// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.ui.def.nonpublic.support;

import java.util.*;

import org.litesoft.ui.def.*;

public abstract class AbstractUiChildrenHelper implements UiChildrenHelper
{
    public static final UiDef[] NO_CHILDREN = new UiDef[0];

    private UiDef[] mChildren = NO_CHILDREN;
    protected final UiContainerMarker mOwner;
    private int mMinChildren;
    private int mMaxChildren; // 0 - unlimited

    protected AbstractUiChildrenHelper( UiContainerMarker pOwner, int pMinChildren, int pMaxChildren )
    {
        mOwner = pOwner;
        mMinChildren = pMinChildren;
        mMaxChildren = pMaxChildren;
    }

    protected AbstractUiChildrenHelper( UiContainerMarker pOwner, int pMinChildren )
    {
        this( pOwner, pMinChildren, 0 );
    }

    protected boolean anyChildren()
    {
        return (mChildren.length != 0);
    }

    public UiDef getFirstChild()
    {
        return anyChildren() ? mChildren[0] : null;
    }

    public UiDef[] getChildren()
    {
        return mChildren;
    }

    public void addChild( UiDef pChild )
    {
        if ( pChild != null )
        {
            validateChild( pChild );
            extendChildren( pChild, mChildren.length );
        }
    }

    public void insertChildBefore( UiDef pChild, int pAt )
    {
        if ( pChild != null )
        {
            validateChild( pChild );
            extendChildren( pChild, ((0 <= pAt) && (pAt < mChildren.length)) ? pAt : mChildren.length );
        }
    }

    public boolean removeChild( UiDef pChild )
    {
        for ( int i = 0; i < mChildren.length; i++ )
        {
            if ( pChild == mChildren[i] )
            {
                reduceChildren( i );
                return true;
            }
        }
        return false;
    }

    public UiDef removeChildAt( int pAt )
    {
        if ( (0 <= pAt) && (pAt < mChildren.length) )
        {
            UiDef rv = mChildren[pAt];
            reduceChildren( pAt );
            return rv;
        }
        return null;
    }

    public UiDef convertToActionOrInput( String pActionOrInput )
    {
        return null;
    }

    public int getMinChildren()
    {
        return mMinChildren;
    }

    public int getMaxChildren()
    {
        return mMaxChildren;
    }

    public void customValidateChildren()
    {
        customValidateMinimumChildren( mMinChildren );
    }

    protected void customValidateMinimumChildren( int pMinChildren )
    {
        if ( mChildren.length < pMinChildren )
        {
            throw new IllegalArgumentException(
                    mOwner + " MUST have at least " + nChildren( pMinChildren ) + " for a layout" );
        }
    }

    private void validateChild( UiDef pChild )
    {
        if ( !acceptableChild( pChild ) )
        {
            throw new IllegalArgumentException( "Unacceptable Child (" + pChild + ") for " + mOwner );
        }
    }

    protected void prepareToRender( UiDef pComponent )
    {
        if ( pComponent != null )
        {
            pComponent.prepareToRender();
        }
    }

    protected UiDef[] deNullSingleChildAndReturnAsArray( UiDef pUiDef )
    {
        return (pUiDef == null) ? NO_CHILDREN : new UiDef[]{pUiDef};
    }

    private String nChildren( int pNth )
    {
        return "" + pNth + ((pNth == 1) ? " Child" : " Children");
    }

    protected UiDef[] getChildren( List pCurrentChildren )
    {
        UiDef[] defs = new UiDef[pCurrentChildren.size()];
        for ( int i = 0; i < pCurrentChildren.size(); i++ )
        {
            defs[i] = (UiDef) pCurrentChildren.get( i );
        }
        return defs;
    }

    protected void childrenChanged()
    {
    }

    // vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv Array Management vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
    private void extendChildren( UiDef pChild, int pAt )
    {
        int newLength = mChildren.length + 1;
        if ( (mMaxChildren != 0) && (newLength > mMaxChildren) )
        {
            throw new IllegalArgumentException( mOwner + " will only accept " + nChildren( mMaxChildren ) +
                                                ".  Attempting to add:" + pChild );
        }
        UiDef[] zChildren = new UiDef[newLength];
        int zCurIndex = 0;
        for ( int zNewIndex = 0; zNewIndex < zChildren.length; zNewIndex++ )
        {
            if ( zNewIndex == pAt )
            {
                zChildren[zNewIndex] = pChild;
            }
            else
            {
                zChildren[zNewIndex] = mChildren[zCurIndex++];
            }
        }
        mChildren = zChildren;
        childrenChanged();
    }

    private void reduceChildren( int pAt )
    {
        UiDef[] zChildren = new UiDef[mChildren.length];
        int zNewIndex = 0;
        for ( int zCurIndex = 0; zCurIndex < mChildren.length; zCurIndex++ )
        {
            if ( zCurIndex != pAt )
            {
                zChildren[zNewIndex++] = mChildren[zCurIndex];
            }
        }
        mChildren = zChildren;
        childrenChanged();
    }
}