/**
    *    Copyright 2009-2019 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.builder.annotation;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Array;
  import java.lang.reflect.GenericArrayType;
  import java.lang.reflect.Method;
  import java.lang.reflect.ParameterizedType;
  import java.lang.reflect.Type;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Properties;
  import java.util.Set;
  
  import org.apache.ibatis.annotations.Arg;
  import org.apache.ibatis.annotations.CacheNamespace;
  import org.apache.ibatis.annotations.CacheNamespaceRef;
  import org.apache.ibatis.annotations.Case;
  import org.apache.ibatis.annotations.Delete;
  import org.apache.ibatis.annotations.DeleteProvider;
  import org.apache.ibatis.annotations.Insert;
  import org.apache.ibatis.annotations.InsertProvider;
  import org.apache.ibatis.annotations.Lang;
  import org.apache.ibatis.annotations.MapKey;
  import org.apache.ibatis.annotations.Options;
  import org.apache.ibatis.annotations.Options.FlushCachePolicy;
  import org.apache.ibatis.annotations.Property;
  import org.apache.ibatis.annotations.Result;
  import org.apache.ibatis.annotations.ResultMap;
  import org.apache.ibatis.annotations.ResultType;
  import org.apache.ibatis.annotations.Results;
  import org.apache.ibatis.annotations.Select;
  import org.apache.ibatis.annotations.SelectKey;
  import org.apache.ibatis.annotations.SelectProvider;
  import org.apache.ibatis.annotations.TypeDiscriminator;
  import org.apache.ibatis.annotations.Update;
  import org.apache.ibatis.annotations.UpdateProvider;
  import org.apache.ibatis.binding.BindingException;
  import org.apache.ibatis.binding.MapperMethod.ParamMap;
  import org.apache.ibatis.builder.BuilderException;
  import org.apache.ibatis.builder.CacheRefResolver;
  import org.apache.ibatis.builder.IncompleteElementException;
  import org.apache.ibatis.builder.MapperBuilderAssistant;
  import org.apache.ibatis.builder.xml.XMLMapperBuilder;
  import org.apache.ibatis.cursor.Cursor;
  import org.apache.ibatis.executor.keygen.Jdbc3KeyGenerator;
  import org.apache.ibatis.executor.keygen.KeyGenerator;
  import org.apache.ibatis.executor.keygen.NoKeyGenerator;
  import org.apache.ibatis.executor.keygen.SelectKeyGenerator;
  import org.apache.ibatis.io.Resources;
  import org.apache.ibatis.mapping.Discriminator;
  import org.apache.ibatis.mapping.FetchType;
  import org.apache.ibatis.mapping.MappedStatement;
  import org.apache.ibatis.mapping.ResultFlag;
  import org.apache.ibatis.mapping.ResultMapping;
  import org.apache.ibatis.mapping.ResultSetType;
  import org.apache.ibatis.mapping.SqlCommandType;
  import org.apache.ibatis.mapping.SqlSource;
  import org.apache.ibatis.mapping.StatementType;
  import org.apache.ibatis.parsing.PropertyParser;
  import org.apache.ibatis.reflection.TypeParameterResolver;
  import org.apache.ibatis.scripting.LanguageDriver;
  import org.apache.ibatis.session.Configuration;
  import org.apache.ibatis.session.ResultHandler;
  import org.apache.ibatis.session.RowBounds;
  import org.apache.ibatis.type.JdbcType;
  import org.apache.ibatis.type.TypeHandler;
  import org.apache.ibatis.type.UnknownTypeHandler;
  
