/*
 *    Copyright 2009-2013 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.xml;

import java.io.InputStream;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import org.apache.ibatis.builder.BaseBuilder;
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.ResultMapResolver;
import org.apache.ibatis.cache.Cache;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.mapping.Discriminator;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.mapping.ResultFlag;
import org.apache.ibatis.mapping.ResultMap;
import org.apache.ibatis.mapping.ResultMapping;
import org.apache.ibatis.parsing.XNode;
import org.apache.ibatis.parsing.XPathParser;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;

/**
 * @author Clinton Begin
 * @description 增加解析方法，原方法不解析相同的resource
 */
public class XMLMapperBuilder extends BaseBuilder {

	private XPathParser parser;
	private MapperBuilderAssistant builderAssistant;
	private Map<String, XNode> sqlFragments;
	private String resource;

	@Deprecated
	public XMLMapperBuilder(Reader reader, Configuration configuration,
			String resource, Map<String, XNode> sqlFragments, String namespace) {
		this(reader, configuration, resource, sqlFragments);
		this.builderAssistant.setCurrentNamespace(namespace);
	}

	@Deprecated
	public XMLMapperBuilder(Reader reader, Configuration configuration,
			String resource, Map<String, XNode> sqlFragments) {
		this(new XPathParser(reader, true, configuration.getVariables(),
				new XMLMapperEntityResolver()), configuration, resource,
				sqlFragments);
	}

	public XMLMapperBuilder(InputStream inputStream,
			Configuration configuration, String resource,
			Map<String, XNode> sqlFragments, String namespace) {
		this(inputStream, configuration, resource, sqlFragments);
		this.builderAssistant.setCurrentNamespace(namespace);
	}

	public XMLMapperBuilder(InputStream inputStream,
			Configuration configuration, String resource,
			Map<String, XNode> sqlFragments) {
		this(new XPathParser(inputStream, true, configuration.getVariables(),
				new XMLMapperEntityResolver()), configuration, resource,
				sqlFragments);
	}

	private XMLMapperBuilder(XPathParser parser, Configuration configuration,
			String resource, Map<String, XNode> sqlFragments) {
		super(configuration);
		this.builderAssistant = new MapperBuilderAssistant(configuration,
				resource);
		this.parser = parser;
		this.sqlFragments = sqlFragments;
		this.resource = resource;
	}

	public void parse() {
		if (!configuration.isResourceLoaded(resource)) {
			configurationElement(parser.evalNode("/mapper"));
			configuration.addLoadedResource(resource);
			bindMapperForNamespace();
		}

		parsePendingResultMaps();
		parsePendingChacheRefs();
		parsePendingStatements();
	}

	// TODO 增加解析方法，原方法不解析相同的resource
	public void parse1() {
		// if (!configuration.isResourceLoaded(resource)) {
		configurationElement(parser.evalNode("/mapper"));
		configuration.addLoadedResource(resource);
		bindMapperForNamespace();
		// }

		parsePendingResultMaps();
		parsePendingChacheRefs();
		parsePendingStatements();
	}

	public XNode getSqlFragment(String refid) {
		return sqlFragments.get(refid);
	}

	private void configurationElement(XNode context) {
		try {
			String namespace = context.getStringAttribute("namespace");
			if (namespace.equals("")) {
				throw new BuilderException("Mapper's namespace cannot be empty");
			}
			builderAssistant.setCurrentNamespace(namespace);
			cacheRefElement(context.evalNode("cache-ref"));
			cacheElement(context.evalNode("cache"));
			parameterMapElement(context.evalNodes("/mapper/parameterMap"));
			resultMapElements(context.evalNodes("/mapper/resultMap"));
			sqlElement(context.evalNodes("/mapper/sql"));
			buildStatementFromContext(context
					.evalNodes("select|insert|update|delete"));
		} catch (Exception e) {
			throw new BuilderException("Error parsing Mapper XML. Cause: " + e,
					e);
		}
	}

	private void buildStatementFromContext(List<XNode> list) {
		if (configuration.getDatabaseId() != null) {
			buildStatementFromContext(list, configuration.getDatabaseId());
		}
		buildStatementFromContext(list, null);
	}

