text: from typing import Dict, List, Optional
  
  from electionguard.group import ElementModQ
  
  from .ballot import SubmittedBallot
  from .decryption import (
      compute_lagrange_coefficients_for_guardians,
      reconstruct_decryption_share,
      reconstruct_decryption_share_for_ballot,
  )
  from .decryption_share import DecryptionShare, CompensatedDecryptionShare
  from .decrypt_with_shares import decrypt_ballot, decrypt_tally
  from .election import CiphertextElectionContext
  from .key_ceremony import ElectionPublicKey
  from .key_ceremony_mediator import GuardianPair
  from .logs import log_info, log_warning
  from .tally import (
      CiphertextTally,
      PlaintextTally,
  )
  from .type import BALLOT_ID, GUARDIAN_ID, MEDIATOR_ID
  
  
  class DecryptionMediator:
      """
      The Decryption Mediator composes partial decryptions from each Guardian
      to form a decrypted representation of an election tally.
      """
  
      # pylint: disable=too-many-instance-attributes
      id: MEDIATOR_ID
      _context: CiphertextElectionContext
  
      # Guardians
      _available_guardians: Dict[GUARDIAN_ID, ElectionPublicKey]
      _missing_guardians: Dict[GUARDIAN_ID, ElectionPublicKey]
  
      # Decryption Shares
      _tally_shares: Dict[GUARDIAN_ID, DecryptionShare]
      _ballot_shares: Dict[BALLOT_ID, Dict[GUARDIAN_ID, DecryptionShare]]
  
      # Compensated Shares
      _compensated_tally_shares: Dict[GuardianPair, CompensatedDecryptionShare]
      _compensated_ballot_shares: Dict[
          BALLOT_ID, Dict[GuardianPair, CompensatedDecryptionShare]
      ]
  
      def __init__(self, id: MEDIATOR_ID, context: CiphertextElectionContext):
          """Initialize the decryption mediator."""
          self.id = id
          self._context = context
  
          self._available_guardians = {}
          self._missing_guardians = {}
  
          self._tally_shares = {}
          self._ballot_shares = {}
  
          self._compensated_tally_shares = {}
          self._compensated_ballot_shares = {}
  
      def announce(
          self,
          guardian_key: ElectionPublicKey,
          tally_share: DecryptionShare,
          ballot_shares: Dict[BALLOT_ID, Optional[DecryptionShare]] = None,
      ) -> None:
          """
          Announce that a Guardian is present and participating in the decryption.
  
          A guardian announces by presenting their id and their shares of the decryption
  
          :param guardian_key: The election public key of the guardian who will participate in the decryption.
          :param tally_share: Guardian's decryption share of the tally
          :param ballot_shares: Guardian's decryption shares of the ballots
          """
          guardian_id = guardian_key.owner_id
  
          # Only allow a guardian to announce once
          if guardian_id in self._available_guardians:
              log_info(f"guardian {guardian_id} already announced")
              return
  
          self._save_tally_share(guardian_id, tally_share)
  
          if ballot_shares is not None:
              self._save_ballot_shares(guardian_id, ballot_shares)
  
          self._mark_available(guardian_key)
  
      def announce_missing(self, missing_guardian_key: ElectionPublicKey) -> None:
          """
          Announce that a Guardian is missing and not participating in the decryption.
  
          :param missing_guardian_key: The election public key of the missing guardian
          """
          missing_guardian_id = missing_guardian_key.owner_id
  
          # If guardian is available, can't be marked missing
          if missing_guardian_id in self._available_guardians:
              log_info(f"guardian {missing_guardian_id} already announced")
              return
  
          self._mark_missing(missing_guardian_key)
  
      def validate_missing_guardians(
          self, guardian_keys: List[ElectionPublicKey]
      ) -> bool:
          """Check the guardian's collections of keys and ensure the public keys match for the guardians."""
          # Check this guardian's collection of public keys
          # for other guardians that have not announced
          missing_guardians: Dict[GUARDIAN_ID, ElectionPublicKey] = {
              guardian_key.owner_id: guardian_key
              for guardian_key in guardian_keys
              if guardian_key.owner_id not in self._available_guardians
          }
  
