////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2015 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////

package com.puppycrawl.tools.checkstyle.checks.coding;

import com.google.common.collect.ImmutableSet;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.checks.AbstractDeclarationCollector;
import com.puppycrawl.tools.checkstyle.utils.ScopeUtils;

/**
 * <p>Checks that code doesn't rely on the &quot;this&quot; default.
 * That is references to instance variables and methods of the present
 * object are explicitly of the form &quot;this.varName&quot; or
 * &quot;this.methodName(args)&quot;.
 *</p>
 *
 * <p>Examples of use:
 * <pre>
 * &lt;module name=&quot;RequireThis&quot;/&gt;
 * </pre>
 * An example of how to configure to check {@code this} qualifier for
 * methods only:
 * <pre>
 * &lt;module name=&quot;RequireThis&quot;&gt;
 *   &lt;property name=&quot;checkFields&quot; value=&quot;false&quot;/&gt;
 *   &lt;property name=&quot;checkMethods&quot; value=&quot;true&quot;/&gt;
 * &lt;/module&gt;
 * </pre>
 *
 * <p>Limitations: I'm not currently doing anything about static variables
 * or catch-blocks.  Static methods invoked on a class name seem to be OK;
 * both the class name and the method name have a DOT parent.
 * Non-static methods invoked on either this or a variable name seem to be
 * OK, likewise.</p>
 * <p>Much of the code for this check was cribbed from Rick Giles's
 * {@code HiddenFieldCheck}.</p>
 *
 * @author Stephen Bloch
 * @author o_sukhodolsky
 */
public class RequireThisCheck extends AbstractDeclarationCollector {

    /**
     * A key is pointing to the warning message text in "messages.properties"
     * file.
     */
    public static final String MSG_METHOD = "require.this.method";

    /**
     * A key is pointing to the warning message text in "messages.properties"
     * file.
     */
    public static final String MSG_VARIABLE = "require.this.variable";

    /**
     * Set of all declaration tokens.
     */
    private static final ImmutableSet<Integer> DECLARATION_TOKENS = ImmutableSet.of(
            TokenTypes.VARIABLE_DEF,
            TokenTypes.CTOR_DEF,
            TokenTypes.METHOD_DEF,
            TokenTypes.CLASS_DEF,
            TokenTypes.ENUM_DEF,
            TokenTypes.INTERFACE_DEF,
            TokenTypes.PARAMETER_DEF,
            TokenTypes.TYPE_ARGUMENT
    );

    /** Whether we should check fields usage. */
    private boolean checkFields = true;
    /** Whether we should check methods usage. */
    private boolean checkMethods = true;

    /**
     * Setter for checkFields property.
     * @param checkFields should we check fields usage or not.
     */
    public void setCheckFields(boolean checkFields) {
        this.checkFields = checkFields;
    }

    /**
     * Setter for checkMethods property.
     * @param checkMethods should we check methods usage or not.
     */
    public void setCheckMethods(boolean checkMethods) {
        this.checkMethods = checkMethods;
    }

    @Override
    public int[] getDefaultTokens() {
        return getAcceptableTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return getAcceptableTokens();
    }

    @Override
    public int[] getAcceptableTokens() {
        return new int[] {
            TokenTypes.CLASS_DEF,
            TokenTypes.INTERFACE_DEF,
            TokenTypes.ENUM_DEF,
            TokenTypes.CTOR_DEF,
            TokenTypes.METHOD_DEF,
            TokenTypes.SLIST,
            TokenTypes.IDENT,
        };
    }

    @Override
    public void visitToken(DetailAST ast) {
        super.visitToken(ast);
        if (ast.getType() == TokenTypes.IDENT) {
            processIdent(ast);
        }
    }

    /**
     * Checks if a given IDENT is method call or field name which
     * require explicit {@code this} qualifier.
     *
     * @param ast IDENT to check.
     */
    private void processIdent(DetailAST ast) {
        final int parentType = ast.getParent().getType();
        switch (parentType) {
            case TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR:
            case TokenTypes.ANNOTATION:
            case TokenTypes.ANNOTATION_FIELD_DEF:
                // no need to check annotations content
                break;
            case TokenTypes.METHOD_CALL:
                // let's check method calls
                if (checkMethods && isClassMethod(ast.getText())) {
                    log(ast, MSG_METHOD, ast.getText());
                }
                break;
            default:
                if (checkFields) {
                    processField(ast, parentType);
                }
                break;
        }
    }

    /**
     * Process validation of Field.
     * @param ast field definition ast token
     * @param parentType type of the parent
     */
    private void processField(DetailAST ast, int parentType) {
        final boolean importOrPackage = ScopeUtils.getSurroundingScope(ast) == null;
        final boolean methodNameInMethodCall = parentType == TokenTypes.DOT
                && ast.getPreviousSibling() != null;
        final boolean typeName = parentType == TokenTypes.TYPE
                || parentType == TokenTypes.LITERAL_NEW;

        if (!importOrPackage
                && !methodNameInMethodCall
                && !typeName
                && !isDeclarationToken(parentType)) {

            final String name = ast.getText();

            if (isClassField(name)) {
                log(ast, MSG_VARIABLE, name);
            }
        }
    }

    /**
     * Check that token is related to Definition tokens.
     * @param parentType token Type
     * @return true if token is related to Definition Tokens
     */
    private static boolean isDeclarationToken(int parentType) {
        return DECLARATION_TOKENS.contains(parentType);
    }
}