/*
    *    Copyright 2009-2021 the original author or authors.
    *
    *    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.apache.ibatis.executor.loader;
  
  import java.io.Serializable;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.security.AccessController;
  import java.security.PrivilegedActionException;
  import java.security.PrivilegedExceptionAction;
  import java.sql.SQLException;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.ibatis.cursor.Cursor;
  import org.apache.ibatis.executor.BaseExecutor;
  import org.apache.ibatis.executor.BatchResult;
  import org.apache.ibatis.executor.ExecutorException;
  import org.apache.ibatis.logging.Log;
  import org.apache.ibatis.logging.LogFactory;
  import org.apache.ibatis.mapping.BoundSql;
  import org.apache.ibatis.mapping.MappedStatement;
  import org.apache.ibatis.reflection.MetaObject;
  import org.apache.ibatis.session.Configuration;
  import org.apache.ibatis.session.ResultHandler;
  import org.apache.ibatis.session.RowBounds;
  
  /**
   * @author Clinton Begin
   * @author Franta Mejta
   */
  public class ResultLoaderMap {
  
    private final Map<String, LoadPair> loaderMap = new HashMap<>();
  
    public void addLoader(String property, MetaObject metaResultObject, ResultLoader resultLoader) {
      String upperFirst = getUppercaseFirstProperty(property);
      if (!upperFirst.equalsIgnoreCase(property) && loaderMap.containsKey(upperFirst)) {
        throw new ExecutorException("Nested lazy loaded result property '" + property
                + "' for query id '" + resultLoader.mappedStatement.getId()
                + " already exists in the result map. The leftmost property of all lazy loaded properties must be unique within a result map.");
      }
      loaderMap.put(upperFirst, new LoadPair(property, metaResultObject, resultLoader));
    }
  
    public final Map<String, LoadPair> getProperties() {
      return new HashMap<>(this.loaderMap);
    }
  
    public Set<String> getPropertyNames() {
      return loaderMap.keySet();
    }
  
    public int size() {
      return loaderMap.size();
    }
  
    public boolean hasLoader(String property) {
      return loaderMap.containsKey(property.toUpperCase(Locale.ENGLISH));
    }
  
    public boolean load(String property) throws SQLException {
      LoadPair pair = loaderMap.remove(property.toUpperCase(Locale.ENGLISH));
      if (pair != null) {
        pair.load();
        return true;
      }
      return false;
    }
  
    public void remove(String property) {
      loaderMap.remove(property.toUpperCase(Locale.ENGLISH));
    }
  
    public void loadAll() throws SQLException {
      final Set<String> methodNameSet = loaderMap.keySet();
      String[] methodNames = methodNameSet.toArray(new String[methodNameSet.size()]);
      for (String methodName : methodNames) {
        load(methodName);
      }
    }
  
    private static String getUppercaseFirstProperty(String property) {
     String[] parts = property.split("\\.");
     return parts[0].toUpperCase(Locale.ENGLISH);
   }
 
   /**
    * Property which was not loaded yet.
    */
   public static class LoadPair implements Serializable {
 
     private static final long serialVersionUID = 20130412;
     /**
      * Name of factory method which returns database connection.
      */
     private static final String FACTORY_METHOD = "getConfiguration";
     /**
      * Object to check whether we went through serialization..
      */
     private final transient Object serializationCheck = new Object();
     /**
      * Meta object which sets loaded properties.
      */
     private transient MetaObject metaResultObject;
     /**
      * Result loader which loads unread properties.
      */
     private transient ResultLoader resultLoader;
     /**
      * Wow, logger.
      */
     private transient Log log;
     /**
      * Factory class through which we get database connection.
      */
     private Class<?> configurationFactory;
     /**
      * Name of the unread property.
      */
     private String property;
     /**
      * ID of SQL statement which loads the property.
      */
     private String mappedStatement;
     /**
      * Parameter of the sql statement.
      */
     private Serializable mappedParameter;
 
     private LoadPair(final String property, MetaObject metaResultObject, ResultLoader resultLoader) {
       this.property = property;
       this.metaResultObject = metaResultObject;
       this.resultLoader = resultLoader;
 
       /* Save required information only if original object can be serialized. */
       if (metaResultObject != null && metaResultObject.getOriginalObject() instanceof Serializable) {
         final Object mappedStatementParameter = resultLoader.parameterObject;
 
