package org.apache.ibatis.builder.xml;

import java.io.InputStream;
import java.io.Reader;
import java.util.Properties;

import org.apache.ibatis.builder.BaseBuilder;
import org.apache.ibatis.builder.BuilderException;
import org.apache.ibatis.datasource.DataSourceFactory;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.mapping.Environment;
import org.apache.ibatis.parsing.XNode;
import org.apache.ibatis.parsing.XPathParser;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.reflection.MetaClass;
import org.apache.ibatis.reflection.factory.ObjectFactory;
import org.apache.ibatis.reflection.wrapper.ObjectWrapperFactory;
import org.apache.ibatis.session.AutoMappingBehavior;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.transaction.TransactionFactory;
import org.apache.ibatis.type.TypeHandler;

public class XMLConfigBuilder extends BaseBuilder {

  private boolean parsed;
  private XPathParser parser;
  private String environment;

  public XMLConfigBuilder(Reader reader) {
    this(reader, null, null);
  }
  
  public XMLConfigBuilder(Reader reader, String environment) {
    this(reader, environment, null);
  }

  public XMLConfigBuilder(Reader reader, String environment, Properties props) {
    this(new XPathParser(reader, true, props, new XMLMapperEntityResolver()), environment, props);
  }
  
  public XMLConfigBuilder(InputStream inputStream) {
    this(inputStream, null, null);
  }

  public XMLConfigBuilder(InputStream inputStream, String environment) {
    this(inputStream, environment, null);
  }

  public XMLConfigBuilder(InputStream inputStream, String environment, Properties props) {
    this(new XPathParser(inputStream, true, props, new XMLMapperEntityResolver()), environment, props);
  }
  
  private XMLConfigBuilder(XPathParser parser, String environment, Properties props) {
    super(new Configuration());
    ErrorContext.instance().resource("SQL Mapper Configuration");
    this.configuration.setVariables(props);
    this.parsed = false;
    this.environment = environment;
    this.parser = parser; 
  }
  
  public Configuration parse() {
    if (parsed) {
      throw new BuilderException("Each MapperConfigParser can only be used once.");
    }
    parsed = true;
    parseConfiguration(parser.evalNode("/configuration"));
    return configuration;
  }

  private void parseConfiguration(XNode root) {
    try {
      typeAliasesElement(root.evalNode("typeAliases"));
      pluginElement(root.evalNode("plugins"));
      objectFactoryElement(root.evalNode("objectFactory"));
      objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
      propertiesElement(root.evalNode("properties"));
      settingsElement(root.evalNode("settings"));
      environmentsElement(root.evalNode("environments"));
      typeHandlerElement(root.evalNode("typeHandlers"));
      mapperElement(root.evalNode("mappers"));
    } catch (Exception e) {
      throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);
    }
  }

  private void typeAliasesElement(XNode parent) {
    if (parent != null) {
      for (XNode child : parent.getChildren()) {
        String alias = child.getStringAttribute("alias");
        String type = child.getStringAttribute("type");
        try {
          Class<?> clazz = Resources.classForName(type);
          if (alias == null) {
            typeAliasRegistry.registerAlias(clazz);
          } else {
            typeAliasRegistry.registerAlias(alias, clazz);
          }
        } catch (ClassNotFoundException e) {
          throw new BuilderException("Error registering typeAlias for '" + alias + "'. Cause: " + e, e);
        }
      }
    }
  }

  private void pluginElement(XNode parent) throws Exception {
    if (parent != null) {
      for (XNode child : parent.getChildren()) {
        String interceptor = child.getStringAttribute("interceptor");
        Properties properties = child.getChildrenAsProperties();
        Interceptor interceptorInstance = (Interceptor) resolveClass(interceptor).newInstance();
        interceptorInstance.setProperties(properties);
        configuration.addInterceptor(interceptorInstance);
      }
    }
  }


  private void objectFactoryElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type");
      Properties properties = context.getChildrenAsProperties();
      ObjectFactory factory = (ObjectFactory) resolveClass(type).newInstance();
      factory.setProperties(properties);
      configuration.setObjectFactory(factory);
    }
  }
  
  private void objectWrapperFactoryElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type");
      ObjectWrapperFactory factory = (ObjectWrapperFactory) resolveClass(type).newInstance();
      configuration.setObjectWrapperFactory(factory);
    }
  }

  private void propertiesElement(XNode context) throws Exception {
    if (context != null) {
      Properties defaults = context.getChildrenAsProperties();
      String resource = context.getStringAttribute("resource");
      String url = context.getStringAttribute("url");
      if (resource != null && url != null) {
        throw new BuilderException("The properties element cannot specify both a URL and a resource based property file reference.  Please specify one or the other.");
      }
      if (resource != null) {
        defaults.putAll(Resources.getResourceAsProperties(resource));
      } else if (url != null) {
        defaults.putAll(Resources.getUrlAsProperties(url));
      }
      Properties vars = configuration.getVariables();
      if (vars != null) {
        defaults.putAll(vars);
      }
      parser.setVariables(defaults);
      configuration.setVariables(defaults);
    }
  }

