Port wot-dijkstra Java classes to Kotlin

build.gradle

@@ -42,7 +42,7 @@ allprojects {
     }
 
     // For library modules, enable android api compatibility check
-    if (it.name != 'pgpainless-cli') {
+    if (it.name != 'pgpainless-cli' && it.name != 'wot-dijkstra') {
         // animalsniffer
         apply plugin: 'ru.vyarus.animalsniffer'
         dependencies {

pgpainless-wot/src/main/java/org/pgpainless/wot/CertificationFactory.java

@@ -14,7 +14,6 @@ import org.pgpainless.signature.subpackets.SignatureSubpacketsUtil;
 import org.pgpainless.wot.dijkstra.sq.CertSynopsis;
 import org.pgpainless.wot.dijkstra.sq.Certification;
 import org.pgpainless.wot.dijkstra.sq.Depth;
-import org.pgpainless.wot.dijkstra.sq.Optional;
 import org.pgpainless.wot.dijkstra.sq.RegexSet;
 
 /**
@@ -34,7 +33,7 @@ public class CertificationFactory {
     public static Certification fromDelegation(CertSynopsis issuer,
                                                CertSynopsis target,
                                                PGPSignature signature) {
-        return fromSignature(issuer, Optional.empty(), target, signature);
+        return fromSignature(issuer, null, target, signature);
     }
 
     /**
@@ -50,7 +49,7 @@ public class CertificationFactory {
                                                   String targetUserId,
                                                   CertSynopsis target,
                                                   PGPSignature signature) {
-        return fromSignature(issuer, Optional.just(targetUserId), target, signature);
+        return fromSignature(issuer, targetUserId, target, signature);
     }
 
     /**
@@ -63,7 +62,7 @@ public class CertificationFactory {
      * @return certification
      */
     public static Certification fromSignature(CertSynopsis issuer,
-                                              Optional<String> targetUserId,
+                                              String targetUserId,
                                               CertSynopsis target,
                                               PGPSignature signature) {
         return new Certification(
@@ -71,7 +70,7 @@ public class CertificationFactory {
                 target,
                 targetUserId,
                 SignatureSubpacketsUtil.getSignatureCreationTime(signature).getTime(),
-                Optional.maybe(SignatureSubpacketsUtil.getSignatureExpirationTimeAsDate(signature)),
+                SignatureSubpacketsUtil.getSignatureExpirationTimeAsDate(signature),
                 SignatureSubpacketsUtil.isExportable(signature),
                 getTrustAmountFrom(signature),
                 getTrustDepthFrom(signature),

pgpainless-wot/src/main/java/org/pgpainless/wot/WebOfTrust.java

@@ -33,7 +33,6 @@ import org.pgpainless.wot.dijkstra.sq.CertSynopsis;
 import org.pgpainless.wot.dijkstra.sq.Certification;
 import org.pgpainless.wot.dijkstra.sq.CertificationSet;
 import org.pgpainless.wot.dijkstra.sq.Network;
-import org.pgpainless.wot.dijkstra.sq.Optional;
 import org.pgpainless.wot.dijkstra.sq.ReferenceTime;
 import org.pgpainless.wot.sugar.IterableIterator;
 import org.pgpainless.wot.sugar.PrefixedIterator;
@@ -80,7 +79,7 @@ public class WebOfTrust implements CertificateAuthority {
         Iterator<Certificate> certificates = certificateStore.items();
         Iterator<Certificate> withTrustRoot = new PrefixedIterator<>(trustRoot, certificates);
         IterableIterator<Certificate> iterable = new IterableIterator<>(withTrustRoot);
-        network = fromCertificates(iterable, PGPainless.getPolicy(), Optional.just(ReferenceTime.now()));
+        network = fromCertificates(iterable, PGPainless.getPolicy(), ReferenceTime.now());
     }
 
 
@@ -95,9 +94,9 @@ public class WebOfTrust implements CertificateAuthority {
     public static Network fromCertificates(
             Iterable<Certificate> certificates,
             Policy policy,
-            Optional<ReferenceTime> optReferenceTime) {
+            ReferenceTime optReferenceTime) {
 
-        ReferenceTime referenceTime = optReferenceTime.isPresent() ? optReferenceTime.get() : ReferenceTime.now();
+        ReferenceTime referenceTime = optReferenceTime == null ? ReferenceTime.now() : optReferenceTime;
         List<KeyRingInfo> validCerts = parseValidCertificates(certificates, policy, referenceTime.getTimestamp());
 
         LOGGER.debug("Successfully parsed " + validCerts.size() + " certificates.");

