/* ====================================================================
   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.poi.ss.formula.atp;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.TreeSet;

import org.apache.logging.log4j.Logger;
import org.apache.poi.logging.PoiLogManager;
import org.apache.poi.ss.formula.OperationEvaluationContext;
import org.apache.poi.ss.formula.eval.NotImplementedFunctionException;
import org.apache.poi.ss.formula.eval.ValueEval;
import org.apache.poi.ss.formula.function.FunctionMetadata;
import org.apache.poi.ss.formula.function.FunctionMetadataRegistry;
import org.apache.poi.ss.formula.functions.*;
import org.apache.poi.ss.formula.udf.UDFFinder;

/**
 * Analysis Toolpack Function Definitions
 */
public final class AnalysisToolPak implements UDFFinder {

    public static final UDFFinder instance = new AnalysisToolPak();

    private static final Logger LOG = PoiLogManager.getLogger(AnalysisToolPak.class);

    private static final class NotImplemented implements FreeRefFunction {
        private final String _functionName;

        public NotImplemented(String functionName) {
            _functionName = functionName;
        }

        public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
            throw new NotImplementedFunctionException(_functionName);
        }
    }

    private final Map<String, FreeRefFunction> _functionsByName = createFunctionsMap();

    private AnalysisToolPak() {
        // enforce singleton
    }

    public FreeRefFunction findFunction(String name) {
        // functions that are available in Excel 2007+ have a prefix _xlfn.
        // if you save such a .xlsx workbook as .xls
        final String prefix = "_xlfn.";
        // case-sensitive
        if(name.startsWith(prefix)) name = name.substring(prefix.length());

        // FIXME: inconsistent case-sensitivity
        return _functionsByName.get(name.toUpperCase(Locale.ROOT));
    }

    private Map<String, FreeRefFunction> createFunctionsMap() {
        Map<String, FreeRefFunction> m = new HashMap<>(127);

