package myhw2.data;

import java.util.Map;
import java.util.HashMap;
import java.util.Comparator;
import java.util.Collections;
import java.util.Iterator;

/**
 * Implementation of Inventory interface.
 * @see Data
 */
final class InventorySet implements Inventory {
        // Chose to use Map of Record, rather than RecordObj, because of
        // Java's broken generic types.  The story is too sad to retell, but
        // involves the fact that Iterable<? extends Record> is not a valid
        // type, and that Iterator<RecordObj> is not a subtype of
        // Iterator<Record>.
        //
        // Seems like the best approach for Java generics is to use the
        // external representation internally and downcast when necessary.
        private final Map<Video,Record> data;

        InventorySet() {
                data = new HashMap<Video,Record>();
        }

        public int size() {
                // TODO
                return 0;
        }

        public Record get(Video v) {
                // TODO
                return null;
        }

        public Iterator<Record> iterator() {
                return Collections.unmodifiableCollection(data.values()).iterator();
        }

        public Iterator<Record> iterator(Comparator<Record> comparator) {
                // Hint: Look at Collections.sort
                // TODO
                return null;
        }

        /**
         * Add or remove copies of a video from the inventory.
         * If a video record is not already present (and change is
         * positive), a record is created.
         * If a record is already present, <code>numOwned</code> is
         * modified using <code>change</code>.
         * If <code>change</code> brings the number of copies to be zero,
         * the record is removed from the inventory.
         * @param video the video to be added.
         * @param change the number of copies to add (or remove if negative).
         * @throws IllegalArgumentException if video null, change is zero, if attempting to remove more copies than are owned, or if attempting to remove copies that are checked out.
         */
        void addNumOwned(Video video, int change) {
                // TODO
        }

        /**
         * Check out a video.
         * @param video the video to be checked out.
         * @throws IllegalArgumentException if video has no record or numOut
         * equals numOwned.
         */
        void checkOut(Video video) {
                // TODO
        }

        /**
         * Check in a video.
         * @param video the video to be checked in.
         * @throws IllegalArgumentException if video has no record or numOut
         * non-positive.
         */
        void checkIn(Video video) {
                // TODO
        }

        /**
         * Remove all records from the inventory.
         */
        void clear() {
                // TODO
        }

        public String toString() {
                StringBuilder buffer = new StringBuilder();
                buffer.append("Database:\n");
                for (Record r : data.values()) {
                        buffer.append("  ");
                        buffer.append(r);
                        buffer.append("\n");
                }
                return buffer.toString();
        }


        /**
         * Implementation of Record interface.
         *
         * <p>This is a utility class for Inventory.  Fields are mutable and
         * package-private.</p>
         *
         * <p><b>Class Invariant:</b> No two instances may reference the same Video.</p>
         *
         * @see Record
         */
        private static final class RecordObj implements Record {
                Video video;    // the video
                int numOwned;   // copies owned
                int numOut;     // copies currently rented
                int numRentals; // total times video has been rented

                RecordObj(Video video, int numOwned, int numOut, int numRentals) {
                        this.video = video;
                        this.numOwned = numOwned;
                        this.numOut = numOut;
                        this.numRentals = numRentals;
                }
                public Video video() {
                        return video;
                }
                public int numOwned() {
                        return numOwned;
                }
                public int numOut() {
                        return numOut;
                }
                public int numRentals() {
                        return numRentals;
                }
                public String toString() {
                        StringBuilder buffer = new StringBuilder();
                        buffer.append(video);
                        buffer.append(" [");
                        buffer.append(numOwned);
                        buffer.append(",");
                        buffer.append(numOut);
                        buffer.append(",");
                        buffer.append(numRentals);
                        buffer.append("]");
                        return buffer.toString();
                }
        }
}