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/IntegerUtils.java

@@ -1,24 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra;
-
-public final class IntegerUtils {
-
-    private IntegerUtils() {
-
-    }
-
-    /**
-     * Backported method from Java 8.
-     *
-     * @param x x
-     * @param y y
-     * @return result of comparison
-     */
-    public static int compare(int x, int y) {
-        // noinspection UseCompareMethod
-        return x < y ? -1 : (x == y ? 0 : 1);
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/Certification.java

@@ -1,148 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import java.util.Date;
-
-public class Certification {
-
-    private final CertSynopsis issuer;
-    private final CertSynopsis target;
-    private final Optional<String> userId;
-
-    private final Date creationTime;
-    private final Optional<Date> expirationTime;
-    private final boolean exportable;
-    private final int trustAmount;
-    private final Depth trustDepth;
-    private final RegexSet regex;
-
-    public Certification(
-            CertSynopsis issuer,
-            CertSynopsis target,
-            Optional<String> userId,
-            Date creationTime,
-            Optional<Date> expirationTime,
-            boolean exportable,
-            int trustAmount,
-            Depth trustDepth,
-            RegexSet regex) {
-        this.issuer = issuer;
-        this.target = target;
-        this.userId = userId;
-        this.creationTime = creationTime;
-        this.expirationTime = expirationTime;
-        this.exportable = exportable;
-        this.trustAmount = trustAmount;
-        this.trustDepth = trustDepth;
-        this.regex = regex;
-    }
-
-    public Certification(CertSynopsis issuer,
-                         Optional<String> targetUserId,
-                         CertSynopsis target,
-                         Date creationTime) {
-        this.issuer = issuer;
-        this.target = target;
-        this.userId = targetUserId;
-        this.creationTime = creationTime;
-
-        this.expirationTime = Optional.empty();
-        this.exportable = true;
-        this.trustDepth = Depth.limited(0);
-        this.trustAmount = 120;
-        this.regex = RegexSet.wildcard();
-    }
-
-    /**
-     * Get the issuer of the certification.
-     *
-     * @return issuer
-     */
-    public CertSynopsis getIssuer() {
-        return issuer;
-    }
-
-    /**
-     * Get the target of the certification.
-     *
-     * @return target
-     */
-    public CertSynopsis getTarget() {
-        return target;
-    }
-
-    /**
-     * Get the target user-id.
-     *
-     * @return user-id
-     */
-    public Optional<String> getUserId() {
-        return userId;
-    }
-
-    /**
-     * Get the creation time of the certification.
-     *
-     * @return creation time
-     */
-    public Date getCreationTime() {
-        return creationTime;
-    }
-
-    /**
-     * Get the (optional) expiration time of the certification.
-     *
-     * @return optional expiration time
-     */
-    public Optional<Date> getExpirationTime() {
-        return expirationTime;
-    }
-
-    /**
-     * Return true if the certification is marked as exportable.
-     *
-     * @return exportable
-     */
-    public boolean isExportable() {
-        return exportable;
-    }
-
-    /**
-     * Get the trust amount of the certification.
-     *
-     * @return trust amount
-     */
-    public int getTrustAmount() {
-        return trustAmount;
-    }
-
-    /**
-     * Get the trust depth of the certification.
-     *
-     * @return trust depth
-     */
-    public Depth getTrustDepth() {
-        return trustDepth;
-    }
-
-    /**
-     * Return the set of regular expressions.
-     *
-     * @return regex set
-     */
-    public RegexSet getRegexes() {
-        return regex;
-    }
-
-    @Override
-    public String toString() {
-        StringBuilder sb = new StringBuilder();
-        sb.append(issuer.getFingerprint()).append((issuer.getUserIds().isEmpty() ? " " : " (" + issuer.getUserIds().keySet().iterator().next() + ") "));
-        sb.append(userId.isPresent() ? "certifies" : "delegates to").append(userId.isPresent() ? " [" + userId.get() + "] " : " ").append(target.getFingerprint())
-                .append(userId.isEmpty() && !target.getUserIds().isEmpty() ? " (" + target.getUserIds().keySet().iterator().next() + ")" : "");
-        return sb.toString();
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/CertificationSet.java

