/*
 * 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.apache.maven.model.inheritance;

import javax.inject.Named;
import javax.inject.Singleton;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.apache.maven.api.model.InputLocation;
import org.apache.maven.api.model.Model;
import org.apache.maven.api.model.ModelBase;
import org.apache.maven.api.model.Plugin;
import org.apache.maven.api.model.PluginContainer;
import org.apache.maven.api.model.ReportPlugin;
import org.apache.maven.api.model.Reporting;
import org.apache.maven.model.building.ModelBuildingRequest;
import org.apache.maven.model.building.ModelProblemCollector;
import org.apache.maven.model.merge.MavenModelMerger;

/**
 * Handles inheritance of model values.
 *
 */
@SuppressWarnings({"checkstyle:methodname"})
@Named
@Singleton
public class DefaultInheritanceAssembler implements InheritanceAssembler {

    private static final String CHILD_DIRECTORY = "child-directory";

    private static final String CHILD_DIRECTORY_PROPERTY = "project.directory";

    private final InheritanceModelMerger merger = new InheritanceModelMerger();

    @Override
    public Model assembleModelInheritance(
            Model child, Model parent, ModelBuildingRequest request, ModelProblemCollector problems) {
        Map<Object, Object> hints = new HashMap<>();
        String childPath = child.getProperties().getOrDefault(CHILD_DIRECTORY_PROPERTY, child.getArtifactId());
        hints.put(CHILD_DIRECTORY, childPath);
        hints.put(MavenModelMerger.CHILD_PATH_ADJUSTMENT, getChildPathAdjustment(child, parent, childPath));
        return merger.merge(child, parent, false, hints);
    }

    /**
     * Calculates the relative path from the base directory of the parent to the parent directory of the base directory
     * of the child. The general idea is to adjust inherited URLs to match the project layout (in SCM).
     *
     * <p>This calculation is only a heuristic based on our conventions.
     * In detail, the algo relies on the following assumptions: <ul>
     * <li>The parent uses aggregation and refers to the child via the modules section</li>
     * <li>The module path to the child is considered to
     * point at the POM rather than its base directory if the path ends with ".xml" (ignoring case)</li>
     * <li>The name of the child's base directory matches the artifact id of the child.</li>
     * </ul>
     * Note that for the sake of independence from the user
     * environment, the filesystem is intentionally not used for the calculation.</p>
     *
     * @param child The child model, must not be <code>null</code>.
     * @param parent The parent model, may be <code>null</code>.
     * @param childDirectory The directory defined in child model, may be <code>null</code>.
     * @return The path adjustment, can be empty but never <code>null</code>.
     */
    private String getChildPathAdjustment(Model child, Model parent, String childDirectory) {
        String adjustment = "";

        if (parent != null) {
            String childName = child.getArtifactId();

            /*
             * This logic (using filesystem, against wanted independence from the user environment) exists only for the
             * sake of backward-compat with 2.x (MNG-5000). In general, it is wrong to
             * base URL inheritance on the module directory names as this information is unavailable for POMs in the
             * repository. In other words, modules where artifactId != moduleDirName will see different effective URLs
             * depending on how the model was constructed (from filesystem or from repository).
             */
            if (child.getProjectDirectory() != null) {
                childName = child.getProjectDirectory().getFileName().toString();
            }

            for (String module : parent.getModules()) {
                module = module.replace('\\', '/');

                if (module.regionMatches(true, module.length() - 4, ".xml", 0, 4)) {
                    module = module.substring(0, module.lastIndexOf('/') + 1);
                }

                String moduleName = module;
                if (moduleName.endsWith("/")) {
                    moduleName = moduleName.substring(0, moduleName.length() - 1);
                }

                int lastSlash = moduleName.lastIndexOf('/');

                moduleName = moduleName.substring(lastSlash + 1);

                if ((moduleName.equals(childName) || (moduleName.equals(childDirectory))) && lastSlash >= 0) {
                    adjustment = module.substring(0, lastSlash);
                    break;
                }
            }
        }

        return adjustment;
    }

    /**
     * InheritanceModelMerger
     */
    protected static class InheritanceModelMerger extends MavenModelMerger {

        @Override
        protected String extrapolateChildUrl(String parentUrl, boolean appendPath, Map<Object, Object> context) {
            Object childDirectory = context.get(CHILD_DIRECTORY);
            Object childPathAdjustment = context.get(CHILD_PATH_ADJUSTMENT);

            boolean isBlankParentUrl = true;

            if (parentUrl != null) {
                for (int i = 0; i < parentUrl.length(); i++) {
                    if (!Character.isWhitespace(parentUrl.charAt(i))) {
                        isBlankParentUrl = false;
                    }
                }
            }

            if (isBlankParentUrl || childDirectory == null || childPathAdjustment == null || !appendPath) {
                return parentUrl;
            }

            // append childPathAdjustment and childDirectory to parent url
            return appendPath(parentUrl, childDirectory.toString(), childPathAdjustment.toString());
        }

        private String appendPath(String parentUrl, String childPath, String pathAdjustment) {
            StringBuilder url = new StringBuilder(parentUrl.length()
                    + pathAdjustment.length()
                    + childPath.length()
                    + ((pathAdjustment.length() == 0) ? 1 : 2));

            url.append(parentUrl);
            concatPath(url, pathAdjustment);
            concatPath(url, childPath);

            return url.toString();
        }

        private void concatPath(StringBuilder url, String path) {
            if (path.length() > 0) {
                boolean initialUrlEndsWithSlash = url.charAt(url.length() - 1) == '/';
                boolean pathStartsWithSlash = path.charAt(0) == '/';

                if (pathStartsWithSlash) {
                    if (initialUrlEndsWithSlash) {
                        // 1 extra '/' to remove
                        url.setLength(url.length() - 1);
                    }
                } else if (!initialUrlEndsWithSlash) {
                    // add missing '/' between url and path
                    url.append('/');
                }

                url.append(path);