  /**
   * @author Clinton Begin
   * @author Kazuki Shimizu
   */
  public class MapperAnnotationBuilder {
  
    private static final Set<Class<? extends Annotation>> SQL_ANNOTATION_TYPES = new HashSet<>();
   private static final Set<Class<? extends Annotation>> SQL_PROVIDER_ANNOTATION_TYPES = new HashSet<>();
 
   private final Configuration configuration;
   private final MapperBuilderAssistant assistant;
   private final Class<?> type;
 
   static {
     SQL_ANNOTATION_TYPES.add(Select.class);
     SQL_ANNOTATION_TYPES.add(Insert.class);
     SQL_ANNOTATION_TYPES.add(Update.class);
     SQL_ANNOTATION_TYPES.add(Delete.class);
 
     SQL_PROVIDER_ANNOTATION_TYPES.add(SelectProvider.class);
     SQL_PROVIDER_ANNOTATION_TYPES.add(InsertProvider.class);
     SQL_PROVIDER_ANNOTATION_TYPES.add(UpdateProvider.class);
     SQL_PROVIDER_ANNOTATION_TYPES.add(DeleteProvider.class);
   }
 
   public MapperAnnotationBuilder(Configuration configuration, Class<?> type) {
     String resource = type.getName().replace('.', '/') + ".java (best guess)";
     this.assistant = new MapperBuilderAssistant(configuration, resource);
     this.configuration = configuration;
     this.type = type;
   }
 
   public void parse() {
     String resource = type.toString();
     if (!configuration.isResourceLoaded(resource)) {
       loadXmlResource();
       configuration.addLoadedResource(resource);
       assistant.setCurrentNamespace(type.getName());
       parseCache();
       parseCacheRef();
       Method[] methods = type.getMethods();
       for (Method method : methods) {
         try {
           // issue #237
           if (!method.isBridge()) {
             parseStatement(method);
           }
         } catch (IncompleteElementException e) {
           configuration.addIncompleteMethod(new MethodResolver(this, method));
         }
       }
     }
     parsePendingMethods();
   }
 
   private void parsePendingMethods() {
     Collection<MethodResolver> incompleteMethods = configuration.getIncompleteMethods();
     synchronized (incompleteMethods) {
       Iterator<MethodResolver> iter = incompleteMethods.iterator();
       while (iter.hasNext()) {
         try {
           iter.next().resolve();
           iter.remove();
         } catch (IncompleteElementException e) {
           // This method is still missing a resource
         }
       }
     }
   }
 
   private void loadXmlResource() {
     // Spring may not know the real resource name so we check a flag
     // to prevent loading again a resource twice
     // this flag is set at XMLMapperBuilder#bindMapperForNamespace
     if (!configuration.isResourceLoaded("namespace:" + type.getName())) {
       String xmlResource = type.getName().replace('.', '/') + ".xml";
       // #1347
       InputStream inputStream = type.getResourceAsStream("/" + xmlResource);
       if (inputStream == null) {
         // Search XML mapper that is not in the module but in the classpath.
         try {
           inputStream = Resources.getResourceAsStream(type.getClassLoader(), xmlResource);
         } catch (IOException e2) {
           // ignore, resource is not required
         }
       }
       if (inputStream != null) {
         XMLMapperBuilderrBuilder.html#XMLMapperBuilder">XMLMapperBuilder xmlParser = new XMLMapperBuilder(inputStream, assistant.getConfiguration(), xmlResource, configuration.getSqlFragments(), type.getName());
         xmlParser.parse();
       }
     }
   }
 
   private void parseCache() {
     CacheNamespace cacheDomain = type.getAnnotation(CacheNamespace.class);
     if (cacheDomain != null) {
       Integer size = cacheDomain.size() == 0 ? null : cacheDomain.size();
       Long flushInterval = cacheDomain.flushInterval() == 0 ? null : cacheDomain.flushInterval();
       Properties props = convertToProperties(cacheDomain.properties());
       assistant.useNewCache(cacheDomain.implementation(), cacheDomain.eviction(), flushInterval, size, cacheDomain.readWrite(), cacheDomain.blocking(), props);
     }
   }
 
