/*
 * Copyright 2012 JBoss Inc
 *
 * 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.uberfire.security.server;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.uberfire.security.Resource;
import org.uberfire.security.ResourceManager;
import org.uberfire.security.Role;
import org.uberfire.security.impl.RoleImpl;
// BUG: CWE-264 Permissions, Privileges, and Access Controls
// import org.uberfire.security.server.util.AntPathMatcher;
// FIXED:
import org.uberfire.commons.regex.util.AntPathMatcher;
import org.yaml.snakeyaml.Yaml;

import static java.util.Collections.*;
import static org.uberfire.commons.validation.PortablePreconditions.checkNotNull;
import static org.uberfire.commons.validation.Preconditions.*;
import static org.uberfire.security.server.SecurityConstants.*;

public class URLResourceManager implements ResourceManager {

    private static final AntPathMatcher ANT_PATH_MATCHER = new AntPathMatcher();
    private static final Collection<Class<? extends Resource>> SUPPORTED_TYPES = new ArrayList<Class<? extends Resource>>( 1 ) {{
        add( URLResource.class );
    }};

    private static final String DEFAULT_CONFIG = "exclude:\n" +
            "   - /*.ico\n" +
            "   - /image/**\n" +
            "   - /css/**";

    private String configFile = URL_FILTER_CONFIG_YAML;

    private final Resources resources;
    private final Set<String> excludeCache = Collections.newSetFromMap( new ConcurrentHashMap<String, Boolean>() );

    public URLResourceManager( final String configFile ) {
        if ( configFile != null && !configFile.isEmpty() ) {
            this.configFile = configFile;
        }
        this.resources = loadConfigData();
    }

    private Resources loadConfigData() {
        final Yaml yaml = new Yaml();
        final InputStream stream = URLResourceManager.class.getClassLoader().getResourceAsStream( this.configFile );
        final Map result;
        if ( stream != null ) {
            result = (Map) yaml.load( stream );
        } else {
            result = (Map) yaml.load( DEFAULT_CONFIG );
        }
        return new Resources( result );
    }

    @Override
    public boolean supports( final Resource resource ) {
        if ( resource instanceof URLResource ) {
            return true;
        }
        return false;
    }

    @Override
    public boolean requiresAuthentication( final Resource resource ) {
        final URLResource urlResource;
        try {
            urlResource = checkInstanceOf( "context", resource, URLResource.class );
        } catch ( IllegalArgumentException e ) {
            return false;
        }

        if ( !excludeCache.contains( urlResource.getURL() ) ) {
            boolean isExcluded = false;
            for ( String excluded : resources.getExcludedResources() ) {
                if ( ANT_PATH_MATCHER.match( excluded, urlResource.getURL() ) ) {
                    isExcluded = true;
                    excludeCache.add( urlResource.getURL() );
                    break;
                }
            }
            if ( isExcluded ) {
                return false;
            }
        } else {
            return false;
        }

        return true;
    }

    public List<Role> getMandatoryRoles( final URLResource urlResource ) {
        for ( Map.Entry<String, List<Role>> activeFilteredResource : resources.getMandatoryFilteredResources().entrySet() ) {
            if ( ANT_PATH_MATCHER.match( activeFilteredResource.getKey(), urlResource.getURL() ) ) {
                return activeFilteredResource.getValue();
            }
        }
        return emptyList();
    }

    private static class Resources {

        private final Map<String, List<Role>> filteredResources;
        private final Map<String, List<Role>> mandatoryFilteredResources;
        private final Set<String> excludedResources;

        private Resources( final Map yaml ) {
            checkNotNull( "yaml", yaml );

            final Object ofilter = yaml.get( "filter" );
            if ( ofilter != null ) {
                final List<Map<String, String>> filter = checkInstanceOf( "ofilter", ofilter, List.class );

                this.filteredResources = new HashMap<String, List<Role>>( filter.size() );
                this.mandatoryFilteredResources = new HashMap<String, List<Role>>( filter.size() );
                for ( final Map<String, String> activeFilter : filter ) {
                    final String pattern = activeFilter.get( "pattern" );
                    final String access = activeFilter.get( "access" );
                    checkNotNull( "pattern", pattern );
                    final List<Role> roles;
                    if ( access != null ) {
                        final String[] textRoles = access.split( "," );
                        roles = new ArrayList<Role>( textRoles.length );
                        for ( final String textRole : textRoles ) {
                            roles.add( new RoleImpl( textRole ) );
                        }
                        mandatoryFilteredResources.put( pattern, roles );
                    } else {
                        roles = emptyList();
                    }
                    filteredResources.put( pattern, roles );
                }
            } else {
                this.filteredResources = emptyMap();
                this.mandatoryFilteredResources = emptyMap();
            }

            final Object oexclude = yaml.get( "exclude" );
            final List exclude = checkInstanceOf( "exclude", oexclude, List.class );

            this.excludedResources = new HashSet<String>( exclude );
        }

        public Map<String, List<Role>> getFilteredResources() {
            return filteredResources;
        }

        public Set<String> getExcludedResources() {
            return excludedResources;
        }

        public Map<String, List<Role>> getMandatoryFilteredResources() {
            return mandatoryFilteredResources;
        }
    }
}