Filter.java

package de.hftstuttgart.unifiedticketing.core;

import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * <b>Filtered Ticket Request</b><br>
 *<br>
 * This class provides a builder like interface,
 * to get a filtered list of Tickets.<br>
 * <br>
 * It provides some basic filter options by itself.
 * The request logic has to be provided from each System specific
 * implementation for it.
 *
 * @param <T> The type of Ticket this Filter implementation delivers
 * @param <F> The type of the System specific implementation of this class
 */
public abstract class Filter<T extends Ticket, F extends Filter<?,?>>
{
    private static Logger logger = Logging.getLogger(Filter.class.getName());

    protected int lastReceivedItemCount;
    protected Map<String, Object> setFilters;// = new HashMap<>();

    protected enum FilterNames
    {
        ASSIGNEEID,
        ASSIGNEENAME,
        DESCRIPTION_CONTAIN,
        DESCRIPTION_MATCH,
        IDS,
        LABELS,
        OPEN,
        PAGE,
        PAGINATION,
        TITLE_CONTAINS,
        TITLE_MATCH,
    }

    public Filter()
    {
        logger.log(Level.FINEST, String.format(
            "%s request builder started",
            this.getClass().getSimpleName()
        ));
        setFilters = new HashMap<>();

        lastReceivedItemCount = -1;
    }

    /**
     * Counter how many items received on last {@link #get()} call.
     *
     * As local filtering can lower the items delivered from {@link #get()},
     * you can't check that no more pages are available comparing the delivered item
     * count with your set page size.<br>
     *
     * @return item count received from external Ticketsystem on last call of {@link #get()}
     */
    public int getLastReceivedItemCount()
    {
        return lastReceivedItemCount;
    }

    /**
     * Add assignee id to query
     * @return this query builder
     */
    public F withAssigneeId(String id)
    {
        addToSet(FilterNames.ASSIGNEEID, this.setFilters, id);
        return (F) this;
    }

    /**
     * Add assignee name to query
     * @return this query builder
     */
    public F withAssigneeName(String name)
    {
        addToSet(FilterNames.ASSIGNEENAME, this.setFilters, name);
        return (F) this;
    }

    /**
     * adds description contain constraint
     * @param substring element to be contained in the description
     * @return this query builder
     */
    public F withDescriptionContain(String substring)
    {
        setFilters.put(FilterNames.DESCRIPTION_CONTAIN.name(), substring);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", FilterNames.DESCRIPTION_CONTAIN.name(), substring));
        return (F) this;
    }

    /**
     * regex that the whole description must match
     * @param regex fully qualified regex
     * @return this query builder
     */
    public F withDescriptionMatch(String regex)
    {
        setFilters.put(FilterNames.DESCRIPTION_MATCH.name(), regex);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", FilterNames.DESCRIPTION_MATCH.name(), regex));
        return (F) this;
    }

    /**
     * adds an ticket id to the constraint list
     * @param id
     * @return this query builder
     */
    public F withId(String id)
    {
        addToSet(FilterNames.IDS, this.setFilters, id);
        return (F) this;
    }

    /**
     * adds a constraint for only open considered tickets
     * @return this query builder
     */
    public F isOpen()
    {
        setFilters.put(FilterNames.OPEN.name(), true);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", FilterNames.OPEN.name(), true));
        return (F) this;
    }

    /**
     * adds a constraint for only closed considered tickets
     * @return this query builder
     */
    public F isClosed()
    {
        setFilters.put(FilterNames.OPEN.name(), false);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", FilterNames.OPEN.name(), false));
        return (F) this;
    }

    /**
     * add a label to the constraints list<br>
     *<br>
     * multiple calls of this delivers only tickets holding ALL given labels.
     * @param label
     * @return this query builder
     */
    public F withLabel(String label)
    {
        addToSet(FilterNames.LABELS, this.setFilters, label);
        return (F) this;
    }

    /**
     * set the page number of the pagination<br>
     *<br>
     * <b>Attention:</b> some systems paginate by default.
     * You can check that with {@link TicketSystem}s "has..." methods.
     * @param page
     * @return this query builder
     */
    public F setPage(int page)
    {
        this.setFilters.put(FilterNames.PAGE.name(), page);
        logger.log(Level.FINEST, String.format("set page: %d", page));
        return (F) this;
    }

    /**
     * defines the page size of a single pagination page<br>
     *<br>
     * <b>Attention:</b> some systems have a default in place, if nothing custom is set.
     * You can check that with {@link TicketSystem}s "has..." methods.
     * @param size
     * @return this query builder
     */
    public F setPageSize(int size)
    {
        this.setFilters.put(FilterNames.PAGINATION.name(), size);
        logger.log(Level.FINEST, String.format("set pagination size: %d", size));
        return (F) this;
    }

    /**
     * adds a constraint for title containing the given string
     * @param substring string the title must contain
     * @return this query builder
     */
    public F withTitleContain(String substring)
    {
        setFilters.put(FilterNames.TITLE_CONTAINS.name(), substring);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", FilterNames.TITLE_CONTAINS.name(), substring));
        return (F) this;
    }

    /**
     * adds a regex constraint, that the title has to match
     * @param regex fully qualified regex
     * @return this query builder
     */
    public F withTitleMatch(String regex)
    {
        setFilters.put(FilterNames.TITLE_MATCH.name(), regex);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", FilterNames.TITLE_MATCH.name(), regex));
        return (F) this;
    }

    /**
     * <b>Requesting the tickets</b><br>
     *<br>
     * This will  prepare the request according to the system specific implementation,
     * run the request, if needed post-filter the results and form it into a List
     * @return List of Tickets, matching all previously set constraints
     */
    public abstract List<T> get();

    protected static void addToSet(FilterNames filterName, Map<String, Object> map, String newValue)
    {
        logger.log(Level.FINEST, String.format("attempting to add new %s constraint", filterName.name()));
        Set<String> values;
        if (map.containsKey(filterName.name()))
        {
            logger.log(Level.FINEST, String.format("existing %s constraints found", filterName.name()));
            Object stored = map.get(filterName.name());
            if (stored instanceof Set<?>)
            {
                values = (Set<String>) stored;
            } else
            {
                logger.log(Level.WARNING, String.format(
                    "found filter object under key %s was not from Type %s but %s",
                    filterName.name(),
                    Set.class.getName(),
                    stored.getClass().getName()));

                values = new HashSet<>();
                map.put(filterName.name(), values);

                logger.log(Level.INFO, String.format(
                    "replaced wrong typed filter object under key %s with new instance of type %s",
                    filterName.name(),
                    Set.class.getName()));
            }
        } else
        {
            logger.log(Level.FINEST, String.format("no previous %s constraints found", filterName));
            values = new HashSet<>();
            map.put(filterName.name(), values);
        }

        values.add(newValue);
        logger.log(Level.FINEST, String.format("added constraint: %s %s", filterName.name(), newValue));
    }
}