   private Properties convertToProperties(Property[] properties) {
     if (properties.length == 0) {
       return null;
     }
     Properties props = new Properties();
     for (Property property : properties) {
       props.setProperty(property.name(),
           PropertyParser.parse(property.value(), configuration.getVariables()));
     }
     return props;
   }
 
   private void parseCacheRef() {
     CacheNamespaceRef cacheDomainRef = type.getAnnotation(CacheNamespaceRef.class);
     if (cacheDomainRef != null) {
       Class<?> refType = cacheDomainRef.value();
       String refName = cacheDomainRef.name();
       if (refType == void.class && refName.isEmpty()) {
         throw new BuilderException("Should be specified either value() or name() attribute in the @CacheNamespaceRef");
       }
       if (refType != void.class && !refName.isEmpty()) {
         throw new BuilderException("Cannot use both value() and name() attribute in the @CacheNamespaceRef");
       }
       String namespace = (refType != void.class) ? refType.getName() : refName;
       try {
         assistant.useCacheRef(namespace);
       } catch (IncompleteElementException e) {
         configuration.addIncompleteCacheRef(new CacheRefResolver(assistant, namespace));
       }
     }
   }
 
   private String parseResultMap(Method method) {
     Class<?> returnType = getReturnType(method);
     Arg[] args = method.getAnnotationsByType(Arg.class);
     Result[] results = method.getAnnotationsByType(Result.class);
     TypeDiscriminator typeDiscriminator = method.getAnnotation(TypeDiscriminator.class);
     String resultMapId = generateResultMapName(method);
     applyResultMap(resultMapId, returnType, args, results, typeDiscriminator);
     return resultMapId;
   }
 
   private String generateResultMapName(Method method) {
     Results results = method.getAnnotation(Results.class);
     if (results != null && !results.id().isEmpty()) {
       return type.getName() + "." + results.id();
     }
     StringBuilder suffix = new StringBuilder();
     for (Class<?> c : method.getParameterTypes()) {
       suffix.append("-");
       suffix.append(c.getSimpleName());
     }
     if (suffix.length() < 1) {
       suffix.append("-void");
     }
     return type.getName() + "." + method.getName() + suffix;
   }
 
   private void applyResultMap(String resultMapId, Class<?> returnType, Arg[] args, Result[] results, TypeDiscriminator discriminator) {
     List<ResultMapping> resultMappings = new ArrayList<>();
     applyConstructorArgs(args, returnType, resultMappings);
     applyResults(results, returnType, resultMappings);
     Discriminator disc = applyDiscriminator(resultMapId, returnType, discriminator);
     // TODO add AutoMappingBehaviour
     assistant.addResultMap(resultMapId, returnType, null, disc, resultMappings, null);
     createDiscriminatorResultMaps(resultMapId, returnType, discriminator);
   }
 
   private void createDiscriminatorResultMaps(String resultMapId, Class<?> resultType, TypeDiscriminator discriminator) {
     if (discriminator != null) {
       for (Case c : discriminator.cases()) {
         String caseResultMapId = resultMapId + "-" + c.value();
         List<ResultMapping> resultMappings = new ArrayList<>();
         // issue #136
         applyConstructorArgs(c.constructArgs(), resultType, resultMappings);
         applyResults(c.results(), resultType, resultMappings);
         // TODO add AutoMappingBehaviour
         assistant.addResultMap(caseResultMapId, c.type(), resultMapId, null, resultMappings, null);
       }
     }
   }
 
   private Discriminator applyDiscriminator(String resultMapId, Class<?> resultType, TypeDiscriminator discriminator) {
     if (discriminator != null) {
       String column = discriminator.column();
       Class<?> javaType = discriminator.javaType() == void.class ? String.class : discriminator.javaType();
       JdbcType jdbcType = discriminator.jdbcType() == JdbcType.UNDEFINED ? null : discriminator.jdbcType();
       @SuppressWarnings("unchecked")
       Class<? extends TypeHandler<?>> typeHandler = (Class<? extends TypeHandler<?>>)
               (discriminator.typeHandler() == UnknownTypeHandler.class ? null : discriminator.typeHandler());
       Case[] cases = discriminator.cases();
       Map<String, String> discriminatorMap = new HashMap<>();
       for (Case c : cases) {
         String value = c.value();
         String caseResultMapId = resultMapId + "-" + value;
         discriminatorMap.put(value, caseResultMapId);
       }
       return assistant.buildDiscriminator(resultType, column, javaType, jdbcType, typeHandler, discriminatorMap);
     }
     return null;
   }
 
