import { Buffer } from 'buffer';
import { deflateSync, inflateSync } from 'node:zlib';
import { RevocationStatusList } from './revocationStatusList.js';
import MultiBitArray from './multiBitArray.js';
import { STATUS_LIST } from '../config.js';
import InvalidCredentialIndexException from './exceptions/invalidCredentialIndexException.js';
import { base64url } from 'jose';

export class TokenStatusList implements RevocationStatusList {
  private readonly bitArray: MultiBitArray;

  constructor(bitArray: MultiBitArray) {
    this.bitArray = bitArray;
  }

  static fromEncoded(
    encodedLst: string,
    bitsPerEntry: number,
  ): TokenStatusList {
    const decoded = Buffer.from(base64url.decode(encodedLst));
    const uncompressed = inflateSync(decoded);

    const bitArray = MultiBitArray.fromBuffer(uncompressed, bitsPerEntry);

    return new TokenStatusList(bitArray);
  }

  encoded(): string {
    const buffer = this.bitArray.toArray();
    const compressed = deflateSync(buffer);
    return base64url.encode(compressed);
  }

  revokeCredential(credentialId: number): void {
    this.checkCredentialId(credentialId);

    this.bitArray.set(this.mirrorBitInByte(credentialId), 1);
  }

  isRevoked(credentialId: number): boolean {
    this.checkCredentialId(credentialId);

    return this.bitArray.get(this.mirrorBitInByte(credentialId)) !== 0;
  }

  checkCredentialId(credentialId: number): void {
    if (credentialId < 0 || credentialId > STATUS_LIST.MAX_CREDENTIAL_ID) {
      throw new InvalidCredentialIndexException(credentialId.toString());
    }
  }

  private mirrorBitInByte(index: number): number {
    const byte = Math.floor(index / 8);
    const bit = index % 8;
    return byte * 8 + (7 - bit);
  }
}