/*

 * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.replacements.verifier;

import java.lang.annotation.Annotation;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.Formatter;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.annotation.processing.ProcessingEnvironment;

import javax.lang.model.element.AnnotationMirror;

import javax.lang.model.element.Element;

import javax.lang.model.element.ElementKind;

import javax.lang.model.element.ExecutableElement;

import javax.lang.model.element.Modifier;

import javax.lang.model.element.TypeElement;

import javax.lang.model.element.VariableElement;

import javax.lang.model.type.ArrayType;

import javax.lang.model.type.TypeKind;

import javax.lang.model.type.TypeMirror;

import javax.lang.model.type.TypeVariable;

import javax.lang.model.util.ElementFilter;

import javax.tools.Diagnostic.Kind;

import org.graalvm.compiler.graph.Node.ConstantNodeParameter;

import org.graalvm.compiler.graph.Node.InjectedNodeParameter;

import org.graalvm.compiler.graph.Node.NodeIntrinsic;

import org.graalvm.compiler.nodeinfo.InputType;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodeinfo.StructuralInput.MarkerType;

public final class NodeIntrinsicVerifier extends AbstractVerifier {

    private static final String NODE_CLASS_NAME = "value";

    private TypeMirror nodeType() {

        return env.getElementUtils().getTypeElement("org.graalvm.compiler.graph.Node").asType();

    }

    private TypeMirror stampType() {

        return env.getElementUtils().getTypeElement("org.graalvm.compiler.core.common.type.Stamp").asType();

    }

    private TypeMirror valueNodeType() {

        return env.getElementUtils().getTypeElement("org.graalvm.compiler.nodes.ValueNode").asType();

    }

    private TypeMirror classType() {

        return env.getElementUtils().getTypeElement("java.lang.Class").asType();

    }

    private TypeMirror resolvedJavaTypeType() {

        return env.getElementUtils().getTypeElement("jdk.vm.ci.meta.ResolvedJavaType").asType();

    }

    private TypeMirror resolvedJavaMethodType() {

        return env.getElementUtils().getTypeElement("jdk.vm.ci.meta.ResolvedJavaMethod").asType();

    }

    private TypeMirror structuralInputType() {

        return env.getElementUtils().getTypeElement("org.graalvm.compiler.nodeinfo.StructuralInput").asType();

    }

    private TypeMirror graphBuilderContextType() {

        return env.getElementUtils().getTypeElement("org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderContext").asType();

    }

    public NodeIntrinsicVerifier(ProcessingEnvironment env) {

        super(env);

    }

    @Override

    public Class<? extends Annotation> getAnnotationClass() {

        return NodeIntrinsic.class;

    }

    @Override

    public void verify(Element element, AnnotationMirror annotation, PluginGenerator generator) {

        if (element.getKind() != ElementKind.METHOD) {

            assert false : "Element is guaranteed to be a method.";

            return;

        }

        ExecutableElement intrinsicMethod = (ExecutableElement) element;

        if (!intrinsicMethod.getModifiers().contains(Modifier.STATIC)) {

            env.getMessager().printMessage(Kind.ERROR, String.format("A @%s method must be static.", NodeIntrinsic.class.getSimpleName()), element, annotation);

        }

        if (!intrinsicMethod.getModifiers().contains(Modifier.NATIVE)) {

            env.getMessager().printMessage(Kind.ERROR, String.format("A @%s method must be native.", NodeIntrinsic.class.getSimpleName()), element, annotation);

        }

        TypeMirror nodeClassMirror = resolveAnnotationValue(TypeMirror.class, findAnnotationValue(annotation, NODE_CLASS_NAME));

        TypeElement nodeClass = (TypeElement) env.getTypeUtils().asElement(nodeClassMirror);

        if (nodeClass.getSimpleName().contentEquals(NodeIntrinsic.class.getSimpleName())) {

            // default value

            Element enclosingElement = intrinsicMethod.getEnclosingElement();

            while (enclosingElement != null && enclosingElement.getKind() != ElementKind.CLASS) {

                enclosingElement = enclosingElement.getEnclosingElement();

            }

            if (enclosingElement != null) {

                nodeClass = (TypeElement) enclosingElement;

            }

        }

        TypeMirror returnType = intrinsicMethod.getReturnType();

        if (returnType instanceof TypeVariable) {

            env.getMessager().printMessage(Kind.ERROR, "@NodeIntrinsic cannot have a generic return type.", element, annotation);

        }

        boolean injectedStampIsNonNull = intrinsicMethod.getAnnotation(NodeIntrinsic.class).injectedStampIsNonNull();

        if (returnType.getKind() == TypeKind.VOID) {

            for (VariableElement parameter : intrinsicMethod.getParameters()) {

                if (parameter.getAnnotation(InjectedNodeParameter.class) != null) {

                    env.getMessager().printMessage(Kind.ERROR, "@NodeIntrinsic with an injected Stamp parameter cannot have a void return type.", element, annotation);

                    break;