   void parseStatement(Method method) {
     Class<?> parameterTypeClass = getParameterType(method);
     LanguageDriver languageDriver = getLanguageDriver(method);
     SqlSource sqlSource = getSqlSourceFromAnnotations(method, parameterTypeClass, languageDriver);
     if (sqlSource != null) {
       Options options = method.getAnnotation(Options.class);
       final String mappedStatementId = type.getName() + "." + method.getName();
       Integer fetchSize = null;
       Integer timeout = null;
       StatementType statementType = StatementType.PREPARED;
       ResultSetType resultSetType = configuration.getDefaultResultSetType();
       SqlCommandType sqlCommandType = getSqlCommandType(method);
       boolean isSelect = sqlCommandType == SqlCommandType.SELECT;
       boolean flushCache = !isSelect;
       boolean useCache = isSelect;
 
       KeyGenerator keyGenerator;
       String keyProperty = null;
       String keyColumn = null;
       if (SqlCommandType.INSERT.equals(sqlCommandType) || SqlCommandType.UPDATE.equals(sqlCommandType)) {
         // first check for SelectKey annotation - that overrides everything else
         SelectKey selectKey = method.getAnnotation(SelectKey.class);
         if (selectKey != null) {
           keyGenerator = handleSelectKeyAnnotation(selectKey, mappedStatementId, getParameterType(method), languageDriver);
           keyProperty = selectKey.keyProperty();
         } else if (options == null) {
           keyGenerator = configuration.isUseGeneratedKeys() ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;
         } else {
           keyGenerator = options.useGeneratedKeys() ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;
           keyProperty = options.keyProperty();
           keyColumn = options.keyColumn();
         }
       } else {
         keyGenerator = NoKeyGenerator.INSTANCE;
       }
 
       if (options != null) {
         if (FlushCachePolicy.TRUE.equals(options.flushCache())) {
           flushCache = true;
         } else if (FlushCachePolicy.FALSE.equals(options.flushCache())) {
           flushCache = false;
         }
         useCache = options.useCache();
         fetchSize = options.fetchSize() > -1 || options.fetchSize() == Integer.MIN_VALUE ? options.fetchSize() : null; //issue #348
         timeout = options.timeout() > -1 ? options.timeout() : null;
         statementType = options.statementType();
         if (options.resultSetType() != ResultSetType.DEFAULT) {
           resultSetType = options.resultSetType();
         }
       }
 
       String resultMapId = null;
       ResultMap resultMapAnnotation = method.getAnnotation(ResultMap.class);
       if (resultMapAnnotation != null) {
         resultMapId = String.join(",", resultMapAnnotation.value());
       } else if (isSelect) {
         resultMapId = parseResultMap(method);
       }
 
       assistant.addMappedStatement(
           mappedStatementId,
           sqlSource,
           statementType,
           sqlCommandType,
           fetchSize,
           timeout,
           // ParameterMapID
           null,
           parameterTypeClass,
           resultMapId,
           getReturnType(method),
           resultSetType,
           flushCache,
           useCache,
           // TODO gcode issue #577
           false,
           keyGenerator,
           keyProperty,
           keyColumn,
           // DatabaseID
           null,
           languageDriver,
           // ResultSets
           options != null ? nullOrEmpty(options.resultSets()) : null);
     }
   }
 
