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/*
 * Copyright MapStruct Authors.
 *
 * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 */
package org.mapstruct.ap.spi;

import java.util.Collection;
import javax.lang.model.element.ExecutableElement;

/**
 * Holder for the builder information.
 *
 * @author Filip Hrisafov
 *
 * @since 1.3
 */
public class BuilderInfo {

    private final ExecutableElement builderCreationMethod;
    private final Collection buildMethods;

    private BuilderInfo(ExecutableElement builderCreationMethod, Collection buildMethods) {
        this.builderCreationMethod = builderCreationMethod;
        this.buildMethods = buildMethods;
    }

    /**
     * The method that can be used for instantiating a builder. This can be:
     * 
     * A {@code public static} method in the type being build
     * A {@code public static} method in the builder itself
     * The default constructor of the builder
     * 
     *
     * @return the creation method for the builder
     */
    public ExecutableElement getBuilderCreationMethod() {
        return builderCreationMethod;
    }

    /**
     * The methods that can be used to build the type being built.
     * This should be {@code public} methods within the builder itself
     *
     * @return the build method for the type
     */
    public Collection getBuildMethods() {
        return buildMethods;
    }

    public static class Builder {
        private ExecutableElement builderCreationMethod;
        private Collection buildMethods;

        /**
         * @param method The creation method for the builder
         *
         * @return the builder for chaining
         *
         * @see BuilderInfo#getBuilderCreationMethod()
         */
        public Builder builderCreationMethod(ExecutableElement method) {
            this.builderCreationMethod = method;
            return this;
        }

        /**
         * @param methods the build methods for the type
         *
         * @return the builder for chaining
         *
         * @see BuilderInfo#getBuildMethods()
         */
        public Builder buildMethod(Collection methods) {
            this.buildMethods = methods;
            return this;
        }

        /**
         * Create the {@link BuilderInfo}.
         *
         * @return the created {@link BuilderInfo}
         *
         * @throws IllegalArgumentException if the builder creation or build methods are {@code null}
         */
        public BuilderInfo build() {
            if ( builderCreationMethod == null ) {
                throw new IllegalArgumentException( "Builder creation method is mandatory" );
            }
            else if ( buildMethods == null ) {
                throw new IllegalArgumentException( "Build methods are mandatory" );
            }
            else if ( buildMethods.isEmpty() ) {
                throw new IllegalArgumentException( "Build methods must not be empty" );
            }
            return new BuilderInfo( builderCreationMethod, buildMethods );
        }
    }
}