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 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.nashorn.internal.runtime.arrays;

import java.lang.reflect.Array;

import jdk.nashorn.internal.runtime.ScriptRuntime;

/**

 * This filter handles the deletion of array elements.

 */

final class DeletedRangeArrayFilter extends ArrayFilter {

    /** Range (inclusive) tracking deletions */

    private long lo, hi;

    DeletedRangeArrayFilter(final ArrayData underlying, final long lo, final long hi) {

        super(maybeSparse(underlying, hi));

        this.lo = lo;

        this.hi = hi;

    }

    private static ArrayData maybeSparse(final ArrayData underlying, final long hi) {

        if (hi < SparseArrayData.MAX_DENSE_LENGTH || underlying instanceof SparseArrayData) {

            return underlying;

        }

        return new SparseArrayData(underlying, underlying.length());

    }

    private boolean isEmpty() {

        return lo > hi;

    }

    private boolean isDeleted(final int index) {

        final long longIndex = ArrayIndex.toLongIndex(index);

        return lo <= longIndex && longIndex <= hi;

    }

    @Override

    public ArrayData copy() {

        return new DeletedRangeArrayFilter(underlying.copy(), lo, hi);

    }

    @Override

    public Object[] asObjectArray() {

        final Object[] value = super.asObjectArray();

        if (lo < Integer.MAX_VALUE) {

            final int end = (int)Math.min(hi + 1, Integer.MAX_VALUE);

            for (int i = (int)lo; i < end; i++) {

                value[i] = ScriptRuntime.UNDEFINED;

            }

        }

        return value;

    }

    @Override

    public Object asArrayOfType(final Class<?> componentType) {

        final Object value = super.asArrayOfType(componentType);

        final Object undefValue = convertUndefinedValue(componentType);

        if (lo < Integer.MAX_VALUE) {

            final int end = (int)Math.min(hi + 1, Integer.MAX_VALUE);

            for (int i = (int)lo; i < end; i++) {

                Array.set(value, i, undefValue);

            }

        }

        return value;

    }

    @Override

    public ArrayData ensure(final long safeIndex) {

        if (safeIndex >= SparseArrayData.MAX_DENSE_LENGTH && safeIndex >= length()) {

            return new SparseArrayData(this, safeIndex + 1);

        }

        return super.ensure(safeIndex);

    }

    @Override

    public ArrayData shiftLeft(final int by) {

        super.shiftLeft(by);

        lo = Math.max(0, lo - by);

        hi = Math.max(-1, hi - by);

        return isEmpty() ? getUnderlying() : this;

    }

    @Override

    public ArrayData shiftRight(final int by) {

        super.shiftRight(by);

        final long len = length();

        lo = Math.min(len, lo + by);

        hi = Math.min(len - 1, hi + by);

        return isEmpty() ? getUnderlying() : this;

    }

    @Override

    public ArrayData shrink(final long newLength) {

        super.shrink(newLength);

        lo = Math.min(newLength, lo);

        hi = Math.min(newLength - 1, hi);

        return isEmpty() ? getUnderlying() : this;

    }

    @Override

    public ArrayData set(final int index, final Object value, final boolean strict) {

        final long longIndex = ArrayIndex.toLongIndex(index);

        if (longIndex < lo || longIndex > hi) {

            return super.set(index, value, strict);

        } else if (longIndex > lo && longIndex < hi) {

            return getDeletedArrayFilter().set(index, value, strict);

        }

        if (longIndex == lo) {

            lo++;

        } else {

            assert longIndex == hi;

            hi--;

        }

        return isEmpty() ? getUnderlying().set(index, value, strict) : super.set(index, value, strict);

    }

    @Override

    public ArrayData set(final int index, final int value, final boolean strict) {

        final long longIndex = ArrayIndex.toLongIndex(index);

        if (longIndex < lo || longIndex > hi) {

            return super.set(index, value, strict);

        } else if (longIndex > lo && longIndex < hi) {

            return getDeletedArrayFilter().set(index, value, strict);

        }

        if (longIndex == lo) {

            lo++;

        } else {

            assert longIndex == hi;

            hi--;

        }

        return isEmpty() ? getUnderlying().set(index, value, strict) : super.set(index, value, strict);

    }

    @Override

    public ArrayData set(final int index, final double value, final boolean strict) {

        final long longIndex = ArrayIndex.toLongIndex(index);

        if (longIndex < lo || longIndex > hi) {

            return super.set(index, value, strict);

        } else if (longIndex > lo && longIndex < hi) {

            return getDeletedArrayFilter().set(index, value, strict);

        }

        if (longIndex == lo) {

            lo++;

        } else {

            assert longIndex == hi;

            hi--;

        }

        return isEmpty() ? getUnderlying().set(index, value, strict) : super.set(index, value, strict);

    }

    @Override

    public boolean has(final int index) {

        return super.has(index) && !isDeleted(index);

    }

    private ArrayData getDeletedArrayFilter() {

        final ArrayData deleteFilter = new DeletedArrayFilter(getUnderlying());

        deleteFilter.delete(lo, hi);

        return deleteFilter;

    }

    @Override

    public ArrayData delete(final int index) {

        final long longIndex = ArrayIndex.toLongIndex(index);

        underlying.setEmpty(index);

        if (longIndex + 1 == lo) {

            lo = longIndex;

        } else if (longIndex - 1 == hi) {

            hi = longIndex;

        } else if (longIndex < lo || hi < longIndex) {

           return getDeletedArrayFilter().delete(index);

        }

        return this;

    }

    @Override

    public ArrayData delete(final long fromIndex, final long toIndex) {

        if (fromIndex > hi + 1  || toIndex < lo - 1) {

            return getDeletedArrayFilter().delete(fromIndex, toIndex);

        }

        lo = Math.min(fromIndex, lo);

        hi = Math.max(toIndex, hi);

        underlying.setEmpty(lo, hi);

        return this;

    }

    @Override

    public Object pop() {

        final int index = (int)length() - 1;

        if (super.has(index)) {

            final boolean isDeleted = isDeleted(index);

            final Object value      = super.pop();

            lo = Math.min(index + 1, lo);

            hi = Math.min(index, hi);

            return isDeleted ? ScriptRuntime.UNDEFINED : value;

        }

        return super.pop();

    }

    @Override

    public ArrayData slice(final long from, final long to) {

        return new DeletedRangeArrayFilter(underlying.slice(from, to), Math.max(0, lo - from), Math.max(0, hi - from));

    }

}