/*
 ***************************************************************************************
 *  Copyright (C) 2006 EsperTech, Inc. All rights reserved.                            *
 *  http://www.espertech.com/esper                                                     *
 *  http://www.espertech.com                                                           *
 *  ---------------------------------------------------------------------------------- *
 *  The software in this package is published under the terms of the GPL license       *
 *  a copy of which has been included with this distribution in the license.txt file.  *
 ***************************************************************************************
 */
package com.espertech.esper.type;

/**
 * Placeholder for a String value in an event expression.
 */
public final class StringValue extends PrimitiveValueBase {
    private String stringValue;

    /**
     * Constructor.
     *
     * @param stringValue sets initial value
     */
    public StringValue(String stringValue) {
        this.stringValue = stringValue;
    }

    /**
     * Constructor.
     */
    public StringValue() {
    }

    public PrimitiveValueType getType() {
        return PrimitiveValueType.STRING;
    }

    /**
     * Parse the string array returning a string array.
     *
     * @param values - string array
     * @return typed array
     */
    public static String[] parseString(String[] values) {
        String[] result = new String[values.length];
        for (int i = 0; i < result.length; i++) {
            result[i] = parseString(values[i]);
        }
        return result;
    }

    public final void parse(String value) {
        stringValue = parseString(value);
    }

    public final Object getValueObject() {
        return stringValue;
    }

    public final void setString(String x) {
        this.stringValue = x;
    }

    public final String toString() {
        if (stringValue == null) {
            return "null";
        }
        return stringValue;
    }

    /**
     * Parse the string literal consisting of text between double-quotes or single-quotes.
     *
     * @param value is the text wthin double or single quotes
     * @return parsed value
     */
    public static String parseString(String value) {
        if ((value.startsWith("\"")) && (value.endsWith("\"")) ||
                (value.startsWith("'")) && (value.endsWith("'"))) {
            if (value.length() > 1) {
                if (value.indexOf('\\') != -1) {
                    return unescape(value.substring(1, value.length() - 1));
                }
                return value.substring(1, value.length() - 1);
            }
        }

        throw new IllegalArgumentException("String value of '" + value + "' cannot be parsed");
    }

    private static String unescape(String s) {
        int i = 0, len = s.length();
        char c;
        StringBuilder sb = new StringBuilder(len);
        while (i < len) {
            c = s.charAt(i++);
            if (c == '\\') {
                if (i < len) {
                    c = s.charAt(i++);
                    if (c == 'u') {
                        c = (char) Integer.parseInt(s.substring(i, i + 4), 16);
                        i += 4;
                    } // add other cases here as desired...
                }
            } // fall through: \ escapes itself, quotes any character but u
            sb.append(c);
        }
        return sb.toString();
    }
}