@@ -1,127 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import javax.annotation.Nonnull;
-
-/**
- * A {@link CertificationSet} is a set of {@link Certification Certifications} made by the same issuer, on the same
- * target certificate.
- * In some sense, a {@link CertificationSet} can be considered an edge in the web of trust.
- */
-public final class CertificationSet {
-
-    private final CertSynopsis issuer;
-    private final CertSynopsis target;
-
-    private final Map<Optional<String>, List<Certification>> certifications;
-
-    /**
-     * Create an empty {@link CertificationSet}.
-     *
-     * @param issuer issuer
-     * @param target target
-     * @return empty set
-     */
-    public static CertificationSet empty(CertSynopsis issuer, CertSynopsis target) {
-        return new CertificationSet(issuer, target, new HashMap<>());
-    }
-
-    public static CertificationSet fromCertification(Certification certification) {
-        CertificationSet set = CertificationSet.empty(certification.getIssuer(), certification.getTarget());
-        set.add(certification);
-        return set;
-    }
-
-    private CertificationSet(CertSynopsis issuer,
-                             CertSynopsis target,
-                             Map<Optional<String>, List<Certification>> certifications) {
-        this.issuer = issuer;
-        this.target = target;
-        this.certifications = new HashMap<>(certifications);
-    }
-
-    public CertSynopsis getIssuer() {
-        return issuer;
-    }
-
-    public CertSynopsis getTarget() {
-        return target;
-    }
-
-    public Map<Optional<String>, List<Certification>> getCertifications() {
-        // Copy to avoid side effects
-        Map<Optional<String>, List<Certification>> copy = new HashMap<>();
-        for (Optional<String> key : certifications.keySet()) {
-            copy.put(key, new ArrayList<>(certifications.get(key)));
-        }
-        return copy;
-    }
-
-    /**
-     * Merge this {@link CertificationSet} with another instance.
-     * After the operation, this will contain {@link Certification Certifications} from both sets.
-     *
-     * @param other other {@link CertificationSet}
-     */
-    public void merge(@Nonnull CertificationSet other) {
-        if (other == this) {
-            return;
-        }
-
-        if (!issuer.getFingerprint().equals(other.issuer.getFingerprint())) {
-            throw new IllegalArgumentException("Issuer fingerprint mismatch.");
-        }
-
-        if (!target.getFingerprint().equals(other.target.getFingerprint())) {
-            throw new IllegalArgumentException("Target fingerprint mismatch.");
-        }
-
-        for (Map.Entry<Optional<String>, List<Certification>> entry : other.certifications.entrySet()) {
-            for (Certification certification : entry.getValue()) {
-                add(certification);
-            }
-        }
-    }
-
-    /**
-     * Add a {@link Certification} into this {@link CertificationSet}.
-     *
-     * @param certification certification
-     */
-    public void add(@Nonnull Certification certification) {
-        if (!issuer.getFingerprint().equals(certification.getIssuer().getFingerprint())) {
-            throw new IllegalArgumentException("Issuer fingerprint mismatch.");
-        }
-        if (!target.getFingerprint().equals(certification.getTarget().getFingerprint())) {
-            throw new IllegalArgumentException("Target fingerprint mismatch.");
-        }
-
-        List<Certification> certificationsForUserId = certifications.get(certification.getUserId());
-        // noinspection Java8MapApi
-        if (certificationsForUserId == null) {
-            certificationsForUserId = new ArrayList<>();
-            certifications.put(certification.getUserId(), certificationsForUserId);
-        }
-        // TODO: Prevent duplicates, only keep newest timestamped sig?
-        certificationsForUserId.add(certification);
-    }
-
-    @Override
-    public String toString() {
-        StringBuilder sb = new StringBuilder();
-        for (Map.Entry<Optional<String>, List<Certification>> entry : certifications.entrySet()) {
-            for (Certification certification : entry.getValue()) {
-                sb.append(certification).append('\n');
-            }
-        }
-        return sb.toString();
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/Depth.java

@@ -1,82 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import org.pgpainless.wot.dijkstra.IntegerUtils;
-
-import javax.annotation.Nonnull;
-
-public final class Depth implements Comparable<Depth> {
-
-    private final Optional<Integer> depth;
-
-    private Depth(Optional<Integer> depth) {
-        this.depth = depth;
-        if (!isUnconstrained() && (getLimit().get() < 0 || getLimit().get() > 255)) {
-            throw new IllegalArgumentException("Depth must be a value between 0 and 255");
-        }
-    }
-
-    public static Depth unconstrained() {
-        return new Depth(Optional.empty());
-    }
-
-    public static Depth limited(int depth) {
-        return new Depth(Optional.just(depth));
-    }
-
-    public static Depth auto(int depth) {
-        return depth == 255 ? unconstrained() : limited(depth);
-    }
-
-    public Optional<Integer> getLimit() {
-        return depth;
-    }
-
-    public boolean isUnconstrained() {
-        return getLimit().isEmpty();
-    }
-
-    public Depth decrease(int value) {
-        if (isUnconstrained()) {
-            return unconstrained();
-        }
-        if (getLimit().get() >= value) {
-            return limited(getLimit().get() - value);
-        }
-        throw new IllegalArgumentException("Depth cannot be decreased.");
-    }
-
-    @Override
-    public int compareTo(@Nonnull Depth o) {
-        if (isUnconstrained()) {
-            if (o.isUnconstrained()) {
-                return 0;
-            } else {
-                return 1;
-            }
-        } else {
-            if (o.isUnconstrained()) {
-                return -1;
-            } else {
-                return IntegerUtils.compare(getLimit().get(), o.getLimit().get());
-            }
-        }
-    }
-
-    @Override
-    public String toString() {
-        return isUnconstrained() ? "unconstrained" : getLimit().get().toString();
-    }
-
-    public Depth min(Depth other) {
-        if (compareTo(other) <= 0) {
-            return this;
-        } else {
-            return other;
-        }
-    }
-
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/Network.java

