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/*
 * BSD 2-Clause License
 *
 * Copyright (c) 2018, Ondrej Fischer
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 *  Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

package fluent.api.generator.processor;

import fluent.api.generator.Templates;
import fluent.api.generator.model.ModelFactory;
import fluent.api.generator.model.TemplateModel;

import javax.annotation.processing.Filer;
import javax.lang.model.element.*;
import java.io.IOException;
import java.io.Writer;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.util.Objects.nonNull;


/**
 * Generator of java code, which creates different models for different visited elements.
 * The annotation can be applied on method, constructor, but also class or interface.
 */
class GeneratingVisitor implements ElementVisitor {

    private static final Pattern PACKAGE = Pattern.compile("package\\s+([^;]+)\\s*;");
    private static final Pattern CLASS = Pattern.compile("(class|interface)\\s+(\\w+)");

    private final Filer filer;
    private final Set generated = new HashSet<>();
    private final ModelFactory factory;
    private final ParameterScanner parametersScanner;

    GeneratingVisitor(Filer filer, ModelFactory factory, ParameterScanner parametersScanner) {
        this.filer = filer;
        this.factory = factory;
        this.parametersScanner = parametersScanner;
    }

    @Override
    public Void visit(Element e, TypeElement annotation) {
        return null;
    }

    @Override
    public Void visit(Element e) {
        return null;
    }

    @Override
    public Void visitPackage(PackageElement e, TypeElement annotation) {
        return null;
    }

    @Override
    public Void visitType(TypeElement e, TypeElement annotation) {
        return render(factory.model().with("type", factory.type(e.asType())), e, annotation);
    }

    @Override
    public Void visitVariable(VariableElement e, TypeElement annotation) {
        return render(factory.model().with("var", factory.variable(e)), e, annotation);
    }

    @Override
    public Void visitExecutable(ExecutableElement e, TypeElement annotation) {
        return render(factory.model().with("method", factory.method(e)), e, annotation);
    }

    @Override
    public Void visitTypeParameter(TypeParameterElement e, TypeElement annotation) {
        return null;
    }

    @Override
    public Void visitUnknown(Element e, TypeElement annotation) {
        return null;
    }

    private Void render(TemplateModel model, Element annotatedElement, TypeElement annotation) {
        parametersScanner.scan(annotatedElement, model);
        annotation.getEnclosedElements().forEach(new DefaultValueVisitor(
                method -> {
                    if(nonNull(method.getDefaultValue())) {
                        model.with(method.getSimpleName().toString(), factory.annotationValue(method.getDefaultValue()));
                    }
                }
        ));
        annotatedElement.getAnnotationMirrors().stream().filter(
                mirror -> mirror.getAnnotationType().asElement().equals(annotation)
        ).forEach(mirror -> mirror.getElementValues().forEach(
                (name, value) -> model.with(name.getSimpleName().toString(), factory.annotationValue(value))
        ));
        for(String path : annotation.getAnnotation(Templates.class).value()) {
            String source = model.render(path);
            Matcher packageName = PACKAGE.matcher(source);
            Matcher className = CLASS.matcher(source);
            if(packageName.find() && className.find()) {
                String sourcePath = packageName.group(1) + "." + className.group(2);
                if(generated.add(sourcePath)) {
                    try(Writer output = filer.createSourceFile(sourcePath).openWriter()) {
                        output.append(source);
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        }
        return null;
    }

}