/*
    *    Copyright 2015-2023 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.util.List;
  import java.util.Map;
  
  import freemarker.core.Environment;
  import freemarker.ext.util.WrapperTemplateModel;
  import freemarker.template.DefaultListAdapter;
  import freemarker.template.SimpleScalar;
  import freemarker.template.TemplateBooleanModel;
  import freemarker.template.TemplateDateModel;
  import freemarker.template.TemplateDirectiveBody;
  import freemarker.template.TemplateDirectiveModel;
  import freemarker.template.TemplateException;
  import freemarker.template.TemplateModel;
  import freemarker.template.TemplateNumberModel;
  import freemarker.template.TemplateScalarModel;
  
  /**
   * Custom FreeMarker directive for generating "#{paramName}" declarations in convenient way. Problem is FreeMarker
   * supports this syntax natively and there are no chance to disable this (although it is deprecated). And to get
   * "#{paramName}" we should write ${r"#{paramName}"}. With this directive you can write more simple:
   * <p>
   * <blockquote>
   *
   * <pre>
   *     &lt;@p name="paramName"/&gt;
   * </pre>
   *
   * </blockquote>
   * <p>
   * Also directive supports `value` attribute. If it is specified, param will take passed value and create the
   * corresponding #{}-parameter. This is useful in loops:
   * </p>
   * <blockquote>
   *
   * <pre>
   *     &lt;#list ids as id&gt;
   *       &lt;@p value=id/&gt;
   *       &lt;#if id_has_next&gt;,&lt;/#if&gt;
   *     &lt;/#list&gt;
   * </pre>
   *
   * </blockquote>
   * <p>
   * will be translated into
   * </p>
   * <blockquote>
   *
   * <pre>
   *     #{_p0},#{_p1},#{_p2}
   * </pre>
   *
   * </blockquote>
   * <p>
   * And MyBatis engine will convert it to `?`-params finally.
   * </p>
   *
   * @author elwood
   */
  public class MyBatisParamDirective implements TemplateDirectiveModel {
    public static String DEFAULT_KEY = "p";
    public static String DATABASE_ID_KEY = "_databaseId";
  
    @Override
    public void execute(Environment env, Map params, TemplateModel[] loopVars, TemplateDirectiveBody body)
        throws TemplateException, IOException {
      SimpleScalar name = (SimpleScalar) params.get("name");
      if (params.containsKey("value")) {
        Object valueObject = params.get("value");
        Object value;
        if (valueObject == null) {
          value = null;
        } else if (valueObject instanceof WrapperTemplateModel) {
          value = ((WrapperTemplateModel) valueObject).getWrappedObject();
        } else if (valueObject instanceof TemplateScalarModel) {
          value = ((TemplateScalarModel) valueObject).getAsString();
        } else if (valueObject instanceof TemplateNumberModel) {
          value = ((TemplateNumberModel) valueObject).getAsNumber();
        } else if (valueObject instanceof TemplateDateModel) {
          value = ((TemplateDateModel) valueObject).getAsDate();
        } else if (valueObject instanceof TemplateBooleanModel) {
          value = ((TemplateBooleanModel) valueObject).getAsBoolean();
       } else {
         throw new UnsupportedOperationException(
             String.format("Type %s is not supported yet in this context.", valueObject.getClass().getSimpleName()));
       }
 
       TemplateModel generatedParamsObject = env.getGlobalVariables().get(FreeMarkerSqlSource.GENERATED_PARAMS_KEY);
       List generatedParams;
       if (generatedParamsObject instanceof DefaultListAdapter) {
         generatedParams = (List) ((DefaultListAdapter) generatedParamsObject).getWrappedObject();
       } else {
         generatedParams = ((GeneratedParamsTemplateModel) generatedParamsObject).getGeneratedParams();
       }
       String generatedParamName = "_p" + generatedParams.size();
       env.getOut().write(String.format("#{%s}", generatedParamName));
       generatedParams.add(value);
     } else {
       env.getOut().write(String.format("#{%s}", name));
     }
   }
 }