import java.text.ParseException;
import java.time.LocalDate;
import java.util.ArrayList;
import java.util.Date;

/**
 * LoanRequestQueue class, which deals with system for reserving resources which are currently all in use
 * @author John-Mark Strickland, W J Buchanan
 */
public class LoanRequestQueue {

    private static ArrayList<Queue> queues = new ArrayList<>();
    private static Inventory inv = new Inventory();

    /**
     * Gets a list of all resources a user has requested
     * @param username The username to filter by
     * @return list of resource names
     */
    public static ArrayList<String> requestedItems(String username) {
    	ArrayList<String> result = new ArrayList<String>();
    	for (int i = 0; i < queues.size(); i ++) {
    		Queue current = queues.get(i);
    		if (current.containsUser(username)) {
    			result.add(inv.getTitle(current.getResourceIDQueue()));
    		}
    	}
    	return result;
    }

    /**
     * Gets a list of all resources a user has reserved (front of queue)
     * @param username The username to filter by
     * @return list of resource names
     */
    public static ArrayList<String> reservedItems(String username) {
    	ArrayList<String> result = new ArrayList<String>();
    	for (int i = 0; i < queues.size(); i ++) {
    		Queue current = queues.get(i);
    		if (((User)current.peek()).getUsername().equals(username)) {
    			result.add(inv.getTitle(current.getResourceIDQueue()));
    		}
    	}
    	return result;
    }

    /**
     * Removes the Front element of the queue
     * @param rID Specifies the queue to modify
     */
    public static void removeHead(String rID) {
    	for (int i = 0; i < queues.size(); i ++) {
    		if (rID.equals(queues.get(i).getResourceIDQueue())) {
    			queues.get(i).dequeue();
    		}
    	}
    }

    /**
     * Removes an entire queue instance
     * @param rID Specifies queue to modify
     */
    public static void removeQueue(String rID) {
    	for (int i = 0; i < queues.size(); i ++) {
    		if (rID.equals(queues.get(i).getResourceIDQueue())) {
    			queues.remove(i);
    		}
    	}
    }

    /**
     * Returns boolean of whether a queue exists
     * @param rID Specifies queue to search for
     * @return true if queue is found, false otherwise
     */
    public static boolean queueExists(String rID) {
    	for (int i = 0; i < queues.size(); i ++) {
    		if (rID.equals(queues.get(i).getResourceIDQueue())) {
    			return true;
    		}
    	}
    	return false;
    }

    /**
     * Returns the queue with a given rID
     * @param rID Specifies the queue to return
     * @return The queue with the matching rID
     */
    public static Queue getQueue(String rID) {
    	for (int i = 0; i < queues.size(); i ++) {
    		if (rID.equals(queues.get(i).getResourceIDQueue())) {
    			return queues.get(i);
    		}
    	}
    	return null;
    }

    /**
     * Alerts a user that the resource they have requested has been returned
     * and is ready to collect.
     * @param user The User to be alerted.
     * @param resourceID The Resource to which the Alert refers.
     */
    public static void alertUserReturn(User user, String resourceID){
    	user.addAlert(new Alert(2, inv.getTitle(resourceID)));
    }

    /**
     * Alerts a user that a due date has been set on their resource as another
     * user has requested it.
     * @param user The User to be alerted.
     * @param resourceID The Resource to which the Alert refers.
     */
    public static void alertResourceNeedsReturing(User user, String resourceID){
    	user.addAlert(new Alert(1, inv.getTitle(resourceID)));
    }

    /**
     * This function try's to either locate the queue if one has been created for a resource
     * or will create a new one if one has not been created
     * @param resourceID the ID to be checked against other queues
     * @param userProfile the profile of the user who requests a resource
     */
    public static void addResourceRequest(String resourceID, User userProfile) {
    	if (!queueExists(resourceID)) {
    		Queue queue = new Queue(resourceID);
            queue.enqueue(userProfile);
            queues.add(queue);
    	} else {
    		for (int i = 0; i < queues.size(); i++) {
	    		if (queues.get(i).getResourceIDQueue() == resourceID) {
	    			queues.get(i).enqueue(userProfile);
	    		}
	    	}
    	}
    	System.out.println("(true) Resource Requested: " + resourceID + " | " + userProfile.getUsername());
    	//calculateDueDate(resourceID, userProfile);
    }

    public static void calculateDueDate(String resourceID, User userProfile) {

    	//sets due date and notifies current loaner
    	String loanID = LoanRecord.getLID(userProfile.getUsername(), resourceID);
    	if(LoanRecord.getDueDate(loanID) == null) {
	    	Date date = LoanRecord.getDateSet(loanID);
	    	try {
				date = DateHandler.getDateFormat().parse(LocalDate.parse(date.toString()).
						plusDays(inv.getDuration(loanID)).toString());
			} catch (ParseException e) {
				e.printStackTrace();
			}
	    	boolean before = true;
			try {
				before = date.before(DateHandler.getDateFormat().parse(DateHandler.currentDateString()));
			} catch (ParseException e) {
				e.printStackTrace();
			}
	    	if (before) {
	    		LoanRecord.setDueDate(loanID, (LocalDate.parse(DateHandler.currentDateString()).
	    				plusDays(1)).toString());
	    	} else {
	    		LoanRecord.setDueDate(loanID, date.toString());
	    	}
	    	Alert alert = new Alert(1, resourceID);
	    	System.out.println("Alert sent to : " + userProfile.getUsername());
    	}
    }
}