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package org.yamcs.yarch;

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

/**
 * @see org.yamcs.yarch.streamsql.SelectExpression
 *
 */
public class SelectStream extends Stream implements StreamSubscriber {
    CompiledExpression whereExp;
    Stream input;
    final private List aggInputList;
    final private List selectList;
    final private WindowProcessor windowProc;
    final private boolean hasStars;

    // used as a marker for the * in "select a,*,b from..." expressions
    final static public CompiledExpression STAR = new CompiledExpression() {
        @Override
        public Object getValue(Tuple tuple) {
            return null;
        }

        @Override
        public ColumnDefinition getDefinition() {
            return null;
        }
    };

    /**
     * 
     * @param ydb
     * @param input
     * @param cWhereClause
     *            if null, then no where filtering
     * @param wp
     *            if null, then no windowProcessing (aggInputList is also null in this case)
     * @param cselectList
     * @param outputDef
     *            //output definition containing the expanded stars
     * @param minOutputDef
     *            //output definition where stars are not included
     */
    public SelectStream(YarchDatabaseInstance ydb, Stream input, CompiledExpression cWhereClause,
            List caggInputList, WindowProcessor wp,
            List cselectList, TupleDefinition outputDef, TupleDefinition minOutputDef) {

        super(ydb, input.getName() + "_select", outputDef);
        this.input = input;
        input.addSubscriber(this);

        this.aggInputList = caggInputList;
        this.whereExp = cWhereClause;
        this.windowProc = wp;
        this.selectList = cselectList;
        boolean hs = false;
        if (selectList != null) {
            for (CompiledExpression ce : selectList) {
                if (ce == STAR) {
                    hs = true;
                    break;
                }
            }
        }
        hasStars = hs;
    }

    @Override
    public void onTuple(Stream stream, Tuple t) {
        if (whereExp != null) {
            Boolean v = (Boolean) whereExp.getValue(t);
            if (v == null || !v) {
                return;
            }
        }
        if (windowProc != null) {
            processWindow(t);
        } else {
            processSelectList(t);
        }
    }

    private void processWindow(Tuple tuple) {
        if (aggInputList != null) {
            Object[] v = new Object[aggInputList.size()];
            for (int i = 0; i < v.length; i++) {
                v[i] = aggInputList.get(i).getValue(tuple);
            }
            tuple = new Tuple(windowProc.aggInputDef, v);
        }
        for (Tuple t : windowProc.newData(tuple)) {
            processSelectList(t);
        }
    }

    private void processSelectList(Tuple tuple) {
        if (selectList == null) {
            emitTuple(tuple);
            return;
        }
        ArrayList