com.metreeca.mark.Opts Maven / Gradle / Ivy

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/*
 * Copyright © 2019-2023 Metreeca srl
 *
 * 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 com.metreeca.mark;

import org.apache.maven.plugin.logging.Log;
import org.jetbrains.annotations.Nullable;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.lang.reflect.InvocationTargetException;
import java.nio.file.Path;
import java.util.*;
import java.util.function.BiFunction;
import java.util.function.Function;

import static java.util.Arrays.stream;
import static java.util.function.Predicate.not;

/**
 * Site generation options.
 */
public interface Opts {

    /**
     * @return the path of source site folder
     */
    public Path source();

    /**
     * @return the path of target site folder
     */
    public Path target();

    /**
     * @return the source-relative path of the default site layout
     */
    public Path layout();


    /**
     * @return flag indicating whether to generate a README.md file in the project base folder from {@link #source()}
     * source}/index.md}
     */
    public boolean readme();


    /**
     * @return the global variables
     */
    public Map global();

    /**
     * @param path the dotted path of a global variable
     * @param   the expected value type
     *
     * @return the optional value of the global variable identified by {@code path} or an empty optional is no matching
     * value is found
     *
     * @throws NullPointerException if either {@code type} or {@code path} is null
     */
    public default  Optional global(final Class type, final String path) {

        if ( type == null ) {
            throw new NullPointerException("null type");
        }

        if ( path == null ) {
            throw new NullPointerException("null path");
        }


        final BiFunction getter=(bean, property) -> {
            try {

                return stream(Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors())

                        .filter(descriptor -> descriptor.getName().equals(property))

                        .map(descriptor -> {
                            try {

                                return descriptor.getReadMethod().invoke(bean);

                            } catch ( final IllegalAccessException|InvocationTargetException e ) {

                                return null;

                            }

                        })

                        .filter(not(Objects::isNull))
                        .findFirst()
                        .orElse(null);

            } catch ( final IntrospectionException e ) {

                return null;

            }

        };


        @Nullable Object value=global();

        for (final String step : path.split("\\.")) {

            if ( value instanceof Map ) {

                value=((Map)value).get(step);

            } else if ( value != null ) {

                value=getter.apply(value, step);

            }

        }

        return Optional.ofNullable(value)
                .filter(type::isInstance)
                .map(type::cast);

    }


    /**
     * Retrieves a pipeline option.
     *
     * @param option the name of the option to be retrieved
     * @param mapper a function mapping from a possibly null string value to an option value of the expected type
     * @param     the expected type of the option value
     *
     * @return the value produced by applying {@code mapper} to a possibly null string value retrieved from a
     * system-specific source or {@code null} the option is not defined
     *
     * @throws NullPointerException if {@code mapper} is null
     */
    public  V option(final String option, final Function mapper);


    /**
     * @return the system logger
     */
    public Log logger();

}