library-ts/browser/random/IncrementalIDGenerator.ts

import { RandomEngine } from "./RandomEngine";
import { JSRandomEngine } from "./JSRandomEngine";

export class IncrementalIDGenerator
{ 
  static readonly LETTERS_CHARACTER_SET = 
  "ABCDEFGHIJKLMNOPQRSTUVWYXZabcdefghijklmnopqrstuvwyz";

  static readonly BASE_62_CHARACTER_SET = 
  "ABCDEFGHIJKLMNOPQRSTUVWYXZabcdefghijklmnopqrstuvwyz0123456789";

  static readonly BASE_64_URL_CHARACTER_SET = 
    "ABCDEFGHIJKLMNOPQRSTUVWYXZabcdefghijklmnopqrstuvwyz0123456789-_";

  static readonly BASE_64_CHARACTER_SET = 
    "ABCDEFGHIJKLMNOPQRSTUVWYXZabcdefghijklmnopqrstuvwyz0123456789+/";

  private _set = IncrementalIDGenerator.BASE_64_URL_CHARACTER_SET;
  private _state:number[] = [];

  constructor( set:string = null )
  {
    this._set = set || IncrementalIDGenerator.BASE_64_URL_CHARACTER_SET;
  }

  setState( state:number[] )
  {
    this._state = state;
  }

  private _incrementAt( position:number )
  {
    if ( position >= this._state.length )
    {
      this._state.push( 0 );
    }
    else if ( this._state[ position ] === ( this._set.length - 1 ) )
    {
      this._state[ position ] = 0;
      this._incrementAt( position + 1 );
    }
    else
    {
      this._state[ position ] ++;
    }
  }

  private _getID()
  {
    let id = "";
    
    for ( let i = 0; i < this._state.length; i++ )
    {
      id += this._set[ this._state[ i ] ];
    }

    return id;
  }

  createID()
  {
    this._incrementAt( 0 );
    return this._getID();
  }

  
  
}