info.gehrels.voting.singleTransferableVote.VoteState.java Source code

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Here is the source code for info.gehrels.voting.singleTransferableVote.VoteState.java

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/*
 * Copyright  2014 Benjamin Gehrels
 *
 * This file is part of The Single Transferable Vote Elections Library.
 *
 * The Single Transferable Vote Elections Web Interface is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * The Single Transferable Vote Elections Web Interface is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License along with The Single Transferable Vote
 * Elections Web Interface. If not, see <http://www.gnu.org/licenses/>.
 */
package info.gehrels.voting.singleTransferableVote;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import info.gehrels.voting.Ballot;
import info.gehrels.voting.Candidate;
import info.gehrels.voting.Election;
import info.gehrels.voting.Vote;
import org.apache.commons.math3.fraction.BigFraction;

import static info.gehrels.parameterValidation.MatcherValidation.validateThat;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.notNullValue;

public final class VoteState<CANDIDATE_TYPE extends Candidate> {
    private final ImmutableList<CANDIDATE_TYPE> rankedCandidates;
    private final long ballotId;
    private final BigFraction voteWeight;
    private final int currentPositionInRankedCandidatesList;
    private final Vote<CANDIDATE_TYPE> vote;

    public static <CANDIDATE_TYPE extends Candidate> Optional<VoteState<CANDIDATE_TYPE>> forBallotAndElection(
            Ballot<CANDIDATE_TYPE> ballot, Election<CANDIDATE_TYPE> election) {
        validateThat(ballot, is(notNullValue()));
        validateThat(election, is(notNullValue()));

        Optional<Vote<CANDIDATE_TYPE>> vote = ballot.getVote(election);
        if (!vote.isPresent()) {
            return Optional.absent();
        }

        return Optional.of(new VoteState<>(ballot.id, vote.get()));
    }

    private VoteState(long ballotId, Vote<CANDIDATE_TYPE> vote) {
        this(ballotId, vote, BigFraction.ONE, 0);
    }

    private VoteState(long ballotId, Vote<CANDIDATE_TYPE> vote, BigFraction voteWeight,
            int currentPositionInRankedCandidatesList) {
        this.ballotId = ballotId;
        this.vote = vote;
        this.rankedCandidates = vote.getRankedCandidates().asList();
        this.voteWeight = voteWeight;
        this.currentPositionInRankedCandidatesList = currentPositionInRankedCandidatesList;
    }

    public VoteState<CANDIDATE_TYPE> withFirstHopefulCandidate(CandidateStates<CANDIDATE_TYPE> candidateStates) {
        VoteState<CANDIDATE_TYPE> result = this;

        Optional<CANDIDATE_TYPE> preferredCandidate = result.getPreferredCandidate();
        while (preferredCandidate.isPresent()) {
            CandidateState<CANDIDATE_TYPE> candidateState = candidateStates
                    .getCandidateState(preferredCandidate.get());
            if ((candidateState != null) && candidateState.isHopeful()) {
                return result;
            }

            result = result.withNextPreference();
            preferredCandidate = result.getPreferredCandidate();
        }

        return result;
    }

    public Optional<CANDIDATE_TYPE> getPreferredCandidate() {
        if (currentPositionInRankedCandidatesList >= rankedCandidates.size()) {
            return Optional.absent();
        }

        return Optional.of(rankedCandidates.asList().get(currentPositionInRankedCandidatesList));
    }

    public BigFraction getVoteWeight() {
        return voteWeight;
    }

    private VoteState<CANDIDATE_TYPE> withNextPreference() {
        return new VoteState<>(ballotId, vote, voteWeight, currentPositionInRankedCandidatesList + 1);
    }

    public VoteState<CANDIDATE_TYPE> withVoteWeight(BigFraction newVoteWeight) {
        return new VoteState<>(ballotId, vote, newVoteWeight, currentPositionInRankedCandidatesList);
    }

    public long getBallotId() {
        return ballotId;
    }

    @Override
    public String toString() {
        return "VoteState<" + ballotId + "; preferred: " + getPreferredCandidate() + "; " + voteWeight + ">";
    }

    public boolean isInvalid() {
        return !vote.isValid();
    }

    public boolean isNoVote() {
        return vote.isNo() || !getPreferredCandidate().isPresent();
    }
}