text: """Indy verifier implementation."""
  
  from enum import Enum
  import json
  import logging
  
  import indy.anoncreds
  from indy.error import IndyError
  
  from ..messaging.util import canon, encode
  from ..ledger.base import BaseLedger
  
  from .base import BaseVerifier
  
  LOGGER = logging.getLogger(__name__)
  
  
  class PreVerifyResult(Enum):
      """Represent the result of IndyVerifier.pre_verify."""
  
      OK = "ok"
      INCOMPLETE = "missing essential components"
      ENCODING_MISMATCH = "demonstrates tampering with raw values"
  
  
  class IndyVerifier(BaseVerifier):
      """Indy verifier class."""
  
      def __init__(self, ledger: BaseLedger):
          """
          Initialize an IndyVerifier instance.
  
          Args:
              ledger: ledger instance
  
          """
          self.ledger = ledger
  
      async def pre_verify(self, pres_req: dict, pres: dict) -> (PreVerifyResult, str):
          """
          Check for essential components and tampering in presentation.
  
          Visit encoded attribute values against raw, and predicate bounds,
          in presentation, cross-reference against presentation request.
  
          Args:
              pres_req: presentation request
              pres: corresponding presentation
  
          Returns:
              A tuple with `PreVerifyResult` representing the validation result and
              reason text for failure or None for OK.
  
          """
          if not (
              pres_req
              and "requested_predicates" in pres_req
              and "requested_attributes" in pres_req
          ):
              return (PreVerifyResult.INCOMPLETE, "Incomplete or missing proof request")
          if not pres:
              return (PreVerifyResult.INCOMPLETE, "No proof provided")
          if "requested_proof" not in pres:
              return (PreVerifyResult.INCOMPLETE, "Missing 'requested_proof'")
          if "proof" not in pres:
              return (PreVerifyResult.INCOMPLETE, "Missing 'proof'")
  
          async with self.ledger:
              for (index, ident) in enumerate(pres["identifiers"]):
                  if not ident.get("timestamp"):
                      cred_def_id = ident["cred_def_id"]
                      cred_def = await self.ledger.get_credential_definition(cred_def_id)
                      if cred_def["value"].get("revocation"):
                          return (
                              PreVerifyResult.INCOMPLETE,
                              (
                                  f"Missing timestamp in presentation identifier "
                                  f"#{index} for cred def id {cred_def_id}"
                              ),
                          )
  
          for (uuid, req_pred) in pres_req["requested_predicates"].items():
              try:
                  canon_attr = canon(req_pred["name"])
                  for ge_proof in pres["proof"]["proofs"][
                      pres["requested_proof"]["predicates"][uuid]["sub_proof_index"]
                  ]["primary_proof"]["ge_proofs"]:
                      pred = ge_proof["predicate"]
                      if pred["attr_name"] == canon_attr:
                          if pred["value"] != req_pred["p_value"]:
                              return (
                                  PreVerifyResult.INCOMPLETE,
                                  f"Predicate value != p_value: {pred['attr_name']}",
                              )
                          break
                  else:
                      return (
                          PreVerifyResult.INCOMPLETE,
                          f"Missing requested predicate '{uuid}'",
                      )
              except (KeyError, TypeError):
                  return (
                      PreVerifyResult.INCOMPLETE,
                      f"Missing requested predicate '{uuid}'",
                  )
  
          revealed_attrs = pres["requested_proof"].get("revealed_attrs", {})
          revealed_groups = pres["requested_proof"].get("revealed_attr_groups", {})
          self_attested = pres["requested_proof"].get("self_attested_attrs", {})
          for (uuid, req_attr) in pres_req["requested_attributes"].items():
              if "name" in req_attr:
                  if uuid in revealed_attrs:
                      pres_req_attr_spec = {req_attr["name"]: revealed_attrs[uuid]}
                  elif uuid in self_attested:
                      if not req_attr.get("restrictions"):
                          continue
                      else:
                          return (
                              PreVerifyResult.INCOMPLETE,
                              "Attribute with restrictions cannot be self-attested "
                              f"'{req_attr['name']}'",
                          )
                  else:
                      return (
                          PreVerifyResult.INCOMPLETE,
                          f"Missing requested attribute '{req_attr['name']}'",
                      )
              elif "names" in req_attr:
                  group_spec = revealed_groups.get(uuid)
                  if (
                      group_spec is None
                      or "sub_proof_index" not in group_spec
                      or "values" not in group_spec
                  ):
                      return (
                          PreVerifyResult.INCOMPLETE,
                          f"Missing requested attribute group '{uuid}'",
                      )
                  pres_req_attr_spec = {
                      attr: {
                          "sub_proof_index": group_spec["sub_proof_index"],
                          **group_spec["values"].get(attr),
                      }
                      for attr in req_attr["names"]
                  }
              else:
                  return (
                      PreVerifyResult.INCOMPLETE,
                      f"Request attribute missing 'name' and 'names': '{uuid}'",
                  )
  
              for (attr, spec) in pres_req_attr_spec.items():
                  try:
                      primary_enco = pres["proof"]["proofs"][spec["sub_proof_index"]][
                          "primary_proof"
                      ]["eq_proof"]["revealed_attrs"][canon(attr)]
                  except (KeyError, TypeError):
                      return (
                          PreVerifyResult.INCOMPLETE,
                          f"Missing revealed attribute: '{attr}'",
                      )
                  if primary_enco != spec["encoded"]:
                      return (
                          PreVerifyResult.ENCODING_MISMATCH,
                          f"Encoded representation mismatch for '{attr}'",
                      )
                  if primary_enco != encode(spec["raw"]):
                      return (
                          PreVerifyResult.ENCODING_MISMATCH,
                          f"Encoded representation mismatch for '{attr}'",
                      )
  
          return (PreVerifyResult.OK, None)
  
      async def verify_presentation(
          self,
          presentation_request,
          presentation,
          schemas,
          credential_definitions,
          rev_reg_defs,
          rev_reg_entries,
      ) -> bool:
          """
          Verify a presentation.
  
          Args:
              presentation_request: Presentation request data
              presentation: Presentation data
              schemas: Schema data
              credential_definitions: credential definition data
              rev_reg_defs: revocation registry definitions
              rev_reg_entries: revocation registry entries
          """
  
          (pv_result, pv_msg) = await self.pre_verify(presentation_request, presentation)
          if pv_result != PreVerifyResult.OK:
              LOGGER.error(
                  f"Presentation on nonce={presentation_request['nonce']} "
                  f"cannot be validated: {pv_result.value} [{pv_msg}]"
              )
              return False
  
          try:
              verified = await indy.anoncreds.verifier_verify_proof(
                  json.dumps(presentation_request),
                  json.dumps(presentation),
                  json.dumps(schemas),
                  json.dumps(credential_definitions),
                  json.dumps(rev_reg_defs),
                  json.dumps(rev_reg_entries),
              )
          except IndyError:
              LOGGER.exception(
                  f"Validation of presentation on nonce={presentation_request['nonce']} "
                  "failed with error"
              )
              verified = False
  
          return verified
  