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/**
 * Copyright (c) 2013, impossibl.com
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *  * Neither the name of impossibl.com nor the names of its contributors may
 *    be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package com.impossibl.postgres.mapper;

import com.impossibl.postgres.protocol.ResultField;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.util.List;
import java.util.Map;

import static java.util.Arrays.asList;

/**
 * Builds lists of PropertySetters that match the a list of result fields. This
 * accelerates the mapping from fields to arrays/lists/maps/beans.
 *
 * @author kdubb
 *
 */
public class Mapper {

  /**
   * Builds a list of mapping setters for the row and fields.
   *
   * @param rowType Row type to map to
   * @param fields Result fields to map from
   * @return List of setters that can perform the mapping
   */
  public static List buildMapping(Class rowType, List fields) {

    PropertySetter[] setters;

    if (rowType.isArray() && rowType.getComponentType() == Object.class) {
      setters = initArraySetters(fields);
    }
    else if (List.class.isAssignableFrom(rowType)) {
      setters = initListSetters(fields);
    }
    else if (Map.class.isAssignableFrom(rowType)) {
      setters = initMapSetters(fields);
    }
    else {
      setters = initBeanSetters(rowType, fields);
    }

    return asList(setters);
  }

  /**
   * Builds a list of mapping setters for an array row type.
   *
   * @param fields Fields to map from
   * @return List of setters that can perform the mapping
   */
  protected static PropertySetter[] initArraySetters(List fields) {

    PropertySetter[] setters = new PropertySetter[fields.size()];

    for (int c = 0; c < setters.length; ++c) {
      setters[c] = new ArrayPropertySetter(c);
    }

    return setters;
  }

  /**
   * Builds a list of mapping setters for a list row type.
   *
   * @param fields Fields to map from
   * @return List of setters that can perform the mapping
   */
  protected static PropertySetter[] initListSetters(List fields) {

    PropertySetter[] setters = new PropertySetter[fields.size()];

    for (int c = 0; c < setters.length; ++c) {
      setters[c] = new ListPropertySetter(c);
    }

    return setters;
  }

  /**
   * Builds a list of mapping setters for a map row type.
   *
   * @param fields Fields to map from
   * @return List of setters that can perform the mapping
   */
  protected static PropertySetter[] initMapSetters(List fields) {

    PropertySetter[] setters = new PropertySetter[fields.size()];

    for (int c = 0; c < setters.length; ++c) {
      setters[c] = new MapPropertySetter(fields.get(c).name);
    }

    return setters;
  }

  /**
   * Builds a list of mapping setters for bean row type.
   *
   * @param instanceType The bean instance type to map to
   * @param fields List of setters that can perform the mapping
   * @return List of setters that can perform the mapping
   */
  protected static PropertySetter[] initBeanSetters(Class instanceType, List fields) {

    PropertySetter[] setters = new PropertySetter[fields.size()];

    //Get the bean info
    PropertyDescriptor[] propDescs;
    try {
      BeanInfo beanInfo = Introspector.getBeanInfo(instanceType);
      propDescs = beanInfo.getPropertyDescriptors();
    }
    catch (IntrospectionException e) {
      //Ignore...
      propDescs = new PropertyDescriptor[0];
    }

    for (int c = 0; c < setters.length; ++c) {

      //Look for a valid property to map to
      PropertyDescriptor propDesc = findPropertyDescriptor(propDescs, fields.get(c).name);
      if (propDesc != null) {
        setters[c] = new MethodPropertySetter(propDesc.getWriteMethod());
        continue;
      }

      //Look for a valid field to map to
      Field field = findField(instanceType, fields.get(c).name);
      if (field != null) {
        setters[c] = new FieldPropertySetter(field);
        continue;
      }

      //Can't find a valid property setter
      setters[c] = null;
    }

    return setters;
  }

  private static Field findField(Class instanceType, String name) {

    try {
      return instanceType.getField(name);
    }
    catch (NoSuchFieldException | SecurityException e) {
      // Ignore
    }

    return null;
  }

  private static PropertyDescriptor findPropertyDescriptor(PropertyDescriptor[] propDescs, String name) {

    for (PropertyDescriptor propDesc : propDescs) {

      if (propDesc.getName().equals(name)) {
        return propDesc;
      }

    }

    return null;
  }

}