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package org.exist.xquery;

import java.util.List;

import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.FunctionReference;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;

public class DynamicFunctionCall extends AbstractExpression {

    private Expression functionExpr;
    private List arguments;
    private boolean isPartial = false;
    
    private AnalyzeContextInfo cachedContextInfo;

    public DynamicFunctionCall(XQueryContext context, Expression fun, List args, boolean partial) {
        super(context);
        setLocation(fun.getLine(), fun.getColumn());
        this.functionExpr = fun;
        this.arguments = args;
        this.isPartial = partial;
    }

    @Override
    public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
        cachedContextInfo = new AnalyzeContextInfo(contextInfo);
        functionExpr.analyze(contextInfo);
    }

    @Override
    public void dump(ExpressionDumper dumper) {
        functionExpr.dump(dumper);
        dumper.display('(');
        for (final Expression arg : arguments) {
            arg.dump(dumper);
        }
        dumper.display(')');
    }

    @Override
    public Sequence eval(Sequence contextSequence, Item contextItem)
            throws XPathException {
        context.proceed(this);
        final Sequence funcSeq = functionExpr.eval(contextSequence, contextItem);
        if (funcSeq.getCardinality() != Cardinality.EXACTLY_ONE)
            {throw new XPathException(this, ErrorCodes.XPTY0004,
                "Expected exactly one item for the function to be called, got " + funcSeq.getItemCount() +
                ". Expression: " + ExpressionDumper.dump(functionExpr));}
        final Item item0 = funcSeq.itemAt(0);
        if (!Type.subTypeOf(item0.getType(), Type.FUNCTION_REFERENCE))
            {throw new XPathException(this, ErrorCodes.XPTY0004,
                "Type error: expected function, got " + Type.getTypeName(item0.getType()));}
        final FunctionReference ref = (FunctionReference)item0;
        // if the call is a partial application, create a new function
        if (isPartial) {
        	try {
	        	final FunctionCall call = ref.getCall();
	        	call.setArguments(arguments);
	        	final PartialFunctionApplication partialApp = new PartialFunctionApplication(context, call);
                partialApp.analyze(new AnalyzeContextInfo(cachedContextInfo));
	        	return partialApp.eval(contextSequence, contextItem);
        	} catch (final XPathException e) {
				e.setLocation(line, column, getSource());
				throw e;
        	}
        } else {
	        ref.setArguments(arguments);
            // need to create a new AnalyzeContextInfo to avoid memory leak
            // cachedContextInfo will stay in memory
	        ref.analyze(new AnalyzeContextInfo(cachedContextInfo));
	        // Evaluate the function
            try {
                return ref.eval(contextSequence);
            } catch (XPathException e) {
                if (e.getLine() <= 0) {
                    e.setLocation(getLine(), getColumn(), getSource());
                }
                throw e;
            } finally {
                ref.close();
            }
        }
    }

    @Override
    public int returnsType() {
        return Type.ITEM; // Unknown until the reference is resolved
    }

    @Override
    public void resetState(final boolean postOptimization) {
        super.resetState(postOptimization);
        functionExpr.resetState(postOptimization);
        arguments.forEach(arg -> arg.resetState(postOptimization));
    }
}