/*
 *  Copyright 2010 Anyware Services
 *
 *  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.ametys.web.repository.page;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.configuration.DefaultConfigurationBuilder;
import org.apache.avalon.framework.logger.AbstractLogEnabled;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.Serviceable;
import org.apache.excalibur.source.Source;
import org.apache.excalibur.source.SourceResolver;
import org.xml.sax.SAXException;

import org.ametys.web.repository.site.Site;
import org.ametys.web.repository.site.SiteType;
import org.ametys.web.repository.site.SiteTypesExtensionPoint;
import org.ametys.web.service.ServiceExtensionPoint;

/**
 * This implementation of the services handler is based on services declared in the whole application
 */
public class DefaultServicesAssignmentHandler extends AbstractLogEnabled  implements ServicesAssignmentHandler, Serviceable
{
    /** The services manager */
    protected ServiceExtensionPoint _serviceEP;
    /** The site type manager */
    protected SiteTypesExtensionPoint _siteTypeExtensionPoint;
    /** The source resolver */
    protected SourceResolver _srcResolver;
    
    private Map<String, Cache> _cache = new HashMap<>();
    
    
    @Override
    public void service(ServiceManager manager) throws ServiceException
    {
        _serviceEP = (ServiceExtensionPoint) manager.lookup(ServiceExtensionPoint.ROLE);
        _siteTypeExtensionPoint = (SiteTypesExtensionPoint) manager.lookup(SiteTypesExtensionPoint.ROLE);
        _srcResolver = (SourceResolver) manager.lookup(SourceResolver.ROLE);
    }
    
    @Override
    public Set<String> getAvailableServices(Page page, String zoneName)
    {
        Site site = page.getSite();
        SiteType siteType = _siteTypeExtensionPoint.getExtension(site.getType());
        
        Set<String> services = _getServicesForZone(siteType.getName(), site.getSkinId(), page.getTemplate(), zoneName);
        if (services != null)
        {
            services.retainAll(_getPublicServices());
            return services;
        }
        
        services = _getServicesForTemplate(siteType.getName(), site.getSkinId(), page.getTemplate());
        if (services != null)
        {
            services.retainAll(_getPublicServices());
            return services;
        }
        
        services = _getServicesForSkin(siteType.getName(), site.getSkinId());
        if (services != null)
        {
            services.retainAll(_getPublicServices());
            return services;
        }
        
        services = _getServicesForSiteType(siteType.getName());
        if (services != null)
        {
            services.retainAll(_getPublicServices());
            return services;
        }
        
        return _getPublicServices();
    }
    
    private Set<String> _getServicesForZone(String siteType, String skinName, String templateName, String zoneName)
    {
        String key = siteType + "/" + skinName + "/" + templateName + "/" + zoneName;
        String file = "context://skins/" + skinName + "/templates/" + templateName + "/conf/services-" + siteType + ".xml";

        Source configFile = null;
        try
        {
            configFile = _srcResolver.resolveURI(file);
            if (!configFile.exists())
            {
                return null;
            }

            Cache data = _cache.get(key); 
            if (data == null || !data.isValid(configFile.getLastModified()))
            {
                data = _parseZoneServices(configFile, zoneName);
                _cache.put(key, data);
            }
            return data;

        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        finally
        {
            _srcResolver.release(configFile);
        }
    }
    
    private Set<String> _getServicesForTemplate (String siteType, String skinName, String templateName)
    {
        String key = siteType + "/" + skinName + "/" + templateName;
        String file = "context://skins/" + skinName + "/templates/" + templateName + "/conf/services-" + siteType + ".xml";

        Source configFile = null;
        try
        {
            configFile = _srcResolver.resolveURI(file);
            if (!configFile.exists())
            {
                return null;
            }

            Cache data = _cache.get(key); 
            if (data == null || !data.isValid(configFile.getLastModified()))
            {
                data = _parseTemplateServices(configFile);
                _cache.put(key, data);
            }
            return data;

        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        finally
        {
            _srcResolver.release(configFile);
        }
    }
    
    private Set<String> _getServicesForSkin (String siteType, String skinName)
    {
        String key = siteType + "/" + skinName;
        String file = "context://skins/" + skinName + "/conf/services-" + siteType + ".xml";

        Source configFile = null;
        try
        {
            configFile = _srcResolver.resolveURI(file);
            if (!configFile.exists())
            {
                return null;
            }

            Cache data = _cache.get(key); 
            if (data == null || !data.isValid(configFile.getLastModified()))
            {
                data = _parseServices(configFile);
                _cache.put(key, data);
            }
            return data;

        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        finally
        {
            _srcResolver.release(configFile);
        }
    }
    
    private Set<String> _getServicesForSiteType (String siteType)
    {
        String key = siteType;
        String file = "context://WEB-INF/param/services-" + siteType + ".xml";
        
        Source configFile = null;
        try
        {
            configFile = _srcResolver.resolveURI(file);
            if (!configFile.exists())
            {
                return null;
            }

