/*
    *    Copyright 2015-2022 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
    *
    *       https://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.mybatis.scripting.freemarker;
  
  import java.io.IOException;
  import java.io.StringReader;
  import java.nio.charset.StandardCharsets;
  
  import org.apache.ibatis.executor.parameter.ParameterHandler;
  import org.apache.ibatis.mapping.BoundSql;
  import org.apache.ibatis.mapping.MappedStatement;
  import org.apache.ibatis.mapping.SqlSource;
  import org.apache.ibatis.parsing.XNode;
  import org.apache.ibatis.scripting.LanguageDriver;
  import org.apache.ibatis.scripting.defaults.DefaultParameterHandler;
  import org.apache.ibatis.session.Configuration;
  import org.mybatis.scripting.freemarker.support.TemplateFilePathProvider;
  
  import freemarker.cache.ClassTemplateLoader;
  import freemarker.cache.TemplateLoader;
  import freemarker.template.Template;
  import freemarker.template.TemplateException;
  
  /**
   * Adds FreeMarker templates support to scripting in MyBatis. If you want to change or extend template loader
   * configuration, use can inherit from this class and override {@link #createFreeMarkerConfiguration()} method.
   *
   * @author elwood
   * @author Kazuki Shimizu
   */
  public class FreeMarkerLanguageDriver implements LanguageDriver {
  
    protected final FreeMarkerLanguageDriverConfig driverConfig;
    protected final freemarker.template.Configuration freemarkerCfg;
  
    /**
     * Constructor.
     *
     * @see FreeMarkerLanguageDriverConfig#newInstance()
     */
    public FreeMarkerLanguageDriver() {
      this(FreeMarkerLanguageDriverConfig.newInstance());
    }
  
    /**
     * Constructor.
     *
     * @param driverConfig
     *          a language driver configuration
     *
     * @since 1.2.0
     */
    public FreeMarkerLanguageDriver(FreeMarkerLanguageDriverConfig driverConfig) {
      this.driverConfig = driverConfig;
      this.freemarkerCfg = createFreeMarkerConfiguration();
      TemplateFilePathProvider.setLanguageDriverConfig(driverConfig);
    }
  
    /**
     * Creates the {@link freemarker.template.Configuration} instance and sets it up. If you want to change it (set
     * another props, for example), you can override it in inherited class and use your own class in @Lang directive.
     */
    protected freemarker.template.Configuration createFreeMarkerConfiguration() {
      freemarker.template.Configuration cfg = new freemarker.template.Configuration(
          freemarker.template.Configuration.VERSION_2_3_22);
  
      TemplateLoader templateLoader = new ClassTemplateLoader(this.getClass().getClassLoader(),
          driverConfig.getTemplateFile().getBaseDir());
      cfg.setTemplateLoader(templateLoader);
  
      // To avoid formatting numbers using spaces and commas in SQL
      cfg.setNumberFormat("computer");
  
      // Because it defaults to default system encoding, we should set it always explicitly
      cfg.setDefaultEncoding(StandardCharsets.UTF_8.name());
  
      driverConfig.getFreemarkerSettings().forEach((name, value) -> {
        try {
          cfg.setSetting(name, value);
        } catch (TemplateException e) {
          throw new IllegalStateException(
              String.format("Fail to configure FreeMarker template setting. name[%s] value[%s]", name, value), e);
        }
      });
  
      return cfg;
   }
 
   /**
    * Creates a {@link ParameterHandler} that passes the actual parameters to the the JDBC statement.
    *
    * @see DefaultParameterHandler
    *
    * @param mappedStatement
    *          The mapped statement that is being executed
    * @param parameterObject
    *          The input parameter object (can be null)
    * @param boundSql
    *          The resulting SQL once the dynamic language has been executed.
    */
   @Override
   public ParameterHandler createParameterHandler(MappedStatement mappedStatement, Object parameterObject,
       BoundSql boundSql) {
     // As default XMLLanguageDriver
     return new DefaultParameterHandler(mappedStatement, parameterObject, boundSql);
   }
 
   /**
    * Creates an {@link SqlSource} that will hold the statement read from a mapper xml file. It is called during startup,
    * when the mapped statement is read from a class or an xml file.
    *
    * @param configuration
    *          The MyBatis configuration
    * @param script
    *          XNode parsed from a XML file
    * @param parameterType
    *          input parameter type got from a mapper method or specified in the parameterType xml attribute. Can be
    *          null.
    */
   @Override
   public SqlSource createSqlSource(Configuration configuration, XNode script, Class<?> parameterType) {
     return createSqlSource(configuration, script.getNode().getTextContent());
   }
 
   /**
    * Creates an {@link SqlSource} that will hold the statement read from an annotation. It is called during startup,
    * when the mapped statement is read from a class or an xml file.
    *
    * @param configuration
    *          The MyBatis configuration
    * @param script
    *          The content of the annotation
    * @param parameterType
    *          input parameter type got from a mapper method or specified in the parameterType xml attribute. Can be
    *          null.
    */
   @Override
   public SqlSource createSqlSource(Configuration configuration, String script, Class<?> parameterType) {
     return createSqlSource(configuration, script);
   }
 
   protected SqlSource createSqlSource(Template template, Configuration configuration) {
     return new FreeMarkerSqlSource(template, configuration, freemarkerCfg.getIncompatibleImprovements());
   }
 
   private SqlSource createSqlSource(Configuration configuration, String scriptText) {
     Template template;
     if (scriptText.trim().contains(" ")) {
       // Consider that script is inline script
       try {
         template = new Template(null, new StringReader(scriptText), freemarkerCfg);
       } catch (IOException e) {
         throw new RuntimeException(e);
       }
     } else {
       // Consider that script is template name, trying to find the template in classpath
       try {
         template = freemarkerCfg.getTemplate(scriptText.trim());
       } catch (IOException e) {
         throw new RuntimeException(e);
       }
     }
 
     return createSqlSource(template, configuration);
   }
 
 }