package org.rug.tracker;

import org.rug.data.smells.ArchitecturalSmell;
import org.rug.data.smells.CDSmell;

import java.util.*;


/* CURRENTLY NOT WORKING */
/**
 * A set that stores {@link LinkScoreTriple}. The set takes care of keeping only matches that maximize {@link LinkScoreTriple#getC()} score.
 * If two matches have the same score, the choice is made according to the pair that maintains type and shape.
 * This dreedy strategy guarantees the correct result because discarded links are, by definition, not optimal for linking
 * for both smells.
 * This set uses a {@link HashMap} as an underlying collection for storing objects.
 */
public class BestMatchSet implements Set<LinkScoreTriple> {

    private Set<LinkScoreTriple> triples = new LinkedHashSet<>();

    private Set<ArchitecturalSmell> current = new LinkedHashSet<>();
    private Set<ArchitecturalSmell> next = new LinkedHashSet<>();

    /**
     * Initializes this set by adding all the elements to the internal collection.
     * @param c the elements to add
     */
    public BestMatchSet(Collection<? extends LinkScoreTriple> c){
        addAll(c);
    }

    public BestMatchSet(){}

    /**
     * Returns the number of elements in this set (its cardinality).  If this
     * set contains more than {@code Integer.MAX_VALUE} elements, returns
     * {@code Integer.MAX_VALUE}.
     *
     * @return the number of elements in this set (its cardinality)
     */
    @Override
    public int size() {
        return triples.size();
    }

    /**
     * Returns {@code true} if this set contains no elements.
     *
     * @return {@code true} if this set contains no elements
     */
    @Override
    public boolean isEmpty() {
        return triples.isEmpty();
    }

    /**
     * Returns {@code true} if this set contains the specified element.
     * More formally, returns {@code true} if and only if this set
     * contains an element {@code e} such that
     * {@code Objects.equals(o, e)}.
     *
     * @param o element whose presence in this set is to be tested
     * @return {@code true} if this set contains the specified element
     * @throws ClassCastException   if the type of the specified element
     *                              is incompatible with this set
     *                              (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException if the specified element is null and this
     *                              set does not permit null elements
     *                              (<a href="Collection.html#optional-restrictions">optional</a>)
     */
    @Override
    public boolean contains(Object o) {
        return triples.contains(o);
    }

    /**
     * Returns an iterator over the elements in this set.  The elements are
     * returned in no particular order (unless this set is an instance of some
     * class that provides a guarantee).
     *
     * @return an iterator over the elements in this set
     */
    @Override
    public Iterator<LinkScoreTriple> iterator() {
        return triples.iterator();
    }

    /**
     * Returns an array containing all of the elements in this set.
     * If this set makes any guarantees as to what order its elements
     * are returned by its iterator, this method must return the
     * elements in the same order.
     *
     * <p>The returned array will be "safe" in that no references to it
     * are maintained by this set.  (In other words, this method must
     * allocate a new array even if this set is backed by an array).
     * The caller is thus free to modify the returned array.
     *
     * <p>This method acts as bridge between array-based and collection-based
     * APIs.
     *
     * @return an array containing all the elements in this set
     */
    @Override
    public Object[] toArray() {
        return triples.toArray();
    }

    /**
     * Returns an array containing all of the elements in this set; the
     * runtime type of the returned array is that of the specified array.
     * If the set fits in the specified array, it is returned therein.
     * Otherwise, a new array is allocated with the runtime type of the
     * specified array and the size of this set.
     *
     * <p>If this set fits in the specified array with room to spare
     * (i.e., the array has more elements than this set), the element in
     * the array immediately following the end of the set is set to
     * {@code null}.  (This is useful in determining the length of this
     * set <i>only</i> if the caller knows that this set does not contain
     * any null elements.)
     *
     * <p>If this set makes any guarantees as to what order its elements
     * are returned by its iterator, this method must return the elements
     * in the same order.
     *
     * <p>Like the {@link #toArray()} method, this method acts as bridge between
     * array-based and collection-based APIs.  Further, this method allows
     * precise control over the runtime type of the output array, and may,
     * under certain circumstances, be used to save allocation costs.
     *
     * <p>Suppose {@code x} is a set known to contain only strings.
     * The following code can be used to dump the set into a newly allocated
     * array of {@code String}:
     *
     * <pre>
     *     String[] y = x.toArray(new String[0]);</pre>
     * <p>
     * Note that {@code toArray(new Object[0])} is identical in function to
     * {@code toArray()}.
     *
     * @param a the array into which the elements of this set are to be
     *          stored, if it is big enough; otherwise, a new array of the same
     *          runtime type is allocated for this purpose.
     * @return an array containing all the elements in this set
     * @throws ArrayStoreException  if the runtime type of the specified array
     *                              is not a supertype of the runtime type of every element in this
     *                              set
     * @throws NullPointerException if the specified array is null
     */
    @Override
    public <T> T[] toArray(T[] a) {
        return triples.toArray(a);
    }

