/*
 * Copyright 2012-2022 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
 *
 *      https://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 io.spring.initializr.generator.buildsystem.maven;

import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import io.spring.initializr.generator.buildsystem.BillOfMaterials;
import io.spring.initializr.generator.buildsystem.BomContainer;
import io.spring.initializr.generator.buildsystem.Dependency;
import io.spring.initializr.generator.buildsystem.Dependency.Exclusion;
import io.spring.initializr.generator.buildsystem.DependencyComparator;
import io.spring.initializr.generator.buildsystem.DependencyContainer;
import io.spring.initializr.generator.buildsystem.DependencyScope;
import io.spring.initializr.generator.buildsystem.MavenRepository;
import io.spring.initializr.generator.buildsystem.MavenRepositoryContainer;
import io.spring.initializr.generator.buildsystem.PropertyContainer;
import io.spring.initializr.generator.buildsystem.maven.MavenDistributionManagement.DeploymentRepository;
import io.spring.initializr.generator.buildsystem.maven.MavenDistributionManagement.Relocation;
import io.spring.initializr.generator.buildsystem.maven.MavenDistributionManagement.Site;
import io.spring.initializr.generator.buildsystem.maven.MavenPlugin.Configuration;
import io.spring.initializr.generator.buildsystem.maven.MavenPlugin.Execution;
import io.spring.initializr.generator.buildsystem.maven.MavenPlugin.Setting;
import io.spring.initializr.generator.io.IndentingWriter;
import io.spring.initializr.generator.version.VersionProperty;
import io.spring.initializr.generator.version.VersionReference;

import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * A {@link MavenBuild} writer for {@code pom.xml}.
 *
 * @author Andy Wilkinson
 * @author Stephane Nicoll
 * @author Olga Maciaszek-Sharma
 * @author Jafer Khan Shamshad
 * @author Joachim Pasquali
 */
public class MavenBuildWriter {

	/**
	 * Write a {@linkplain MavenBuild pom.xml} using the specified
	 * {@linkplain IndentingWriter writer}.
	 * @param writer the writer to use
	 * @param build the maven build to write
	 */
	public void writeTo(IndentingWriter writer, MavenBuild build) {
		MavenBuildSettings settings = build.getSettings();
		writeProject(writer, () -> {
			writeParent(writer, build);
			writeProjectCoordinates(writer, settings);
			writePackaging(writer, settings);
			writeProjectName(writer, settings);
			writeCollectionElement(writer, "licenses", settings.getLicenses(), this::writeLicense);
			writeCollectionElement(writer, "developers", settings.getDevelopers(), this::writeDeveloper);
			writeScm(writer, settings.getScm());
			writeProperties(writer, build.properties());
			writeDependencies(writer, build.dependencies());
			writeDependencyManagement(writer, build.boms());
			writeBuild(writer, build);
			writeRepositories(writer, build.repositories(), build.pluginRepositories());
			writeDistributionManagement(writer, build.getDistributionManagement());
			writeProfiles(writer, build);
		});
	}

	/**
	 * Return the {@link Comparator} to use to sort dependencies.
	 * @return a dependency comparator
	 */
	protected Comparator<Dependency> getDependencyComparator() {
		return DependencyComparator.INSTANCE;
	}

	private void writeProject(IndentingWriter writer, Runnable whenWritten) {
		writer.println("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
		writer.println(
				"<project xmlns=\"http://maven.apache.org/POM/4.0.0\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"");
		writer.indented(() -> {
			writer.println(
					"xsi:schemaLocation=\"http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd\">");
			writeSingleElement(writer, "modelVersion", "4.0.0");
			whenWritten.run();
		});
		writer.println();
		writer.println("</project>");
	}

	private void writeParent(IndentingWriter writer, MavenBuild build) {
		MavenParent parent = build.getSettings().getParent();
		if (parent == null) {
			return;
		}
		writer.println("<parent>");
		writer.indented(() -> {
			writeSingleElement(writer, "groupId", parent.getGroupId());
			writeSingleElement(writer, "artifactId", parent.getArtifactId());
			writeSingleElement(writer, "version", parent.getVersion());
			String relativePath = parent.getRelativePath();
			if (relativePath != null) {
				if (StringUtils.hasText(relativePath)) {
					writeSingleElement(writer, "relativePath", relativePath);
				}
				else {
					writer.println("<relativePath/> <!-- lookup parent from repository -->");
				}
			}
		});
		writer.println("</parent>");
	}

