import {RangeDecoder} from './RangeDecoder'
import {LZMA} from './LZMA'
/**
 * LZMA Decoder
 * @author Nidin Vinayakan | nidinthb@gmail.com
 */
export class BitTreeDecoder {
  public probs: Uint16Array
  private numBits: number

  constructor(numBits: number) {
    this.numBits = numBits
    this.probs = new Uint16Array(1 << this.numBits)
  }
  static constructArray(numBits: number,len: number): Array<BitTreeDecoder> {
    let vec: BitTreeDecoder[] = []
    for  (let i: number = 0; i < len; i++){
      vec[i] = new BitTreeDecoder(numBits)
    }
    return vec
  }
  public init(): void {
    LZMA.INIT_PROBS(this.probs)
  }
  public decode(rc: RangeDecoder): number {
    let m: number = 1// Uint16
    for (let i: number = 0; i < this.numBits; i++) {
      m = (m << 1) + rc.decodeBit(this.probs,m)
    }
    return m - (1 << this.numBits)
  }
  public reverseDecode(rc: RangeDecoder): number {
    return LZMA.BitTreeReverseDecode(this.probs, this.numBits, rc)
  }
}