/*

 * Copyright (C) 2007-2010 Júlio Vilmar Gesser.

 * Copyright (C) 2011, 2013-2021 The JavaParser Team.

 *

 * This file is part of JavaParser.

 *

 * JavaParser can be used either under the terms of

 * a) the GNU Lesser General Public License as published by

 *     the Free Software Foundation, either version 3 of the License, or

 *     (at your option) any later version.

 * b) the terms of the Apache License

 *

 * You should have received a copy of both licenses in LICENCE.LGPL and

 * LICENCE.APACHE. Please refer to those files for details.

 *

 * JavaParser 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 Lesser General Public License for more details.

 */

package com.github.javaparser.ast.expr;

import com.github.javaparser.TokenRange;

import com.github.javaparser.ast.AllFieldsConstructor;

import com.github.javaparser.ast.Generated;

import com.github.javaparser.ast.Node;

import com.github.javaparser.ast.NodeList;

import com.github.javaparser.ast.body.Parameter;

import com.github.javaparser.ast.nodeTypes.NodeWithParameters;

import com.github.javaparser.ast.observer.ObservableProperty;

import com.github.javaparser.ast.stmt.BlockStmt;

import com.github.javaparser.ast.stmt.ExpressionStmt;

import com.github.javaparser.ast.stmt.ReturnStmt;

import com.github.javaparser.ast.stmt.Statement;

import com.github.javaparser.ast.visitor.CloneVisitor;

import com.github.javaparser.ast.visitor.GenericVisitor;

import com.github.javaparser.ast.visitor.VoidVisitor;

import com.github.javaparser.metamodel.DerivedProperty;

import com.github.javaparser.metamodel.JavaParserMetaModel;

import com.github.javaparser.metamodel.LambdaExprMetaModel;

import java.util.Optional;

import java.util.function.Consumer;

import static com.github.javaparser.utils.Utils.assertNotNull;

/**

 * <h1>A lambda expression</h1>

 * <h2>Java 1-7</h2>

 * Does not exist.

 * <h2>Java 8+</h2>

 * {@code (a, b) -> a + b}

 * <br>{@code a -> ...}

 * <br>{@code (Long a) -> { println(a); }}

 * <p>The parameters are on the left side of the -&gt;.

 * If a parameter uses type inference (it has no type specified) then its type is set to {@code UnknownType}.

 * If they are in ( ), "isEnclosingParameters" is true.

 * <br>The body is to the right of the -&gt;.

 * The body is either a BlockStmt when it is in { } braces, or an ExpressionStmt when it is not in braces.

 *

 * @author Raquel Pau

 */

public class LambdaExpr extends Expression implements NodeWithParameters<LambdaExpr> {

    private NodeList<Parameter> parameters;

    private boolean isEnclosingParameters;

    private Statement body;

    public LambdaExpr() {

        this(null, new NodeList<>(), new ReturnStmt(), false);

    }

    /**

     * Creates a single parameter lambda expression.

     */

    public LambdaExpr(Parameter parameter, BlockStmt body) {

        this(null, new NodeList<>(parameter), body, false);

    }

    /**

     * Creates a zero or multi-parameter lambda expression with its parameters wrapped in ( ).

     */

    public LambdaExpr(NodeList<Parameter> parameters, BlockStmt body) {

        this(null, parameters, body, true);

    }

    /**

     * Creates a single parameter lambda expression.

     */

    public LambdaExpr(Parameter parameter, Expression body) {

        this(null, new NodeList<>(parameter), new ExpressionStmt(body), false);

    }

    /**

     * Creates a zero or multi-parameter lambda expression with its parameters wrapped in ( ).

     */

    public LambdaExpr(NodeList<Parameter> parameters, Expression body) {

        this(null, parameters, new ExpressionStmt(body), true);

    }

    @AllFieldsConstructor

    public LambdaExpr(NodeList<Parameter> parameters, Statement body, boolean isEnclosingParameters) {

        this(null, parameters, body, isEnclosingParameters);

    }

    /**

     * This constructor is used by the parser and is considered private.