    /**
     * Add to the set only triples that represent tracking links among smells that are not already present.
     * If a smell is already linked within this collection, the link with the highest score that preservers
     * both type, and shape in case of CDSmells, is kept as the best linking.
     * @param otherTriple the triple to add
     * @return true if the underlying collection was modified as a result of the call
     *         to this method, or false otherwise.
     */
    @Override
    public boolean add(LinkScoreTriple otherTriple) {
        if (current.contains(otherTriple.getA()) || next.contains(otherTriple.getB())){
            var currentTripleOpt = triples.stream()
                    .filter(t -> t.getA().equals(otherTriple.getA()) || t.getB().equals(otherTriple.getB()))
                    .findFirst();
            assert currentTripleOpt.isPresent(); // this should be always true
            var currentTriple = currentTripleOpt.get();
            int comparison = currentTriple.compareTo(otherTriple);
            if (comparison == 0){
                var currentMaintainsType = currentTriple.getA().getType() == currentTriple.getB().getType();
                var otherMaintainsType = otherTriple.getA().getType() == otherTriple.getB().getType();
                if (!currentMaintainsType && otherMaintainsType){
                    replace(currentTriple, otherTriple);
                    return true;
                } else if (currentMaintainsType && otherMaintainsType) {
                    if (currentTriple.getA() instanceof CDSmell &&
                            currentTriple.getB() instanceof CDSmell &&
                            otherTriple.getA() instanceof CDSmell &&
                            otherTriple.getB() instanceof CDSmell) {
                        var currentMaintainsShape = ((CDSmell) currentTriple.getA()).getShape() == ((CDSmell) currentTriple.getB()).getShape();
                        var otherMaintainsShape = ((CDSmell) currentTriple.getA()).getShape() == ((CDSmell) currentTriple.getB()).getShape();
                        if (!currentMaintainsShape && otherMaintainsShape) {
                            replace(currentTriple, otherTriple);
                            return true;
                        }
                    }
                }
            }else if (comparison < 0){
                replace(currentTriple, otherTriple);
                return true;
            }
            return false;
        }else {
            current.add(otherTriple.getA());
            next.add(otherTriple.getB());
            return triples.add(otherTriple);
        }
    }

    /**
     * Removes the specified element from this set if it is present
     * (optional operation).  More formally, removes an element {@code e}
     * such that
     * {@code Objects.equals(o, e)}, if
     * this set contains such an element.  Returns {@code true} if this set
     * contained the element (or equivalently, if this set changed as a
     * result of the call).  (This set will not contain the element once the
     * call returns.)
     *
     * @param o object to be removed from this set, if present
     * @return {@code true} if this set contained the specified element
     * @throws ClassCastException            if the type of the specified element
     *                                       is incompatible with this set
     *                                       (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException          if the specified element is null and this
     *                                       set does not permit null elements
     *                                       (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws UnsupportedOperationException if the {@code remove} operation
     *                                       is not supported by this set
     */
    @Override
    public boolean remove(Object o) {
        return triples.remove(o);
    }