   private LanguageDriver getLanguageDriver(Method method) {
     Lang lang = method.getAnnotation(Lang.class);
     Class<? extends LanguageDriver> langClass = null;
     if (lang != null) {
       langClass = lang.value();
     }
     return configuration.getLanguageDriver(langClass);
   }
 
   private Class<?> getParameterType(Method method) {
     Class<?> parameterType = null;
     Class<?>[] parameterTypes = method.getParameterTypes();
     for (Class<?> currentParameterType : parameterTypes) {
       if (!RowBounds.class.isAssignableFrom(currentParameterType) && !ResultHandler.class.isAssignableFrom(currentParameterType)) {
         if (parameterType == null) {
           parameterType = currentParameterType;
         } else {
           // issue #135
           parameterType = ParamMap.class;
         }
       }
     }
     return parameterType;
   }
 
   private Class<?> getReturnType(Method method) {
     Class<?> returnType = method.getReturnType();
     Type resolvedReturnType = TypeParameterResolver.resolveReturnType(method, type);
     if (resolvedReturnType instanceof Class) {
       returnType = (Class<?>) resolvedReturnType;
       if (returnType.isArray()) {
         returnType = returnType.getComponentType();
       }
       // gcode issue #508
       if (void.class.equals(returnType)) {
         ResultType rt = method.getAnnotation(ResultType.class);
         if (rt != null) {
           returnType = rt.value();
         }
       }
     } else if (resolvedReturnType instanceof ParameterizedType) {
       ParameterizedType parameterizedType = (ParameterizedType) resolvedReturnType;
       Class<?> rawType = (Class<?>) parameterizedType.getRawType();
       if (Collection.class.isAssignableFrom(rawType) || Cursor.class.isAssignableFrom(rawType)) {
         Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
         if (actualTypeArguments != null && actualTypeArguments.length == 1) {
           Type returnTypeParameter = actualTypeArguments[0];
           if (returnTypeParameter instanceof Class<?>) {
             returnType = (Class<?>) returnTypeParameter;
           } else if (returnTypeParameter instanceof ParameterizedType) {
             // (gcode issue #443) actual type can be a also a parameterized type
             returnType = (Class<?>) ((ParameterizedType) returnTypeParameter).getRawType();
           } else if (returnTypeParameter instanceof GenericArrayType) {
             Class<?> componentType = (Class<?>) ((GenericArrayType) returnTypeParameter).getGenericComponentType();
             // (gcode issue #525) support List<byte[]>
             returnType = Array.newInstance(componentType, 0).getClass();
           }
         }
       } else if (method.isAnnotationPresent(MapKey.class) && Map.class.isAssignableFrom(rawType)) {
         // (gcode issue 504) Do not look into Maps if there is not MapKey annotation
         Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
         if (actualTypeArguments != null && actualTypeArguments.length == 2) {
           Type returnTypeParameter = actualTypeArguments[1];
           if (returnTypeParameter instanceof Class<?>) {
             returnType = (Class<?>) returnTypeParameter;
           } else if (returnTypeParameter instanceof ParameterizedType) {
             // (gcode issue 443) actual type can be a also a parameterized type
             returnType = (Class<?>) ((ParameterizedType) returnTypeParameter).getRawType();
           }
         }
       } else if (Optional.class.equals(rawType)) {
         Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
         Type returnTypeParameter = actualTypeArguments[0];
         if (returnTypeParameter instanceof Class<?>) {
           returnType = (Class<?>) returnTypeParameter;
         }
       }
     }
 
