Signal-Android/app/src/main/java/org/thoughtcrime/securesms/backup/BackupVerifier.kt

package org.thoughtcrime.securesms.backup

import org.greenrobot.eventbus.EventBus
import org.signal.core.util.logging.Log
import org.thoughtcrime.securesms.backup.BackupProtos.BackupFrame
import java.io.IOException
import java.io.InputStream
import java.io.OutputStream

/**
 * Given a backup file, run over it and verify it will decrypt properly when attempting to import it.
 */
object BackupVerifier {

  private val TAG = Log.tag(BackupVerifier::class.java)

  @JvmStatic
  @Throws(IOException::class)
  fun verifyFile(cipherStream: InputStream, passphrase: String, expectedCount: Long): Boolean {
    val inputStream = BackupRecordInputStream(cipherStream, passphrase)

    var count = 0L
    var frame: BackupFrame = inputStream.readFrame()

    while (!frame.end) {
      val verified = when {
        frame.hasAttachment() -> verifyAttachment(frame.attachment, inputStream)
        frame.hasSticker() -> verifySticker(frame.sticker, inputStream)
        frame.hasAvatar() -> verifyAvatar(frame.avatar, inputStream)
        else -> true
      }

      if (!verified) {
        return false
      }

      EventBus.getDefault().post(BackupEvent(BackupEvent.Type.PROGRESS_VERIFYING, ++count, expectedCount))

      frame = inputStream.readFrame()
    }

    cipherStream.close()

    return true
  }

  private fun verifyAttachment(attachment: BackupProtos.Attachment, inputStream: BackupRecordInputStream): Boolean {
    try {
      inputStream.readAttachmentTo(NullOutputStream, attachment.length)
    } catch (e: IOException) {
      Log.w(TAG, "Bad attachment id: ${attachment.attachmentId} len: ${attachment.length}", e)
      return false
    }

    return true
  }

  private fun verifySticker(sticker: BackupProtos.Sticker, inputStream: BackupRecordInputStream): Boolean {
    try {
      inputStream.readAttachmentTo(NullOutputStream, sticker.length)
    } catch (e: IOException) {
      Log.w(TAG, "Bad sticker id: ${sticker.rowId} len: ${sticker.length}", e)
      return false
    }
    return true
  }

  private fun verifyAvatar(avatar: BackupProtos.Avatar, inputStream: BackupRecordInputStream): Boolean {
    try {
      inputStream.readAttachmentTo(NullOutputStream, avatar.length)
    } catch (e: IOException) {
      Log.w(TAG, "Bad avatar id: ${avatar.recipientId} len: ${avatar.length}", e)
      return false
    }
    return true
  }

  private object NullOutputStream : OutputStream() {
    override fun write(b: Int) = Unit
    override fun write(b: ByteArray?) = Unit
    override fun write(b: ByteArray?, off: Int, len: Int) = Unit
  }
}