	private void buildStatementFromContext(List<XNode> list,
			String requiredDatabaseId) {
		for (XNode context : list) {
			final XMLStatementBuilder statementParser = new XMLStatementBuilder(
					configuration, builderAssistant, context,
					requiredDatabaseId);
			try {
				statementParser.parseStatementNode();
			} catch (IncompleteElementException e) {
				configuration.addIncompleteStatement(statementParser);
			}
		}
	}

	private void parsePendingResultMaps() {
		Collection<ResultMapResolver> incompleteResultMaps = configuration
				.getIncompleteResultMaps();
		synchronized (incompleteResultMaps) {
			Iterator<ResultMapResolver> iter = incompleteResultMaps.iterator();
			while (iter.hasNext()) {
				try {
					iter.next().resolve();
					iter.remove();
				} catch (IncompleteElementException e) {
					// ResultMap is still missing a resource...
				}
			}
		}
	}

	private void parsePendingChacheRefs() {
		Collection<CacheRefResolver> incompleteCacheRefs = configuration
				.getIncompleteCacheRefs();
		synchronized (incompleteCacheRefs) {
			Iterator<CacheRefResolver> iter = incompleteCacheRefs.iterator();
			while (iter.hasNext()) {
				try {
					iter.next().resolveCacheRef();
					iter.remove();
				} catch (IncompleteElementException e) {
					// Cache ref is still missing a resource...
				}
			}
		}
	}

	private void parsePendingStatements() {
		Collection<XMLStatementBuilder> incompleteStatements = configuration
				.getIncompleteStatements();
		synchronized (incompleteStatements) {
			Iterator<XMLStatementBuilder> iter = incompleteStatements
					.iterator();
			while (iter.hasNext()) {
				try {
					iter.next().parseStatementNode();
					iter.remove();
				} catch (IncompleteElementException e) {
					// Statement is still missing a resource...
				}
			}
		}
	}

	private void cacheRefElement(XNode context) {
		if (context != null) {
			configuration.addCacheRef(builderAssistant.getCurrentNamespace(),
					context.getStringAttribute("namespace"));
			CacheRefResolver cacheRefResolver = new CacheRefResolver(
					builderAssistant, context.getStringAttribute("namespace"));
			try {
				cacheRefResolver.resolveCacheRef();
			} catch (IncompleteElementException e) {
				configuration.addIncompleteCacheRef(cacheRefResolver);
			}
		}
	}

	private void cacheElement(XNode context) throws Exception {
		if (context != null) {
			String type = context.getStringAttribute("type", "PERPETUAL");
			Class<? extends Cache> typeClass = typeAliasRegistry
					.resolveAlias(type);
			String eviction = context.getStringAttribute("eviction", "LRU");
			Class<? extends Cache> evictionClass = typeAliasRegistry
					.resolveAlias(eviction);
			Long flushInterval = context.getLongAttribute("flushInterval");
			Integer size = context.getIntAttribute("size");
			boolean readWrite = !context.getBooleanAttribute("readOnly", false);
			Properties props = context.getChildrenAsProperties();
			builderAssistant.useNewCache(typeClass, evictionClass,
					flushInterval, size, readWrite, props);
		}
	}

	private void parameterMapElement(List<XNode> list) throws Exception {
		for (XNode parameterMapNode : list) {
			String id = parameterMapNode.getStringAttribute("id");
			String type = parameterMapNode.getStringAttribute("type");
			Class<?> parameterClass = resolveClass(type);
			List<XNode> parameterNodes = parameterMapNode
					.evalNodes("parameter");
			List<ParameterMapping> parameterMappings = new ArrayList<ParameterMapping>();
			for (XNode parameterNode : parameterNodes) {
				String property = parameterNode.getStringAttribute("property");
				String javaType = parameterNode.getStringAttribute("javaType");
				String jdbcType = parameterNode.getStringAttribute("jdbcType");
				String resultMap = parameterNode
						.getStringAttribute("resultMap");
				String mode = parameterNode.getStringAttribute("mode");
				String typeHandler = parameterNode
						.getStringAttribute("typeHandler");
				Integer numericScale = parameterNode
						.getIntAttribute("numericScale");
				ParameterMode modeEnum = resolveParameterMode(mode);
				Class<?> javaTypeClass = resolveClass(javaType);
				JdbcType jdbcTypeEnum = resolveJdbcType(jdbcType);
				@SuppressWarnings("unchecked")
				Class<? extends TypeHandler<?>> typeHandlerClass = (Class<? extends TypeHandler<?>>) resolveClass(typeHandler);
				ParameterMapping parameterMapping = builderAssistant
						.buildParameterMapping(parameterClass, property,
								javaTypeClass, jdbcTypeEnum, resultMap,
								modeEnum, typeHandlerClass, numericScale);
				parameterMappings.add(parameterMapping);
			}
			builderAssistant.addParameterMap(id, parameterClass,
					parameterMappings);
		}
	}

