////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2020 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.filters;

import java.util.Collections;
import java.util.Set;

import com.puppycrawl.tools.checkstyle.api.AuditEvent;
import com.puppycrawl.tools.checkstyle.api.AutomaticBean;
import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
import com.puppycrawl.tools.checkstyle.api.ExternalResourceHolder;
import com.puppycrawl.tools.checkstyle.api.Filter;
import com.puppycrawl.tools.checkstyle.api.FilterSet;
import com.puppycrawl.tools.checkstyle.utils.FilterUtil;

/**
 * <p>
 * Filter {@code SuppressionFilter} rejects audit events for Check violations according to a
 * <a href="https://checkstyle.org/dtds/suppressions_1_2.dtd">suppressions XML document</a>
 * in a file. If there is no configured suppressions file or the optional is set to true and
 * suppressions file was not found the Filter accepts all audit events.
 * </p>
 * <p>
 * A <a href="https://checkstyle.org/dtds/suppressions_1_2.dtd">suppressions XML document</a>
 * contains a set of {@code suppress} elements, where each {@code suppress}
 * element can have the following attributes:
 * </p>
 * <ul>
 * <li>
 * {@code files} - a <a href="https://checkstyle.org/property_types.html#regexp">
 * Regular Expression</a> matched against the file name associated with an audit event.
 * It is optional.
 * </li>
 * <li>
 * {@code checks} - a <a href="https://checkstyle.org/property_types.html#regexp">
 * Regular Expression</a> matched against the name of the check associated with an audit event.
 * Optional as long as {@code id} or {@code message} is specified.
 * </li>
 * <li>
 * {@code message} - a <a href="https://checkstyle.org/property_types.html#regexp">
 * Regular Expression</a> matched against the message of the check associated with an audit event.
 * Optional as long as {@code checks} or {@code id} is specified.
 * </li>
 * <li>
 * {@code id} - a <a href="https://checkstyle.org/property_types.html#string">string</a>
 * matched against the <a href="https://checkstyle.org/config.html#Id">check id</a>
 * associated with an audit event.
 * Optional as long as {@code checks} or {@code message} is specified.
 * </li>
 * <li>
 * {@code lines} - a comma-separated list of values, where each value is an
 * <a href="https://checkstyle.org/property_types.html#integer">integer</a>
 * or a range of integers denoted by integer-integer.
 * It is optional.
 * </li>
 * <li>
 * {@code columns} - a comma-separated list of values, where each value is an
 * <a href="https://checkstyle.org/property_types.html#integer">integer</a>
 * or a range of integers denoted by integer-integer.
 * It is optional.
 * </li>
 * </ul>
 * <p>
 * Each audit event is checked against each {@code suppress} element.
 * It is suppressed if all specified attributes match against the audit event.
 * </p>
 * <p>
 * ATTENTION: filtering by message is dependant on runtime locale.
 * If project is running in different languages it is better to avoid filtering by message.
 * </p>
 * <p>
 * You can download template of empty suppression filter
 * <a href="https://checkstyle.org/files/suppressions_none.xml">here</a>.
 * </p>
 * <p>
 * Location of the file defined in {@code file} property is checked in the following order:
 * </p>
 * <ol>
 * <li>
 * as a filesystem location
 * </li>
 * <li>
 * if no file found, and the location starts with either {@code http://} or {@code https://},
 * then it is interpreted as a URL
 * </li>
 * <li>
 * if no file found, then passed to the {@code ClassLoader.getResource()} method.
 * </li>
 * </ol>
 * <ul>
 * <li>
 * Property {@code file} - Specify the location of the <em>suppressions XML document</em> file.
 * Default value is {@code null}.
 * </li>
 * <li>
 * Property {@code optional} - Control what to do when the file is not existing.
 * If {@code optional} is set to {@code false} the file must exist, or else it
 * ends with error. On the other hand if optional is {@code true} and file is
 * not found, the filter accept all audit events.
 * Default value is {@code false}.
 * </li>
 * </ul>
 * <p>
 * For example, the following configuration fragment directs the Checker to use
 * a {@code SuppressionFilter} with suppressions file {@code config/suppressions.xml}:
 * </p>
 * <pre>
 * &lt;module name=&quot;SuppressionFilter&quot;&gt;
 *   &lt;property name=&quot;file&quot; value=&quot;config/suppressions.xml&quot;/&gt;
 *   &lt;property name=&quot;optional&quot; value=&quot;false&quot;/&gt;
 * &lt;/module&gt;
 * </pre>
 * <p>
 * The following suppressions XML document directs a {@code SuppressionFilter} to
 * reject {@code JavadocStyleCheck} violations for lines 82 and 108 to 122 of file
 * {@code AbstractComplexityCheck.java}, and {@code MagicNumberCheck} violations for
 * line 221 of file {@code JavadocStyleCheck.java}, and
 * {@code 'Missing a Javadoc comment'} violations for all lines and files:
 * </p>
 * <pre>
 * &lt;?xml version=&quot;1.0&quot;?&gt;
 *
 * &lt;!DOCTYPE suppressions PUBLIC
 *   &quot;-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN&quot;
 *   &quot;https://checkstyle.org/dtds/suppressions_1_2.dtd&quot;&gt;
 *
 * &lt;suppressions&gt;
 *   &lt;suppress checks=&quot;JavadocStyleCheck&quot;
 *     files=&quot;AbstractComplexityCheck.java&quot;
 *     lines=&quot;82,108-122&quot;/&gt;
 *   &lt;suppress checks=&quot;MagicNumberCheck&quot;
 *     files=&quot;JavadocStyleCheck.java&quot;
 *     lines=&quot;221&quot;/&gt;
 *   &lt;suppress message=&quot;Missing a Javadoc comment&quot;/&gt;
 * &lt;/suppressions&gt;
 * </pre>
 * <p>
 * Suppress check by <a href="https://checkstyle.org/config.html#Id">module id</a>
 * when config have two instances on the same check:
 * </p>
 * <pre>
 * &lt;suppress id=&quot;stringEqual&quot; files=&quot;SomeTestCode.java&quot;/&gt;
 * </pre>
 * <p>
 * Suppress all checks for hidden files and folders:
 * </p>
 * <pre>
 * &lt;suppress files=&quot;[/\\]\..+&quot; checks=&quot;.*&quot;/&gt;
 * </pre>
 * <p>
 * Suppress all checks for Maven-generated code:
 * </p>
 * <pre>
 * &lt;suppress files=&quot;[/\\]target[/\\]&quot; checks=&quot;.*&quot;/&gt;
 * </pre>
 * <p>
 * Suppress all checks for archives, classes and other binary files:
 * </p>
 * <pre>
 * &lt;suppress files=&quot;.+\.(?:jar|zip|war|class|tar|bin)$&quot; checks=&quot;.*&quot;/&gt;
 * </pre>
 * <p>
 * Suppress all checks for image files:
 * </p>
 * <pre>
 * &lt;suppress files=".+\.(?:png|gif|jpg|jpeg)$" checks=".*"/&gt;
 * </pre>
 * <p>
 * Suppress all checks for non-java files:
 * </p>
 * <pre>
 * &lt;suppress files=&quot;.+\.(?:txt|xml|csv|sh|thrift|html|sql|eot|ttf|woff|css|png)$&quot;
 *     checks=&quot;.*&quot;/&gt;
 * </pre>
 * <p>
 * Suppress all checks in generated sources:
 * </p>
 * <pre>
 * &lt;suppress checks=&quot;.*&quot; files=&quot;com[\\/]mycompany[\\/]app[\\/]gen[\\/]&quot;/&gt;
 * </pre>
 * <p>
 * Suppress FileLength check on integration tests in certain folder:
 * </p>
 * <pre>
 * &lt;suppress checks=&quot;FileLength&quot;
 *   files=&quot;com[\\/]mycompany[\\/]app[\\/].*IT.java&quot;/&gt;
 * </pre>
 * <p>
 * Suppress naming violations on variable named 'log' in all files:
 * </p>
 * <pre>
 * &lt;suppress message=&quot;Name 'log' must match pattern&quot;/&gt;
 * </pre>
 *
 * @since 3.2
 */
public class SuppressionFilter extends AutomaticBean implements Filter, ExternalResourceHolder {

