/**
    *    Copyright 2009-2015 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.lang.reflect.Method;
  import java.util.HashMap;
  
  import org.apache.ibatis.builder.BuilderException;
  import org.apache.ibatis.builder.SqlSourceBuilder;
  import org.apache.ibatis.mapping.BoundSql;
  import org.apache.ibatis.mapping.SqlSource;
  import org.apache.ibatis.session.Configuration;
  
  /**
   * @author Clinton Begin
   */
  public class ProviderSqlSource implements SqlSource {
  
    private SqlSourceBuilder sqlSourceParser;
    private Class<?> providerType;
    private Method providerMethod;
    private boolean providerTakesParameterObject;
  
    public ProviderSqlSource(Configuration config, Object provider) {
      String providerMethodName = null;
      try {
        this.sqlSourceParser = new SqlSourceBuilder(config);
        this.providerType = (Class<?>) provider.getClass().getMethod("type").invoke(provider);
        providerMethodName = (String) provider.getClass().getMethod("method").invoke(provider);
  
        for (Method m : this.providerType.getMethods()) {
          if (providerMethodName.equals(m.getName())) {
            if (m.getParameterTypes().length < 2
                && m.getReturnType() == String.class) {
              this.providerMethod = m;
              this.providerTakesParameterObject = m.getParameterTypes().length == 1;
            }
          }
        }
      } catch (Exception e) {
        throw new BuilderException("Error creating SqlSource for SqlProvider.  Cause: " + e, e);
      }
      if (this.providerMethod == null) {
        throw new BuilderException("Error creating SqlSource for SqlProvider. Method '"
            + providerMethodName + "' not found in SqlProvider '" + this.providerType.getName() + "'.");
      }
    }
  
    @Override
    public BoundSql getBoundSql(Object parameterObject) {
      SqlSource sqlSource = createSqlSource(parameterObject);
      return sqlSource.getBoundSql(parameterObject);
    }
  
    private SqlSource createSqlSource(Object parameterObject) {
      try {
        String sql;
        if (providerTakesParameterObject) {
          sql = (String) providerMethod.invoke(providerType.newInstance(), parameterObject);
        } else {
          sql = (String) providerMethod.invoke(providerType.newInstance());
        }
        Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();
        return sqlSourceParser.parse(sql, parameterType, new HashMap<String, Object>());
      } catch (Exception e) {
        throw new BuilderException("Error invoking SqlProvider method ("
            + providerType.getName() + "." + providerMethod.getName()
            + ").  Cause: " + e, e);
      }
    }
  
  }