@@ -1,156 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import javax.annotation.Nonnull;
-
-import org.pgpainless.key.OpenPgpFingerprint;
-
-/**
- * A network consists of nodes, and edges between them.
- * For the Web of Trust, nodes consist of {@link CertSynopsis CertSynopses}, while the edges between the nodes are
- * {@link CertificationSet CertificationSets}.
- * Edges can hereby be accessed in two ways:
- * <ul>
- *     <li>{@link #getEdges()} returns a {@link Map} keyed by the {@link OpenPgpFingerprint fingerprint} of an issuer,
- *     whose values are {@link List Lists} containing all edges originating from the issuer.</li>
- *     <li>{@link #getReverseEdges()} on the other hand returns a {@link Map} keyed by the
- *     {@link OpenPgpFingerprint fingerprint} of a target, whose value are {@link List Lists} containing all edges
- *     pointing to the target.</li>
- * </ul>
- */
-public class Network {
-
-    private final Map<OpenPgpFingerprint, CertSynopsis> nodes;
-    private final Map<OpenPgpFingerprint, List<CertificationSet>> edges;
-    private final Map<OpenPgpFingerprint, List<CertificationSet>> reverseEdges;
-    private final ReferenceTime referenceTime;
-
-    /**
-     * Create a {@link Network} from a set of nodes, edges, reversed edges and a reference time.
-     *
-     * @param nodes map containing all nodes of the network, keyed by their fingerprints
-     * @param edges map containing all edges of the network, keyed by the fingerprint of the issuer
-     * @param reverseEdges map containing all reversed edges of the network, keyed by the fingerprint of the target
-     * @param referenceTime reference time
-     */
-    public Network(Map<OpenPgpFingerprint, CertSynopsis> nodes,
-                   Map<OpenPgpFingerprint, List<CertificationSet>> edges,
-                   Map<OpenPgpFingerprint, List<CertificationSet>> reverseEdges,
-                   ReferenceTime referenceTime) {
-        this.nodes = nodes;
-        this.edges = edges;
-        this.reverseEdges = reverseEdges;
-        this.referenceTime = referenceTime;
-    }
-
-    /**
-     * Create an empty {@link Network}.
-     *
-     * @param referenceTime reference time for evaluation
-     * @return network
-     */
-    public static Network empty(@Nonnull ReferenceTime referenceTime) {
-        return new Network(
-                new HashMap<>(),
-                new HashMap<>(),
-                new HashMap<>(),
-                referenceTime);
-    }
-
-    /**
-     * Return all nodes ({@link CertSynopsis}) of the {@link Network}, indexed by their
-     * {@link OpenPgpFingerprint fingerprints}.
-     *
-     * @return nodes of the network
-     */
-    public Map<OpenPgpFingerprint, CertSynopsis> getNodes() {
-        return new HashMap<>(nodes);
-    }
-
-    /**
-     * Return all edges of the {@link Network}, indexed by the {@link OpenPgpFingerprint fingerprint} of the issuer.
-     * An edge consists of a {@link CertificationSet} containing all signatures made by the issuer on the target.
-     * TODO: Do we care about immutability, or can we ignore that issue since Network is only used by
-     *  WebOfTrust anyways?
-     *
-     * @return map of edges
-     */
-    public Map<OpenPgpFingerprint, List<CertificationSet>> getEdges() {
-        return new HashMap<>(edges);
-    }
-
-    /**
-     * Return all reversed edges of the {@link Network}, indexed by the {@link OpenPgpFingerprint fingerprint} of the target.
-     * TODO: Do we care about immutability, or can we ignore that issue since Network is only used by
-     *  WebOfTrust anyways?
-     *
-     * @return map of reversed edges
-     */
-    public Map<OpenPgpFingerprint, List<CertificationSet>> getReverseEdges() {
-        return new HashMap<>(reverseEdges);
-    }
-
-    /**
-     * Return the total number of edges on the network.
-     *
-     * @return number of edges
-     */
-    public int getNumberOfEdges() {
-        int num = 0;
-        for (List<CertificationSet> outEdges : edges.values()) {
-            num += outEdges.size();
-        }
-        return num;
-    }
-
-    /**
-     * Return the total number of signatures the network comprises.
-     *
-     * @return number of signatures
-     */
-    public int getNumberOfSignatures() {
-        int num = 0;
-        for (List<CertificationSet> edgesPerIssuer : edges.values()) {
-            for (CertificationSet edge : edgesPerIssuer) {
-                for (List<Certification> sigsPerDatum : edge.getCertifications().values()) {
-                    num += sigsPerDatum.size();
-                }
-            }
-        }
-        return num;
-    }
-
-    /**
-     * Return the {@link ReferenceTime} which was used when creating the {@link Network}.
-     *
-     * @return reference time
-     */
-    public ReferenceTime getReferenceTime() {
-        return referenceTime;
-    }
-
-    public String toString() {
-        int edgeNum = 0;
-        for (List<CertificationSet> edgesFrom : edges.values()) {
-            edgeNum += edgesFrom.size();
-        }
-
-        StringBuilder sb = new StringBuilder("Network with " + getNodes().size() + " nodes, " + edgeNum + " edges:\n");
-        for (OpenPgpFingerprint issuer : getNodes().keySet()) {
-            List<CertificationSet> edges = getEdges().get(issuer);
-            if (edges == null) {
-                continue;
-            }
-            for (CertificationSet edge : edges) {
-                sb.append(edge);
-            }
-        }
-        return sb.toString();
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/Optional.java

