package server;

import java.util.*;

import shared.*;
import shared.remotecall.*;

/**
 * A object of this class encapsulates the whole calendar database on the server side.
 * This class is used for getting/modifying and adding/removing of calendar events.
 * @author buetow
 * 
 */
public final class CalendarDatabase {
	private Vector vecCategories;
	private HashMap mapEvents;
	private HashMap mapCategories;
	
	/**
	 * Simple constructur. Creates a calendar database.
	 * @param vecCategories Specifies the vector of CalendarCategory objects for initial database content.
	 */
	public CalendarDatabase(Vector vecCategories) {
		this.vecCategories = vecCategories;
		initializeMaps();
	}

	/**
	 * Initializes a private hash map so that the server can access events by their id numbers very fast.
	 */
	private void initializeMaps() {
		this.mapEvents = new HashMap();
		this.mapCategories = new HashMap();
		
		Enumeration enumCategory = vecCategories.elements();
		while (enumCategory.hasMoreElements()) {
			CalendarCategory category = (CalendarCategory) enumCategory.nextElement();
			mapCategories.put(category.getName(), category);
			
			Vector vecEvents = category.getEvents();
			Enumeration enumEvents = vecEvents.elements();
			while (enumEvents.hasMoreElements()) {
				CalendarEvent event = (CalendarEvent) enumEvents.nextElement();
				mapEvents.put(new Integer(event.getEventID()), event);
			}
		}
	}

	/**
	 * Returns a specific calendar event using fast hash lookup.
	 * @param iEventID Specifies the ID of the calendar event to lookup.
	 * @return Returns the requested calendar event.
	 */
	public CalendarEvent getEvent(int iEventID) {
		return (CalendarEvent) mapEvents.get(new Integer(iEventID));
	}

	/**
	 * Returns a specific calendar category using fast hash lookup.
	 * @param sCategoryName Specifies the name of the calendar category to lookup.
	 * @return Returns the requested calendar category.
	 */
	public CalendarCategory getCategory(String sCategoryName) {
		return (CalendarCategory) mapCategories.get(sCategoryName);
	}

	/**
	 * Gets all calendar categories.
	 * @return Returns a Vector of all available CalendarCategory objects.
	 */
	public Vector getCategories() {
		return vecCategories;
	}

	/**
	 * This method returns a Vector of all available calendar events.
	 * @return Returns all available CalendarEvent objects of the database.
	 */
	public Vector getAllEvents() {
		MyVector vecAllEvents = new MyVector();
		Enumeration enumCategories = vecCategories.elements();
		
		while (enumCategories.hasMoreElements()) {
			CalendarCategory category = (CalendarCategory) enumCategories.nextElement();
			vecAllEvents.appendVector(category.getEvents());
		}
		
		return vecAllEvents;
	}
	
	/**
	 * This method looks for all calendar events which match the a given client request.
	 * @param clientRequest Specifies the client request sent by the calendar client.
	 * @return Returns a Vector of all matching CalendarEvent objects.
	 */
	public Vector getMatchingEvents(ClientRequest clientRequest) {
		MyVector vecEvents = new MyVector();
		int iNumEventsToRequest = clientRequest.getNumEventsToRequest();

		Enumeration enumCategories = vecCategories.elements();
		while (enumCategories.hasMoreElements()) {
			CalendarCategory category = (CalendarCategory) enumCategories.nextElement();
			Vector vecNewEvents = category.getMatchingEvents(clientRequest);
			vecEvents.appendVector(vecNewEvents);
			
			if (iNumEventsToRequest > -1) { 
				if (iNumEventsToRequest == vecEvents.size()) 
					break;
				
			} else {
				clientRequest.setNumEventsToRequest(iNumEventsToRequest - vecNewEvents.size());
			}
			
		}

		return vecEvents;
	}

	/**
	 * This method adds a calendar event to the calendar database.
	 * @param clientRequest Specifies the client request sent by the netcalendar client. Its containing the new event to add.
	 */
	public void addEvent(ClientRequest clientRequest) {
		CalendarEvent event = clientRequest.getEvent();
		String sCategoryName = event.getCategoryName();
		CalendarCategory category = getCategory(sCategoryName);

