package nl.astraeus.persistence

import java.io.File
import java.io.ObjectInputStream
import java.util.*

class TransactionLog(
  directory: File,
  val decryptionKey: String? = null,
) {
  val fileManager = FileManager(directory)

  fun showTransactions(printer: (String) -> Unit = ::println) {
    fileManager.findLastSnapshot().let { (after, snapshot) ->
      printer("Last snapshot: $snapshot")

      printer("Snapshot:")
      snapshot?.inputStream()?.use { input ->
        ObjectInputStream(DecryptingInputStream(input, decryptionKey)).use { ois ->
          val versionNumber = ois.readInt()
          check(versionNumber == 1) {
            "Unsupported version number: $versionNumber"
          }
          val transactionNumber = ois.readLong()
          printer("[$versionNumber]  $transactionNumber")
          val dataObj = ois.readObject()
          val data = dataObj as MutableMap<Class<*>, TypeData>
          printer("Data:")
          printer("\tClasses:")
          for ((cls, entries) in  data.entries) {
            printer("\t\t- $cls: ${entries.data.keys.size}")
          }
        }
      }

      val transactions = fileManager.findTransactionsAfter(after ?: 0L)

      printer("Transactions:")
      transactions?.forEach { transaction ->
        transaction.inputStream().use { input ->
          ObjectInputStream(DecryptingInputStream(input, decryptionKey)).use { ois ->
            val versionNumber = ois.readInt()
            check(versionNumber == 1) {
              "Unsupported version number: $versionNumber"
            }
            val transactionNumber = ois.readLong()
            val actions = ois.readObject()
            val actionList = when(actions) {
              is Set<*> -> {
                LinkedList(actions as Set<Action>)
              }
              is List<*> -> {
                actions as List<Action>
              }
              else -> {
                emptyList()
              }
            }
            printer("\t[$transactionNumber]")
            for (action in actionList) {
              printer("\t\t- $action")
            }
          }
        }
      }
    }
  }
}