package myhw3.data;

import java.util.Map;
import myhw3.command.CommandHistory;
import java.util.Comparator;
import java.util.Collections;
import java.util.Iterator;

/**
 * Implementation of Inventory interface.
 * @see Data
 */
final class InventorySet implements Inventory {
        private Map<Video,Record> data;
        private final CommandHistory history;

        InventorySet() {
                // TODO
                this.data = null;
                this.history = null;
                 
        }

        /**
         * If <code>record</code> is null, then delete record for <code>video</code>;
         * otherwise replace record for <code>video</code>.
         */
        void replaceEntry(Video video, Record record) {
                data.remove(video);
                if (record != null)
                        data.put(video,record);
        }

        /**
         * Overwrite the map.
         */
        void replaceMap(Map<Video,Record> data) {
                this.data = data;
        }

        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 boolean undo() {
                return history.undo();
        }

        public boolean redo() {
                return history.redo();
        }

        public Iterator<Record> iterator(Comparator<Record> comparator) {
                // 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).
         * @return A copy of the previous record for this video (if any)
         * @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.
         */
        Record addNumOwned(Video video, int change) {
                // TODO
                return null;
        }

        /**
         * Check out a video.
         * @param video the video to be checked out.
         * @return A copy of the previous record for this video
         * @throws IllegalArgumentException if video has no record or numOut
         * equals numOwned.
         */
        Record checkOut(Video video) {
                // TODO
                return null;
        }

        /**
         * Check in a video.
         * @param video the video to be checked in.
         * @return A copy of the previous record for this video
         * @throws IllegalArgumentException if video has no record or numOut
         * non-positive.
         */
        Record checkIn(Video video) {
                Record r = data.get(video);
                if (r == null || r.numOut() == 0)
                        throw new IllegalArgumentException();
                data.put(video, new RecordObj(video, r.numOwned(), r.numOut()-1, r.numRentals()));
                return r;
        }

        /**
         * Remove all records from the inventory.
         * @return A copy of the previous inventory as a Map
         */
        Map<Video,Record> clear() {
                // TODO
                return null;
        }

        /**
         * Return a reference to the history.
         */
        CommandHistory getHistory() {
                // TODO
                return null;
        }

        public String toString() {
                StringBuilder buffer = new StringBuilder();
                buffer.append("Database:\n");
                Iterator<Record> i = data.values().iterator();
                while (i.hasNext()) {
                        buffer.append("  ");
                        buffer.append(i.next());
                        buffer.append("\n");
                }
                return buffer.toString();
        }


        /**
         * Implementation of Record interface.
         *
         * <p>This is a utility class for Inventory.  Fields are immutable 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 {
                final Video video; // the video
                final int numOwned;   // copies owned
                final int numOut;     // copies currently rented
                final 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();
                }
        }
}