        r(m, "ACCRINT", null);
        r(m, "ACCRINTM", null);
        r(m, "AMORDEGRC", null);
        r(m, "AMORLINC", null);
        r(m, "AVERAGEIF", AverageIf.instance);
        r(m, "AVERAGEIFS", Averageifs.instance);
        r(m, "BAHTTEXT", null);
        r(m, "BESSELI", null);
        r(m, "BESSELJ", BesselJ.instance);
        r(m, "BESSELK", null);
        r(m, "BESSELY", null);
        r(m, "BIN2DEC", Bin2Dec.instance);
        r(m, "BIN2HEX", null);
        r(m, "BIN2OCT", null);
        r(m, "COMPLEX", Complex.instance);
        r(m, "CEILING.MATH", CeilingMath.instance);
        r(m, "CEILING.PRECISE", CeilingPrecise.instance);
        r(m, "CONCAT", TextFunction.CONCAT);
        r(m, "CONVERT", null);
        r(m, "COUNTIFS", Countifs.instance);
        r(m, "COUPDAYBS", null);
        r(m, "COUPDAYS", null);
        r(m, "COUPDAYSNC", null);
        r(m, "COUPNCD", null);
        r(m, "COUPNUM", null);
        r(m, "COUPPCD", null);
        r(m, "COVARIANCE.P", Covar.instanceP);
        r(m, "COVARIANCE.S", Covar.instanceS);
        r(m, "CUBEKPIMEMBER", null);
        r(m, "CUBEMEMBER", null);
        r(m, "CUBEMEMBERPROPERTY", null);
        r(m, "CUBERANKEDMEMBER", null);
        r(m, "CUBESET", null);
        r(m, "CUBESETCOUNT", null);
        r(m, "CUBEVALUE", null);
        r(m, "CUMIPMT", null);
        r(m, "CUMPRINC", null);
        r(m, "DAYS", Days.instance);
        r(m, "DEC2BIN", Dec2Bin.instance);
        r(m, "DEC2HEX", Dec2Hex.instance);
        r(m, "DEC2OCT", null);
        r(m, "DELTA", Delta.instance);
        r(m, "DISC", null);
        r(m, "DOLLARDE", DollarDe.instance);
        r(m, "DOLLARFR", DollarFr.instance);
        r(m, "DURATION", null);
        r(m, "EDATE", EDate.instance);
        r(m, "EFFECT", null);
        r(m, "EOMONTH", EOMonth.instance);
        r(m, "ERF", null);
        r(m, "ERFC", null);
        r(m, "FACTDOUBLE", FactDouble.instance);
        r(m, "FLOOR.MATH", FloorMath.instance);
        r(m, "FLOOR.PRECISE", FloorPrecise.instance);
        r(m, "FORECAST.LINEAR", Forecast.instance);
        r(m, "FVSCHEDULE", null);
        r(m, "GCD", Gcd.instance);
        r(m, "GESTEP", null);
        r(m, "HEX2BIN", null);
        r(m, "HEX2DEC", Hex2Dec.instance);
        r(m, "HEX2OCT", null);
        r(m, "IFERROR", IfError.instance);
        r(m, "IFNA", IfNa.instance);
        r(m, "IFS", Ifs.instance);
        r(m, "IMABS", null);
        r(m, "IMAGINARY", Imaginary.instance);
        r(m, "IMARGUMENT", null);
        r(m, "IMCONJUGATE", null);
        r(m, "IMCOS", null);
        r(m, "IMDIV", null);
        r(m, "IMEXP", null);
        r(m, "IMLN", null);
        r(m, "IMLOG10", null);
        r(m, "IMLOG2", null);
        r(m, "IMPOWER", null);
        r(m, "IMPRODUCT", null);
        r(m, "IMREAL", ImReal.instance);
        r(m, "IMSIN", null);
        r(m, "IMSQRT", null);
        r(m, "IMSUB", null);
        r(m, "IMSUM", null);
        r(m, "INTRATE", null);
        r(m, "ISEVEN", ParityFunction.IS_EVEN);
        r(m, "ISODD", ParityFunction.IS_ODD);
        r(m, "JIS", null);
        r(m, "LCM", Lcm.instance);
        r(m, "MAXIFS", Maxifs.instance);
        r(m, "MDURATION", null);
        r(m, "MINIFS", Minifs.instance);
        r(m, "MROUND", MRound.instance);
        r(m, "MULTINOMIAL", null);
        r(m, "NETWORKDAYS", NetworkdaysFunction.instance);
        r(m, "NOMINAL", null);
        r(m, "NORM.DIST", NormDist.instance);
        r(m, "NORM.S.DIST", NormSDist.instance);
        r(m, "NORM.INV", NormInv.instance);
        r(m, "NORM.S.INV", NormSInv.instance);
        r(m, "NUMBERVALUE", NumberValueFunction.instance);
        r(m, "OCT2BIN", null);
        r(m, "OCT2DEC", Oct2Dec.instance);
        r(m, "OCT2HEX", null);
        r(m, "ODDFPRICE", null);
        r(m, "ODDFYIELD", null);
        r(m, "ODDLPRICE", null);
        r(m, "ODDLYIELD", null);
        r(m, "PERCENTRANK.EXC", PercentRankExcFunction.instance);
        r(m, "PERCENTRANK.INC", PercentRankIncFunction.instance);
        r(m, "POISSON.DIST", Poisson.instance);
        r(m, "PRICE", null);
        r(m, "PRICEDISC", null);
        r(m, "PRICEMAT", null);
        r(m, "QUOTIENT", Quotient.instance);
        r(m, "RANDBETWEEN", RandBetween.instance);
        r(m, "RECEIVED", null);
        r(m, "RTD", null);
        r(m, "SERIESSUM", null);
        r(m, "SHEET", Sheet.instance);
        r(m, "SINGLE", Single.instance);
        r(m, "SQRTPI", Sqrtpi.instance);
        r(m, "STDEV.S", Stdevs.instance);
        r(m, "STDEV.P", Stdevp.instance);
        r(m, "SUMIFS", Sumifs.instance);
        r(m, "SWITCH", Switch.instance);
        r(m, "TBILLEQ", null);
        r(m, "TBILLPRICE", null);
        r(m, "TBILLYIELD", null);
        r(m, "T.DIST", TDistLt.instance);
        r(m, "T.DIST.2T", TDist2t.instance);
        r(m, "T.DIST.RT", TDistRt.instance);
        r(m, "TEXTJOIN", TextJoinFunction.instance);
        r(m, "WEEKNUM", WeekNum.instance);
        r(m, "WORKDAY", WorkdayFunction.instance);
        r(m, "WORKDAY.INTL", WorkdayIntlFunction.instance);
        r(m, "XIRR", null);
        r(m, "XLOOKUP", XLookupFunction.instance);
        r(m, "XMATCH", XMatchFunction.instance);
        r(m, "XNPV", null);
        r(m, "YEARFRAC", YearFrac.instance);
        r(m, "YIELD", null);
        r(m, "YIELDDISC", null);
        r(m, "YIELDMAT", null);
        r(m, "VAR.S", Vars.instance);
        r(m, "VAR.P", Varp.instance);