          # Check that the public keys match for any missing guardians already reported
          # note this check naively assumes that the first guardian to annouce is telling the truth
          # but for this implementation it is simply a sanity check on the input data.
          # a consuming application should implement better validation of the guardian state
          # before announcing a guardian is available for decryption.
          for guardian_id, public_key in missing_guardians.items():
              if guardian_id in self._missing_guardians.keys():
                  if self._missing_guardians[guardian_id] != public_key:
                      log_warning(
                          (
                              f"announce guardian: {guardian_id} "
                              f"expected public key mismatch for missing {guardian_id}"
                          )
                      )
                      return False
              else:
                  self._missing_guardians[guardian_id] = missing_guardians[guardian_id]
          return True
  
      def announcement_complete(self) -> bool:
          """
          Determine if the announcement phase is complete
          :return: True if announcement complete
          """
          # If a quorum not announced, not ready
          if len(self._available_guardians) < self._context.quorum:
              log_warning("cannot decrypt with less than quorum available guardians")
              return False
  
          # If guardians missing or available not accounted for, not ready
          if (
              len(self._available_guardians) + len(self._missing_guardians)
              != self._context.number_of_guardians
          ):
              log_warning(
                  "cannot decrypt without accounting for all guardians missing or present"
              )
              return False
          return True
  
      def get_available_guardians(self) -> List[ElectionPublicKey]:
          """
          Get all available guardian keys
          :return: All available guardians election public keys
          """
          return list(self._available_guardians.values())
  
      def get_missing_guardians(self) -> List[ElectionPublicKey]:
          """
          Get all missing guardian keys
          :return: All missing guardians election public keys
          """
          return list(self._missing_guardians.values())
  
      def receive_tally_compensation_share(
          self, tally_compensation_share: CompensatedDecryptionShare
      ) -> None:
          self._compensated_tally_shares[
              GuardianPair(
                  tally_compensation_share.guardian_id,
                  tally_compensation_share.missing_guardian_id,
              )
          ] = tally_compensation_share
  
      def receive_ballot_compensation_shares(
          self, ballot_compensation_shares: Dict[BALLOT_ID, CompensatedDecryptionShare]
      ) -> None:
          for ballot_id, share in ballot_compensation_shares.items():
              ballot_shares = self._compensated_ballot_shares.get(ballot_id)
              if not ballot_shares:
                  ballot_shares = {}
              ballot_shares[
                  GuardianPair(share.guardian_id, share.missing_guardian_id)
              ] = share
              self._compensated_ballot_shares[ballot_id] = ballot_shares
  
      def get_lagrange_coefficients(self) -> Dict[GUARDIAN_ID, ElementModQ]:
          return compute_lagrange_coefficients_for_guardians(
              list(self._available_guardians.values())
          )
  
      def reconstruct_shares_for_tally(self, ciphertext_tally: CiphertextTally) -> None:
          lagrange_coefficients = self.get_lagrange_coefficients()
          for (
              missing_guardian_id,
              missing_guardian_key,
          ) in self._missing_guardians.items():
              # Share already reconstructed
              if missing_guardian_id in self._tally_shares:
                  continue
  
              compensated_shares = _filter_by_missing_guardian(
                  missing_guardian_id, self._compensated_tally_shares
              )
  
              reconstructed_share = reconstruct_decryption_share(
                  missing_guardian_key,
                  ciphertext_tally,
                  compensated_shares,
                  lagrange_coefficients,
              )
  
              # Add reconstructed share into tally shares
              self._tally_shares[missing_guardian_id] = reconstructed_share
  
      def reconstruct_shares_for_ballots(
          self, ciphertext_ballots: List[SubmittedBallot]
      ) -> None:
          lagrange_coefficients = compute_lagrange_coefficients_for_guardians(
              list(self._available_guardians.values())
          )
          for ciphertext_ballot in ciphertext_ballots:
              ballot_id = ciphertext_ballot.object_id
              ballot_shares = self._ballot_shares[ballot_id]
  
              for (
                  missing_guardian_id,
                  missing_guardian_key,
              ) in self._missing_guardians.items():
                  # Share already reconstructed
                  if missing_guardian_id in ballot_shares:
                      continue
  
                  compensated_shares = _filter_by_missing_guardian(
                      missing_guardian_id, self._compensated_ballot_shares[ballot_id]
                  )
  
