/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.tooling.procedure.visitors;

import static javax.lang.model.element.Modifier.PUBLIC;
import static javax.lang.model.element.Modifier.STATIC;
import static javax.lang.model.util.ElementFilter.fieldsIn;

import java.util.Set;
import java.util.stream.Stream;
import javax.lang.model.element.Element;
import javax.lang.model.element.Modifier;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.type.TypeVisitor;
import javax.lang.model.util.SimpleTypeVisitor8;
import javax.lang.model.util.Types;
import org.neo4j.tooling.procedure.compilerutils.TypeMirrorUtils;
import org.neo4j.tooling.procedure.messages.CompilationMessage;
import org.neo4j.tooling.procedure.messages.RecordTypeError;

class RecordTypeVisitor extends SimpleTypeVisitor8<Stream<CompilationMessage>, Void> {

    private final Types typeUtils;
    private final TypeVisitor<Boolean, Void> fieldTypeVisitor;

    RecordTypeVisitor(Types typeUtils, TypeMirrorUtils typeMirrors) {
        this.typeUtils = typeUtils;
        fieldTypeVisitor = new RecordFieldTypeVisitor(typeUtils, typeMirrors);
    }

    @Override
    public Stream<CompilationMessage> visitDeclared(DeclaredType returnType, Void ignored) {
        return returnType.getTypeArguments().stream().flatMap(this::validateRecord);
    }

    private Stream<CompilationMessage> validateRecord(TypeMirror recordType) {
        Element recordElement = typeUtils.asElement(recordType);
        return Stream.concat(validateFieldModifiers(recordElement), validateFieldType(recordElement));
    }

    private Stream<CompilationMessage> validateFieldModifiers(Element recordElement) {
        return fieldsIn(recordElement.getEnclosedElements()).stream()
                .filter(element -> {
                    Set<Modifier> modifiers = element.getModifiers();
                    return !modifiers.contains(PUBLIC) && !modifiers.contains(STATIC);
                })
                .map(element -> new RecordTypeError(
                        element,
                        "Record definition error: field %s#%s must be public",
                        recordElement.getSimpleName(),
                        element.getSimpleName()));
    }

    private Stream<CompilationMessage> validateFieldType(Element recordElement) {
        return fieldsIn(recordElement.getEnclosedElements()).stream()
                .filter(element -> !element.getModifiers().contains(STATIC))
                .filter(element -> !fieldTypeVisitor.visit(element.asType()))
                .map(element -> new RecordTypeError(
                        element,
                        "Record definition error: field %s#%s of type %s is not supported",
                        recordElement.getSimpleName(),
                        element.getSimpleName(),
                        element.asType()));
    }
}