	private void resultMapElements(List<XNode> list) throws Exception {
		for (XNode resultMapNode : list) {
			try {
				resultMapElement(resultMapNode);
			} catch (IncompleteElementException e) {
				// ignore, it will be retried
			}
		}
	}

	private ResultMap resultMapElement(XNode resultMapNode) throws Exception {
		return resultMapElement(resultMapNode,
				Collections.<ResultMapping> emptyList());
	}

	private ResultMap resultMapElement(XNode resultMapNode,
			List<ResultMapping> additionalResultMappings) throws Exception {
		ErrorContext.instance().activity(
				"processing " + resultMapNode.getValueBasedIdentifier());
		String id = resultMapNode.getStringAttribute("id",
				resultMapNode.getValueBasedIdentifier());
		String type = resultMapNode.getStringAttribute("type", resultMapNode
				.getStringAttribute("ofType", resultMapNode.getStringAttribute(
						"resultType",
						resultMapNode.getStringAttribute("javaType"))));
		String extend = resultMapNode.getStringAttribute("extends");
		Boolean autoMapping = resultMapNode.getBooleanAttribute("autoMapping");
		Class<?> typeClass = resolveClass(type);
		Discriminator discriminator = null;
		List<ResultMapping> resultMappings = new ArrayList<ResultMapping>();
		resultMappings.addAll(additionalResultMappings);
		List<XNode> resultChildren = resultMapNode.getChildren();
		for (XNode resultChild : resultChildren) {
			if ("constructor".equals(resultChild.getName())) {
				processConstructorElement(resultChild, typeClass,
						resultMappings);
			} else if ("discriminator".equals(resultChild.getName())) {
				discriminator = processDiscriminatorElement(resultChild,
						typeClass, resultMappings);
			} else {
				ArrayList<ResultFlag> flags = new ArrayList<ResultFlag>();
				if ("id".equals(resultChild.getName())) {
					flags.add(ResultFlag.ID);
				}
				resultMappings.add(buildResultMappingFromContext(resultChild,
						typeClass, flags));
			}
		}
		ResultMapResolver resultMapResolver = new ResultMapResolver(
				builderAssistant, id, typeClass, extend, discriminator,
				resultMappings, autoMapping);
		try {
			return resultMapResolver.resolve();
		} catch (IncompleteElementException e) {
			configuration.addIncompleteResultMap(resultMapResolver);
			throw e;
		}
	}

	private void processConstructorElement(XNode resultChild,
			Class<?> resultType, List<ResultMapping> resultMappings)
			throws Exception {
		List<XNode> argChildren = resultChild.getChildren();
		for (XNode argChild : argChildren) {
			ArrayList<ResultFlag> flags = new ArrayList<ResultFlag>();
			flags.add(ResultFlag.CONSTRUCTOR);
			if ("idArg".equals(argChild.getName())) {
				flags.add(ResultFlag.ID);
			}
			resultMappings.add(buildResultMappingFromContext(argChild,
					resultType, flags));
		}
	}

	private Discriminator processDiscriminatorElement(XNode context,
			Class<?> resultType, List<ResultMapping> resultMappings)
			throws Exception {
		String column = context.getStringAttribute("column");
		String javaType = context.getStringAttribute("javaType");
		String jdbcType = context.getStringAttribute("jdbcType");
		String typeHandler = context.getStringAttribute("typeHandler");
		Class<?> javaTypeClass = resolveClass(javaType);
		@SuppressWarnings("unchecked")
		Class<? extends TypeHandler<?>> typeHandlerClass = (Class<? extends TypeHandler<?>>) resolveClass(typeHandler);
		JdbcType jdbcTypeEnum = resolveJdbcType(jdbcType);
		Map<String, String> discriminatorMap = new HashMap<String, String>();
		for (XNode caseChild : context.getChildren()) {
			String value = caseChild.getStringAttribute("value");
			String resultMap = caseChild.getStringAttribute("resultMap",
					processNestedResultMappings(caseChild, resultMappings));
			discriminatorMap.put(value, resultMap);
		}
		return builderAssistant
				.buildDiscriminator(resultType, column, javaTypeClass,
						jdbcTypeEnum, typeHandlerClass, discriminatorMap);
	}

