/*
 * eXist Open Source Native XML Database
 * Copyright (C) 2001-2009 The eXist Project
 * http://exist-db.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *  
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *  
 *  $Id$
 */
package org.exist.xquery.functions.fn;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.List;

import org.exist.dom.QName;
import org.exist.xquery.AnalyzeContextInfo;
import org.exist.xquery.Atomize;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Dependency;
import org.exist.xquery.DynamicCardinalityCheck;
import org.exist.xquery.ErrorCodes;
import org.exist.xquery.Expression;
import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.Profiler;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.util.Error;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.StringValue;
import org.exist.xquery.value.Type;

/**
 * Implements the library function fn:concat().
 *
 */
public class FunConcat extends Function {

    protected static final Logger logger = LogManager.getLogger(FunConcat.class);

    public final static FunctionSignature signature =
        new FunctionSignature(
            new QName("concat", Function.BUILTIN_FUNCTION_NS),
            "Accepts two or more xdt:anyAtomicType arguments, $atomizable-values, " +
            "and converts them to xs:string. Returns the xs:string that is the " +
            "concatenation of the values of its arguments after conversion. " +
            "If any of the arguments is the empty sequence, the argument " +
            "is treated as the zero-length string.",
            new SequenceType[] {
                //More complicated : see below
                new FunctionParameterSequenceType("atomizable-values",
                    Type.ATOMIC, Cardinality.ZERO_OR_ONE, "The atomizable values")
            },
            new FunctionReturnSequenceType(Type.STRING, Cardinality.ZERO_OR_ONE,
                "The concatenated values"),
            true
        );

    public FunConcat(XQueryContext context) {
        super(context, signature);
    }

    public int returnsType() {
        return Type.STRING;
    }

    /**
     * Overloaded function: no static type checking.
     * 
     * @see org.exist.xquery.Function#setArguments(java.util.List)
     */
    public void setArguments(List<Expression> arguments) throws XPathException {
    	steps.clear();
        for (Expression argument : arguments) {
        	if (!(argument instanceof Placeholder)) {
	            argument = new DynamicCardinalityCheck(context,
	                Cardinality.ZERO_OR_ONE, argument,
	                new Error(Error.FUNC_PARAM_CARDINALITY, "1", mySignature));
	            if (!Type.subTypeOf(argument.returnsType(), Type.ATOMIC))
	                {argument = new Atomize(context, argument);}
        	}
            steps.add(argument);
        }
    }

    public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
        contextInfo.setParent(this);
        // call analyze for each argument
        inPredicate = (contextInfo.getFlags() & IN_PREDICATE) > 0;
        for(int i = 0; i < getArgumentCount(); i++) {
            getArgument(i).analyze(contextInfo);
        }
    }

    public Sequence eval(Sequence contextSequence, Item contextItem)
            throws XPathException {
       if (context.getProfiler().isEnabled()) {
            context.getProfiler().start(this);
            context.getProfiler().message(this, Profiler.DEPENDENCIES,
                "DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
            if (contextSequence != null)
                {context.getProfiler().message(this, Profiler.START_SEQUENCES,
                    "CONTEXT SEQUENCE", contextSequence);}
            if (contextItem != null)
                {context.getProfiler().message(this, Profiler.START_SEQUENCES,
                    "CONTEXT ITEM", contextItem.toSequence());}
        }
       if (getArgumentCount() < 2) {
           throw new XPathException (this, ErrorCodes.XPST0017,
               "concat() requires at least two arguments");
       }
       final StringBuilder concat = new StringBuilder();
       for (int i = 0; i < getArgumentCount(); i++) {
            concat.append(getArgument(i).eval(contextSequence, contextItem).getStringValue());
       }
       final Sequence result = new StringValue(concat.toString());
        if (context.getProfiler().isEnabled())
            {context.getProfiler().end(this, "", result);}
        return result;
    }
}