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 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2024 QuestDB
 *
 *  Licensed 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.
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package io.questdb.griffin.engine.table;

import io.questdb.cairo.BitmapIndexReader;
import io.questdb.cairo.EmptyRowCursor;
import io.questdb.cairo.TableUtils;
import io.questdb.cairo.sql.*;
import io.questdb.griffin.PlanSink;
import io.questdb.griffin.SqlException;
import io.questdb.griffin.SqlExecutionContext;

public class DeferredSymbolIndexRowCursorFactory implements FunctionBasedRowCursorFactory {
    private final boolean cachedIndexReaderCursor;
    private final int columnIndex;
    private final int indexDirection;
    private final Function symbol;
    private int symbolKey;

    public DeferredSymbolIndexRowCursorFactory(
            int columnIndex,
            Function symbol,
            boolean cachedIndexReaderCursor,
            int indexDirection
    ) {
        this.columnIndex = columnIndex;
        this.symbolKey = SymbolTable.VALUE_NOT_FOUND;
        this.symbol = symbol;
        this.cachedIndexReaderCursor = cachedIndexReaderCursor;
        this.indexDirection = indexDirection;
    }

    @Override
    public RowCursor getCursor(PageFrame pageFrame, PageFrameMemory pageFrameMemory) {
        if (symbolKey == SymbolTable.VALUE_NOT_FOUND) {
            return EmptyRowCursor.INSTANCE;
        }

        return pageFrame
                .getBitmapIndexReader(columnIndex, indexDirection)
                .getCursor(cachedIndexReaderCursor, symbolKey, pageFrame.getPartitionLo(), pageFrame.getPartitionHi() - 1);
    }

    @Override
    public Function getFunction() {
        return symbol;
    }

    @Override
    public void init(PageFrameCursor pageFrameCursor, SqlExecutionContext sqlExecutionContext) throws SqlException {
        symbol.init(pageFrameCursor, sqlExecutionContext);
    }

    @Override
    public boolean isEntity() {
        return false;
    }

    @Override
    public boolean isUsingIndex() {
        return true;
    }

    @Override
    public void prepareCursor(PageFrameCursor pageFrameCursor) {
        int symbolKey = pageFrameCursor.getSymbolTable(columnIndex).keyOf(symbol.getSymbol(null));
        this.symbolKey = symbolKey != SymbolTable.VALUE_NOT_FOUND
                ? TableUtils.toIndexKey(symbolKey)
                : SymbolTable.VALUE_NOT_FOUND;
    }

    @Override
    public void toPlan(PlanSink sink) {
        sink.type("Index ").type(BitmapIndexReader.nameOf(indexDirection)).type(" scan").meta("on").putBaseColumnName(columnIndex);
        sink.meta("deferred").val("true");
        sink.attr("filter").putBaseColumnName(columnIndex).val('=').val(symbol);
    }
}