	private void writeProjectCoordinates(IndentingWriter writer, MavenBuildSettings settings) {
		writeSingleElement(writer, "groupId", settings.getGroup());
		writeSingleElement(writer, "artifactId", settings.getArtifact());
		writeSingleElement(writer, "version", settings.getVersion());
	}

	private void writePackaging(IndentingWriter writer, MavenBuildSettings settings) {
		String packaging = settings.getPackaging();
		if (!"jar".equals(packaging)) {
			writeSingleElement(writer, "packaging", packaging);
		}
	}

	private void writeProjectName(IndentingWriter writer, MavenBuildSettings settings) {
		writeSingleElement(writer, "name", settings.getName());
		writeSingleElement(writer, "description", settings.getDescription());
	}

	private void writeProperties(IndentingWriter writer, PropertyContainer properties) {
		if (properties.isEmpty()) {
			return;
		}
		writeElement(writer, "properties", () -> {
			properties.values().forEach((entry) -> writeSingleElement(writer, entry.getKey(), entry.getValue()));
			properties.versions((VersionProperty::toStandardFormat))
					.forEach((entry) -> writeSingleElement(writer, entry.getKey(), entry.getValue()));
		});
	}

	private void writeLicense(IndentingWriter writer, MavenLicense license) {
		writeElement(writer, "license", () -> {
			writeSingleElement(writer, "name", license.getName());
			writeSingleElement(writer, "url", license.getUrl());
			if (license.getDistribution() != null) {
				writeSingleElement(writer, "distribution",
						license.getDistribution().name().toLowerCase(Locale.ENGLISH));
			}
			writeSingleElement(writer, "comments", license.getComments());
		});
	}

	private void writeDeveloper(IndentingWriter writer, MavenDeveloper developer) {
		writeElement(writer, "developer", () -> {
			writeSingleElement(writer, "id", developer.getId());
			writeSingleElement(writer, "name", developer.getName());
			writeSingleElement(writer, "email", developer.getEmail());
			writeSingleElement(writer, "url", developer.getUrl());
			writeSingleElement(writer, "organization", developer.getOrganization());
			writeSingleElement(writer, "organizationUrl", developer.getOrganizationUrl());
			List<String> roles = developer.getRoles();
			if (!roles.isEmpty()) {
				writeElement(writer, "roles", () -> roles.forEach((role) -> writeSingleElement(writer, "role", role)));
			}
			writeSingleElement(writer, "timezone", developer.getTimezone());
			Map<String, String> properties = developer.getProperties();
			if (!properties.isEmpty()) {
				writeElement(writer, "properties",
						() -> properties.forEach((key, value) -> writeSingleElement(writer, key, value)));
			}
		});
	}

	private void writeScm(IndentingWriter writer, MavenScm mavenScm) {
		if (!mavenScm.isEmpty()) {
			writeElement(writer, "scm", () -> {
				writeSingleElement(writer, "connection", mavenScm.getConnection());
				writeSingleElement(writer, "developerConnection", mavenScm.getDeveloperConnection());
				writeSingleElement(writer, "tag", mavenScm.getTag());
				writeSingleElement(writer, "url", mavenScm.getUrl());
			});
		}
	}

	private void writeDependencies(IndentingWriter writer, DependencyContainer dependencies) {
		if (dependencies.isEmpty()) {
			return;
		}
		writeElement(writer, "dependencies", () -> {
			Collection<Dependency> compiledDependencies = writeDependencies(writer, dependencies,
					(scope) -> scope == null || scope == DependencyScope.COMPILE);
			if (!compiledDependencies.isEmpty()) {
				writer.println();
			}
			writeDependencies(writer, dependencies, hasScope(DependencyScope.RUNTIME));
			writeDependencies(writer, dependencies, hasScope(DependencyScope.COMPILE_ONLY));
			writeDependencies(writer, dependencies, hasScope(DependencyScope.ANNOTATION_PROCESSOR));
			writeDependencies(writer, dependencies, hasScope(DependencyScope.PROVIDED_RUNTIME));
			writeDependencies(writer, dependencies,
					hasScope(DependencyScope.TEST_COMPILE, DependencyScope.TEST_RUNTIME));
		});
	}

