/*
 * Copyright 2017 the original author or authors.
 *
 * Licensed 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.gradle.internal.component.external.model;

import com.google.common.base.Objects;
import com.google.common.collect.ImmutableList;
import org.gradle.api.artifacts.VersionConstraint;
import org.gradle.api.artifacts.component.ComponentSelector;
import org.gradle.api.artifacts.component.ModuleComponentIdentifier;
import org.gradle.api.artifacts.component.ModuleComponentSelector;
import org.gradle.api.artifacts.component.ProjectComponentSelector;
import org.gradle.api.internal.attributes.AttributesSchemaInternal;
import org.gradle.api.internal.attributes.ImmutableAttributes;
import org.gradle.internal.component.local.model.DefaultProjectDependencyMetadata;
import org.gradle.internal.component.model.AttributeConfigurationSelector;
import org.gradle.internal.component.model.ComponentResolveMetadata;
import org.gradle.internal.component.model.ConfigurationMetadata;
import org.gradle.internal.component.model.DependencyMetadata;
import org.gradle.internal.component.model.ExcludeMetadata;
import org.gradle.internal.component.model.IvyArtifactName;

import java.util.List;

/**
 * A `ModuleDependencyMetadata` implementation that is backed by an `ExternalDependencyDescriptor` bound to a particular
 * source `ConfigurationMetadata`. The reason for this is that the Ivy and Maven dependency descriptors resolve target components
 * differently based on the configuration that they are sourced from.
 */
public class ConfigurationBoundExternalDependencyMetadata implements ModuleDependencyMetadata {
    private final ConfigurationMetadata configuration;
    private final ModuleComponentIdentifier componentId;
    private final ExternalDependencyDescriptor dependencyDescriptor;
    private final String reason;
    private final boolean isTransitive;

    private boolean alwaysUseAttributeMatching;

    private ConfigurationBoundExternalDependencyMetadata(ConfigurationMetadata configuration, ModuleComponentIdentifier componentId, ExternalDependencyDescriptor dependencyDescriptor, String reason) {
        this.configuration = configuration;
        this.componentId = componentId;
        this.dependencyDescriptor = dependencyDescriptor;
        this.reason = reason;
        this.isTransitive = dependencyDescriptor.isTransitive();
    }

    public ConfigurationBoundExternalDependencyMetadata(ConfigurationMetadata configuration, ModuleComponentIdentifier componentId, ExternalDependencyDescriptor dependencyDescriptor) {
        this(configuration, componentId, dependencyDescriptor, null);
    }

    public ConfigurationBoundExternalDependencyMetadata alwaysUseAttributeMatching() {
        this.alwaysUseAttributeMatching = true;
        return this;
    }

    public ExternalDependencyDescriptor getDependencyDescriptor() {
        return dependencyDescriptor;
    }

    /**
     * Choose a set of target configurations based on: a) the consumer attributes (with associated schema) and b) the target component.
     *
     * Use attribute matching to choose a single variant when the target component has variants,
     * otherwise revert to legacy selection of target configurations.
     */
    @Override
    public List<ConfigurationMetadata> selectConfigurations(ImmutableAttributes consumerAttributes, ComponentResolveMetadata targetComponent, AttributesSchemaInternal consumerSchema) {
        // This is a slight different condition than that used for a dependency declared in a Gradle project,
        // which is (targetHasVariants || consumerHasAttributes), relying on the fallback to 'default' for consumer attributes without any variants.
        if (alwaysUseAttributeMatching || hasVariants(targetComponent)) {
            return ImmutableList.of(AttributeConfigurationSelector.selectConfigurationUsingAttributeMatching(consumerAttributes, targetComponent, consumerSchema));
        }
        return dependencyDescriptor.selectLegacyConfigurations(componentId, configuration, targetComponent);
    }

    private boolean hasVariants(ComponentResolveMetadata targetComponent) {
        return targetComponent.getVariantsForGraphTraversal().isPresent();
    }
    @Override
    public List<IvyArtifactName> getArtifacts() {
        return dependencyDescriptor.getConfigurationArtifacts(configuration);
    }

    @Override
    public List<ExcludeMetadata> getExcludes() {
        return dependencyDescriptor.getConfigurationExcludes(configuration.getHierarchy());
    }

    @Override
    public DependencyMetadata withTarget(ComponentSelector target) {
        if (target instanceof ModuleComponentSelector) {
            ModuleComponentSelector moduleTarget = (ModuleComponentSelector) target;
            ModuleComponentSelector newSelector = DefaultModuleComponentSelector.newSelector(moduleTarget.getModuleIdentifier(), moduleTarget.getVersionConstraint(), moduleTarget.getAttributes());
            if (newSelector.equals(getSelector())) {
                return this;
            }
            return withRequested(newSelector);
        } else if (target instanceof ProjectComponentSelector) {
            ProjectComponentSelector projectTarget = (ProjectComponentSelector) target;
            return new DefaultProjectDependencyMetadata(projectTarget, this);
        } else {
            throw new IllegalArgumentException("Unexpected selector provided: " + target);
        }
    }

    @Override
    public ModuleDependencyMetadata withRequestedVersion(VersionConstraint requestedVersion) {
        ModuleComponentSelector selector = getSelector();
        if (requestedVersion.equals(selector.getVersionConstraint())) {
            return this;
        }
        ModuleComponentSelector newSelector = DefaultModuleComponentSelector.newSelector(selector.getModuleIdentifier(), requestedVersion, selector.getAttributes());
        return withRequested(newSelector);
    }

    @Override
    public ModuleDependencyMetadata withReason(String reason) {
        if (Objects.equal(reason, this.getReason())) {
            return this;
        }
        return new ConfigurationBoundExternalDependencyMetadata(configuration, componentId, dependencyDescriptor, reason);
    }

    private ModuleDependencyMetadata withRequested(ModuleComponentSelector newSelector) {
        ExternalDependencyDescriptor newDelegate = dependencyDescriptor.withRequested(newSelector);
        return new ConfigurationBoundExternalDependencyMetadata(configuration, componentId, newDelegate);
    }

    @Override
    public ModuleComponentSelector getSelector() {
        return dependencyDescriptor.getSelector();
    }

    @Override
    public boolean isChanging() {
        return dependencyDescriptor.isChanging();
    }

    @Override
    public boolean isTransitive() {
        return isTransitive;
    }

    @Override
    public boolean isPending() {
        return dependencyDescriptor.isOptional();
    }

    @Override
    public String getReason() {
        return reason;
    }

    @Override
    public String toString() {
        return dependencyDescriptor.toString();
    }
}
