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/*
 Copyright 2013 Red Hat, Inc. and/or its affiliates.

 This file is part of lightblue.

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see .
 */
package com.redhat.lightblue.eval;

import java.util.regex.Pattern;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.JsonNode;
import com.redhat.lightblue.crud.CrudConstants;
import com.redhat.lightblue.metadata.FieldTreeNode;
import com.redhat.lightblue.query.RegexMatchExpression;
import com.redhat.lightblue.util.Path;
import com.redhat.lightblue.util.KeyValueCursor;

public class RegexEvaluator extends QueryEvaluator {

    private static final Logger LOGGER = LoggerFactory.getLogger(RegexEvaluator.class);

    private final FieldTreeNode fieldMd;
    private final Pattern regex;
    private final Path relativePath;

    /**
     * Constructs evaluator for {field op value} style comparison
     *
     * @param expr The expression
     * @param md Entity metadata
     * @param context The path relative to which the expression will be
     * evaluated
     */
    public RegexEvaluator(RegexMatchExpression expr, FieldTreeNode context) {
        this.relativePath = expr.getField();
        fieldMd = context.resolve(relativePath);
        if (fieldMd == null) {
            throw new EvaluationError(expr, CrudConstants.ERR_FIELD_NOT_THERE + relativePath);
        }
        int flags = 0;
        if (expr.isCaseInsensitive()) {
            flags |= Pattern.CASE_INSENSITIVE;
        }
        if (expr.isMultiline()) {
            flags |= Pattern.MULTILINE;
        }
        if (expr.isExtended()) {
            flags |= Pattern.COMMENTS;
        }
        if (expr.isDotAll()) {
            flags |= Pattern.DOTALL;
        }
        regex = Pattern.compile(expr.getRegex(), flags);
        LOGGER.debug("ctor {} {}", relativePath, regex);
    }

    @Override
    public boolean evaluate(QueryEvaluationContext ctx) {
        LOGGER.debug("evaluate {} {}", relativePath, regex);
        KeyValueCursor cursor = ctx.getNodes(relativePath);
        while (cursor.hasNext()) {
            cursor.next();
            JsonNode valueNode = cursor.getCurrentValue();
            Object docValue;
            if (valueNode != null) {
                docValue = fieldMd.getType().fromJson(valueNode);
            } else {
                docValue = null;
            }
            LOGGER.debug(" value={}", valueNode);
            ctx.setResult(false);
            if (docValue != null) {
                ctx.setResult(regex.matcher(docValue.toString()).matches());
            }
            if (ctx.getResult()) {
                break;
            }
        }
        return ctx.getResult();
    }
}