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Runtime Library for KlumAST
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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015-2024 Stephan Pauxberger
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.blackbuild.klum.ast.util;

import com.blackbuild.annodocimal.annotations.InlineJavadocs;
import groovy.lang.Closure;

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

import static java.util.function.Function.identity;
import static java.util.stream.Collectors.toMap;

/**
 * Handles templates for a given dsl-class.
 * 
 * The template manager is a thread-local singleton that can be used to apply templates to objects created in a given scope.
 * All important methods are static and can be used from anywhere in the code.
 * 
 */
@InlineJavadocs
public class TemplateManager {

    private static final ThreadLocal INSTANCE = new ThreadLocal<>();

    /**
     * Returns the current instance of the TemplateManager.
     * If no instance is active, a new one is created.
     *
     * @return the current instance
     */
    public static TemplateManager getInstance() {
        if (INSTANCE.get() == null)
            INSTANCE.set(new TemplateManager());
        return INSTANCE.get();
    }

    private TemplateManager() {
        // Thread local singleton
    }

    private void deregister() {
        if (templates.isEmpty())
            INSTANCE.remove();
    }

    private final Map, Object> templates = new HashMap<>();

    /**
     * Executes the given closure with the given template as the template for the given type.
     * This means that all objects of the given type created in the scope of the closure will use the given template,
     * which also includes objects deeper in the structure.
     * The old template is restored after the closure has been executed.
     *
     * @param type     the type for which the template will be applied
     * @param template the template
     * @param body     the closure to execute
     * @param       the type of the template
     * @return the result of the closure
     */
    public static  Object withTemplate(Class type, T template, Closure body) {
        TemplateManager manager = getInstance();
        T oldTemplate = manager.getTemplate(type);
        try {
            manager.setTemplate(type, template);
            return body.call();
        } finally {
            manager.setTemplate(type, oldTemplate);
            manager.deregister();
        }
    }

    /**
     * Executes the given closure with an anonymous template for the given type.
     * This means that all objects of the given type created in the scope of the closure will use the given template,
     * which also includes objects deeper in the structure.
     * The template will be created from the given map (using Create.AsTemplate(Map)).
     * The old template is restored after the closure has been executed.
     *
     * @param type     the type for which the template will be applied
     * @param template the Map to construct the template from
     * @param body     the closure to execute
     * @param       the type of the template
     * @return the result of the closure
     */
    public static  Object withTemplate(Class type, Map template, Closure body) {
        T templateInstance = FactoryHelper.createAsTemplate(type, template, null);
        return withTemplate(type, templateInstance, body);
    }

    /**
     * Executes the given closure with the given templates.
     * This means that all objects of the given types created in the scope of the closure will use the given template,
     * which also includes objects deeper in the structure.
     * The old templates are restored after the closure has been executed. Usually it
     * is better to use {@link #withTemplates(List, Closure)}, which maps the templates
     * to their respective classes.
     *
     * @param newTemplates the templates to apply, Mapping classes to their respective templates
     * @param body         the closure to execute
     * @return the result of the closure
     * @deprecated use #withTemplates(List, Closure)
     */
    @Deprecated(forRemoval = true, since = "2.0.0")
    public static Object withTemplates(Map, Object> newTemplates, Closure body) {
        if (newTemplates.isEmpty())
            return body.call();

        TemplateManager manager = getInstance();

        Map, Object> effectiveTemplates = newTemplates.entrySet().stream().collect(toMap(Map.Entry::getKey, TemplateManager::mapToTemplate));
        Map, Object> oldTemplates = new HashMap<>(manager.templates);

        try {
            manager.addTemplates(effectiveTemplates);
            return body.call();
        } finally {
            manager.setTemplates(oldTemplates);
            manager.deregister();
        }
    }

    private static Object mapToTemplate(Map.Entry, Object> entry) {
        if (entry.getValue() instanceof Map)
            //noinspection unchecked
            return FactoryHelper.createAsTemplate(entry.getKey(), (Map) entry.getValue(), null);
        else
            return entry.getValue();
    }

    /**
     * Executes the given closure with the given templates.
     * This means that all objects of the given types created in the scope of the closure will use the given template,
     * which also includes objects deeper in the structure.
     * The old templates are restored after the closure has been executed.
     *
     * @param newTemplates the templates to apply
     * @param body         the closure to execute
     * @return the result of the closure
     */
    public static Object withTemplates(List