	private Predicate<DependencyScope> hasScope(DependencyScope... validScopes) {
		return (scope) -> Arrays.asList(validScopes).contains(scope);
	}

	private Collection<Dependency> writeDependencies(IndentingWriter writer, DependencyContainer dependencies,
			Predicate<DependencyScope> filter) {
		Collection<Dependency> candidates = dependencies.items().filter((dep) -> filter.test(dep.getScope()))
				.sorted(getDependencyComparator()).collect(Collectors.toList());
		writeCollection(writer, candidates, this::writeDependency);
		return candidates;
	}

	private void writeDependency(IndentingWriter writer, Dependency dependency) {
		writeElement(writer, "dependency", () -> {
			writeSingleElement(writer, "groupId", dependency.getGroupId());
			writeSingleElement(writer, "artifactId", dependency.getArtifactId());
			writeSingleElement(writer, "version", determineVersion(dependency.getVersion()));
			writeSingleElement(writer, "scope", scopeForType(dependency.getScope()));
			writeSingleElement(writer, "classifier", dependency.getClassifier());
			if (isOptional(dependency)) {
				writeSingleElement(writer, "optional", Boolean.toString(true));
			}
			writeSingleElement(writer, "type", dependency.getType());
			writeCollectionElement(writer, "exclusions", dependency.getExclusions(), this::writeDependencyExclusion);
		});
	}

	private void writeDependencyExclusion(IndentingWriter writer, Exclusion exclusion) {
		writeElement(writer, "exclusion", () -> {
			writeSingleElement(writer, "groupId", exclusion.getGroupId());
			writeSingleElement(writer, "artifactId", exclusion.getArtifactId());
		});
	}

	private String scopeForType(DependencyScope type) {
		if (type == null) {
			return null;
		}
		switch (type) {
		case ANNOTATION_PROCESSOR:
			return null;
		case COMPILE:
			return null;
		case COMPILE_ONLY:
			return null;
		case PROVIDED_RUNTIME:
			return "provided";
		case RUNTIME:
			return "runtime";
		case TEST_COMPILE:
			return "test";
		case TEST_RUNTIME:
			return "test";
		default:
			throw new IllegalStateException("Unrecognized dependency type '" + type + "'");
		}
	}

	private boolean isOptional(Dependency dependency) {
		if (dependency instanceof MavenDependency && ((MavenDependency) dependency).isOptional()) {
			return true;
		}
		return (dependency.getScope() == DependencyScope.ANNOTATION_PROCESSOR
				|| dependency.getScope() == DependencyScope.COMPILE_ONLY);
	}

	private void writeDependencyManagement(IndentingWriter writer, BomContainer boms) {
		if (boms.isEmpty()) {
			return;
		}
		writeElement(writer, "dependencyManagement",
				() -> writeCollectionElement(writer, "dependencies", boms.items()
						.sorted(Comparator.comparing(BillOfMaterials::getOrder)).collect(Collectors.toList()),
						this::writeBom));
	}

	private void writeBom(IndentingWriter writer, BillOfMaterials bom) {
		writeElement(writer, "dependency", () -> {
			writeSingleElement(writer, "groupId", bom.getGroupId());
			writeSingleElement(writer, "artifactId", bom.getArtifactId());
			writeSingleElement(writer, "version", determineVersion(bom.getVersion()));
			writeSingleElement(writer, "type", "pom");
			writeSingleElement(writer, "scope", "import");
		});
	}

	private String determineVersion(VersionReference versionReference) {
		if (versionReference == null) {
			return null;
		}
		return (versionReference.isProperty()) ? "${" + versionReference.getProperty().toStandardFormat() + "}"
				: versionReference.getValue();
	}

