/*
 * 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.resolution;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

import org.eclipse.aether.RepositorySystem;
import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.repository.ArtifactRepository;
import org.eclipse.aether.repository.LocalArtifactResult;
import org.eclipse.aether.transfer.ArtifactNotFoundException;

import static java.util.Objects.requireNonNull;

/**
 * The result of an artifact resolution request.
 *
 * @see RepositorySystem#resolveArtifacts(org.eclipse.aether.RepositorySystemSession, java.util.Collection)
 * @see Artifact#getPath()
 */
public final class ArtifactResult {

    /**
     * A sentinel object, that is used as key for exceptions that had no related repository during resolution.
     *
     * @since 2.0.0
     */
    public static final ArtifactRepository NO_REPOSITORY = new NoRepository();

    private static final class NoRepository implements ArtifactRepository {

        private NoRepository() {}

        public String getContentType() {
            return "unknown";
        }

        public String getId() {
            return "unknown";
        }

        @Override
        public String toString() {
            return getId();
        }
    }

    private final ArtifactRequest request;

    private final Map<ArtifactRepository, List<Exception>> exceptions;

    private Artifact artifact;

    private ArtifactRepository repository;

    private LocalArtifactResult localArtifactResult;

    /**
     * Creates a new result for the specified request.
     *
     * @param request The resolution request, must not be {@code null}.
     */
    public ArtifactResult(ArtifactRequest request) {
        this.request = requireNonNull(request, "artifact request cannot be null");
        this.exceptions = new ConcurrentHashMap<>();
    }

    /**
     * Gets the resolution request that was made.
     *
     * @return The resolution request, never {@code null}.
     */
    public ArtifactRequest getRequest() {
        return request;
    }

    /**
     * Gets the resolved artifact (if any). Use {@link #getExceptions()} to query the errors that occurred while trying
     * to resolve the artifact.
     *
     * @return The resolved artifact or {@code null} if the resolution failed.
     */
    public Artifact getArtifact() {
        return artifact;
    }

    /**
     * Sets the resolved artifact.
     *
     * @param artifact The resolved artifact, may be {@code null} if the resolution failed.
     * @return This result for chaining, never {@code null}.
     */
    public ArtifactResult setArtifact(Artifact artifact) {
        this.artifact = artifact;
        return this;
    }

    /**
     * Gets the exceptions that occurred while resolving the artifact. Note that this list can be non-empty even if the
     * artifact was successfully resolved, e.g. when one of the contacted remote repositories didn't contain the
     * artifact but a later repository eventually contained it.
     *
     * @return The exceptions that occurred, never {@code null}.
     * @see #isResolved()
     * @see #isMissing()
     */
    public List<Exception> getExceptions() {
        ArrayList<Exception> result = new ArrayList<>();
        exceptions.values().forEach(result::addAll);
        return result;
    }

    /**
     * Gets the exceptions that occurred while resolving the artifact. Note that this map can be non-empty even if the
     * artifact was successfully resolved, e.g. when one of the contacted remote repositories didn't contain the
     * artifact but a later repository eventually contained it.
     *
     * @return Map of exceptions per repository, that occurred during resolution, never {@code null}.
     * @see #isResolved()
     * @see #isMissing()
     * @since 2.0.0
     */
    public Map<ArtifactRepository, List<Exception>> getMappedExceptions() {
        return exceptions;
    }

    /**
     * Records the specified exception while resolving the artifact.
     *
     * @param exception The exception to record, may be {@code null}.
     * @return This result for chaining, never {@code null}.
     * @deprecated Use {@link #addException(ArtifactRepository, Exception)} method instead.
     */
    @Deprecated
    public ArtifactResult addException(Exception exception) {
        return addException(NO_REPOSITORY, exception);
    }

    /**
     * Records the specified exception while resolving the artifact.
     *
     * @param exception The exception to record, may be {@code null}.
     * @return This result for chaining, never {@code null}.
     * @since 2.0.0
     */
    public ArtifactResult addException(ArtifactRepository repository, Exception exception) {
        if (repository != null && exception != null) {
            exceptions
                    .computeIfAbsent(repository, k -> new CopyOnWriteArrayList<>())
                    .add(exception);
        }
        return this;
    }

    /**
     * Gets the repository from which the artifact was eventually resolved. Note that successive resolutions of the same
     * artifact might yield different results if the employed local repository does not track the origin of an artifact.
     *
     * @return The repository from which the artifact was resolved or {@code null} if unknown.
     */
    public ArtifactRepository getRepository() {
        return repository;
    }

    /**
     * Sets the repository from which the artifact was resolved.
     *
     * @param repository The repository from which the artifact was resolved, may be {@code null}.
     * @return This result for chaining, never {@code null}.
     */
    public ArtifactResult setRepository(ArtifactRepository repository) {
        this.repository = repository;
        return this;
    }

    /**
     * Gets the {@link LocalArtifactResult} received during artifact resolution.
     *
     * @return The {@link LocalArtifactResult} or {@code null}.
     * @since 1.9.6
     */
    public LocalArtifactResult getLocalArtifactResult() {
        return localArtifactResult;
    }

    /**
     * Sets the {@link LocalArtifactResult} that is received during artifact resolution.
     *
     * @param localArtifactResult The local artifact result.
     * @since 1.9.6
     */
    public void setLocalArtifactResult(LocalArtifactResult localArtifactResult) {
        this.localArtifactResult = localArtifactResult;
    }

    /**
     * Indicates whether the requested artifact was resolved. Note that the artifact might have been successfully
     * resolved despite {@link #getExceptions()} indicating transfer errors while trying to fetch the artifact from some
     * of the specified remote repositories.
     *
     * @return {@code true} if the artifact was resolved, {@code false} otherwise.
     * @see Artifact#getPath()
     */
    public boolean isResolved() {
        return getArtifact() != null && getArtifact().getPath() != null;
    }

    /**
     * Indicates whether the requested artifact is not present in any of the specified repositories.
     *
     * @return {@code true} if the artifact is not present in any repository, {@code false} otherwise.
     */
    public boolean isMissing() {
        for (Exception e : getExceptions()) {
            if (!(e instanceof ArtifactNotFoundException)) {
                return false;
            }
        }
        return !isResolved();
    }

    @Override
    public String toString() {
        return getArtifact() + " < " + getRepository();
    }
}
