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Datastructures and utility classes for non-negative integers
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/*
 * Copyright (C) 2017 Tobias Meggendorfer
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */

package de.tum.in.naturals.set;

import it.unimi.dsi.fastutil.ints.IntCollection;
import it.unimi.dsi.fastutil.ints.IntIterator;
import it.unimi.dsi.fastutil.ints.IntIterators;
import it.unimi.dsi.fastutil.ints.IntSortedSet;
import java.util.Collection;
import java.util.NoSuchElementException;
import java.util.SortedSet;

final class FixedSizeNatBitSet extends AbstractBoundedNatBitSet {
    private final boolean complement;
    private final FixedSizeNatBitSet complementView;

    FixedSizeNatBitSet(int domainSize) {
        super(domainSize);
        if (domainSize == 0) {
            complement = true;
            complementView = this;
        } else {
            this.complement = false;
            this.complementView = new FixedSizeNatBitSet(this);
        }
    }

    private FixedSizeNatBitSet(FixedSizeNatBitSet other) {
        super(other.domainSize());
        complement = !other.complement;
        complementView = other;
    }

    @Override
    boolean isComplement() {
        return complement;
    }

    @Override
    public boolean isEmpty() {
        return complement;
    }

    @Override
    public int size() {
        return isEmpty() ? 0 : domainSize();
    }

    @Override
    public boolean contains(int index) {
        return !complement && inDomain(index);
    }

    @Override
    public boolean containsAll(IntCollection indices) {
        if (indices.isEmpty()) {
            return true;
        }
        if (complement) {
            // "indices" is not empty here
            return false;
        }
        if (indices instanceof NatBitSet) {
            NatBitSet natBitSet = (NatBitSet) indices;
            return natBitSet.lastInt() < domainSize();
        }
        if (indices instanceof IntSortedSet) {
            IntSortedSet sortedSet = (IntSortedSet) indices;
            return 0 <= sortedSet.firstInt() && sortedSet.lastInt() < domainSize();
        }
        if (indices instanceof SortedSet) {
            //noinspection unchecked
            SortedSet sortedSet = (SortedSet) indices;
            return 0 <= sortedSet.first() && sortedSet.last() < domainSize();
        }

        IntIterator iterator = indices.iterator();
        while (iterator.hasNext()) {
            if (!contains(iterator.nextInt())) {
                return false;
            }
        }
        return true;
    }

    @Override
    public int firstInt() {
        if (isEmpty()) {
            throw new NoSuchElementException();
        }
        return 0;
    }

    @Override
    public int lastInt() {
        if (isEmpty()) {
            throw new NoSuchElementException();
        }
        return domainSize() - 1;
    }

    @Override
    public int nextPresentIndex(int index) {
        NatBitSetsUtil.checkNonNegative(index);
        if (complement) {
            return -1;
        }
        return index < domainSize() ? index : -1;
    }

    @Override
    public int nextAbsentIndex(int index) {
        NatBitSetsUtil.checkNonNegative(index);
        if (complement) {
            return index;
        }
        return Math.max(index, domainSize());
    }

    @Override
    public int previousPresentIndex(int index) {
        NatBitSetsUtil.checkNonNegative(index);
        if (complement) {
            return -1;
        }
        return index >= domainSize() ? domainSize() - 1 : index;
    }

    @Override
    public int previousAbsentIndex(int index) {
        NatBitSetsUtil.checkNonNegative(index);
        if (complement) {
            return index;
        }
        return index >= domainSize() ? index : -1;
    }

    @Override
    public IntIterator iterator() {
        return isEmpty() ? IntIterators.EMPTY_ITERATOR : IntIterators.fromTo(0, domainSize());
    }

    @Override
    public IntIterator reverseIterator() {
        return isEmpty() ? IntIterators.EMPTY_ITERATOR : new ReverseRangeIterator(0, domainSize());
    }

    @Override
    public void set(int index) {
        checkInDomain(index);
        throw new UnsupportedOperationException();
    }

    @Override
    public void set(int index, boolean value) {
        checkInDomain(index);
        throw new UnsupportedOperationException();
    }

    @Override
    public void set(int from, int to) {
        checkInDomain(from, to);
        throw new UnsupportedOperationException();
    }

    @Override
    public void clear() {
        throw new UnsupportedOperationException();
    }

    @Override
    public void clear(int index) {
        checkInDomain(index);
        throw new UnsupportedOperationException();
    }

    @Override
    public void clear(int from, int to) {
        checkInDomain(from, to);
        throw new UnsupportedOperationException();
    }

    @Override
    public void flip(int index) {
        checkInDomain(index);
        throw new UnsupportedOperationException();
    }

    @Override
    public void flip(int from, int to) {
        checkInDomain(from, to);
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean intersects(Collection indices) {
        if (isEmpty() || indices.isEmpty()) {
            return false;
        }
        if (indices instanceof IntCollection) {
            IntCollection intIndices = ((IntCollection) indices);
            if (indices instanceof NatBitSet) {
                NatBitSet natBitSet = (NatBitSet) indices;
                return contains(natBitSet.firstInt());
            }
            if (indices instanceof IntSortedSet) {
                IntSortedSet sortedInts = (IntSortedSet) indices;
                return !sortedInts.subSet(0, domainSize()).isEmpty();
            }
            if (indices.size() <= domainSize()) {
                return IntIterators.any(intIndices.iterator(), this::contains);
            }
            return IntIterators.any(iterator(), indices::contains);
        }
        return super.intersects(indices);
    }

    @Override
    public FixedSizeNatBitSet clone() {
        // Immutable object
        return this;
    }

    @SuppressWarnings("AssignmentOrReturnOfFieldWithMutableType")
    @Override
    public BoundedNatBitSet complement() {
        return complementView;
    }
}