     */

    @Generated("com.github.javaparser.generator.core.node.MainConstructorGenerator")

    public LambdaExpr(TokenRange tokenRange, NodeList<Parameter> parameters, Statement body, boolean isEnclosingParameters) {

        super(tokenRange);

        setParameters(parameters);

        setBody(body);

        setEnclosingParameters(isEnclosingParameters);

        customInitialization();

    }

    @Generated("com.github.javaparser.generator.core.node.PropertyGenerator")

    public NodeList<Parameter> getParameters() {

        return parameters;

    }

    @Generated("com.github.javaparser.generator.core.node.PropertyGenerator")

    public LambdaExpr setParameters(final NodeList<Parameter> parameters) {

        assertNotNull(parameters);

        if (parameters == this.parameters) {

            return this;

        }

        notifyPropertyChange(ObservableProperty.PARAMETERS, this.parameters, parameters);

        if (this.parameters != null)

            this.parameters.setParentNode(null);

        this.parameters = parameters;

        setAsParentNodeOf(parameters);

        return this;

    }

    /**

     * @return a BlockStatement or an ExpressionStatement. See class Javadoc.

     */

    @Generated("com.github.javaparser.generator.core.node.PropertyGenerator")

    public Statement getBody() {

        return body;

    }

    @Generated("com.github.javaparser.generator.core.node.PropertyGenerator")

    public LambdaExpr setBody(final Statement body) {

        assertNotNull(body);

        if (body == this.body) {

            return this;

        }

        notifyPropertyChange(ObservableProperty.BODY, this.body, body);

        if (this.body != null)

            this.body.setParentNode(null);

        this.body = body;

        setAsParentNodeOf(body);

        return this;

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.AcceptGenerator")

    public <R, A> R accept(final GenericVisitor<R, A> v, final A arg) {

        return v.visit(this, arg);

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.AcceptGenerator")

    public <A> void accept(final VoidVisitor<A> v, final A arg) {

        v.visit(this, arg);

    }

    @Generated("com.github.javaparser.generator.core.node.PropertyGenerator")

    public boolean isEnclosingParameters() {

        return isEnclosingParameters;

    }

    @Generated("com.github.javaparser.generator.core.node.PropertyGenerator")

    public LambdaExpr setEnclosingParameters(final boolean isEnclosingParameters) {

        if (isEnclosingParameters == this.isEnclosingParameters) {

            return this;

        }

        notifyPropertyChange(ObservableProperty.ENCLOSING_PARAMETERS, this.isEnclosingParameters, isEnclosingParameters);

        this.isEnclosingParameters = isEnclosingParameters;

        return this;

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.RemoveMethodGenerator")

    public boolean remove(Node node) {

        if (node == null)

            return false;

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

            if (parameters.get(i) == node) {

                parameters.remove(i);

                return true;

            }

        }

        return super.remove(node);

    }

    /**

     * @return if the body of this lambda is a simple expression, return that expression.

     * Otherwise (when the body is a block) return Optional.empty().

     */

    @DerivedProperty

    public Optional<Expression> getExpressionBody() {

        if (body.isExpressionStmt()) {

            return Optional.of(body.asExpressionStmt().getExpression());

        } else {

            return Optional.empty();

        }

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.CloneGenerator")

    public LambdaExpr clone() {

        return (LambdaExpr) accept(new CloneVisitor(), null);

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.GetMetaModelGenerator")

    public LambdaExprMetaModel getMetaModel() {

        return JavaParserMetaModel.lambdaExprMetaModel;

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.ReplaceMethodGenerator")

    public boolean replace(Node node, Node replacementNode) {

        if (node == null)

            return false;

        if (node == body) {

            setBody((Statement) replacementNode);

            return true;

        }

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

            if (parameters.get(i) == node) {

                parameters.set(i, (Parameter) replacementNode);

                return true;

            }

        }

        return super.replace(node, replacementNode);

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.TypeCastingGenerator")

    public boolean isLambdaExpr() {

        return true;

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.TypeCastingGenerator")

    public LambdaExpr asLambdaExpr() {

        return this;

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.TypeCastingGenerator")

    public void ifLambdaExpr(Consumer<LambdaExpr> action) {

        action.accept(this);

    }

    @Override

    @Generated("com.github.javaparser.generator.core.node.TypeCastingGenerator")

    public Optional<LambdaExpr> toLambdaExpr() {

        return Optional.of(this);

    }

    /*

     * Lambda expressions are always poly expressions

     */

    @Override

    public boolean isPolyExpression() {

        return true;

    }

}