@@ -1,78 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-
-public final class Optional<T> {
-
-    private final T item;
-
-    public static <T> Optional<T> empty() {
-        return new Optional<>();
-    }
-
-    public static <T> Optional<T> just(@Nonnull T item) {
-        return new Optional<>(item);
-    }
-
-    public static <T> Optional<T> maybe(@Nullable T item) {
-        return item == null ? empty() : just(item);
-    }
-
-    private Optional() {
-        this.item = null;
-    }
-
-    private Optional(@Nonnull T item) {
-        this.item = item;
-    }
-
-    public boolean isEmpty() {
-        return item == null;
-    }
-
-    public boolean isPresent() {
-        return item != null;
-    }
-
-    public @Nonnull T get() {
-        if (item == null) {
-            throw new NullPointerException("Item is null.");
-        }
-        return item;
-    }
-
-    @Override
-    public int hashCode() {
-        return super.hashCode();
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        if (obj == null) {
-            return false;
-        }
-        if (this == obj) {
-            return true;
-        }
-
-        if (!(obj instanceof Optional)) {
-            return false;
-        }
-
-        Optional other = (Optional) obj;
-        if (isEmpty() && other.isEmpty()) {
-            return true;
-        }
-
-        if (isPresent() && isPresent()) {
-            return get().equals(other.get());
-        }
-
-        return false;
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/Path.java

@@ -1,94 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class Path {
-
-    private CertSynopsis root;
-    private List<Certification> edges;
-    private Depth residualDepth;
-
-    public Path(CertSynopsis root) {
-        this.root = root;
-        this.edges = new ArrayList<>();
-        this.residualDepth = Depth.unconstrained();
-    }
-
-    public CertSynopsis getRoot() {
-        return root;
-    }
-
-    public CertSynopsis getTarget() {
-        if (edges.isEmpty()) {
-            return getRoot();
-        } else {
-            return edges.get(edges.size() - 1).getTarget();
-        }
-    }
-
-    public List<CertSynopsis> getCertificates() {
-        List<CertSynopsis> certs = new ArrayList<>();
-        certs.add(getRoot());
-        for (Certification edge : edges) {
-            certs.add(edge.getTarget());
-        }
-        return certs;
-    }
-
-    public int getLength() {
-        return edges.size() + 1;
-    }
-
-    public List<Certification> getCertifications() {
-        return new ArrayList<>(edges);
-    }
-
-    public Depth getResidualDepth() {
-        return residualDepth;
-    }
-
-    public int getAmount() {
-        if (edges.isEmpty()) {
-            return 120;
-        }
-        int min = 255;
-        for (Certification edge : edges) {
-            min = Math.min(min, edge.getTrustAmount());
-        }
-        return min;
-    }
-
-    public void append(Certification certification) {
-        if (!getTarget().getFingerprint().equals(certification.getIssuer().getFingerprint())) {
-            throw new IllegalArgumentException("Cannot append certification to path: Path's tail is not issuer of the certification.");
-        }
-
-        if (!residualDepth.isUnconstrained() && residualDepth.getLimit().get() == 0) {
-            throw new IllegalArgumentException("Not enough depth.");
-        }
-
-        boolean cyclic = getRoot().getFingerprint().equals(certification.getTarget().getFingerprint());
-        for (int i = 0; i < edges.size() && !cyclic; i++) {
-            Certification edge = edges.get(i);
-
-            if (edge.getTarget().getFingerprint().equals(certification.getTarget().getFingerprint())) {
-                if (i == edges.size() - 1) {
-                    cyclic = edge.getUserId().equals(certification.getUserId());
-                } else {
-                    cyclic = true;
-                }
-            }
-        }
-        if (cyclic) {
-            throw new IllegalArgumentException("Adding the certification to the path would create a cycle.");
-        }
-
-        residualDepth = certification.getTrustDepth().min(residualDepth.decrease(1));
-        edges.add(certification);
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/Paths.java

