Subgraph Mapping function

Mapping function

export function handleDelegateChanged(event: DelegateChanged): void {

  let delegator = event.params.delegator
  let fromDelegate = event.params.fromDelegate
  let toDelegate = event.params.toDelegate
  let txHash = event.transaction.hash.toHex()
  let timestamp = event.block.timestamp
  let blockNumber = event.block.number
  // Load Token Contract to get official votes (rather than computing from events)
  let token = COMP.bind(event.address)
  let delegationAmount = token.getCurrentVotes(delegator)
  //Create VoteDelegationID
  let voteDelegationId = delegator.toHex().concat(toDelegate.toHex())
  //Create and save Delegation Event
  let voteDelegationEvent = new VoteDelegationEvent(txHash)
  voteDelegationEvent.timestamp = timestamp
  voteDelegationEvent.block = blockNumber
  voteDelegationEvent.amount = delegationAmount
  voteDelegationEvent.voteDelegation = voteDelegationId
  voteDelegationEvent.fromDelegate = fromDelegate
  voteDelegationEvent.toDelegate = toDelegate

  //Get Voters voteDelegation history and save update
  let voteDelegation = getVoteDelegation(voteDelegationId)
  voteDelegation.delegator = delegator.toHex()
  voteDelegation.toDelegate = toDelegate.toHex()
  voteDelegation.timestamp = timestamp
  voteDelegation.block = blockNumber
  voteDelegation.amount = delegationAmount


  //Add this delegation event to this relationships history
  let historyOfVotersDelegations = voteDelegation.voteDelegationHistory
  historyOfVotersDelegations.push(voteDelegationEvent.id)
  voteDelegation.voteDelegationHistory = historyOfVotersDelegations
  //Get Voter that has changed their delegation
  let voterDelegator = getVoter(delegator.toHex())
  //Get new delegatee 
  let voterDelegatee = getVoter(toDelegate.toHex())
  //get old delegatee
  let voterFormerDelegatee = getVoter(fromDelegate.toHex())
  //Is the voter delegating to themselves? 
  let selfDelegating = false
  if (delegator == toDelegate) {
    selfDelegating = true
  }
  //Update if voter is delegating or not
  voterDelegator.isVoterDelegating = true
  //Update if the voter is delegating to someone else
  voterDelegator.isDelegatingToAnother = selfDelegating
  //update delegatee
  voterDelegator.delegatingTo = voterDelegatee.id
  //Update history of Delegating to this person
  let voterDelegationHistory = voterDelegator.voteDelegatorHistory
  voterDelegationHistory.push(voteDelegation.id)
  voterDelegator.voteDelegatorHistory = voterDelegationHistory


  //Update the delegatee
  voterDelegatee.isDelegatedTo = true
  //Add voterDelegator to the list of voters delegating to the delegatee
  let voterDelegateeFrom = voterDelegatee.delegatedFrom
  voterDelegateeFrom.push(voterDelegator.id)
  voterDelegatee.delegatedFrom = voterDelegateeFrom
  //Add ths VoteDelegation object to the history of being delegateed too
  let voteDelegateeHistory = voterDelegatee.voteDelegeeHistory
  voteDelegateeHistory.push(voterDelegator.id)
  voterDelegatee.voteDelegeeHistory = voteDelegateeHistory


  //TODO: Look for more perforant way to remove former delegatee as this currently break in sync
  // //update former delegatee to remove delegations
  let formerDelegateelistofDelegators = voterFormerDelegatee.delegatedFrom
  if (formerDelegateelistofDelegators.length == 0) {
    log.warning("Possible Mismatch in how delegators are counted and applied", [delegator.toString(), fromDelegate.toString(), toDelegate.toString()])
  }
  //Remove this voter from the list of delegators, only if they are delegating to someone else
  if (fromDelegate != toDelegate) {
    let delegator2 = event.params.delegator
    let newListofDelegators = formerDelegateelistofDelegators.filter(function (voterId: string, index: i32, array: string[]) {
      return voterId != delegator2.toHex()
    })
    voterFormerDelegatee.delegatedFrom = newListofDelegators
    //If no one is delegating to them, mark them as not being delegated to
    if (newListofDelegators.length < 1) {
      voterFormerDelegatee.isDelegatedTo = false
    }
  }

  //Get History and add Delegation Event and overwrite current delegtation
  let history = getHistory()
  let historyOfDelEvents = history.delegationHistory
  historyOfDelEvents.push(voteDelegationEvent.id)
  history.delegationHistory = historyOfDelEvents

  //Update the current delegations
  //First find the previos delegation if it existed, and delete it. 
  let currentHistoryDelegations = history.delegations
  let previousDelegationId = delegator.toHex().concat(fromDelegate.toHex())
  let previousVoterDelegation = getVoteDelegation(previousDelegationId)
  if (currentHistoryDelegations.length = 0) {
    log.warning("Possible mismatch of how we add delegations on history", [delegator.toString(), fromDelegate.toString(), toDelegate.toString()])
  }

  //TODO: Look for more performant method of removing non-current delegations
  // //Remove this delgation only if the new delegate is different from the old one. 
  if (fromDelegate != toDelegate) {
    let filteredCurrentDelegations = currentHistoryDelegations.filter(function (delegationId: string, index: i32, array: string[]) {
      //For some reason previousVoterDelegation isn't visible inside this block without the following
      let previousDelegationId = event.params.delegator.toHex().concat(event.params.fromDelegate.toHex())
      let previousVoterDelegation = getVoteDelegation(previousDelegationId)
      return delegationId != previousVoterDelegation.id
    })
    //update the new list of current delegations on the history
    history.delegations = filteredCurrentDelegations
  }

  //Save the history
  history.save()
  //Save Vote Delegation
  voteDelegation.save()
  //Save Former Delegatee
  voterFormerDelegatee.save()
  //Save Delegatee
  voterDelegatee.save()
  //save Delegator
  voterDelegator.save()
  //Save vote delegation event
  voteDelegationEvent.save()
}