/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2017. All Rights Reserved.                        */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

package edu.wpi.first.wpilibj;

import java.util.Vector;

import edu.wpi.first.wpilibj.hal.FRCNetComm.tResourceType;
import edu.wpi.first.wpilibj.hal.HAL;
import edu.wpi.first.wpilibj.networktables.NetworkTable;
import edu.wpi.first.wpilibj.tables.ITable;
import edu.wpi.first.wpilibj.tables.ITableListener;
import edu.wpi.first.wpilibj.tables.TableKeyNotDefinedException;

/**
 * The preferences class provides a relatively simple way to save important values to the roboRIO to
 * access the next time the roboRIO is booted.
 *
 * <p> This class loads and saves from a file inside the roboRIO. The user can not access the file
 * directly, but may modify values at specific fields which will then be automatically saved to the
 * file by the NetworkTables server. </p>
 *
 * <p> This class is thread safe. </p>
 *
 * <p> This will also interact with {@link NetworkTable} by creating a table called "Preferences"
 * with all the key-value pairs. </p>
 */
public class Preferences {

  /**
   * The Preferences table name.
   */
  private static final String TABLE_NAME = "Preferences";
  /**
   * The singleton instance.
   */
  private static Preferences instance;
  /**
   * The network table.
   */
  private final NetworkTable m_table;
  /**
   * Listener to set all Preferences values to persistent (for backwards compatibility with old
   * dashboards).
   */
  private final ITableListener m_listener = new ITableListener() {
    @Override
    public void valueChanged(ITable table, String key, Object value, boolean isNew) {
      // unused
    }

    @Override
    public void valueChangedEx(ITable table, String key, Object value, int flags) {
      table.setPersistent(key);
    }
  };

  /**
   * Returns the preferences instance.
   *
   * @return the preferences instance
   */
  public static synchronized Preferences getInstance() {
    if (instance == null) {
      instance = new Preferences();
    }
    return instance;
  }

  /**
   * Creates a preference class.
   */
  private Preferences() {
    m_table = NetworkTable.getTable(TABLE_NAME);
    m_table.addTableListenerEx(m_listener, ITable.NOTIFY_NEW | ITable.NOTIFY_IMMEDIATE);
    HAL.report(tResourceType.kResourceType_Preferences, 0);
  }

  /**
   * Gets the vector of keys.
   * @return a vector of the keys
   */
  public Vector getKeys() {
    Vector<String> keys = new Vector<String>();
    for (String key : m_table.getKeys()) {
      keys.add(key);
    }
    return keys;
  }

  /**
   * Puts the given string into the preferences table.
   *
   * @param key   the key
   * @param value the value
   * @throws NullPointerException if value is null
   */
  public void putString(String key, String value) {
    if (value == null) {
      throw new NullPointerException("Value is null");
    }
    m_table.putString(key, value);
    m_table.setPersistent(key);
  }

  /**
   * Puts the given int into the preferences table.
   *
   * @param key   the key
   * @param value the value
   */
  public void putInt(String key, int value) {
    m_table.putNumber(key, value);
    m_table.setPersistent(key);
  }

  /**
   * Puts the given double into the preferences table.
   *
   * @param key   the key
   * @param value the value
   */
  public void putDouble(String key, double value) {
    m_table.putNumber(key, value);
    m_table.setPersistent(key);
  }

  /**
   * Puts the given float into the preferences table.
   *
   * @param key   the key
   * @param value the value
   */
  public void putFloat(String key, float value) {
    m_table.putNumber(key, value);
    m_table.setPersistent(key);
  }

  /**
   * Puts the given boolean into the preferences table.
   *
   * @param key   the key
   * @param value the value
   */
  public void putBoolean(String key, boolean value) {
    m_table.putBoolean(key, value);
    m_table.setPersistent(key);
  }

  /**
   * Puts the given long into the preferences table.
   *
   * @param key   the key
   * @param value the value
   */
  public void putLong(String key, long value) {
    m_table.putNumber(key, value);
    m_table.setPersistent(key);
  }

  /**
   * Returns whether or not there is a key with the given name.
   *
   * @param key the key
   * @return if there is a value at the given key
   */
  public boolean containsKey(String key) {
    return m_table.containsKey(key);
  }

  /**
   * Remove a preference.
   *
   * @param key the key
   */
  public void remove(String key) {
    m_table.delete(key);
  }

  /**
   * Returns the string at the given key. If this table does not have a value for that position,
   * then the given backup value will be returned.
   *
   * @param key    the key
   * @param backup the value to return if none exists in the table
   * @return either the value in the table, or the backup
   */
  public String getString(String key, String backup) {
    return m_table.getString(key, backup);
  }

  /**
   * Returns the int at the given key. If this table does not have a value for that position, then
   * the given backup value will be returned.
   *
   * @param key    the key
   * @param backup the value to return if none exists in the table
   * @return either the value in the table, or the backup
   */
  public int getInt(String key, int backup) {
    try {
      return (int) m_table.getNumber(key);
    } catch (TableKeyNotDefinedException ex) {
      return backup;
    }
  }

  /**
   * Returns the double at the given key. If this table does not have a value for that position,
   * then the given backup value will be returned.
   *
   * @param key    the key
   * @param backup the value to return if none exists in the table
   * @return either the value in the table, or the backup
   */
  public double getDouble(String key, double backup) {
    return m_table.getDouble(key, backup);
  }

  /**
   * Returns the boolean at the given key. If this table does not have a value for that position,
   * then the given backup value will be returned.
   *
   * @param key    the key
   * @param backup the value to return if none exists in the table
   * @return either the value in the table, or the backup
   */
  public boolean getBoolean(String key, boolean backup) {
    return m_table.getBoolean(key, backup);
  }

  /**
   * Returns the float at the given key. If this table does not have a value for that position, then
   * the given backup value will be returned.
   *
   * @param key    the key
   * @param backup the value to return if none exists in the table
   * @return either the value in the table, or the backup
   */
  public float getFloat(String key, float backup) {
    try {
      return (float) m_table.getNumber(key);
    } catch (TableKeyNotDefinedException ex) {
      return backup;
    }
  }

  /**
   * Returns the long at the given key. If this table does not have a value for that position, then
   * the given backup value will be returned.
   *
   * @param key    the key
   * @param backup the value to return if none exists in the table
   * @return either the value in the table, or the backup
   */
  public long getLong(String key, long backup) {
    try {
      return (long) m_table.getNumber(key);
    } catch (TableKeyNotDefinedException ex) {
      return backup;
    }
  }

  /**
   * This function is no longer required, as NetworkTables automatically saves persistent values
   * (which all Preferences values are) periodically when running as a server.
   *
   * @deprecated backwards compatibility shim
   */
  @Deprecated
  public void save() {
  }
}