/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.sysml.hops.codegen.template;

import org.apache.sysml.hops.Hop;
import org.apache.sysml.hops.codegen.cplan.CNodeTpl;
import org.apache.sysml.runtime.matrix.data.Pair;

public abstract class TemplateBase 
{	
	public enum TemplateType {
		//ordering specifies type preferences
		MultiAggTpl,
		RowTpl,
		OuterProdTpl,
		CellTpl;
		public int getRank() {
			return this.ordinal();
		}
	}
	
	public enum CloseType {
		CLOSED_VALID,
		CLOSED_INVALID,
		OPEN,
	}

	protected TemplateType _type = null;
	protected boolean _closed = false;
	
	protected TemplateBase(TemplateType type) {
		this(type, false);
	}
	
	protected TemplateBase(TemplateType type, boolean closed) {
		_type = type;
		_closed = closed;
	}
	
	public TemplateType getType() {
		return _type;
	}
	
	public boolean isClosed() {
		return _closed;
	}
	
	/////////////////////////////////////////////
	// Open-Fuse-Merge-Close interface 
	// (for candidate generation and exploration)
	
	/**
	 * Indicates if this template can be opened at the given hop,
	 * where hop represents bottom (first operation on the inputs) 
	 * of the fused operator.
	 * 
	 * @param hop current hop
	 * @return true if template can be opened 
	 */
	public abstract boolean open(Hop hop);
	
	/**
	 * Indicates if the template can be expanded to the given hop
	 * starting from an open template at the input.
	 * 
	 * @param hop current hop
	 * @param input hop with open template of same type
	 * @return true if the current hop can be fused into the operator.
	 */
	public abstract boolean fuse(Hop hop, Hop input);
	
	/**
	 * Indicates if the template at the current hop can be expanded
	 * by merging another template available for one of its other inputs
	 * which is not yet covered by the template of the current hop. 
	 * 
	 * @param hop current hop
	 * @param input direct input of current hop with available template
	 * @return true if the the input hop can be fused into the current hop
	 */
	public abstract boolean merge(Hop hop, Hop input);
	
	/**
	 * Indicates if the template must be closed at the current hop; either
	 * due to final operations (e.g., aggregate) or unsupported operations.
	 * 
	 * @param hop current hop
	 * @return close type (closed invalid, closed valid, open)
	 */
	public abstract CloseType close(Hop hop);
	
	/**
	 * Mark the template as closed either invalid or valid.
	 */
	public void close() {
		_closed = true;
	}
	
	/////////////////////////////////////////////
	// CPlan construction interface
	// (for plan creation of selected candidates)
	
	/**
	 * Constructs a single cplan rooted at the given hop, according 
	 * to the plan given in the memo structure for this particular 
	 * hop and its recursive inputs.  
	 * 
	 * @param hop root of cplan
	 * @param memo memoization table for partial subplans
	 * @param compileLiterals if true compile non-integer literals 
	 * as constants, otherwise variables. note: integer literals are 
	 * always compiled as constants.
	 * @return
	 */
	public abstract Pair<Hop[], CNodeTpl> constructCplan(Hop hop, CPlanMemoTable memo, boolean compileLiterals);	
}