	private void writeBuild(IndentingWriter writer, MavenBuild build) {
		MavenBuildSettings settings = build.getSettings();
		if (settings.getDefaultGoal() == null && settings.getFinalName() == null
				&& settings.getSourceDirectory() == null && settings.getTestSourceDirectory() == null
				&& build.resources().isEmpty() && build.testResources().isEmpty() && build.plugins().isEmpty()) {
			return;
		}
		writer.println();
		writeElement(writer, "build", () -> {
			writeSingleElement(writer, "defaultGoal", settings.getDefaultGoal());
			writeSingleElement(writer, "finalName", settings.getFinalName());
			writeSingleElement(writer, "sourceDirectory", settings.getSourceDirectory());
			writeSingleElement(writer, "testSourceDirectory", settings.getTestSourceDirectory());
			writeResources(writer, build.resources(), build.testResources());
			writeCollectionElement(writer, "plugins", build.plugins().values(), this::writePlugin);
		});
	}

	private void writeResources(IndentingWriter writer, MavenResourceContainer resources,
			MavenResourceContainer testResources) {
		writeCollectionElement(writer, "resources", resources.values(), this::writeResource);
		writeCollectionElement(writer, "testResources", testResources.values(), this::writeTestResource);
	}

	private void writeResource(IndentingWriter writer, MavenResource resource) {
		writeResource(writer, resource, "resource");
	}

	private void writeTestResource(IndentingWriter writer, MavenResource resource) {
		writeResource(writer, resource, "testResource");
	}

	private void writeResource(IndentingWriter writer, MavenResource resource, String resourceName) {
		writeElement(writer, resourceName, () -> {
			writeSingleElement(writer, "directory", resource.getDirectory());
			writeSingleElement(writer, "targetPath", resource.getTargetPath());
			if (resource.isFiltering()) {
				writeSingleElement(writer, "filtering", "true");
			}
			writeCollectionElement(writer, "includes", resource.getIncludes(), this::writeResourceInclude);
			writeCollectionElement(writer, "excludes", resource.getExcludes(), this::writeResourceExclude);
		});
	}

	private void writeResourceInclude(IndentingWriter writer, String include) {
		writeSingleElement(writer, "include", include);
	}

	private void writeResourceExclude(IndentingWriter writer, String exclude) {
		writeSingleElement(writer, "exclude", exclude);
	}

	private void writePlugin(IndentingWriter writer, MavenPlugin plugin) {
		writeElement(writer, "plugin", () -> {
			writeSingleElement(writer, "groupId", plugin.getGroupId());
			writeSingleElement(writer, "artifactId", plugin.getArtifactId());
			writeSingleElement(writer, "version", plugin.getVersion());
			if (plugin.isExtensions()) {
				writeSingleElement(writer, "extensions", "true");
			}
			writePluginConfiguration(writer, plugin.getConfiguration());
			writeCollectionElement(writer, "executions", plugin.getExecutions(), this::writePluginExecution);
			writeCollectionElement(writer, "dependencies", plugin.getDependencies(), this::writePluginDependency);
		});
	}

	private void writePluginConfiguration(IndentingWriter writer, Configuration configuration) {
		if (configuration == null || configuration.getSettings().isEmpty()) {
			return;
		}
		writeCollectionElement(writer, "configuration", configuration.getSettings(), this::writeSetting);
	}

	@SuppressWarnings("unchecked")
	private void writeSetting(IndentingWriter writer, Setting setting) {
		if (setting.getValue() instanceof String) {
			writeSingleElement(writer, setting.getName(), setting.getValue());
		}
		else if (setting.getValue() instanceof List) {
			writeCollectionElement(writer, setting.getName(), (List<Setting>) setting.getValue(), this::writeSetting);
		}
	}

	private void writePluginExecution(IndentingWriter writer, Execution execution) {
		writeElement(writer, "execution", () -> {
			writeSingleElement(writer, "id", execution.getId());
			writeSingleElement(writer, "phase", execution.getPhase());
			List<String> goals = execution.getGoals();
			if (!goals.isEmpty()) {
				writeElement(writer, "goals", () -> goals.forEach((goal) -> writeSingleElement(writer, "goal", goal)));
			}
			writePluginConfiguration(writer, execution.getConfiguration());
		});
	}

	private void writePluginDependency(IndentingWriter writer, MavenPlugin.Dependency dependency) {
		writeElement(writer, "dependency", () -> {
			writeSingleElement(writer, "groupId", dependency.getGroupId());
			writeSingleElement(writer, "artifactId", dependency.getArtifactId());
			writeSingleElement(writer, "version", dependency.getVersion());
		});
	}

