//  CryptoSwift
//
//  Copyright (C) 2014-2018 Marcin Krzyżanowski <marcin@krzyzanowskim.com>
//  This software is provided 'as-is', without any express or implied warranty.
//
//  In no event will the authors be held liable for any damages arising from the use of this software.
//
//  Permission is granted to anyone to use this software for any purpose,including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
//
//  - The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation is required.
//  - Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
//  - This notice may not be removed or altered from any source or binary distribution.
//

@usableFromInline
final class BlockEncryptor: Cryptor, Updatable {
  private let blockSize: Int
  private var worker: CipherModeWorker
  private let padding: Padding
  // Accumulated bytes. Not all processed bytes.
  private var accumulated = Array<UInt8>(reserveCapacity: 16)

  private var lastBlockRemainder = 0

  @usableFromInline
  init(blockSize: Int, padding: Padding, _ worker: CipherModeWorker) throws {
    self.blockSize = blockSize
    self.padding = padding
    self.worker = worker
  }

  // MARK: Updatable

  public func update(withBytes bytes: ArraySlice<UInt8>, isLast: Bool) throws -> Array<UInt8> {
    self.accumulated += bytes

    if isLast {
      self.accumulated = self.padding.add(to: self.accumulated, blockSize: self.blockSize)
    }

    var encrypted = Array<UInt8>(reserveCapacity: accumulated.count)
    for chunk in self.accumulated.batched(by: self.blockSize) {
      if isLast || chunk.count == self.blockSize {
        encrypted += self.worker.encrypt(block: chunk)
      }
    }

    // Stream encrypts all, so it removes all elements
    self.accumulated.removeFirst(encrypted.count)

    if var finalizingWorker = worker as? FinalizingEncryptModeWorker, isLast == true {
      encrypted = Array(try finalizingWorker.finalize(encrypt: encrypted.slice))
    }

    return encrypted
  }

  @usableFromInline
  func seek(to: Int) throws {
    fatalError("Not supported")
  }
}