/*
 * File: ToDo.java
 * Copy: Copyright (c)  by David G. Green, All Rights Reserved
 * Vers: 1.0.5 24 Jan 2014 dgg -- update javadoc content
 * Vers: 1.0.4 26 Dec 2006 dgg -- fixed typo
 * Vers: 1.0.3 07 Oct 2006 dgg -- original coding
 */

import java.util.Date;
import java.text.DateFormat;
import java.text.ParseException;

/**
 * Model a ToDo item
 */
public class ToDo {
    
    // Date formatter
    private static DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT);
    
    private static long serialNumberCounter = 1;  // next serial number to assign
    
    private String description;            // Description of todo
    private boolean complete = false;      // Is todo complete?
    private long serialNumber;             // Serial number of this to do
    private long lastModified;             // Time stamp corresponding to last change

    /**
     * Priority values
     */
    public static final int LOW = 0;
    public static final int NORMAL = 1;
    public static final int HIGH = 2;

    private int priority = NORMAL;         // Priority of the ToDo
    private Date dueDate;                  // Due date
    private String context;                // context category
    
    
   /**
    * Constructor to build minimal ToDo given a text description of the ToDo
    */
    public ToDo(String description) {
        this.serialNumber = serialNumberCounter++;
        this.description = description;
        updateLastModified();
    }

    /**
     * Constructor - make a new ToDo using the values of an existing ToDo (duplicates serialNumber)
     */
    public ToDo(ToDo todo) {
        this.complete = todo.complete;
        this.context = todo.context;
        this.description = todo.description;
        this.dueDate = todo.dueDate;
        this.lastModified = todo.lastModified;
        this.priority = todo.priority;
        this.serialNumber = todo.serialNumber;
    }

    /**
     * Query whether the ToDo is complete or not
     * @return the complete
     */
    public boolean isComplete() {
        return complete;
    }


    /**
     * Command to set the complete status of a ToDo
     * @param complete the complete to set
     */
    public void setComplete(boolean complete) {
        this.complete = complete;
        updateLastModified();
    }


    /**
     * Query to obtain the description of the ToDo
     * @return the description
     */
    public String getDescription() {
        return description;
    }


    /**
     * Command to set (change) the description of the ToDo
	 * @param description the description to set
     */
    public void setDescription(String description) {
        this.description = description;
        updateLastModified();
    }


    /**
     * Query to retrieve the priority of the ToDo
     * @return the priority
     */
    public int getPriority() {
        return priority;
    }
    
    /**
     * Query to determine if this ToDo is same as the supplied ToDo
     *    where ToDo's are considered the same if they have the 
     *    same serial number and same last modified values
     * @return ToDo's are equal (same serial number and last modified)
     */
    public boolean equals(Object obj) {
	    // To override the inherited equals method, the equals method 
	    // must take an Object as a parameter
		// if same object return true
	    if ( this == obj )
			return true; 
		// if supplied object is not a ToDo return false
        if ( ! (obj instanceof ToDo) ) 
			return false;
		ToDo todo = (ToDo) obj;
		// compare the attributes per spec
        return this.serialNumber == todo.serialNumber && this.lastModified == todo.lastModified;
    }
    
    /**
     * Query to determin if this ToDo has "all" the same values as 
     * @return ToDo's are same attributes (from cloning or synchronizing)
     */
    public boolean same(ToDo todo) {
        return this.complete == todo.complete &&
               this.context == todo.context &&
               this.description == todo.description &&
               this.dueDate == todo.dueDate &&
               this.lastModified == todo.lastModified &&
               this.priority == todo.priority &&
               this.serialNumber == todo.serialNumber ;
    }

    /**
     * Command to set (change) the priority of a ToDo
     * @param priority the priority to set  (ToDo.LOW, ToDo.NORMAL, ToDo.HIGH)
     */
    public void setPriority(int priority) {
        if (priority == ToDo.LOW || priority == ToDo.NORMAL || priority == ToDo.HIGH ) {
            this.priority = priority;
            updateLastModified();
        }
    }


    /**
     * Query to retrieve the serialNumberCount of the class.  The next
     *   ToDo will have this number as its serial number 
     * @return the serialNumberCounter
     */
    public static long getSerialNumberCounter() {
        return serialNumberCounter;
    }


    /**
     * Query retrieve the timestamp corresponding to when the ToDo was 
 	 * last modified
     * @return the lastModified
     */
    public long getLastModified() {
        return lastModified;
    }


    /**
     * Query to get the serialNumber of the ToDo
     * @return the serialNumber
     */
    public long getSerialNumber() {
        return serialNumber;
    }

    /**
	 * Query to return the context of the ToDo
     * @return the context
     */
    public String getContext() {
        return context;
    }


    /**
     * Command to set the context of the ToDo
     * @param context the context to set
     */
    public void setContext(String context) {
        this.context = context;
        updateLastModified();
    }


    /**
     * Query to retrieve the due date of the ToDo
     * @return the dueDate
     */
    public Date getDueDate() {
        return dueDate;
    }


    /**
     * Command to set the due date of the ToDo
     * @param dueDate the dueDate to set
     */
    public void setDueDate(Date dueDate) {
        // round to a day
        this.dueDate = truncateDate(dueDate);
        updateLastModified();
    }
    
   /**
     * If presented two ToDo's with the same serial number, 
     * update the older ToDo to match other ToDo
     * @param a - first ToDo
     * @param b - second ToDo
     */
    public static void sync( ToDo a, ToDo b) {
        if ( a.getSerialNumber() != b.getSerialNumber() )
            return;
        if ( a.getLastModified() == b.getLastModified() )
            return;
        if ( a.getLastModified() > b.getLastModified() )
            update( a, b );
        else
            update( b, a );
    }
    
    // update the "to" ToDo from the "from" ToDo
    private static void update( ToDo from, ToDo to) {
        to.complete = from.complete;
        to.context = from.context;
        to.description = from.description;
        to.dueDate = from.dueDate;
        to.lastModified = from.lastModified;
        to.priority = from.priority;
     }
 
    /*
     * Command to update the lastModified attribute to now 
     */
    private void updateLastModified() {
        this.lastModified = (new Date()).getTime();
    }
    
    /**
     * Query to return a simple string representation of the ToDo
     * @return [ ] description            -or-
     *         [X] description            -or-
     *         [ ] description Due: date  -or-
     *         [X] description Due: date
     */
    public String toString() {
        String toDo = complete ? "[X] " : "[ ] ";
        toDo += description ;
        if ( dueDate != null ) 
            toDo += " Due: " + df.format(dueDate);
        return toDo;
    }

    /**
	 * Query to determine if the ToDo is overdue or not.  It is overdue
	 * if the due date is earlier (at least one day in current time zone)
	 * than the supplied date
     * @param now
     * @return whether or not the supplied date is later (in days) than todo due date
     */
    public boolean isOverDue(Date now) {
        // check to see if the due date day has past
        return ( truncateDate(now).getTime() > dueDate.getTime() );
    }
    
    // truncate date in current timezone to be 0h 0m 0s 0 ms
    private Date truncateDate(Date aDate) {
        try {
            return df.parse(df.format(aDate));
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
     
}