        return m;
    }

    private static void r(Map<String, FreeRefFunction> m, String functionName, FreeRefFunction pFunc) {
        FreeRefFunction func = pFunc == null ? new NotImplemented(functionName) : pFunc;
        m.put(functionName, func);
    }

    public static boolean isATPFunction(String name){
        AnalysisToolPak inst = (AnalysisToolPak)instance;
        // FIXME: inconsistent case-sensitivity
        return inst._functionsByName.containsKey(name);
    }

    /**
     * Returns a collection of ATP function names implemented by POI.
     *
     * @return an array of supported functions
     * @since 3.8 beta6
     */
    public static Collection<String> getSupportedFunctionNames(){
        AnalysisToolPak inst = (AnalysisToolPak)instance;
        Collection<String> lst = new TreeSet<>();
        for(Map.Entry<String, FreeRefFunction> me : inst._functionsByName.entrySet()){
            FreeRefFunction func = me.getValue();
            if(func != null && !(func instanceof NotImplemented)){
                lst.add(me.getKey());
            }
        }
        return Collections.unmodifiableCollection(lst);
    }

    /**
     * Returns a collection of ATP function names NOT implemented by POI.
     *
     * @return an array of not supported functions
     * @since 3.8 beta6
     */
    public static Collection<String> getNotSupportedFunctionNames(){
        AnalysisToolPak inst = (AnalysisToolPak)instance;
        Collection<String> lst = new TreeSet<>();
        for(Map.Entry<String, FreeRefFunction> me : inst._functionsByName.entrySet()){
            FreeRefFunction func = me.getValue();
            if (func instanceof NotImplemented) {
                lst.add(me.getKey());
            }
        }
        return Collections.unmodifiableCollection(lst);
    }

    /**
     * Register an ATP function in runtime.
     *
     * @param name  the function name
     * @param func  the function to register
     * @throws IllegalArgumentException if the function is unknown or already registered.
     * @since 3.8 beta6
     */
    public static void registerFunction(String name, FreeRefFunction func) {
        registerFunction(name, func, false);
    }

    /**
     * Register an ATP function in runtime.
     *
     * @param name  the function name
     * @param func  the function to register
     * @param force force registration even if the function is already registered or unknown to POI
     * @throws IllegalArgumentException if the function is unknown or already registered (and `force` is not true).
     * @since POI 5.5.0
     */
    public static void registerFunction(String name, FreeRefFunction func, boolean force) {
        AnalysisToolPak inst = (AnalysisToolPak)instance;
        if (force) {
            // Excel regularly adds new functions, so the ones registered in POI
            // can be well out of date - allow users who know what they are doing
            // to force their update
        } else if(!isATPFunction(name)) {
            FunctionMetadata metaData = FunctionMetadataRegistry.getFunctionByName(name);
            if(metaData != null) {
                throw new IllegalArgumentException(name + " is a built-in Excel function. " +
                        "Use FunctionEval.registerFunction(String name, Function func) instead.");
            }

            throw new IllegalArgumentException(name + " is not a function from the Excel Analysis Toolpack.");
        }

        FreeRefFunction f = inst.findFunction(name);
        if(f != null && !(f instanceof NotImplemented)) {
            if (force) {
                LOG.info("POI already implements " + name +
                        ". You are overriding the implementation.");
            } else {
                throw new IllegalArgumentException("POI already implements " + name +
                        ". You cannot override POI's implementations of Excel functions");
            }
        }

        // FIXME: inconsistent case-sensitivity
        inst._functionsByName.put(name, func);
    }

}
