dynamic-token 0.1.7

use crate::auth_options::AuthOptions;
use crate::{utils::*, MAX_API_KEY_OFFSET};
use simple_string_patterns::StripCharacters;

/// Generate a time-sensitive dynamic key from a shared API key as defined in the options
/// the current millisecond timestamp (encoded, split and injected)
/// some random characters and an optional uuid that can be decoded and used for additional authentication
pub fn to_dynamic_key(options: &AuthOptions, uuid_opt: Option<&str>) -> String {  
  let ts = milliseconds_now(); 
  let ts_list = i64_to_base_36(ts).unwrap_or("".to_string()).chars().rev().collect::<String>();
  let ts_list_36 = base_36_str_to_u64(&ts_list[..1]).unwrap_or(0);
  let is_under = ts_list_36 < usize::MAX as u64;
  let offset = if is_under { (ts_list_36 as usize % MAX_API_KEY_OFFSET) + 2 } else { 0 };
  let mut parts: Vec<String> = vec![];

  let merged_list = [&ts_list.as_str()[..offset], options.key(), &ts_list.as_str()[offset..]].concat();
  let rand_separator = rand_char_as_string(&options.rand_chars());
  let base_str = [merged_list, rand_int_36(3)].join(&rand_separator);
  parts.push(base_str);
  if let Some(uuid) = uuid_opt {     
    if let Some(uid_str) = hex_string_to_base36_parts(&uuid.strip_non_alphanum()) {
      let rand_int_str = rand_int_36(3);
      let rand_separator = rand_char_as_string(&options.rand_chars());
      let uid_part = [uid_str, rand_int_str].join(&rand_separator);
      parts.push(uid_part);
    }
  }
  let key_str = parts.join("__");
  encode_base64(&key_str)
}