                }

            }

        }

        TypeMirror[] constructorSignature = constructorSignature(intrinsicMethod);

        Map<ExecutableElement, String> nonMatches = new HashMap<>();

        List<ExecutableElement> factories = findIntrinsifyFactoryMethod(nodeClass, constructorSignature, nonMatches, injectedStampIsNonNull);

        List<ExecutableElement> constructors = Collections.emptyList();

        if (nodeClass.getModifiers().contains(Modifier.ABSTRACT)) {

            if (factories.isEmpty()) {

                env.getMessager().printMessage(Kind.ERROR, String.format("Cannot make a node intrinsic for an abstract class %s.", nodeClass.getSimpleName()), element, annotation);

            }

        } else if (!isNodeType(nodeClass)) {

            if (factories.isEmpty()) {

                env.getMessager().printMessage(Kind.ERROR, String.format("%s is not a subclass of %s.", nodeClass.getSimpleName(), nodeType()), element, annotation);

            }

        } else {

            TypeMirror ret = returnType;

            if (env.getTypeUtils().isAssignable(ret, structuralInputType())) {

                checkInputType(nodeClass, ret, element, annotation);

            }

            constructors = findConstructors(nodeClass, constructorSignature, nonMatches, injectedStampIsNonNull);

        }

        Formatter msg = new Formatter();

        if (factories.size() > 1) {

            msg.format("Found more than one factory in %s matching node intrinsic:", nodeClass);

            for (ExecutableElement candidate : factories) {

                msg.format("%n  %s", candidate);

            }

            env.getMessager().printMessage(Kind.ERROR, msg.toString(), intrinsicMethod, annotation);

        } else if (constructors.size() > 1) {

            msg.format("Found more than one constructor in %s matching node intrinsic:", nodeClass);

            for (ExecutableElement candidate : constructors) {

                msg.format("%n  %s", candidate);

            }

            env.getMessager().printMessage(Kind.ERROR, msg.toString(), intrinsicMethod, annotation);

        } else if (factories.size() == 1) {

            generator.addPlugin(new GeneratedNodeIntrinsicPlugin.CustomFactoryPlugin(intrinsicMethod, factories.get(0), constructorSignature));

        } else if (constructors.size() == 1) {

            generator.addPlugin(new GeneratedNodeIntrinsicPlugin.ConstructorPlugin(intrinsicMethod, constructors.get(0), constructorSignature));

        } else {

            msg.format("Could not find any factories or constructors in %s matching node intrinsic", nodeClass);

            if (!nonMatches.isEmpty()) {

                msg.format("%nFactories and constructors that failed to match:");

                for (Map.Entry<ExecutableElement, String> e : nonMatches.entrySet()) {

                    msg.format("%n  %s: %s", e.getKey(), e.getValue());

                }

            }

            env.getMessager().printMessage(Kind.ERROR, msg.toString(), intrinsicMethod, annotation);

        }

    }

    private void checkInputType(TypeElement nodeClass, TypeMirror returnType, Element element, AnnotationMirror annotation) {

        InputType inputType = getInputType(returnType, element, annotation);

        if (inputType != InputType.Value) {

            boolean allowed = false;

            InputType[] allowedTypes = nodeClass.getAnnotation(NodeInfo.class).allowedUsageTypes();

            for (InputType allowedType : allowedTypes) {

                if (inputType == allowedType) {

                    allowed = true;

                    break;

                }

            }

            if (!allowed) {

                env.getMessager().printMessage(Kind.ERROR, String.format("@NodeIntrinsic returns input type %s, but only %s is allowed.", inputType, Arrays.toString(allowedTypes)), element,

                                annotation);

            }

        }

    }

    private InputType getInputType(TypeMirror type, Element element, AnnotationMirror annotation) {

        TypeElement current = (TypeElement) env.getTypeUtils().asElement(type);

        while (current != null) {

            MarkerType markerType = current.getAnnotation(MarkerType.class);

            if (markerType != null) {

                return markerType.value();

            }

            current = (TypeElement) env.getTypeUtils().asElement(current.getSuperclass());

        }

        env.getMessager().printMessage(Kind.ERROR, String.format("The class %s is a subclass of StructuralInput, but isn't annotated with @MarkerType.", type), element, annotation);

        return InputType.Value;

    }

    private boolean isNodeType(TypeElement nodeClass) {

        return env.getTypeUtils().isSubtype(nodeClass.asType(), nodeType());

    }

    private TypeMirror[] constructorSignature(ExecutableElement method) {

        TypeMirror[] parameters = new TypeMirror[method.getParameters().size()];

        for (int i = 0; i < method.getParameters().size(); i++) {

            VariableElement parameter = method.getParameters().get(i);

            if (parameter.getAnnotation(ConstantNodeParameter.class) == null) {

                parameters[i] = valueNodeType();