            Cache data = _cache.get(key); 
            if (data == null || !data.isValid(configFile.getLastModified()))
            {
                data = _parseServices(configFile);
                _cache.put(key, data);
            }
            return data;

        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        finally
        {
            _srcResolver.release(configFile);
        }        
    }
    
    /**
     * Get the public services.
     * @return the public services.
     */
    protected Cache _getPublicServices()
    {
        Cache publicServices = new Cache(new Date().getTime());
        
        for (String id : _serviceEP.getExtensionsIds())
        {
            if (!_serviceEP.getExtension(id).isPrivate())
            {
                publicServices.add(id);
            }
        }
        
        return publicServices;
    }
    
    /**
     * Parse a template configuration file.
     * @param configFile the template configuration file.
     * @return the set of available services for the template.
     */
    protected Cache _parseTemplateServices(Source configFile)
    {
        Cache services = null;
        
        if (!configFile.exists())
        {
            return null;
        }
        
        try (InputStream is = configFile.getInputStream())
        {
            Configuration configuration = new DefaultConfigurationBuilder().build(is);
            
            Configuration tplConf = configuration.getChild("template", false);
            if (tplConf != null)
            {
                services = _parseServices(tplConf, configFile.getLastModified());
            }
        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        catch (ConfigurationException e)
        {
            getLogger().error("Unable to parse the services configuration file", e);
            return null;
        }
        catch (SAXException e)
        {
            getLogger().error("Unable parse the services configuration file", e);
            return null;
        }
        
        return services;
    }
    
    /**
     * Parse a template configuration file and get the set of available services for a given zone.
     * @param configFile the template configuration file.
     * @param zoneName the zone name.
     * @return the set of available services for the given zone.
     */
    protected Cache _parseZoneServices(Source configFile, String zoneName)
    {
        Cache services = null;
        
        if (!configFile.exists())
        {
            return null;
        }

        try (InputStream is = configFile.getInputStream())
        {
            Configuration configuration = new DefaultConfigurationBuilder().build(is);
            
            Configuration zoneConfs = configuration.getChild("zones", false);
            if (zoneConfs != null)
            {
                for (Configuration zoneConf : zoneConfs.getChildren("zone"))
                {
                    if (zoneConf.getAttribute("id").equals(zoneName))
                    {
                        services = _parseServices(zoneConf, configFile.getLastModified());
                    }
                }
            }
        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        catch (ConfigurationException e)
        {
            getLogger().error("Unable to parse the services configuration file", e);
            return null;
        }
        catch (SAXException e)
        {
            getLogger().error("Unable parse the services configuration file", e);
            return null;
        }
        
        return services;
    }
    
    /**
     * Parses the valid services for the site type
     * @param configFile the configuration file.
     * @return the services id in a Set
     */ 
    protected Cache _parseServices (Source configFile)
    {
        if (!configFile.exists())
        {
            return null;
        }
        
        Cache services = null;
        
        try (InputStream is = configFile.getInputStream())
        {
            Configuration configuration = new DefaultConfigurationBuilder().build(is);
            
            services = _parseServices(configuration, configFile.getLastModified());
        }
        catch (IOException e)
        {
            getLogger().error("Unable to read the services configuration file", e);
            return null;
        }
        catch (ConfigurationException e)
        {
            getLogger().error("Unable to parse the services configuration file", e);
            return null;
        }
        catch (SAXException e)
        {
            getLogger().error("Unable parse the services configuration file", e);
            return null;
        }
        
        return services;
    }
    
    /**
     * Parses the valid services in a configuration.
     * @param configuration the configuration.
     * @param lastModificationDade date de dernière modification
     * @return the services id in a Set
     * @throws ConfigurationException if configuration is invalid
     */ 
    protected Cache _parseServices(Configuration configuration, long lastModificationDade) throws ConfigurationException
    {
        Cache services = new Cache(lastModificationDade);
        
        String mode = configuration.getAttribute("mode", "include");
        if ("exclude".equals(mode))
        {
            services = _getPublicServices();
            for (Configuration serviceConf : configuration.getChildren("service"))
            {
                String id = serviceConf.getAttribute("id");
                services.remove(id);
            }
        }
        else
        {
            for (Configuration serviceConf : configuration.getChildren("service"))
            {
                String id = serviceConf.getAttribute("id");
                services.add(id);
            }
        }
        
        return services;
    }
    
    /**
     * The cache is a HashSet of String + a date 
     */
    protected static class Cache extends HashSet<String>
    {
        private long _sourceLastModified;
        
        /**
         * Build the cache
         * @param sourceLastModified The last modification date
         */
        public Cache(long sourceLastModified)
        {
            super();
        }
        
        /**
         * Determine if the cache is valid
         * @param newSourceLastModified The new last modification date
         * @return true if the cache is still valid
         */
        public boolean isValid(long newSourceLastModified)
        {
            return newSourceLastModified <= _sourceLastModified;
        }
    }
}