@@ -1,50 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class Paths {
-
-    private final List<Item> paths = new ArrayList<>();
-
-    public List<Item> getPaths() {
-        return new ArrayList<>(paths);
-    }
-
-    public void add(Path path, int amount) {
-        if (amount <= path.getAmount()) {
-            throw new AssertionError();
-        }
-        this.paths.add(new Item(path, amount));
-    }
-
-    public int getAmount() {
-        int sum = 0;
-        for (Item item : paths) {
-            sum += item.amount;
-        }
-        return sum;
-    }
-
-    public static class Item {
-        private final Path path;
-        private final int amount;
-
-        public Item(Path path, int amount) {
-            this.path = path;
-            this.amount = amount;
-        }
-
-        public Path getPath() {
-            return path;
-        }
-
-        public int getAmount() {
-            return amount;
-        }
-    }
-}

wot-dijkstra/src/main/java/org/pgpainless/wot/dijkstra/sq/RegexSet.java

@@ -1,50 +0,0 @@
-// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.wot.dijkstra.sq;
-
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-import javax.annotation.Nonnull;
-
-public final class RegexSet {
-
-    private final Set<String> regexStrings;
-
-    private RegexSet(Set<String> regexStrings) {
-        this.regexStrings = regexStrings;
-    }
-
-    public static RegexSet fromExpressionList(@Nonnull List<String> regexList) {
-        Set<String> regexStringSet = new HashSet<>(regexList);
-        return new RegexSet(regexStringSet);
-    }
-
-    public static RegexSet fromExpression(@Nonnull String regex) {
-        return fromExpressionList(Collections.singletonList(regex));
-    }
-
-    public static RegexSet wildcard() {
-        return fromExpressionList(Collections.emptyList());
-    }
-
-    public boolean matches(String string) {
-        if (regexStrings.isEmpty()) {
-            return true;
-        }
-
-        for (String regex : regexStrings) {
-            Matcher matcher = Pattern.compile(regex).matcher(string);
-            if (matcher.matches()) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/CertSynopsis.kt

@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
 package org.pgpainless.wot.dijkstra.sq
 
 import org.pgpainless.algorithm.RevocationState

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/Certification.kt

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+import java.util.*
+
+data class Certification(
+        val issuer: CertSynopsis,
+        val target: CertSynopsis,
+        val userId: String?,
+        val creationTime: Date,
+        val expirationTime: Date?,
+        val exportable: Boolean,
+        val trustAmount: Int,
+        val trustDepth: Depth,
+        val regex: RegexSet
+) {
+
+    constructor(
+            issuer: CertSynopsis,
+            targetUserId: String?,
+            target: CertSynopsis,
+            creationTime: Date) :
+            this(issuer, target, targetUserId, creationTime, null, true, 120, Depth.limited(0), RegexSet.wildcard())
+
+    override fun toString(): String {
+        val relation = if (userId != null) {
+            "certifies"
+        } else {
+            "delegates to"
+        }
+        val relationTarget = if (userId != null) {
+            "[$userId] ${target.fingerprint}"
+        } else {
+            "$target"
+        }
+        return "$issuer $relation $relationTarget"
+    }
+}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/CertificationSet.kt

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+data class CertificationSet(
+        val issuer: CertSynopsis,
+        val target: CertSynopsis,
+        val certifications: MutableMap<String?, MutableList<Certification>>) {
+
+    companion object {
+
+        @JvmStatic
+        fun empty(issuer: CertSynopsis, target: CertSynopsis): CertificationSet {
+            return CertificationSet(issuer, target, HashMap())
+        }
+
+        @JvmStatic
+        fun fromCertification(certification: Certification) : CertificationSet {
+            val set = empty(certification.issuer, certification.target)
+            set.add(certification)
+            return set
+        }
+    }
+
+    fun merge(other: CertificationSet) {
+        if (other == this) {
+            return
+        }
+
+        require(issuer.fingerprint == other.issuer.fingerprint) { "Issuer fingerprint mismatch." }
+        require(target.fingerprint == other.target.fingerprint) { "Target fingerprint mismatch." }
+
+        for (userId in other.certifications.keys) {
+            for (certification in other.certifications[userId]!!) {
+                add(certification)
+            }
+        }
+    }
+
+    fun add(certification : Certification) {
+        require(issuer.fingerprint == certification.issuer.fingerprint) { "Issuer fingerprint mismatch." }
+        require(target.fingerprint == certification.target.fingerprint) { "Target fingerprint mismatch." }
+
+        var certificationsForUserId: MutableList<Certification>? = certifications[certification.userId]
+        if (certificationsForUserId == null) {
+            certificationsForUserId = ArrayList()
+            certifications[certification.userId] = certificationsForUserId
+        }
+        certificationsForUserId.add(certification)
+    }
+
+    override fun toString(): String {
+        return "$certifications"
+    }
+}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/Depth.kt

