package org.apache.samoa.instances;

/*
 * #%L
 * SAMOA
 * %%
 * Copyright (C) 2014 - 2015 Apache Software Foundation
 * %%
 * 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.
 * #L%
 */

import java.io.Serializable;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * Class that keeps all information needed to describe a feature or attribute.
 */
public class Attribute implements Serializable {

  /** The keyword used to denote the start of an arff attribute declaration */
  public final static String ARFF_ATTRIBUTE = "@attribute";

  /** A keyword used to denote a numeric attribute */
  public final static String ARFF_ATTRIBUTE_INTEGER = "integer";

  /** A keyword used to denote a numeric attribute */
  public final static String ARFF_ATTRIBUTE_REAL = "real";

  /** A keyword used to denote a numeric attribute */
  public final static String ARFF_ATTRIBUTE_NUMERIC = "numeric";

  /** The keyword used to denote a string attribute */
  public final static String ARFF_ATTRIBUTE_STRING = "string";

  /** The keyword used to denote a date attribute */
  public final static String ARFF_ATTRIBUTE_DATE = "date";

  /** The keyword used to denote a relation-valued attribute */
  public final static String ARFF_ATTRIBUTE_RELATIONAL = "relational";

  /** The keyword used to denote the end of the declaration of a subrelation */
  public final static String ARFF_END_SUBRELATION = "@end";

  /** Strings longer than this will be stored compressed. */
  private static final int STRING_COMPRESS_THRESHOLD = 200;

  /**
   * The is nominal.
   */
  protected boolean isNominal;

  /**
   * The is numeric.
   */
  protected boolean isNumeric;

  /**
   * The is date.
   */
  protected boolean isDate;

  /**
   * Date format specification for date attributes
   */
  protected SimpleDateFormat m_DateFormat;

  /**
   * The name.
   */
  protected String name;

  /**
   * The attribute values.
   */
  protected List<String> attributeValues;

  /**
   * Gets the attribute values.
   *
   * @return the attribute values
   */
  public List<String> getAttributeValues() {
    return attributeValues;
  }


  /**
   * Instantiates a new attribute.
   *
   * @param string the string
   */
  public Attribute(String string) {
    this.name = string;
    this.isNumeric = true;
  }

  /**
   * Instantiates a new attribute.
   *
   * @param attributeName the attribute name
   * @param attributeValues the attribute values
   */
  public Attribute(String attributeName, List<String> attributeValues) {
    this.name = attributeName;
    this.attributeValues = attributeValues;
    this.isNominal = true;
  }

  /**
   * Instantiates a new attribute.
   *
   * @param attributeName the attribute name
   * @param dateFormat the format of the date used
   */
  public Attribute(String attributeName, String dateFormat) {
    this.name = attributeName;
    this.valuesStringAttribute = null;
    this.isDate = true;

    if (dateFormat != null) {
      m_DateFormat = new SimpleDateFormat(dateFormat);
    } else {
      m_DateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
    }
  }

  /**
   * Instantiates a new attribute.
   */
  public Attribute() {
    this("");
  }

  /**
   * Checks if is nominal.
   *
   * @return true, if is nominal
   */
  public boolean isNominal() {
    return this.isNominal;
  }

  /**
   * Name.
   *
   * @return the string
   */
  public String name() {
    return this.name;
  }

  /**
   * Value.
   *
   * @param value the value
   * @return the string
   */
  public String value(int value) {
    return attributeValues.get(value);
  }

  /**
   * Checks if is numeric.
   *
   * @return true, if is numeric
   */
  public boolean isNumeric() {
    return isNumeric;
  }

  /**
   * Num values.
   *
   * @return the int
   */
  public int numValues() {
    if (isNumeric()) {
      return 0;
    } else {
      return attributeValues.size();
    }
  }

  /**
   * Index.
   *
   * @return the int
   */
  //    public int index() { //RuleClassifier        
  //        return this.index;
  //    }

  /**
   * Format date.
   *
   * @param value the value
   * @return the string
   */
  String formatDate(double value) {
    return this.m_DateFormat.format(new Date((long) value));
  }

  /**
   * Checks if is date.
   *
   * @return true, if is date
   */
  boolean isDate() {
    return isDate;
  }

  /**
   * The values string attribute.
   */
  private Map<String, Integer> valuesStringAttribute;

  /**
   * Index of value.
   *
   * @param value the value
   * @return the int
   */
  public final int indexOfValue(String value) {

    if (isNominal() == false) {
      return -1;
    }
    if (this.valuesStringAttribute == null) {
      this.valuesStringAttribute = new HashMap<String, Integer>();
      int count = 0;
      for (String stringValue : attributeValues) {
        this.valuesStringAttribute.put(stringValue, count);
        count++;
      }
    }
    Integer val = (Integer) this.valuesStringAttribute.get(value);
    
    // in case this value was not on a list of unique values of nominal attribute yet, add it
    // this means, the list of values can be extended with new entries arriving in the stream
    if (val == null) {
      int currentValueCount=this.valuesStringAttribute.size();
      this.valuesStringAttribute.put(value,currentValueCount);
      this.attributeValues.add(value);
      return currentValueCount;
    } else {
      return val.intValue();
    }
  }

  /**
   * Returns a description of this attribute in ARFF format. Quotes
   * strings if they contain whitespace characters, or if they
   * are a question mark.
   *
   * @return a description of this attribute as a string
   */
  public final String toString() {

    StringBuffer text = new StringBuffer();

    text.append(ARFF_ATTRIBUTE).append(" ").append(Utils.quote(this.name())).append(" ");

    if (this.isNominal){
      text.append('{');
      Enumeration enu =  enumerateValues();
      while (enu.hasMoreElements()) {
        text.append(Utils.quote((String) enu.nextElement()));
        if (enu.hasMoreElements())
          text.append(',');
      }
      text.append('}');
    } else if (this.isNumeric){
      text.append(ARFF_ATTRIBUTE_NUMERIC);
    } else if (this.isDate){
      text.append(ARFF_ATTRIBUTE_DATE).append(" ").append(Utils.quote(m_DateFormat.toPattern()));
    } else{
      text.append("UNKNOW");
    }

    return text.toString();
  }

  /**
   * Returns an enumeration of all the attribute's values if the
   * attribute is nominal, null otherwise.
   *
   * @return enumeration of all the attribute's values
   */
  public final /*@ pure @*/ Enumeration enumerateValues() {

    if (this.isNominal()) {
      return Collections.enumeration(this.attributeValues);
    }
    return null;
  }
}