package com.avaje.ebeaninternal.server.query;

import java.util.List;

import com.avaje.ebean.OrderBy;
import com.avaje.ebean.OrderBy.Property;
import com.avaje.ebeaninternal.api.SpiQuery;
import com.avaje.ebeaninternal.server.deploy.BeanDescriptor;
import com.avaje.ebeaninternal.server.deploy.BeanProperty;
import com.avaje.ebeaninternal.server.deploy.BeanPropertyAssoc;
import com.avaje.ebeaninternal.server.deploy.id.IdBinder;
import com.avaje.ebeaninternal.server.el.ElPropertyValue;

/**
 * Creates the order by expression clause.
 */
public class CQueryOrderBy {

  private final BeanDescriptor<?> desc;

  private final SpiQuery<?> query;

  /**
   * Create the logical order by clause.
   */
  public static String parse(BeanDescriptor<?> desc, SpiQuery<?> query) {
    return new CQueryOrderBy(desc, query).parseInternal();
  }

  private CQueryOrderBy(BeanDescriptor<?> desc, SpiQuery<?> query) {
    this.desc = desc;
    this.query = query;
  }

  private String parseInternal() {

    OrderBy<?> orderBy = query.getOrderBy();
    if (orderBy == null) {
      return null;
    }

    StringBuilder sb = new StringBuilder();

    List<Property> properties = orderBy.getProperties();
    if (properties.isEmpty()) {
      // order by clause removed by filterMany()
      return null;
    }
    for (int i = 0; i < properties.size(); i++) {
      if (i > 0) {
        sb.append(", ");
      }
      Property p = properties.get(i);
      String expression = parseProperty(p);
      sb.append(expression);
    }
    return sb.toString();
  }

  private String parseProperty(Property p) {

    String propName = p.getProperty();
    ElPropertyValue el = desc.getElGetValue(propName);
    if (el == null) {
      return p.toStringFormat();
    }

    BeanProperty beanProperty = el.getBeanProperty();
    if (beanProperty instanceof BeanPropertyAssoc<?>) {
      BeanPropertyAssoc<?> ap = (BeanPropertyAssoc<?>) beanProperty;
      IdBinder idBinder = ap.getTargetDescriptor().getIdBinder();
      return idBinder.getOrderBy(el.getElName(), p.isAscending());
    }

    return p.toStringFormat();
  }
}