                // ensure resulting url ends with slash if initial url was
                if (initialUrlEndsWithSlash && !path.endsWith("/")) {
                    url.append('/');
                }
            }
        }

        @Override
        protected void mergeModelBase_Properties(
                ModelBase.Builder builder,
                ModelBase target,
                ModelBase source,
                boolean sourceDominant,
                Map<Object, Object> context) {
            Map<String, String> merged = new HashMap<>();
            if (sourceDominant) {
                merged.putAll(target.getProperties());
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
            } else {
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
                merged.putAll(target.getProperties());
            }
            builder.properties(merged);
            builder.location(
                    "properties",
                    InputLocation.merge(
                            target.getLocation("properties"), source.getLocation("properties"), sourceDominant));
        }

        private void putAll(Map<String, String> s, Map<String, String> t, Object excludeKey) {
            for (Map.Entry<String, String> e : t.entrySet()) {
                if (!e.getKey().equals(excludeKey)) {
                    s.put(e.getKey(), e.getValue());
                }
            }
        }

        @Override
        protected void mergePluginContainer_Plugins(
                PluginContainer.Builder builder,
                PluginContainer target,
                PluginContainer source,
                boolean sourceDominant,
                Map<Object, Object> context) {
            List<Plugin> src = source.getPlugins();
            if (!src.isEmpty()) {
                List<Plugin> tgt = target.getPlugins();
                Map<Object, Plugin> master = new LinkedHashMap<>(src.size() * 2);

                for (Plugin element : src) {
                    if (element.isInherited() || !element.getExecutions().isEmpty()) {
                        // NOTE: Enforce recursive merge to trigger merging/inheritance logic for executions
                        Plugin plugin = Plugin.newInstance(false);
                        plugin = mergePlugin(plugin, element, sourceDominant, context);

                        Object key = getPluginKey().apply(plugin);

                        master.put(key, plugin);
                    }
                }

                Map<Object, List<Plugin>> predecessors = new LinkedHashMap<>();
                List<Plugin> pending = new ArrayList<>();
                for (Plugin element : tgt) {
                    Object key = getPluginKey().apply(element);
                    Plugin existing = master.get(key);
                    if (existing != null) {
                        element = mergePlugin(element, existing, sourceDominant, context);

                        master.put(key, element);

                        if (!pending.isEmpty()) {
                            predecessors.put(key, pending);
                            pending = new ArrayList<>();
                        }
                    } else {
                        pending.add(element);
                    }
                }

                List<Plugin> result = new ArrayList<>(src.size() + tgt.size());
                for (Map.Entry<Object, Plugin> entry : master.entrySet()) {
                    List<Plugin> pre = predecessors.get(entry.getKey());
                    if (pre != null) {
                        result.addAll(pre);
                    }
                    result.add(entry.getValue());
                }
                result.addAll(pending);

                builder.plugins(result);
            }
        }

        @Override
        protected Plugin mergePlugin(
                Plugin target, Plugin source, boolean sourceDominant, Map<Object, Object> context) {
            Plugin.Builder builder = Plugin.newBuilder(target);
            if (source.isInherited()) {
                mergeConfigurationContainer(builder, target, source, sourceDominant, context);
            }
            mergePlugin_GroupId(builder, target, source, sourceDominant, context);
            mergePlugin_ArtifactId(builder, target, source, sourceDominant, context);
            mergePlugin_Version(builder, target, source, sourceDominant, context);
            mergePlugin_Extensions(builder, target, source, sourceDominant, context);
            mergePlugin_Executions(builder, target, source, sourceDominant, context);
            mergePlugin_Dependencies(builder, target, source, sourceDominant, context);
            return builder.build();
        }

        @Override
        protected void mergeReporting_Plugins(
                Reporting.Builder builder,
                Reporting target,
                Reporting source,
                boolean sourceDominant,
                Map<Object, Object> context) {
            List<ReportPlugin> src = source.getPlugins();
            if (!src.isEmpty()) {
                List<ReportPlugin> tgt = target.getPlugins();
                Map<Object, ReportPlugin> merged = new LinkedHashMap<>((src.size() + tgt.size()) * 2);

                for (ReportPlugin element : src) {
                    if (element.isInherited()) {
                        // NOTE: Enforce recursive merge to trigger merging/inheritance logic for executions as well
                        ReportPlugin plugin = ReportPlugin.newInstance(false);
                        plugin = mergeReportPlugin(plugin, element, sourceDominant, context);

                        merged.put(getReportPluginKey().apply(element), plugin);
                    }
                }

                for (ReportPlugin element : tgt) {
                    Object key = getReportPluginKey().apply(element);
                    ReportPlugin existing = merged.get(key);
                    if (existing != null) {
                        element = mergeReportPlugin(element, existing, sourceDominant, context);
                    }
                    merged.put(key, element);
                }

                builder.plugins(merged.values());
            }
        }
    }
}
