/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.acegisecurity.intercept.web;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.beans.PropertyEditorSupport;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;


/**
 * Property editor to assist with the setup of a {@link FilterInvocationDefinitionSource}.<p>The class creates and
 * populates a {@link RegExpBasedFilterInvocationDefinitionMap} or {@link PathBasedFilterInvocationDefinitionMap}
 * (depending on the type of patterns presented).</p>
 *  <p>By default the class treats presented patterns as regular expressions. If the keyword
 * <code>PATTERN_TYPE_APACHE_ANT</code> is present (case sensitive), patterns will be treated as Apache Ant paths
 * rather than regular expressions.</p>
 *
 * @author Ben Alex
 * @version $Id$
 */
public class FilterInvocationDefinitionSourceEditor extends PropertyEditorSupport {
    //~ Static fields/initializers =====================================================================================

    private static final Log logger = LogFactory.getLog(FilterInvocationDefinitionSourceEditor.class);
    public static final String DIRECTIVE_CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON = "CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON";
    public static final String DIRECTIVE_PATTERN_TYPE_APACHE_ANT = "PATTERN_TYPE_APACHE_ANT";

    //~ Methods ========================================================================================================

    public void setAsText(String s) throws IllegalArgumentException {
        FilterInvocationDefinitionDecorator source = new FilterInvocationDefinitionDecorator();
        source.setDecorated(new RegExpBasedFilterInvocationDefinitionMap());

        if ((s == null) || "".equals(s)) {
            // Leave target object empty
        } else {
            // Check if we need to override the default definition map
            if (s.lastIndexOf(DIRECTIVE_PATTERN_TYPE_APACHE_ANT) != -1) {
                source.setDecorated(new PathBasedFilterInvocationDefinitionMap());

                if (logger.isDebugEnabled()) {
                    logger.debug(("Detected " + DIRECTIVE_PATTERN_TYPE_APACHE_ANT
                        + " directive; using Apache Ant style path expressions"));
                }
            }

            if (s.lastIndexOf(DIRECTIVE_CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON) != -1) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Detected " + DIRECTIVE_CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON
                        + " directive; Instructing mapper to convert URLs to lowercase before comparison");
                }

                source.setConvertUrlToLowercaseBeforeComparison(true);
            }

            BufferedReader br = new BufferedReader(new StringReader(s));
            int counter = 0;
            String line;
            
            List mappings = new ArrayList();

            while (true) {
                counter++;

                try {
                    line = br.readLine();
                } catch (IOException ioe) {
                    throw new IllegalArgumentException(ioe.getMessage());
                }

                if (line == null) {
                    break;
                }

                line = line.trim();

                if (logger.isDebugEnabled()) {
                    logger.debug("Line " + counter + ": " + line);
                }

                if (line.startsWith("//")) {
                    continue;
                }

                // Attempt to detect malformed lines (as per SEC-204)
                if (line.lastIndexOf(DIRECTIVE_CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON) != -1) {
                    // Directive found; check for second directive or name=value
                    if ((line.lastIndexOf(DIRECTIVE_PATTERN_TYPE_APACHE_ANT) != -1) || (line.lastIndexOf("=") != -1)) {
                        throw new IllegalArgumentException("Line appears to be malformed: " + line);
                    }
                }

                // Attempt to detect malformed lines (as per SEC-204)
                if (line.lastIndexOf(DIRECTIVE_PATTERN_TYPE_APACHE_ANT) != -1) {
                    // Directive found; check for second directive or name=value
                    if ((line.lastIndexOf(DIRECTIVE_CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON) != -1)
                        || (line.lastIndexOf("=") != -1)) {
                        throw new IllegalArgumentException("Line appears to be malformed: " + line);
                    }
                }

                // Skip lines that are not directives
                if (line.lastIndexOf('=') == -1) {
                    continue;
                }

                if (line.lastIndexOf("==") != -1) {
                    throw new IllegalArgumentException("Only single equals should be used in line " + line);
                }

                // Tokenize the line into its name/value tokens
                // As per SEC-219, use the LAST equals as the delimiter between LHS and RHS
                String name = StringUtils.substringBeforeLast(line, "=");
                String value = StringUtils.substringAfterLast(line, "=");

                if (StringUtils.isBlank(name) || StringUtils.isBlank(value)) {
                    throw new IllegalArgumentException("Failed to parse a valid name/value pair from " + line);
                }

                // Attempt to detect malformed lines (as per SEC-204)
                if (source.isConvertUrlToLowercaseBeforeComparison()
                    && source.getDecorated() instanceof PathBasedFilterInvocationDefinitionMap) {
                    // Should all be lowercase; check each character
                    // We only do this for Ant (regexp have control chars)
                    for (int i = 0; i < name.length(); i++) {
                        String character = name.substring(i, i + 1);

                        if (!character.toLowerCase().equals(character)) {
                            throw new IllegalArgumentException("You are using the "
                                + DIRECTIVE_CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON
                                + " with Ant Paths, yet you have specified an uppercase character in line: " + line
                                + " (character '" + character + "')");
                        }
                    }
                }

                FilterInvocationDefinitionSourceMapping mapping = new FilterInvocationDefinitionSourceMapping();
                mapping.setUrl(name);

                String[] tokens = org.springframework.util.StringUtils
                        .commaDelimitedListToStringArray(value);

                for (int i = 0; i < tokens.length; i++) {
                    mapping.addConfigAttribute(tokens[i].trim());
                }

                mappings.add(mapping);
            }
            source.setMappings(mappings);
        }

        setValue(source.getDecorated());
    }
}