		// Check if the have to create a new category
		if (category == null) {
			category = new CalendarCategory(sCategoryName);
			mapCategories.put(sCategoryName, category);
			vecCategories.add(category);
		}

		category.addEvent(event);
		category.setHasChanged(true);
		event.setCategory(category);
		mapEvents.put(new Integer(event.getEventID()), event);
	}
	
	/**
	 * This method modifies an calendar event of the calendar database.
	 * @param clientRequest Specifies the client request sent by the calendar client.
	 */
	public void modifyEvent(ClientRequest clientRequest) {
		CalendarEvent newEvent = clientRequest.getEvent();
		CalendarEvent orgEvent = getEvent(newEvent.getEventID());

		// If the event doesnt exist any more, recreate it
		if (orgEvent == null) {
			clientRequest.setEvent(newEvent);
			addEvent(clientRequest);
			return;
		}
		
		orgEvent.setDate(newEvent.getDate());
		orgEvent.setYearly(newEvent.isYearly());
		orgEvent.setDescription(newEvent.getDescription());
		orgEvent.setPlace(newEvent.getPlace());
		
		// Modify the events category
		if (!orgEvent.getCategoryName().equals(newEvent.getCategoryName())) {
			String sNewCategoryName = newEvent.getCategoryName();
			
			// First remove the event from its current category
			orgEvent.removeFromCurrentCategory();
			CalendarCategory category = getCategory(sNewCategoryName);

			if (category == null) {
				category = new CalendarCategory(sNewCategoryName);
				mapCategories.put(sNewCategoryName, category);
				vecCategories.add(category);
			}

			category.addEvent(orgEvent);
			category.setHasChanged(true);
			orgEvent.setCategory(category);
			
		} else {
			orgEvent.getCategory().setHasChanged(true);
		}
	}

	/**
	 * This method deletes a calendar event of the calendar database. If the specified calendar event doesnt
	 * exist eny more, nothing will be changed.
	 * @param clientRequest Specifies the client request sent by the netcalendar client.
	 */
	public void deleteEvent(ClientRequest clientRequest) {
		// Get the server side reference of the calendar event
		CalendarEvent event = getEvent(clientRequest.getEvent().getEventID());
		
		if (event != null) {
			event.getCategory().setHasChanged(true);
			event.removeFromCurrentCategory();
			mapEvents.remove(new Integer(event.getEventID()));
		}
	}
	
	/**
	 * This method renames a calendar category.
	 * @param clientRequest Specifies the client request sent by the netcalendar client.
	 */
	public void renameCategory(ClientRequest clientRequest) {
		String sOldCategoryName = clientRequest.getEvent().getCategoryName();
		CalendarCategory category = getCategory(sOldCategoryName);

		if (category == null)
			return;

		String sNewCategoryName = clientRequest.getString();

		if (sOldCategoryName.equals(sNewCategoryName))
			return;
		
		mapCategories.remove(sOldCategoryName);

		category.setName(sNewCategoryName);

		Vector vecEvents = category.getEvents();
		Enumeration enumEvents = vecEvents.elements();
		while (enumEvents.hasMoreElements()) {
			CalendarEvent event = (CalendarEvent) enumEvents.nextElement();
			event.setCategoryName(sNewCategoryName);
		}

		// Check if the category exists already
		CalendarCategory categoryExists = getCategory(sNewCategoryName);
		
		if (categoryExists == null) {
			mapCategories.put(category.getName(), category);
		} else {
			vecCategories.remove(category);
			categoryExists.merge(category);
		}

	}
	
	/**
	 * This method daletes a calendar category.
	 * @param clientRequest Specifies the client request sent by the netcalendar client.
	 */
	public void deleteCategory(ClientRequest clientRequest) {
		String sCategoryName = clientRequest.getEvent().getCategoryName();
		CalendarCategory category = getCategory(sCategoryName);

		if (category == null)
			return;

		mapCategories.remove(sCategoryName);
		vecCategories.remove(category);
		category.deleteDatabaseFile();
	}
	
	/**
	 * This method flushes all the changed calendar categories of the calendar database to the filesystem.
	 */
	public void flush() {
		Enumeration enumCategories = vecCategories.elements();
		
		while (enumCategories.hasMoreElements()) {
			CalendarCategory category = (CalendarCategory) enumCategories.nextElement();
			if (category.hasChanged())
				category.flush();
		}
		
		Main.execExternalCommand(Config.getStringValue("server_updatedb_command"));
	}
	
}