/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.eclipse.aether.util.graph.selector;

import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.TreeSet;

import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.collection.DependencyCollectionContext;
import org.eclipse.aether.collection.DependencySelector;
import org.eclipse.aether.graph.Dependency;
import org.eclipse.aether.graph.Exclusion;

import static java.util.Objects.requireNonNull;

/**
 * A dependency selector that applies exclusions based on artifact coordinates.
 *
 * @see Dependency#getExclusions()
 */
public final class ExclusionDependencySelector implements DependencySelector {

    // sorted and dupe-free array, faster to iterate than LinkedHashSet
    private final Exclusion[] exclusions;

    private int hashCode;

    /**
     * Creates a new selector without any exclusions.
     */
    public ExclusionDependencySelector() {
        this.exclusions = new Exclusion[0];
    }

    /**
     * Creates a new selector with the specified exclusions.
     *
     * @param exclusions The exclusions, may be {@code null}.
     */
    public ExclusionDependencySelector(Collection<Exclusion> exclusions) {
        if (exclusions != null && !exclusions.isEmpty()) {
            TreeSet<Exclusion> sorted = new TreeSet<>(ExclusionComparator.INSTANCE);
            sorted.addAll(exclusions);
            this.exclusions = sorted.toArray(new Exclusion[0]);
        } else {
            this.exclusions = new Exclusion[0];
        }
    }

    private ExclusionDependencySelector(Exclusion[] exclusions) {
        this.exclusions = exclusions;
    }

    public boolean selectDependency(Dependency dependency) {
        requireNonNull(dependency, "dependency cannot be null");
        Artifact artifact = dependency.getArtifact();
        for (Exclusion exclusion : exclusions) {
            if (matches(exclusion, artifact)) {
                return false;
            }
        }
        return true;
    }

    private boolean matches(Exclusion exclusion, Artifact artifact) {
        if (!matches(exclusion.getArtifactId(), artifact.getArtifactId())) {
            return false;
        }
        if (!matches(exclusion.getGroupId(), artifact.getGroupId())) {
            return false;
        }
        if (!matches(exclusion.getExtension(), artifact.getExtension())) {
            return false;
        }
        return matches(exclusion.getClassifier(), artifact.getClassifier());
    }

    private boolean matches(String pattern, String value) {
        return "*".equals(pattern) || pattern.equals(value);
    }

    public DependencySelector deriveChildSelector(DependencyCollectionContext context) {
        requireNonNull(context, "context cannot be null");
        Dependency dependency = context.getDependency();
        Collection<Exclusion> exclusions = (dependency != null) ? dependency.getExclusions() : null;
        if (exclusions == null || exclusions.isEmpty()) {
            return this;
        }

        Exclusion[] merged = this.exclusions;
        int count = merged.length;
        for (Exclusion exclusion : exclusions) {
            int index = Arrays.binarySearch(merged, exclusion, ExclusionComparator.INSTANCE);
            if (index < 0) {
                index = -(index + 1);
                if (count >= merged.length) {
                    Exclusion[] tmp = new Exclusion[merged.length + exclusions.size()];
                    System.arraycopy(merged, 0, tmp, 0, index);
                    tmp[index] = exclusion;
                    System.arraycopy(merged, index, tmp, index + 1, count - index);
                    merged = tmp;
                } else {
                    System.arraycopy(merged, index, merged, index + 1, count - index);
                    merged[index] = exclusion;
                }
                count++;
            }
        }
        if (merged == this.exclusions) {
            return this;
        }
        if (merged.length != count) {
            Exclusion[] tmp = new Exclusion[count];
            System.arraycopy(merged, 0, tmp, 0, count);
            merged = tmp;
        }

        return new ExclusionDependencySelector(merged);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        } else if (null == obj || !getClass().equals(obj.getClass())) {
            return false;
        }

        ExclusionDependencySelector that = (ExclusionDependencySelector) obj;
        return Arrays.equals(exclusions, that.exclusions);
    }

    @Override
    public int hashCode() {
        if (hashCode == 0) {
            int hash = getClass().hashCode();
            hash = hash * 31 + Arrays.hashCode(exclusions);
            hashCode = hash;
        }
        return hashCode;
    }

    @Override
    public String toString() {
        StringBuilder builder =
                new StringBuilder().append(this.getClass().getSimpleName()).append('(');
        for (int i = 0; i < this.exclusions.length; i++) {
            builder.append(this.exclusions[i]);
            if (i < this.exclusions.length - 1) {
                builder.append(", ");
            }
        }
        return builder.append(')').toString();
    }

    private static class ExclusionComparator implements Comparator<Exclusion> {

        static final ExclusionComparator INSTANCE = new ExclusionComparator();

        public int compare(Exclusion e1, Exclusion e2) {
            if (e1 == null) {
                return (e2 == null) ? 0 : 1;
            } else if (e2 == null) {
                return -1;
            }
            int rel = e1.getArtifactId().compareTo(e2.getArtifactId());
            if (rel == 0) {
                rel = e1.getGroupId().compareTo(e2.getGroupId());
                if (rel == 0) {
                    rel = e1.getExtension().compareTo(e2.getExtension());
                    if (rel == 0) {
                        rel = e1.getClassifier().compareTo(e2.getClassifier());
                    }
                }
            }
            return rel;
        }
    }
}