package com.linkedin.thirdeye.detector.email.filter;

import java.lang.reflect.Field;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


public abstract class BaseAlertFilter implements AlertFilter {
  private final static Logger LOG = LoggerFactory.getLogger(BaseAlertFilter.class);
  /**
   * Parses the parameter setting for this filter.
   *
   * This method goes through the parameters defined by the method AlertFilter.getPropertyNames() of each AlertFilter
   * class and get the parameter value from the given parameter setting. If a parameter (property) is missing, then it
   * gets the default value, which is defined within the corresponding filter class with prefix "DEFAULT_". For example,
   * for a parameter whose field name is "Abc_Def", its default value has to have this name "DEFAULT_ABC_DEF".
   *
   * @param parameterSetting a mapping from field name to user specified value for that field
   */
  @Override
  public void setParameters(Map<String, String> parameterSetting) {
    Class c = this.getClass();
    for (String fieldName : getPropertyNames()) {
      Double value = null;
      // Get user's value for the specified field
      if (parameterSetting.containsKey(fieldName)) {
        value = Double.parseDouble(parameterSetting.get(fieldName));
      } else {
        // If user's value does not exist, try to get the default value from Class definition
        try {
          Field field = c.getDeclaredField("DEFAULT_" + fieldName.toUpperCase());
          boolean accessible = field.isAccessible();
          field.setAccessible(true);
          value = Double.parseDouble((String) field.get(this));
          field.setAccessible(accessible);
        } catch (NoSuchFieldException | IllegalAccessException e) {
          LOG.error("Failed to get default value for field {} of class {}; exception: {}", "DEFAULT_" + fieldName,
              c.getSimpleName(), e.toString());
        }
        // If failed to get the default value from Class definition, then use value 0d
        if (value == null) {
          value = 0d;
        }
        LOG.warn("Unable to read the setting for the field {} of class {}; the value {} is used.", fieldName,
            c.getSimpleName(), value);
      }
      // Set the final value to the specified field
      try {
        Field field = c.getDeclaredField(fieldName);
        boolean accessible = field.isAccessible();
        field.setAccessible(true);
        field.set(this, Double.valueOf(value));
        field.setAccessible(accessible);
      } catch (NoSuchFieldException | IllegalAccessException e) {
        LOG.warn("Failed to set the field {} for class {} exception: {}", fieldName, c.getSimpleName(), e.toString());
      }
    }
  }
}