	private void writeRepositories(IndentingWriter writer, MavenRepositoryContainer buildRepositories,
			MavenRepositoryContainer buildPluginRepositories) {
		List<MavenRepository> repositories = filterRepositories(buildRepositories.items());
		List<MavenRepository> pluginRepositories = filterRepositories(buildPluginRepositories.items());
		if (repositories.isEmpty() && pluginRepositories.isEmpty()) {
			return;
		}
		writeCollectionElement(writer, "repositories", repositories, this::writeRepository);
		writeCollectionElement(writer, "pluginRepositories", pluginRepositories, this::writePluginRepository);
	}

	private List<MavenRepository> filterRepositories(Stream<MavenRepository> repositories) {
		return repositories.filter((repository) -> !MavenRepository.MAVEN_CENTRAL.equals(repository))
				.collect(Collectors.toList());
	}

	private void writeRepository(IndentingWriter writer, MavenRepository repository) {
		writeRepository(writer, repository, "repository");
	}

	private void writePluginRepository(IndentingWriter writer, MavenRepository repository) {
		writeRepository(writer, repository, "pluginRepository");
	}

	private void writeRepository(IndentingWriter writer, MavenRepository repository, String childName) {
		writeElement(writer, childName, () -> {
			writeSingleElement(writer, "id", repository.getId());
			writeSingleElement(writer, "name", repository.getName());
			writeSingleElement(writer, "url", repository.getUrl());
			if (!repository.isReleasesEnabled()) {
				writeElement(writer, "releases", () -> writeSingleElement(writer, "enabled", Boolean.toString(false)));
			}
			if (!repository.isSnapshotsEnabled()) {
				writeElement(writer, "snapshots", () -> writeSingleElement(writer, "enabled", Boolean.toString(false)));
			}
		});
	}

	private void writeDistributionManagement(IndentingWriter writer,
			MavenDistributionManagement distributionManagement) {
		if (distributionManagement.isEmpty()) {
			return;
		}
		writeElement(writer, "distributionManagement", () -> {
			writeSingleElement(writer, "downloadUrl", distributionManagement.getDownloadUrl());
			writeDeploymentRepository(writer, "repository", distributionManagement.getRepository());
			writeDeploymentRepository(writer, "snapshotRepository", distributionManagement.getSnapshotRepository());
			Site site = distributionManagement.getSite();
			if (!site.isEmpty()) {
				writeElement(writer, "site", () -> {
					writeSingleElement(writer, "id", site.getId());
					writeSingleElement(writer, "name", site.getName());
					writeSingleElement(writer, "url", site.getUrl());
				});
			}
			Relocation relocation = distributionManagement.getRelocation();
			if (!relocation.isEmpty()) {
				writeElement(writer, "relocation", () -> {
					writeSingleElement(writer, "groupId", relocation.getGroupId());
					writeSingleElement(writer, "artifactId", relocation.getArtifactId());
					writeSingleElement(writer, "version", relocation.getVersion());
					writeSingleElement(writer, "message", relocation.getMessage());
				});
			}
		});
	}

	private void writeDeploymentRepository(IndentingWriter writer, String name, DeploymentRepository repository) {
		if (!repository.isEmpty()) {
			writeElement(writer, name, () -> {
				writeSingleElement(writer, "id", repository.getId());
				writeSingleElement(writer, "name", repository.getName());
				writeSingleElement(writer, "url", repository.getUrl());
				writeSingleElement(writer, "layout", repository.getLayout());
				if (repository.getUniqueVersion() != null) {
					writeSingleElement(writer, "uniqueVersion", Boolean.toString(repository.getUniqueVersion()));
				}
			});
		}
	}

	private void writeProfiles(IndentingWriter writer, MavenBuild build) {
		MavenProfileContainer profiles = build.profiles();
		if (profiles.isEmpty()) {
			return;
		}
		writer.println();
		writeElement(writer, "profiles", () -> profiles.values().forEach((profile) -> writeProfile(writer, profile)));
	}

	private void writeProfile(IndentingWriter writer, MavenProfile profile) {
		writeElement(writer, "profile", () -> {
			writeSingleElement(writer, "id", profile.getId());
			writeProfileActivation(writer, profile.getActivation());
			writeProperties(writer, profile.properties());
			writeDependencies(writer, profile.dependencies());
			writeDependencyManagement(writer, profile.boms());
			writeProfileBuild(writer, profile);
			writeRepositories(writer, profile.repositories(), profile.pluginRepositories());
			writeDistributionManagement(writer, profile.getDistributionManagement());
		});
	}

