv[0]);
        fprintf(stderr, "Example: %s \"*.TXT\" \"IMAGE_*.JPG\"\n", argv[0]);
        return 1;
    }

    glob_t glob_result;
    int flags = GLOB_NOCHECK | GLOB_TILDE;

    for (int i = 1; i < argc; i++) {
        // Expand wildcards
        if (glob(argv[i], (i == 1 ? flags : flags | GLOB_APPEND), NULL, &glob_result) != 0) {
            fprintf(stderr, "Error matching pattern: %s\n", argv[i]);
            continue;
        }
    }

    for (size_t i = 0; i < glob_result.gl_pathc; i++) {
        // Process matching regular files only
        if (access(glob_result.gl_pathv[i], F_OK) == 0) {
            to_lowercase_filename(glob_result.gl_pathv[i]);
        }
    }

    globfree(&glob_result);
    return 0;
}