                  reconstructed_share = reconstruct_decryption_share_for_ballot(
                      missing_guardian_key,
                      ciphertext_ballot,
                      compensated_shares,
                      lagrange_coefficients,
                  )
  
                  ballot_shares[missing_guardian_id] = reconstructed_share
  
              # Add shares into ballot shares
              self._ballot_shares[ballot_id] = ballot_shares
  
      def get_plaintext_tally(
          self, ciphertext_tally: CiphertextTally
      ) -> Optional[PlaintextTally]:
          """
          Get the plaintext tally for the election by composing each Guardian's
          decrypted representation of each selection into a decrypted representation
  
          :return: a `PlaintextTally` or `None`
          """
  
          if not self.announcement_complete() or not self._ready_to_decrypt(
              self._tally_shares
          ):
              return None
  
          return decrypt_tally(
              ciphertext_tally,
              self._tally_shares,
              self._context.crypto_extended_base_hash,
          )
  
      def get_plaintext_ballots(
          self, ciphertext_ballots: List[SubmittedBallot]
      ) -> Optional[Dict[BALLOT_ID, PlaintextTally]]:
          """
          Get the plaintext ballots for the election by composing each Guardian's
          decrypted representation of each selection into a decrypted representation
          This is typically used in the spoiled ballot use case.
  
          :return: a Plaintext Ballots or `None`
          """
  
          if not self.announcement_complete():
              return None
  
          ballots = {}
  
          for ciphertext_ballot in ciphertext_ballots:
              ballot_shares = self._ballot_shares.get(ciphertext_ballot.object_id)
              if not ballot_shares or not self._ready_to_decrypt(ballot_shares):
                  # Skip ballot if not ready to decrypt
                  continue
              ballot = decrypt_ballot(
                  ciphertext_ballot,
                  ballot_shares,
                  self._context.crypto_extended_base_hash,
              )
  
              if ballot:
                  ballots[ballot.object_id] = ballot
  
          return ballots
  
      def _save_tally_share(
          self, guardian_id: GUARDIAN_ID, guardians_tally_share: DecryptionShare
      ) -> None:
          """Save a guardians tally share."""
          self._tally_shares[guardian_id] = guardians_tally_share
  
      def _save_ballot_shares(
          self,
          guardian_id: GUARDIAN_ID,
          guardians_ballot_shares: Dict[BALLOT_ID, Optional[DecryptionShare]],
      ) -> None:
          """Save a guardian's set of ballot shares."""
          for ballot_id, guardian_ballot_share in guardians_ballot_shares.items():
              shares = self._ballot_shares.get(ballot_id)
              if shares is None:
                  shares = {}
              if guardian_ballot_share is not None:
                  shares[guardian_id] = guardian_ballot_share
              self._ballot_shares[ballot_id] = shares
  
      def _mark_available(self, guardian_key: ElectionPublicKey) -> None:
          """
          This guardian removes itself from the missing list since it generated a valid share.
          """
          guardian_id = guardian_key.owner_id
          self._available_guardians[guardian_id] = guardian_key
          if guardian_id in self._missing_guardians:
              self._missing_guardians.pop(guardian_id)
  
      def _mark_missing(self, guardian_key: ElectionPublicKey) -> None:
          """"""
          self._missing_guardians[guardian_key.owner_id] = guardian_key
  
      def _ready_to_decrypt(self, shares: Dict[GUARDIAN_ID, DecryptionShare]) -> bool:
          """Shares are ready to decrypt."""
          # If all guardian shares are represented including if necessary
          # the missing guardians reconstructed shares, the decryption can be made
          return len(shares) == self._context.number_of_guardians
  
  
  def _filter_by_missing_guardian(
      missing_guardian_id: GUARDIAN_ID,
      shares: Dict[GuardianPair, CompensatedDecryptionShare],
  ) -> Dict[GUARDIAN_ID, CompensatedDecryptionShare]:
      """
      Filter a guardian pair and compensated share dictionary by missing guardian.
      """
      missing_guardian_shares = {}
      for pair, share in shares.items():
          if pair.designated_id is missing_guardian_id:
              missing_guardian_shares[pair.owner_id] = share
      return missing_guardian_shares
  