    /** Specify the location of the <em>suppressions XML document</em> file. */
    private String file;
    /**
     * Control what to do when the file is not existing. If {@code optional} is
     * set to {@code false} the file must exist, or else it ends with error.
     * On the other hand if optional is {@code true} and file is not found,
     * the filter accept all audit events.
     */
    private boolean optional;
    /** Set of individual suppresses. */
    private FilterSet filters = new FilterSet();

    /**
     * Setter to specify the location of the <em>suppressions XML document</em> file.
     * @param fileName name of the suppressions file.
     */
    public void setFile(String fileName) {
        file = fileName;
    }

    /**
     * Setter to control what to do when the file is not existing.
     * If {@code optional} is set to {@code false} the file must exist, or else
     * it ends with error. On the other hand if optional is {@code true}
     * and file is not found, the filter accept all audit events.
     * @param optional tells if config file existence is optional.
     */
    public void setOptional(boolean optional) {
        this.optional = optional;
    }

    @Override
    public boolean accept(AuditEvent event) {
        return filters.accept(event);
    }

    @Override
    protected void finishLocalSetup() throws CheckstyleException {
        if (file != null) {
            if (optional) {
                if (FilterUtil.isFileExists(file)) {
                    filters = SuppressionsLoader.loadSuppressions(file);
                }
                else {
                    filters = new FilterSet();
                }
            }
            else {
                filters = SuppressionsLoader.loadSuppressions(file);
            }
        }
    }

    @Override
    public Set<String> getExternalResourceLocations() {
        return Collections.singleton(file);
    }

}
