package  org.simantics.interop.update.model;

import java.util.ArrayList;
import java.util.Collection;

import org.simantics.db.Resource;
import org.simantics.db.Statement;
import org.simantics.db.WriteGraph;
import org.simantics.db.exception.DatabaseException;
import org.simantics.interop.test.GraphChanges;

/**
 * Base class for update operations (adding and deleting objects)  
 * 
 * @author Marko Luukkainen <marko.luukkainen@vtt.fi>
 *
 */
public abstract class UpdateOp {
	
	private GraphChanges changes;
	
	private boolean selected = false;
	private boolean manualSelection = false;
	protected boolean applied = false;
	protected boolean visible = true;
	protected boolean enabled = true;
	
	private Collection<UpdateOp> parentOps = new ArrayList<UpdateOp>();
	private Collection<UpdateOp> subOps = new ArrayList<UpdateOp>();
	
	
	public UpdateOp(GraphChanges changes) {
		this.changes = changes;
	}
	
	public Collection<UpdateOp> getParentOps() {
		return parentOps;
	}
	
	public Collection<UpdateOp> getSubOps() {
		return subOps;
	}
	
	public void addParentOp(UpdateOp op) {
		assert (!op.equals(this));
		parentOps.add(op);
	}
	
	public void addSubOp(UpdateOp op) {
		assert (!op.equals(this));
		subOps.add(op);
	}
	
	public void removeParentOp(UpdateOp op) {
		parentOps.remove(op);
	}
	
	public void removeSubOp(UpdateOp op) {
		subOps.remove(op);
	}
	
	public GraphChanges getChanges() {
		return changes;
	}
	
	public abstract boolean isAdd();
	public abstract boolean isDelete();
	
	public boolean isChange() {
		return isAdd() || isDelete();
	}
	
	/**
	 * Is parent operation applied before this.
	 * @return
	 */
	public abstract boolean requiresParentOps();
	/**
	 * Is child operation applied before this.
	 * @return
	 */
	public abstract boolean requiresSubOps(); 
	
	/**
	 * Is parent operation selected when this is selected
	 * @return
	 */
	public boolean selectParentOps() {
		return requiresParentOps();
	}
	
	/**
	 * Is child operation selected when this is selected
	 * @return
	 */
	public boolean selectSubOps() {
		return requiresSubOps();
	}
	
	public boolean select(boolean select) {
	    if (!enabled)
	        return false;
	    if (!isChange())
	        return false;
		boolean b = _select(select);
		if (b)
			manualSelection = true;
		return b;
	}
	
	private boolean _select(boolean select) {
		if (select == selected)
			return true;
		if (applied)
			return false;
		if (!isChange())
		    return false;
		if (select) {
			if (selectParentOps()) {
				for (UpdateOp op : parentOps)
					op._select(true);
			}
			
			selected = true;
			manualSelection = false;
			if (selectSubOps()) {
				for (UpdateOp op : subOps)
					op._select(true);
			}
			
		} else {
			selected = false;
			manualSelection = false;
			for (UpdateOp op : subOps) {
				if (op.selectParentOps())
					op._select(false);
				else if (!op.manualSelection)
					op._select(false);
			}
			for (UpdateOp op : parentOps)
				if (op.selectSubOps())
					op._select(false);
			return true;
		}
		return false;
	}
	public boolean selected() {
		return selected;
	}
	
	public boolean applied() {
		return applied;
	}
	
	public boolean isVisible() {
		return visible;
	}
	
	/**
     * Is change enabled. Disabled changes do not allow changing selected state.
     * @return
     */
    public boolean enabled() {
        return enabled;
    }
    
    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }
	
	
	public void apply(WriteGraph g) throws DatabaseException {
		if (applied)
			return;
		_apply(g);
		applied = true;
		
	}
	
	/**
	 * Applies the changes into the database.
	 * 
	 * @param g
	 * @throws DatabaseException
	 */
	protected abstract void _apply(WriteGraph g) throws DatabaseException;
	
	/**
	 * Returns resource that this operation is changing.
	 * @return
	 */
	public abstract Resource getResource();
	
	/**
	 * Returns resource that this operation is changing.
	 * @return
	 */
	public abstract Statement getStatement();
	
	/**
	 * Returns resource that this operation created during apply operation. If operation did not add anything, this returns null.
	 * @return
	 */
	public abstract Resource getCreatedResource();

}