/**************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Copyright (C) 2017 BlackBerry Limited <qt@blackberry.com>
** Copyright (C) 2017 Andre Hartmann <aha_1980@gmx.de>
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
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** GNU General Public License Usage
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** General Public License version 3 as published by the Free Software
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#include "camelhumpmatcher.h"

#include <QRegularExpression>
#include <QString>

/**
 * \brief Creates a regexp that represents a specified camel hump pattern,
 *        underscores are not included.
 *
 * \param pattern the camel hump pattern
 * \param caseSensitivity case sensitivity used for camel hump matching;
 *                        does not affect wildcard style matching
 * \return the regexp
 */
QRegularExpression CamelHumpMatcher::createCamelHumpRegExp(
        const QString &pattern, CamelHumpMatcher::CaseSensitivity caseSensitivity)
{
    if (pattern.isEmpty())
        return QRegularExpression();

    /*
     * This code builds a regular expression in order to more intelligently match
     * camel-case and underscore names.
     *
     * For any but the first letter, the following replacements are made:
     *   A => [a-z0-9_]*A
     *   a => (?:[a-zA-Z0-9]*_)?a
     *
     * That means any sequence of lower-case or underscore characters can preceed an
     * upper-case character. And any sequence of lower-case or upper case characters -
     * followed by an underscore can preceed a lower-case character.
     *
     * Examples: (case sensitive mode)
     *   gAC matches getActionController
     *   gac matches get_action_controller
     *
     * It also implements the fully and first-letter-only case sensitivity.
     */

    QString keyRegExp;
    bool first = true;
    const QChar asterisk = '*';
    const QChar question = '?';
    const QLatin1String uppercaseWordContinuation("[a-z0-9_]*");
    const QLatin1String lowercaseWordContinuation("(?:[a-zA-Z0-9]*_)?");
    for (const QChar &c : pattern) {
        if (!c.isLetter()) {
            if (c == question)
                keyRegExp += '.';
            else if (c == asterisk)
                keyRegExp += ".*";
            else
                keyRegExp += QRegularExpression::escape(c);
        } else if (caseSensitivity == CaseSensitivity::CaseInsensitive ||
            (caseSensitivity == CaseSensitivity::FirstLetterCaseSensitive && !first)) {

            keyRegExp += "(?:";
            if (!first)
                keyRegExp += uppercaseWordContinuation;
            keyRegExp += QRegularExpression::escape(c.toUpper());
            keyRegExp += '|';
            if (!first)
                keyRegExp += lowercaseWordContinuation;
            keyRegExp += QRegularExpression::escape(c.toLower());
            keyRegExp += ')';
        } else {
            if (!first) {
                if (c.isUpper())
                    keyRegExp += uppercaseWordContinuation;
                else
                    keyRegExp += lowercaseWordContinuation;
            }
            keyRegExp += QRegularExpression::escape(c);
        }

        first = false;
    }
    return QRegularExpression(keyRegExp);
}