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package org.apache.cayenne.lifecycle.audit;

import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Map.Entry;

/**
 * Aggregates audit events per audit root object, and passes them to delegate processor at
 * the end of the transaction.
 * 
 * @since 3.1
 */
class AuditableAggregator {

    private static final int[] OP_PRECEDENCE;

    static {
        OP_PRECEDENCE = new int[AuditableOperation.values().length];

        // decreasing precedence of operations when recording audits is DELETE,
        // INSERT, UPDATE
        OP_PRECEDENCE[AuditableOperation.DELETE.ordinal()] = 3;
        OP_PRECEDENCE[AuditableOperation.INSERT.ordinal()] = 2;
        OP_PRECEDENCE[AuditableOperation.UPDATE.ordinal()] = 1;
    }

    private AuditableProcessor delegate;

    private Map ops;

    AuditableAggregator(AuditableProcessor delegate) {
        this.delegate = delegate;
        this.ops = new IdentityHashMap();
    }

    void audit(Object object, AuditableOperation operation) {
        AuditableOperation oldOp = ops.put(object, operation);
        if (oldOp != null) {
            if (OP_PRECEDENCE[operation.ordinal()] < OP_PRECEDENCE[oldOp.ordinal()]) {
                ops.put(object, oldOp);
            }
        }
    }

    void postSync() {
        for (Entry op : ops.entrySet()) {
            delegate.audit(op.getKey(), op.getValue());
        }
    }

}