package jdk.nashorn.internal.runtime.arrays;

import java.util.Iterator;

import java.util.List;

import java.util.SortedMap;

import java.util.TreeMap;

import jdk.nashorn.internal.runtime.JSType;

import jdk.nashorn.internal.runtime.ScriptRuntime;

/**

 * Filter to use for ArrayData where the length is not writable.

 * The default behavior is just to ignore {@link ArrayData#setLength}

 */

final class LengthNotWritableFilter extends ArrayFilter {

    private final SortedMap<Long, Object> extraElements; //elements with index >= length

    /**

     * Constructor

     * @param underlying array

     */

    LengthNotWritableFilter(final ArrayData underlying) {

        this(underlying, new TreeMap<Long, Object>());

    }

    private LengthNotWritableFilter(final ArrayData underlying, final SortedMap<Long, Object> extraElements) {

        super(underlying);

        this.extraElements = extraElements;

    }

    @Override

    public ArrayData copy() {

        return new LengthNotWritableFilter(underlying.copy(), new TreeMap<>(extraElements));

    }

    @Override

    public boolean has(final int index) {

        return super.has(index) || extraElements.containsKey((long)index);

    }

    /**

     * Set the length of the data array

     *

     * @param length the new length for the data array

     */

    @Override

    public void setLength(final long length) {

        //empty - setting length for a LengthNotWritableFilter is always a nop

    }

    @Override

    public ArrayData ensure(final long index) {

        return this;

    }

    @Override

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

        //return array[from...to), or array[from...length] if undefined, in this case not as we are an ArrayData

        return new LengthNotWritableFilter(underlying.slice(from, to), extraElements.subMap(from, to));

    }

    private boolean checkAdd(final long index, final Object value) {

        if (index >= length()) {

            extraElements.put(index, value);

            return true;

        }

        return false;

    }

    private Object get(final long index) {

        final Object obj = extraElements.get(index);

        if (obj == null) {

            return ScriptRuntime.UNDEFINED;

        }

        return obj;

    }

    @Override

    public int getInt(final int index) {

        if (index >= length()) {

            return JSType.toInt32(get(index));

        }

        return underlying.getInt(index);

    }

    @Override

    public int getIntOptimistic(final int index, final int programPoint) {

        if (index >= length()) {

            return JSType.toInt32Optimistic(get(index), programPoint);

        }

        return underlying.getIntOptimistic(index, programPoint);

    }

    @Override

    public double getDouble(final int index) {

        if (index >= length()) {

            return JSType.toNumber(get(index));

        }

        return underlying.getDouble(index);

    }

    @Override

    public double getDoubleOptimistic(final int index, final int programPoint) {

        if (index >= length()) {

            return JSType.toNumberOptimistic(get(index), programPoint);

        }

        return underlying.getDoubleOptimistic(index, programPoint);

    }

    @Override

    public Object getObject(final int index) {

        if (index >= length()) {

            return get(index);

        }

        return underlying.getObject(index);

    }

    @Override

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

        if (checkAdd(index, value)) {

            return this;

        }

        underlying = underlying.set(index, value, strict);

        return this;

    }

    @Override

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

        if (checkAdd(index, value)) {

            return this;

        }

        underlying = underlying.set(index, value, strict);

        return this;

    }

    @Override

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

        if (checkAdd(index, value)) {

            return this;

        }

        underlying = underlying.set(index, value, strict);

        return this;

    }

    @Override

    public ArrayData delete(final int index) {

        underlying = underlying.delete(index);

        return this;

    }

    @Override

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

        for (final Iterator<Long> iter = extraElements.keySet().iterator(); iter.hasNext();) {

            final long next = iter.next();

            if (next >= fromIndex && next <= toIndex) {

                iter.remove();

            }

            if (next > toIndex) { //ordering guaranteed because TreeSet

                break;

            }

        }

        underlying = underlying.delete(fromIndex, toIndex);

        return this;

    }

    @Override

    public Iterator<Long> indexIterator() {

        final List<Long> keys = computeIteratorKeys();

        keys.addAll(extraElements.keySet()); //even if they are outside length this is fine

        return keys.iterator();

    }

}