@@ -0,0 +1,76 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+class Depth(val limit: Int?) : Comparable<Depth> {
+
+    companion object {
+        @JvmStatic
+        fun unconstrained() : Depth {
+            return Depth(null)
+        }
+
+        @JvmStatic
+        fun limited(limit: Int): Depth {
+            require(limit in 0..255) {
+                "Trust depth MUST be a value between 0 and 255."
+            }
+            return Depth(limit)
+        }
+
+        @JvmStatic
+        fun auto(limit: Int): Depth {
+            return if (limit == 255) {
+                unconstrained()
+            } else {
+                limited(limit)
+            }
+        }
+    }
+
+    fun isUnconstrained() : Boolean {
+        return limit == null
+    }
+
+    fun decrease(value : Int) : Depth {
+        return if (isUnconstrained()) {
+            unconstrained()
+        } else {
+            if (limit!! >= value) {
+                limited(limit - value)
+            } else {
+                throw IllegalArgumentException("Depth cannot be decreased.")
+            }
+        }
+    }
+
+    fun min(other: Depth) : Depth {
+        return if (compareTo(other) <= 0) {
+            this
+        } else {
+            other
+        }
+    }
+
+    override fun compareTo(o: Depth): Int {
+        return if (isUnconstrained()) {
+            if (o.isUnconstrained()) {
+                0
+            } else {
+                1
+            }
+        } else {
+            if (o.isUnconstrained()) {
+                -1
+            } else {
+                limit!!.compareTo(o.limit!!)
+            }
+        }
+    }
+
+    override fun toString() : String {
+        return if (isUnconstrained()) { "unconstrained" } else { limit!!.toString() }
+    }
+}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/Network.kt

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+import org.pgpainless.key.OpenPgpFingerprint
+
+/**
+ * A network consists of nodes, and edges between them.
+ * For the Web of Trust, nodes consist of [CertSynopses][CertSynopsis], while the edges between the nodes are
+ * [CertificationSets][CertificationSet].
+ *
+ * @constructor creates a new network
+ * @param nodes contains a [Map] of [CertSynopsis] keyed by their [OpenPgpFingerprint]
+ * @param edges [Map] keyed by the [fingerprint][OpenPgpFingerprint] of an issuer, whose values are [Lists][List] containing all edges originating from the issuer.
+ * @param reverseEdges [Map] keyed by the [fingerprint][OpenPgpFingerprint] of a target, whose values are [Lists][List] containing all edges pointing to the target
+ * @param referenceTime reference time at which the [Network] was built
+ */
+class Network(
+        val nodes: Map<OpenPgpFingerprint, CertSynopsis>,
+        val edges: Map<OpenPgpFingerprint, List<CertificationSet>>,
+        val reverseEdges: Map<OpenPgpFingerprint, List<CertificationSet>>,
+        val referenceTime: ReferenceTime) {
+
+    companion object {
+        @JvmStatic
+        fun empty(referenceTime: ReferenceTime): Network {
+            return Network(HashMap(), HashMap(), HashMap(), referenceTime)
+        }
+    }
+
+    val numberOfEdges: Int
+        get() {
+            return edges.values.sumOf { it.size }
+        }
+
+    val numberOfSignatures: Int
+        get() {
+            return edges.values
+                    .flatten()
+                    .flatMap { it.certifications.values }
+                    .sumOf { it.size }
+        }
+
+    override fun toString(): String {
+        val sb = StringBuilder()
+        sb.append("Network with ${nodes.size} nodes, $numberOfEdges edges:\n")
+        for (issuer in nodes.keys) {
+            val outEdges = edges[issuer] ?: continue
+            for (edge in outEdges) {
+                sb.append(edge)
+            }
+        }
+        return sb.toString()
+    }
+}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/Path.kt