            } else {

                TypeMirror type = parameter.asType();

                if (isTypeCompatible(type, classType())) {

                    type = resolvedJavaTypeType();

                }

                parameters[i] = type;

            }

        }

        return parameters;

    }

    private List<ExecutableElement> findConstructors(TypeElement nodeClass, TypeMirror[] signature, Map<ExecutableElement, String> nonMatches, boolean requiresInjectedStamp) {

        List<ExecutableElement> constructors = ElementFilter.constructorsIn(nodeClass.getEnclosedElements());

        List<ExecutableElement> found = new ArrayList<>(constructors.size());

        for (ExecutableElement constructor : constructors) {

            if (matchSignature(0, constructor, signature, nonMatches, requiresInjectedStamp)) {

                found.add(constructor);

            }

        }

        return found;

    }

    private List<ExecutableElement> findIntrinsifyFactoryMethod(TypeElement nodeClass, TypeMirror[] signature, Map<ExecutableElement, String> nonMatches, boolean requiresInjectedStamp) {

        List<ExecutableElement> methods = ElementFilter.methodsIn(nodeClass.getEnclosedElements());

        List<ExecutableElement> found = new ArrayList<>(methods.size());

        for (ExecutableElement method : methods) {

            if (!method.getSimpleName().toString().equals("intrinsify")) {

                continue;

            }

            if (method.getParameters().size() < 2) {

                continue;

            }

            VariableElement firstArg = method.getParameters().get(0);

            if (!isTypeCompatible(firstArg.asType(), graphBuilderContextType())) {

                continue;

            }

            VariableElement secondArg = method.getParameters().get(1);

            if (!isTypeCompatible(secondArg.asType(), resolvedJavaMethodType())) {

                continue;

            }

            if (method.getReturnType().getKind() != TypeKind.BOOLEAN) {

                continue;

            }

            if (matchSignature(2, method, signature, nonMatches, requiresInjectedStamp)) {

                found.add(method);

            }

        }

        return found;

    }

    private boolean matchSignature(int numSkippedParameters, ExecutableElement method, TypeMirror[] signature, Map<ExecutableElement, String> nonMatches, boolean requiresInjectedStamp) {

        int sIdx = 0;

        int cIdx = numSkippedParameters;

        boolean missingStampArgument = requiresInjectedStamp;

        while (cIdx < method.getParameters().size()) {

            VariableElement parameter = method.getParameters().get(cIdx++);

            TypeMirror paramType = parameter.asType();

            if (parameter.getAnnotation(InjectedNodeParameter.class) != null) {

                if (missingStampArgument && env.getTypeUtils().isSameType(paramType, stampType())) {

                    missingStampArgument = false;

                }

                // skip injected parameters

                continue;

            }

            if (missingStampArgument) {

                nonMatches.put(method, String.format("missing injected %s argument", stampType()));

                return false;

            }

            if (cIdx == method.getParameters().size() && paramType.getKind() == TypeKind.ARRAY) {

                // last argument of constructor is varargs, match remaining intrinsic arguments

                TypeMirror varargsType = ((ArrayType) paramType).getComponentType();

                while (sIdx < signature.length) {

                    if (!isTypeCompatible(varargsType, signature[sIdx++])) {

                        nonMatches.put(method, String.format("the types of argument %d are incompatible: %s != %s", sIdx, varargsType, signature[sIdx - 1]));

                        return false;

                    }

                }

            } else if (sIdx >= signature.length) {

                // too many arguments in intrinsic method

                nonMatches.put(method, "too many arguments");

                return false;

            } else if (!isTypeCompatible(paramType, signature[sIdx++])) {

                nonMatches.put(method, String.format("the type of argument %d is incompatible: %s != %s", sIdx, paramType, signature[sIdx - 1]));

                return false;

            }

        }

        if (missingStampArgument) {

            nonMatches.put(method, String.format("missing injected %s argument", stampType()));

            return false;

        }

        if (sIdx != signature.length) {

            nonMatches.put(method, "not enough arguments");

            return false;

        }

        return true;

    }

    private boolean isTypeCompatible(TypeMirror originalType, TypeMirror substitutionType) {

        TypeMirror original = originalType;

        TypeMirror substitution = substitutionType;

        if (needsErasure(original)) {

            original = env.getTypeUtils().erasure(original);

        }

        if (needsErasure(substitution)) {

            substitution = env.getTypeUtils().erasure(substitution);

        }

        return env.getTypeUtils().isSameType(original, substitution);

    }

    private static boolean needsErasure(TypeMirror typeMirror) {

        return typeMirror.getKind() != TypeKind.NONE && typeMirror.getKind() != TypeKind.VOID && !typeMirror.getKind().isPrimitive() && typeMirror.getKind() != TypeKind.OTHER &&

                        typeMirror.getKind() != TypeKind.NULL;

    }

}