////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.functions;

import com.saxonica.bytecode.ContainsCompiler;
import com.saxonica.bytecode.ExpressionCompiler;
import net.sf.saxon.expr.Callable;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.sort.CodepointCollator;
import net.sf.saxon.expr.sort.RuleBasedSubstringMatcher;
import net.sf.saxon.expr.sort.SimpleCollation;
import net.sf.saxon.lib.StringCollator;
import net.sf.saxon.lib.SubstringMatcher;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.BooleanValue;
import net.sf.saxon.value.StringValue;

import java.text.RuleBasedCollator;

/**
 * Implements the fn:contains() function
 */
public class Contains extends CollatingFunction implements Callable {


    /**
     * Get the argument position (0-based) containing the collation name
     * @return the position of the argument containing the collation URI
     */
    @Override
    protected int getCollationArgument() {
        return 2;
    }

    /**
	 * Evaluate the function
	 */

	public BooleanValue evaluateItem(/*@NotNull*/ XPathContext context) throws XPathException {
		return BooleanValue.get(effectiveBooleanValue(context));
	}

	/**
	 * Get the effective boolean value of the expression. This returns false if the value
	 * is the empty sequence, a zero-length string, a number equal to zero, or the boolean
	 * false. Otherwise it returns true.
	 * @param context The context in which the expression is to be evaluated
	 * @return the effective boolean value
	 * @throws net.sf.saxon.trans.XPathException
	 *          if any dynamic error occurs evaluating the
	 *          expression
	 */

	public boolean effectiveBooleanValue(XPathContext context) throws XPathException {
        try {
            StringValue arg0 = (StringValue)argument[0].evaluateItem(context);
            StringValue arg1 = (StringValue)argument[1].evaluateItem(context);
            return contains(arg0, arg1, getCollator(context));
        } catch (XPathException e) {
            e.maybeSetLocation(this);
            e.maybeSetContext(context);
            throw e;
        }
    }

	private static boolean contains(StringValue arg0, StringValue arg1, StringCollator collator) throws XPathException{
		if (arg1==null || arg1.isZeroLength()) {
            return true;
        }
        if (arg0==null || arg0.isZeroLength()) {
            return false;
        }
        String s0 = arg0.getStringValue();
		String s1 = arg1.getStringValue();
        if (collator instanceof CodepointCollator) {
			// fast path for this common case
			return s0.indexOf(s1, 0) >= 0;
		} else {
			if (collator instanceof SimpleCollation &&
					((SimpleCollation)collator).getCollation() instanceof RuleBasedCollator) {
				collator = new RuleBasedSubstringMatcher((RuleBasedCollator)((SimpleCollation)collator).getCollation());
			}

			if (collator instanceof SubstringMatcher) {
				return ((SubstringMatcher)collator).contains(s0, s1);
			} else {
				throw new XPathException("The collation requested for fn:contains does not support substring matching", "FOCH0004");
			}
		}
	} 



	public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
        try {
            StringValue s0 = (StringValue)arguments[0].head();
            StringValue s1 = (StringValue)arguments[1].head();
            return BooleanValue.get( contains(s0, s1, getCollatorFromLastArgument(arguments, 2, context)));
        } catch (XPathException e) {
            e.maybeSetLocation(this);
            e.maybeSetContext(context);
            throw e;
        }
    }

//#ifdefined BYTECODE
     /**
     * Return the compiler of the Contains expression
     *
     * @return the relevant ExpressionCompiler
     */
    @Override
    public ExpressionCompiler getExpressionCompiler() {
        return new ContainsCompiler();
    }
//#endif

}