	private void writeProfileActivation(IndentingWriter writer, MavenProfileActivation activation) {
		if (activation.isEmpty()) {
			return;
		}
		writeElement(writer, "activation", () -> {
			writeSingleElement(writer, "activeByDefault", activation.getActiveByDefault());
			writeSingleElement(writer, "jdk", activation.getJdk());
			ifNotNull(activation.getOs(), (os) -> writeElement(writer, "os", () -> {
				writeSingleElement(writer, "name", os.getName());
				writeSingleElement(writer, "arch", os.getArch());
				writeSingleElement(writer, "family", os.getFamily());
				writeSingleElement(writer, "version", os.getVersion());
			}));
			ifNotNull(activation.getProperty(), (property) -> writeElement(writer, "property", () -> {
				writeSingleElement(writer, "name", property.getName());
				writeSingleElement(writer, "value", property.getValue());
			}));
			ifNotNull(activation.getFile(), (file) -> writeElement(writer, "file", () -> {
				writeSingleElement(writer, "exists", file.getExists());
				writeSingleElement(writer, "missing", file.getMissing());
			}));
		});
	}

	private void writeProfileBuild(IndentingWriter writer, MavenProfile profile) {
		MavenProfile.Settings settings = profile.getSettings();
		if (settings.getDefaultGoal() == null && settings.getFinalName() == null && profile.resources().isEmpty()
				&& profile.testResources().isEmpty() && profile.plugins().isEmpty()) {
			return;
		}
		writeElement(writer, "build", () -> {
			writeSingleElement(writer, "defaultGoal", settings.getDefaultGoal());
			writeSingleElement(writer, "finalName", settings.getFinalName());
			writeResources(writer, profile.resources(), profile.testResources());
			writeCollectionElement(writer, "plugins", profile.plugins().values(), this::writePlugin);
		});
	}

	private void writeSingleElement(IndentingWriter writer, String name, Object value) {
		if (value != null) {
			CharSequence text = (value instanceof CharSequence) ? (CharSequence) value : value.toString();
			if (!StringUtils.hasLength(text)) {
				writer.println(String.format("<%s/>", name));
			}
			else {
				writer.print(String.format("<%s>", name));
				writer.print(encodeText(text));
				writer.println(String.format("</%s>", name));
			}
		}
	}

	private void writeElement(IndentingWriter writer, String name, Runnable withContent) {
		writer.println(String.format("<%s>", name));
		writer.indented(withContent);
		writer.println(String.format("</%s>", name));
	}

	private <T> void writeCollectionElement(IndentingWriter writer, String name, Stream<T> items,
			BiConsumer<IndentingWriter, T> itemWriter) {
		writeCollectionElement(writer, name, items.collect(Collectors.toList()), itemWriter);
	}

	private <T> void writeCollectionElement(IndentingWriter writer, String name, Collection<T> items,
			BiConsumer<IndentingWriter, T> itemWriter) {
		if (!ObjectUtils.isEmpty(items)) {
			writeElement(writer, name, () -> writeCollection(writer, items, itemWriter));
		}
	}

	private <T> void writeCollection(IndentingWriter writer, Collection<T> collection,
			BiConsumer<IndentingWriter, T> itemWriter) {
		if (!collection.isEmpty()) {
			collection.forEach((item) -> itemWriter.accept(writer, item));
		}
	}

	private <T> void ifNotNull(T value, Consumer<T> elementWriter) {
		if (value != null) {
			elementWriter.accept(value);
		}
	}

	private String encodeText(CharSequence text) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < text.length(); i++) {
			char character = text.charAt(i);
			switch (character) {
			case '\'':
				sb.append("&apos;");
				break;
			case '\"':
				sb.append("&quot;");
				break;
			case '<':
				sb.append("&lt;");
				break;
			case '>':
				sb.append("&gt;");
				break;
			case '&':
				sb.append("&amp;");
				break;
			default:
				sb.append(character);
			}
		}
		return sb.toString();
	}

}
