package org.simantics.acorn.internal;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.simantics.acorn.ClusterManager;
import org.simantics.acorn.exception.AcornAccessVerificationException;
import org.simantics.acorn.exception.IllegalAcornStateException;
import org.simantics.acorn.lru.ClusterChangeSet;
import org.simantics.acorn.lru.ClusterStreamChunk;
import org.simantics.acorn.lru.ClusterChangeSet.Entry;
import org.simantics.acorn.lru.ClusterChangeSet.Type;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.service.ClusterUID;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class UndoClusterUpdateProcessor extends ClusterUpdateProcessorBase {

	private static final Logger LOGGER = LoggerFactory.getLogger(UndoClusterUpdateProcessor.class);

	public final static boolean DEBUG = false;

	final private ClusterChangeSet ccs;

	private int oldValuesIndex = 0;
	private int statementMaskIndex = 0;

	final public List<Entry> entries = new ArrayList<>();
	
	public UndoClusterUpdateProcessor(ClusterManager client, ClusterStreamChunk chunk, ClusterChangeSet ccs) throws DatabaseException {
		super(client, readOperation(client, chunk, ccs));
		this.ccs = ccs;
	}
	
	private static byte[] readOperation(ClusterManager manager, ClusterStreamChunk chunk, ClusterChangeSet ccs) throws AcornAccessVerificationException, IllegalAcornStateException {
		chunk.makeResident();
		return chunk.getOperation(ccs.chunkOffset);
	}
	
	@Override
	void create() throws DatabaseException {
	}

	@Override
	void delete(int ri) throws DatabaseException {
		
		byte[] old = ccs.oldValues.get(oldValuesIndex);
		boolean oldValueEx = ccs.oldValueEx.get(oldValuesIndex) > 0;
		oldValuesIndex++;
		
		if(old != null) {
			entries.add(new Entry(ri, oldValueEx, old, null));
		}
		
	}

	@Override
	void modify(int resourceKey, long offset, int size, byte[] bytes, int pos)
			throws DatabaseException {
		
	}

	@Override
	void set(int resourceKey, byte[] bytes, int length)
			throws DatabaseException {

		byte[] old = ccs.oldValues.get(oldValuesIndex);
		boolean oldValueEx = ccs.oldValueEx.get(oldValuesIndex) > 0;
		oldValuesIndex++;

		entries.add(new Entry(resourceKey, oldValueEx, old, Arrays.copyOf(valueBuffer, length)));
		
	}

	@Override
	void claim(int resourceKey, int predicateKey, int objectKey, ClusterUID puid, ClusterUID ouid)
			throws DatabaseException {
		
		boolean add = ccs.statementMask.get(statementMaskIndex++) > 0;
		if(add) {
			entries.add(new Entry(Type.ADD, resourceKey, puid, predicateKey & 0xFFF, ouid, objectKey & 0xFFF));
		}
		
	}

	@Override
	void deny(int resourceKey, int predicateKey, int objectKey, ClusterUID puid, ClusterUID ouid)
			throws DatabaseException {
		
		boolean remove = ccs.statementMask.get(statementMaskIndex++) > 0;
		if(remove) {
			entries.add(new Entry(Type.REMOVE, resourceKey, puid, predicateKey & 0xFFF, ouid, objectKey & 0xFFF));
		}

	}

	@Override
	void setImmutable(boolean value) {
		LOGGER.error("Attempted to undo `setImmutable({})` cluster operation for cluster {} which is not supported.", value, ccs.cuid);
	}

}