	private void sqlElement(List<XNode> list) throws Exception {
		if (configuration.getDatabaseId() != null) {
			sqlElement(list, configuration.getDatabaseId());
		}
		sqlElement(list, null);
	}

	private void sqlElement(List<XNode> list, String requiredDatabaseId)
			throws Exception {
		for (XNode context : list) {
			String databaseId = context.getStringAttribute("databaseId");
			String id = context.getStringAttribute("id");
			id = builderAssistant.applyCurrentNamespace(id, false);
			if (databaseIdMatchesCurrent(id, databaseId, requiredDatabaseId))
				sqlFragments.put(id, context);
		}
	}

	private boolean databaseIdMatchesCurrent(String id, String databaseId,
			String requiredDatabaseId) {
		if (requiredDatabaseId != null) {
			if (!requiredDatabaseId.equals(databaseId)) {
				return false;
			}
		} else {
			if (databaseId != null) {
				return false;
			}
			// skip this fragment if there is a previous one with a not null
			// databaseId
			if (this.sqlFragments.containsKey(id)) {
				XNode context = this.sqlFragments.get(id);
				if (context.getStringAttribute("databaseId") != null) {
					return false;
				}
			}
		}
		return true;
	}

	private ResultMapping buildResultMappingFromContext(XNode context,
			Class<?> resultType, ArrayList<ResultFlag> flags) throws Exception {
		String property = context.getStringAttribute("property");
		String column = context.getStringAttribute("column");
		String javaType = context.getStringAttribute("javaType");
		String jdbcType = context.getStringAttribute("jdbcType");
		String nestedSelect = context.getStringAttribute("select");
		String nestedResultMap = context.getStringAttribute(
				"resultMap",
				processNestedResultMappings(context,
						Collections.<ResultMapping> emptyList()));
		String notNullColumn = context.getStringAttribute("notNullColumn");
		String columnPrefix = context.getStringAttribute("columnPrefix");
		String typeHandler = context.getStringAttribute("typeHandler");
		String resulSet = context.getStringAttribute("resultSet");
		String foreignColumn = context.getStringAttribute("foreignColumn");
		boolean lazy = "lazy".equals(context.getStringAttribute("fetchType",
				configuration.isLazyLoadingEnabled() ? "lazy" : "eager"));
		Class<?> javaTypeClass = resolveClass(javaType);
		@SuppressWarnings("unchecked")
		Class<? extends TypeHandler<?>> typeHandlerClass = (Class<? extends TypeHandler<?>>) resolveClass(typeHandler);
		JdbcType jdbcTypeEnum = resolveJdbcType(jdbcType);
		return builderAssistant.buildResultMapping(resultType, property,
				column, javaTypeClass, jdbcTypeEnum, nestedSelect,
				nestedResultMap, notNullColumn, columnPrefix, typeHandlerClass,
				flags, resulSet, foreignColumn, lazy);
	}

	private String processNestedResultMappings(XNode context,
			List<ResultMapping> resultMappings) throws Exception {
		if ("association".equals(context.getName())
				|| "collection".equals(context.getName())
				|| "case".equals(context.getName())) {
			if (context.getStringAttribute("select") == null) {
				ResultMap resultMap = resultMapElement(context, resultMappings);
				return resultMap.getId();
			}
		}
		return null;
	}

	private void bindMapperForNamespace() {
		String namespace = builderAssistant.getCurrentNamespace();
		if (namespace != null) {
			Class<?> boundType = null;
			try {
				boundType = Resources.classForName(namespace);
			} catch (ClassNotFoundException e) {
				// ignore, bound type is not required
			}
			if (boundType != null) {
				if (!configuration.hasMapper(boundType)) {
					// Spring may not know the real resource name so we set a
					// flag
					// to prevent loading again this resource from the mapper
					// interface
					// look at MapperAnnotationBuilder#loadXmlResource
					configuration.addLoadedResource("namespace:" + namespace);
					configuration.addMapper(boundType);
				}
			}
		}
	}

}