    /**
     * Returns {@code true} if this set contains all of the elements of the
     * specified collection.  If the specified collection is also a set, this
     * method returns {@code true} if it is a <i>subset</i> of this set.
     *
     * @param c collection to be checked for containment in this set
     * @return {@code true} if this set contains all of the elements of the
     * specified collection
     * @throws ClassCastException   if the types of one or more elements
     *                              in the specified collection are incompatible with this
     *                              set
     *                              (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException if the specified collection contains one
     *                              or more null elements and this set does not permit null
     *                              elements
     *                              (<a href="Collection.html#optional-restrictions">optional</a>),
     *                              or if the specified collection is null
     * @see #contains(Object)
     */
    @Override
    public boolean containsAll(Collection<?> c) {
        return triples.containsAll(c);
    }

    /**
     * Adds all of the elements in the specified collection to this set if
     * they're not already present (optional operation).  If the specified
     * collection is also a set, the {@code addAll} operation effectively
     * modifies this set so that its value is the <i>union</i> of the two
     * sets.  The behavior of this operation is undefined if the specified
     * collection is modified while the operation is in progress.
     *
     * @param c collection containing elements to be added to this set
     * @return {@code true} if this set changed as a result of the call
     * @throws UnsupportedOperationException if the {@code addAll} operation
     *                                       is not supported by this set
     * @throws ClassCastException            if the class of an element of the
     *                                       specified collection prevents it from being added to this set
     * @throws NullPointerException          if the specified collection contains one
     *                                       or more null elements and this set does not permit null
     *                                       elements, or if the specified collection is null
     * @throws IllegalArgumentException      if some property of an element of the
     *                                       specified collection prevents it from being added to this set
     * @see #add(LinkScoreTriple)
     */
    @Override
    public boolean addAll(Collection<? extends LinkScoreTriple> c) {
        boolean modified = false;
        for(LinkScoreTriple t : c){
            modified = modified || this.add(t);
        }
        return modified;
    }

    /**
     * Retains only the elements in this set that are contained in the
     * specified collection (optional operation).  In other words, removes
     * from this set all of its elements that are not contained in the
     * specified collection.  If the specified collection is also a set, this
     * operation effectively modifies this set so that its value is the
     * <i>intersection</i> of the two sets.
     *
     * @param c collection containing elements to be retained in this set
     * @return {@code true} if this set changed as a result of the call
     * @throws UnsupportedOperationException if the {@code retainAll} operation
     *                                       is not supported by this set
     * @throws ClassCastException            if the class of an element of this set
     *                                       is incompatible with the specified collection
     *                                       (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException          if this set contains a null element and the
     *                                       specified collection does not permit null elements
     *                                       (<a href="Collection.html#optional-restrictions">optional</a>),
     *                                       or if the specified collection is null
     * @see #remove(Object)
     */
    @Override
    public boolean retainAll(Collection<?> c) {
        return triples.retainAll(c);
    }

    /**
     * Removes from this set all of its elements that are contained in the
     * specified collection (optional operation).  If the specified
     * collection is also a set, this operation effectively modifies this
     * set so that its value is the <i>asymmetric set difference</i> of
     * the two sets.
     *
     * @param c collection containing elements to be removed from this set
     * @return {@code true} if this set changed as a result of the call
     * @throws UnsupportedOperationException if the {@code removeAll} operation
     *                                       is not supported by this set
     * @throws ClassCastException            if the class of an element of this set
     *                                       is incompatible with the specified collection
     *                                       (<a href="Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException          if this set contains a null element and the
     *                                       specified collection does not permit null elements
     *                                       (<a href="Collection.html#optional-restrictions">optional</a>),
     *                                       or if the specified collection is null
     * @see #remove(Object)
     * @see #contains(Object)
     */
    @Override
    public boolean removeAll(Collection<?> c) {
        return triples.retainAll(c);
    }

    /**
     * Removes all of the elements from this set (optional operation).
     * The set will be empty after this call returns.
     *
     * @throws UnsupportedOperationException if the {@code clear} method
     *                                       is not supported by this set
     */
    @Override
    public void clear() {
        triples.clear();
    }

    private void replace(LinkScoreTriple current, LinkScoreTriple other){
        this.current.remove(current.getA());
        this.next.remove(current.getB());
        this.triples.remove(current);

        this.current.add(other.getA());
        this.next.add(other.getB());
        this.triples.add(other);
    }
}
