BS 集約 + ドメインロジック

BalanceSheet.scala

import edomata.core.*
import edomata.syntax.all.*

enum BalanceSheet {
  case NotReady
  case Ready(
      assets: Map[AccountTitle, BigDecimal],
      liabilities: Map[AccountTitle, BigDecimal]
  )

  def initialize(
      assets: Map[AccountTitle, BigDecimal],
      liabilities: Map[AccountTitle, BigDecimal]
  ): Decision[BsRejection, BsEvent, Ready] =
    this
      .decide {
        case NotReady    => Decision.accept(Initialized(assets, liabilities))
        case Ready(_, _) => Decision.reject(AlreadyInitialized)
      }
      .validate(_.mustBeReady)

  def journalize(
      entry: JournalEntry
  ): Decision[BsRejection, BsEvent, Ready] =
    this
      .perform(mustBeReady.toDecision.flatMap { _ =>
        if entry.amount > 0
        then Decision.accept(Journalized(entry))
        else Decision.reject(NegativeAmountJournalEntry)
      })
      .validate(_.mustNotBeNegativeBalance)

  private def mustBeReady: ValidatedNec[BsRejection, Ready] = this match
    case bs @ Ready(_, _) => bs.validNec
    case NotReady         => BsRejection.NotReady.invalidNec

  private def mustNotBeNegativeBalance: ValidatedNec[BsRejection, Ready] =
    mustBeReady andThen { bs =>
      if bs.assets.forall { case (_, amount) => amount >= 0 } &&
        bs.liabilities.forall { case (_, amount) => amount >= 0 }
      then bs.validNec
      else NegativeBalance.invalidNec
    }
}