     return returnType;
   }
 
   private SqlSource getSqlSourceFromAnnotations(Method method, Class<?> parameterType, LanguageDriver languageDriver) {
     try {
       Class<? extends Annotation> sqlAnnotationType = getSqlAnnotationType(method);
       Class<? extends Annotation> sqlProviderAnnotationType = getSqlProviderAnnotationType(method);
       if (sqlAnnotationType != null) {
         if (sqlProviderAnnotationType != null) {
           throw new BindingException("You cannot supply both a static SQL and SqlProvider to method named " + method.getName());
         }
         Annotation sqlAnnotation = method.getAnnotation(sqlAnnotationType);
         final String[] strings = (String[]) sqlAnnotation.getClass().getMethod("value").invoke(sqlAnnotation);
         return buildSqlSourceFromStrings(strings, parameterType, languageDriver);
       } else if (sqlProviderAnnotationType != null) {
         Annotation sqlProviderAnnotation = method.getAnnotation(sqlProviderAnnotationType);
         return new ProviderSqlSource(assistant.getConfiguration(), sqlProviderAnnotation, type, method);
       }
       return null;
     } catch (Exception e) {
       throw new BuilderException("Could not find value method on SQL annotation.  Cause: " + e, e);
     }
   }
 
   private SqlSource buildSqlSourceFromStrings(String[] strings, Class<?> parameterTypeClass, LanguageDriver languageDriver) {
     final StringBuilder sql = new StringBuilder();
     for (String fragment : strings) {
       sql.append(fragment);
       sql.append(" ");
     }
     return languageDriver.createSqlSource(configuration, sql.toString().trim(), parameterTypeClass);
   }
 
   private SqlCommandType getSqlCommandType(Method method) {
     Class<? extends Annotation> type = getSqlAnnotationType(method);
 
     if (type == null) {
       type = getSqlProviderAnnotationType(method);
 
       if (type == null) {
         return SqlCommandType.UNKNOWN;
       }
 
       if (type == SelectProvider.class) {
         type = Select.class;
       } else if (type == InsertProvider.class) {
         type = Insert.class;
       } else if (type == UpdateProvider.class) {
         type = Update.class;
       } else if (type == DeleteProvider.class) {
         type = Delete.class;
       }
     }
 
     return SqlCommandType.valueOf(type.getSimpleName().toUpperCase(Locale.ENGLISH));
   }
 
   private Class<? extends Annotation> getSqlAnnotationType(Method method) {
     return chooseAnnotationType(method, SQL_ANNOTATION_TYPES);
   }
 
   private Class<? extends Annotation> getSqlProviderAnnotationType(Method method) {
     return chooseAnnotationType(method, SQL_PROVIDER_ANNOTATION_TYPES);
   }
 
   private Class<? extends Annotation> chooseAnnotationType(Method method, Set<Class<? extends Annotation>> types) {
     for (Class<? extends Annotation> type : types) {
       Annotation annotation = method.getAnnotation(type);
       if (annotation != null) {
         return type;
       }
     }
     return null;
   }
 
   private void applyResults(Result[] results, Class<?> resultType, List<ResultMapping> resultMappings) {
     for (Result result : results) {
       List<ResultFlag> flags = new ArrayList<>();
       if (result.id()) {
         flags.add(ResultFlag.ID);
       }
       @SuppressWarnings("unchecked")
       Class<? extends TypeHandler<?>> typeHandler = (Class<? extends TypeHandler<?>>)
               ((result.typeHandler() == UnknownTypeHandler.class) ? null : result.typeHandler());
       ResultMapping resultMapping = assistant.buildResultMapping(
           resultType,
           nullOrEmpty(result.property()),
           nullOrEmpty(result.column()),
           result.javaType() == void.class ? null : result.javaType(),
           result.jdbcType() == JdbcType.UNDEFINED ? null : result.jdbcType(),
           hasNestedSelect(result) ? nestedSelectId(result) : null,
           null,
           null,
           null,
           typeHandler,
           flags,
           null,
           null,
           isLazy(result));
       resultMappings.add(resultMapping);
     }
   }
 
   private String nestedSelectId(Result result) {
     String nestedSelect = result.one().select();
     if (nestedSelect.length() < 1) {
       nestedSelect = result.many().select();
     }
     if (!nestedSelect.contains(".")) {
       nestedSelect = type.getName() + "." + nestedSelect;
     }
     return nestedSelect;
   }
 
