typedef struct {
    bool is_dir;
    SV name;
    SV full_path;
    struct tm modified_at;
} Library_Entry;

typedef struct {
    Library_Entry *elems;
    size_t count;
    size_t capacity;
} Library_Entries;

/*
 * Helper to format an entry's last modified date into a temporary buffer.
 * The same buffer will be reused the next time this function is called.
 */
static char *format_time(Library_Entry entry) {
    static char time_buffer[32];
    strftime((char*)&time_buffer, 32, "%Y-%m-%dT%H:%M:%S.0000000Z", &entry.modified_at);
    return (char*)time_buffer;
}

static int compare_library_entries(const void *a, const void *b) {
    Library_Entry lea = *(Library_Entry*)a;
    Library_Entry leb = *(Library_Entry*)b;

    if (lea.is_dir && !leb.is_dir) return -1;
    if (!lea.is_dir && leb.is_dir) return 1;

    return noh_sv_compare(lea.name, leb.name);
}

static void set_modified_time(Library_Entry *entry) {
    struct stat attr;
    if (stat(noh_arena_sprintf(&temp, Nsv_Fmt, entry->full_path), &attr) == 0) {
        struct tm *timeinfo = localtime(&attr.st_mtime);
        entry->modified_at = *timeinfo;
    } else {
        entry->modified_at = (struct tm){0};
    }
}

/**
 * Creates a Library entry from a dirent structure.
 */
static bool create_entry(struct dirent *dir_entry, const char *parent_path, Library_Entry *result) {
    SV name = sv(dir_entry->d_name);
    SV parent_path_sv = sv(parent_path);
    Noh_String full_path = build_path(false, false, &parent_path_sv, &name);
    int type = dir_entry->d_type;

    // Check if the entry is relevant.
    if (type != DT_DIR && type != DT_REG) return false;
    if (noh_sv_eq(name, sv(".")) || noh_sv_eq(name, sv(".."))) return false;
    if (type == DT_REG && !noh_sv_ends_with_ci(name, sv(".epub"))) return false;

    // Set entry data.
    result->is_dir = type == DT_DIR;
    result->full_path = noh_sv_from_string(full_path);
    result->name = noh_sv_copy_cstr(&temp, dir_entry->d_name);
    set_modified_time(result);

    return true;
}