@@ -0,0 +1,80 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+import kotlin.math.min
+
+class Path(
+        val root: CertSynopsis,
+        val edges: MutableList<Certification>,
+        var residualDepth: Depth
+) {
+    constructor(root: CertSynopsis) : this(
+            root, mutableListOf<Certification>(), Depth.unconstrained())
+
+    val target: CertSynopsis
+        get() {
+            return if (edges.isEmpty()) {
+                root
+            } else {
+                edges[edges.size - 1].target
+            }
+        }
+
+    val certificates: List<CertSynopsis>
+        get() {
+            val certs: MutableList<CertSynopsis> = ArrayList()
+            certs.add(root)
+            for (certification in edges) {
+                certs.add(certification.target)
+            }
+            return certs
+        }
+
+    val length: Int
+        get() = edges.size + 1
+
+    val certifications: List<Certification>
+        get() = ArrayList(edges)
+
+    val amount: Int
+        get() = if (edges.isEmpty()) {
+            120
+        } else {
+            var min = 255
+            for (edge in edges) {
+                min = min(min, edge.trustAmount)
+            }
+            min
+        }
+
+    fun append(certification: Certification) {
+        require(target.fingerprint == certification.issuer.fingerprint) {
+            "Cannot append certification to path: Path's tail is not issuer of the certification."
+        }
+        require(residualDepth.isUnconstrained() || residualDepth.limit!! > 0) {
+            "Not enough depth."
+        }
+
+        var cyclic = root.fingerprint == certification.target.fingerprint
+        for (i in 0..edges.size) {
+            val edge = edges[i]
+            if (cyclic) {
+                break
+            }
+            if (edge.target.fingerprint == certification.target.fingerprint) {
+                cyclic = if (i == edges.size - 1) {
+                    edge.userId == certification.userId
+                } else {
+                    true
+                }
+            }
+        }
+        require(!cyclic) { "Adding the certification to the path would create a cycle." }
+
+        residualDepth = certification.trustDepth.min(residualDepth.decrease(1))
+        edges.add(certification)
+    }
+}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/Paths.kt

@@ -0,0 +1,24 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+class Paths(val paths: MutableList<Item>) {
+
+    fun add(path: Path, amount: Int) {
+        require(amount <= path.amount) {
+            "Amount too small. TODO: Better error message"
+        }
+        paths.add(Item(path, amount))
+    }
+
+    val amount: Int
+        get() {
+            return paths.sumOf { it.amount }
+        }
+
+    data class Item(val path: Path, val amount: Int) {
+
+    }
+}

wot-dijkstra/src/main/kotlin/org/pgpainless/wot/dijkstra/sq/RegexSet.kt

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.wot.dijkstra.sq
+
+import java.util.regex.Pattern
+
+data class RegexSet(val regexStrings: Set<String>) {
+
+    companion object {
+        @JvmStatic
+        fun fromExpressionList(regexList: List<String>): RegexSet {
+            return RegexSet(regexList.toSet())
+        }
+
+        @JvmStatic
+        fun fromExpression(regex: String): RegexSet {
+            return fromExpressionList(listOf(regex))
+        }
+
+        @JvmStatic
+        fun wildcard(): RegexSet {
+            return fromExpressionList(listOf())
+        }
+    }
+
+    fun matches(string: String): Boolean {
+        if (regexStrings.isEmpty()) {
+            return true
+        }
+
+        for (regex in regexStrings) {
+            val matcher = Pattern.compile(regex).matcher(string)
+            if (matcher.matches()) {
+                return true
+            }
+        }
+        return false
+    }
+}

wot-dijkstra/src/test/java/org/pgpainless/wot/dijkstra/sq/DepthTest.java

@@ -8,6 +8,8 @@ import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -17,15 +19,15 @@ public class DepthTest {
     public void testUnlimitedItem() {
         Depth depth = Depth.unconstrained();
         assertTrue(depth.isUnconstrained());
-        assertFalse(depth.getLimit().isPresent());
+        assertNull(depth.getLimit());
     }
 
     @Test
     public void testLimitedItem() {
         Depth limited = Depth.limited(2);
         assertFalse(limited.isUnconstrained());
-        assertTrue(limited.getLimit().isPresent());
+        assertNotNull(limited.getLimit());
-        assertEquals(2, limited.getLimit().get());
+        assertEquals(2, limited.getLimit());
     }
 
     @Test
@@ -40,7 +42,7 @@ public class DepthTest {
         Depth limited = Depth.limited(1);
         Depth decreased = limited.decrease(1);
         assertFalse(decreased.isUnconstrained());
-        assertEquals(0, decreased.getLimit().get());
+        assertEquals(0, decreased.getLimit());
     }
 
     @Test
@@ -76,7 +78,7 @@ public class DepthTest {
     public void testAutoLimited() {
         Depth depth = Depth.auto(120);
         assertFalse(depth.isUnconstrained());
-        assertEquals(120, depth.getLimit().get());
+        assertEquals(120, depth.getLimit());
     }
 
     @Test