         /* @todo May the parameter be null? */
         if (mappedStatementParameter instanceof Serializable) {
           this.mappedStatement = resultLoader.mappedStatement.getId();
           this.mappedParameter = (Serializable) mappedStatementParameter;
 
           this.configurationFactory = resultLoader.configuration.getConfigurationFactory();
         } else {
           Log log = this.getLogger();
           if (log.isDebugEnabled()) {
             log.debug("Property [" + this.property + "] of ["
                     + metaResultObject.getOriginalObject().getClass() + "] cannot be loaded "
                     + "after deserialization. Make sure it's loaded before serializing "
                     + "forenamed object.");
           }
         }
       }
     }
 
     public void load() throws SQLException {
       /* These field should not be null unless the loadpair was serialized.
        * Yet in that case this method should not be called. */
       if (this.metaResultObject == null) {
         throw new IllegalArgumentException("metaResultObject is null");
       }
       if (this.resultLoader == null) {
         throw new IllegalArgumentException("resultLoader is null");
       }
 
       this.load(null);
     }
 
     public void load(final Object userObject) throws SQLException {
       if (this.metaResultObject == null || this.resultLoader == null) {
         if (this.mappedParameter == null) {
           throw new ExecutorException("Property [" + this.property + "] cannot be loaded because "
                   + "required parameter of mapped statement ["
                   + this.mappedStatement + "] is not serializable.");
         }
 
         final Configuration config = this.getConfiguration();
         final MappedStatement ms = config.getMappedStatement(this.mappedStatement);
         if (ms == null) {
           throw new ExecutorException("Cannot lazy load property [" + this.property
                   + "] of deserialized object [" + userObject.getClass()
                   + "] because configuration does not contain statement ["
                   + this.mappedStatement + "]");
         }
 
         this.metaResultObject = config.newMetaObject(userObject);
         this.resultLoader = new ResultLoader(config, new ClosedExecutor(), ms, this.mappedParameter,
                 metaResultObject.getSetterType(this.property), null, null);
       }
 
       /* We are using a new executor because we may be (and likely are) on a new thread
        * and executors aren't thread safe. (Is this sufficient?)
        *
        * A better approach would be making executors thread safe. */
       if (this.serializationCheck == null) {
         final ResultLoader old = this.resultLoader;
         this.resultLoader = new ResultLoader(old.configuration, new ClosedExecutor(), old.mappedStatement,
                 old.parameterObject, old.targetType, old.cacheKey, old.boundSql);
       }
 
       this.metaResultObject.setValue(property, this.resultLoader.loadResult());
     }
 
     private Configuration getConfiguration() {
       if (this.configurationFactory == null) {
         throw new ExecutorException("Cannot get Configuration as configuration factory was not set.");
       }
 
       Object configurationObject;
       try {
         final Method factoryMethod = this.configurationFactory.getDeclaredMethod(FACTORY_METHOD);
         if (!Modifier.isStatic(factoryMethod.getModifiers())) {
           throw new ExecutorException("Cannot get Configuration as factory method ["
                   + this.configurationFactory + "]#["
                   + FACTORY_METHOD + "] is not static.");
         }
 
         if (!factoryMethod.isAccessible()) {
           configurationObject = AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () -> {
             try {
               factoryMethod.setAccessible(true);
               return factoryMethod.invoke(null);
             } finally {
               factoryMethod.setAccessible(false);
             }
           });
         } else {
           configurationObject = factoryMethod.invoke(null);
         }
       } catch (final ExecutorException ex) {
         throw ex;
       } catch (final NoSuchMethodException ex) {
         throw new ExecutorException("Cannot get Configuration as factory class ["
                 + this.configurationFactory + "] is missing factory method of name ["
                 + FACTORY_METHOD + "].", ex);
       } catch (final PrivilegedActionException ex) {
         throw new ExecutorException("Cannot get Configuration as factory method ["
                 + this.configurationFactory + "]#["
                 + FACTORY_METHOD + "] threw an exception.", ex.getCause());
       } catch (final Exception ex) {
         throw new ExecutorException("Cannot get Configuration as factory method ["
                 + this.configurationFactory + "]#["
                 + FACTORY_METHOD + "] threw an exception.", ex);
       }
 
       if (!(configurationObject instanceof Configuration)) {
         throw new ExecutorException("Cannot get Configuration as factory method ["
                 + this.configurationFactory + "]#["
                 + FACTORY_METHOD + "] didn't return [" + Configuration.class + "] but ["
                 + (configurationObject == null ? "null" : configurationObject.getClass()) + "].");
       }
 
       return Configuration.class.cast(configurationObject);
     }
 
     private Log getLogger() {
       if (this.log == null) {
         this.log = LogFactory.getLog(this.getClass());
       }
       return this.log;
     }
   }
 
   private static final class ClosedExecutor extends BaseExecutor {
 
     public ClosedExecutor() {
       super(null, null);
     }
 
     @Override
     public boolean isClosed() {
       return true;
     }
 
     @Override
     protected int doUpdate(MappedStatement ms, Object parameter) throws SQLException {
       throw new UnsupportedOperationException("Not supported.");
     }
 
     @Override
     protected List<BatchResult> doFlushStatements(boolean isRollback) throws SQLException {
       throw new UnsupportedOperationException("Not supported.");
     }
 
     @Override
     protected <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
       throw new UnsupportedOperationException("Not supported.");
     }
 
     @Override
     protected <E> Cursor<E> doQueryCursor(MappedStatement ms, Object parameter, RowBounds rowBounds, BoundSql boundSql) throws SQLException {
       throw new UnsupportedOperationException("Not supported.");
     }
   }
 }