   private boolean isLazy(Result result) {
     boolean isLazy = configuration.isLazyLoadingEnabled();
     if (result.one().select().length() > 0 && FetchType.DEFAULT != result.one().fetchType()) {
       isLazy = result.one().fetchType() == FetchType.LAZY;
     } else if (result.many().select().length() > 0 && FetchType.DEFAULT != result.many().fetchType()) {
       isLazy = result.many().fetchType() == FetchType.LAZY;
     }
     return isLazy;
   }
 
   private boolean hasNestedSelect(Result result) {
     if (result.one().select().length() > 0 && result.many().select().length() > 0) {
       throw new BuilderException("Cannot use both @One and @Many annotations in the same @Result");
     }
     return result.one().select().length() > 0 || result.many().select().length() > 0;
   }
 
   private void applyConstructorArgs(Arg[] args, Class<?> resultType, List<ResultMapping> resultMappings) {
     for (Arg arg : args) {
       List<ResultFlag> flags = new ArrayList<>();
       flags.add(ResultFlag.CONSTRUCTOR);
       if (arg.id()) {
         flags.add(ResultFlag.ID);
       }
       @SuppressWarnings("unchecked")
       Class<? extends TypeHandler<?>> typeHandler = (Class<? extends TypeHandler<?>>)
               (arg.typeHandler() == UnknownTypeHandler.class ? null : arg.typeHandler());
       ResultMapping resultMapping = assistant.buildResultMapping(
           resultType,
           nullOrEmpty(arg.name()),
           nullOrEmpty(arg.column()),
           arg.javaType() == void.class ? null : arg.javaType(),
           arg.jdbcType() == JdbcType.UNDEFINED ? null : arg.jdbcType(),
           nullOrEmpty(arg.select()),
           nullOrEmpty(arg.resultMap()),
           null,
           nullOrEmpty(arg.columnPrefix()),
           typeHandler,
           flags,
           null,
           null,
           false);
       resultMappings.add(resultMapping);
     }
   }
 
   private String nullOrEmpty(String value) {
     return value == null || value.trim().length() == 0 ? null : value;
   }
 
   private KeyGenerator handleSelectKeyAnnotation(SelectKey selectKeyAnnotation, String baseStatementId, Class<?> parameterTypeClass, LanguageDriver languageDriver) {
     String id = baseStatementId + SelectKeyGenerator.SELECT_KEY_SUFFIX;
     Class<?> resultTypeClass = selectKeyAnnotation.resultType();
     StatementType statementType = selectKeyAnnotation.statementType();
     String keyProperty = selectKeyAnnotation.keyProperty();
     String keyColumn = selectKeyAnnotation.keyColumn();
     boolean executeBefore = selectKeyAnnotation.before();
 
     // defaults
     boolean useCache = false;
     KeyGenerator keyGenerator = NoKeyGenerator.INSTANCE;
     Integer fetchSize = null;
     Integer timeout = null;
     boolean flushCache = false;
     String parameterMap = null;
     String resultMap = null;
     ResultSetType resultSetTypeEnum = null;
 
     SqlSource sqlSource = buildSqlSourceFromStrings(selectKeyAnnotation.statement(), parameterTypeClass, languageDriver);
     SqlCommandType sqlCommandType = SqlCommandType.SELECT;
 
     assistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType, fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass, resultSetTypeEnum,
         flushCache, useCache, false,
         keyGenerator, keyProperty, keyColumn, null, languageDriver, null);
 
     id = assistant.applyCurrentNamespace(id, false);
 
     MappedStatement keyStatement = configuration.getMappedStatement(id, false);
     SelectKeyGeneratorectKeyGenerator.html#SelectKeyGenerator">SelectKeyGenerator answer = new SelectKeyGenerator(keyStatement, executeBefore);
     configuration.addKeyGenerator(id, answer);
     return answer;
   }
 
 }