  private void settingsElement(XNode context) throws Exception {
    if (context != null) {
      Properties props = context.getChildrenAsProperties();
      // Check that all settings are known to the configuration class
      MetaClass metaConfig = MetaClass.forClass(Configuration.class);
      for (Object key : props.keySet()) {
        if (!metaConfig.hasSetter(String.valueOf(key))) {
          throw new BuilderException("The setting " + key + " is not known.  Make sure you spelled it correctly (case sensitive).");
        }
      }
      configuration.setAutoMappingBehavior(AutoMappingBehavior.valueOf(stringValueOf(props.getProperty("autoMappingBehavior"), "PARTIAL")));
      configuration.setCacheEnabled(booleanValueOf(props.getProperty("cacheEnabled"), true));
      configuration.setLazyLoadingEnabled(booleanValueOf(props.getProperty("lazyLoadingEnabled"), false));
      configuration.setAggressiveLazyLoading(booleanValueOf(props.getProperty("aggressiveLazyLoading"), true));
      configuration.setMultipleResultSetsEnabled(booleanValueOf(props.getProperty("multipleResultSetsEnabled"), true));
      configuration.setUseColumnLabel(booleanValueOf(props.getProperty("useColumnLabel"), true));
      configuration.setUseGeneratedKeys(booleanValueOf(props.getProperty("useGeneratedKeys"), false));
      configuration.setDefaultExecutorType(ExecutorType.valueOf(stringValueOf(props.getProperty("defaultExecutorType"), "SIMPLE")));
      configuration.setDefaultStatementTimeout(integerValueOf(props.getProperty("defaultStatementTimeout"), null));
      configuration.setMapUnderscoreToCamelCase(booleanValueOf(props.getProperty("mapUnderscoreToCamelCase"), false));
      configuration.setSafeRowBoundsEnabled(booleanValueOf(props.getProperty("safeRowBoundsEnabled"), true));      
    }
  }

  private void environmentsElement(XNode context) throws Exception {
    if (context != null) {
      if (environment == null) {
        environment = context.getStringAttribute("default");
      }
      for (XNode child : context.getChildren()) {
        String id = child.getStringAttribute("id");
        if (isSpecifiedEnvironment(id)) {
          TransactionFactory txFactory = transactionManagerElement(child.evalNode("transactionManager"));
          DataSourceFactory dsFactory = dataSourceElement(child.evalNode("dataSource"));
          Environment.Builder environmentBuilder = new Environment.Builder(id)
              .transactionFactory(txFactory)
              .dataSource(dsFactory.getDataSource());
          configuration.setEnvironment(environmentBuilder.build());
        }
      }
    }
  }

  private TransactionFactory transactionManagerElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type");
      Properties props = context.getChildrenAsProperties();
      TransactionFactory factory = (TransactionFactory) resolveClass(type).newInstance();
      factory.setProperties(props);
      return factory;
    }
    throw new BuilderException("Environment declaration requires a TransactionFactory.");
  }

  private DataSourceFactory dataSourceElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type");
      Properties props = context.getChildrenAsProperties();
      DataSourceFactory factory = (DataSourceFactory) resolveClass(type).newInstance();
      factory.setProperties(props);
      return factory;
    }
    throw new BuilderException("Environment declaration requires a DataSourceFactory.");
  }


  private void typeHandlerElement(XNode parent) throws Exception {
    if (parent != null) {
      for (XNode child : parent.getChildren()) {
        String javaType = child.getStringAttribute("javaType");
        String jdbcType = child.getStringAttribute("jdbcType");
        String handler = child.getStringAttribute("handler");

        Class<?> javaTypeClass = resolveClass(javaType);
        TypeHandler typeHandlerInstance = (TypeHandler) resolveClass(handler).newInstance();

        if (jdbcType == null) {
          typeHandlerRegistry.register(javaTypeClass, typeHandlerInstance);
        } else {
          typeHandlerRegistry.register(javaTypeClass, resolveJdbcType(jdbcType), typeHandlerInstance);
        }
      }
    }
  }


  private void mapperElement(XNode parent) throws Exception {
    if (parent != null) {
      for (XNode child : parent.getChildren()) {
        String resource = child.getStringAttribute("resource");
        String url = child.getStringAttribute("url");
        InputStream inputStream;
        if (resource != null && url == null) {
          ErrorContext.instance().resource(resource);
          inputStream = Resources.getResourceAsStream(resource);
          XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, resource, configuration.getSqlFragments());
          mapperParser.parse();
        } else if (url != null && resource == null) {
          ErrorContext.instance().resource(url);
          inputStream = Resources.getUrlAsStream(url);
          XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, url, configuration.getSqlFragments());
          mapperParser.parse();
        } else {
          throw new BuilderException("A mapper element may only specify a url or resource, but not both.");
        }
      }
    }
  }

  private boolean isSpecifiedEnvironment(String id) {
    if (environment == null) {
      throw new BuilderException("No environment specified.");
    } else if (id == null) {
      throw new BuilderException("Environment requires an id attribute.");
    } else if (environment.equals(id)) {
      return true;
    }
    return false;
  }
}
