/** LICENSE ********************************************************************
 **
 ** smolbote: yet another qute browser
 ** Copyright (C) 2017  Xian Nox
 **
 ** 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 <http://www.gnu.org/licenses/>.
 **
 ******************************************************************************/

#include "blockerrule.h"

/* AdBlock filter reference
 * https://adblockplus.org/en/filters
 * https://adblockplus.org/en/filter-cheatsheet
 */

BlockerRule::BlockerRule(QString rule, QObject *parent) :
    QObject(parent)
{
    m_rule = rule;
    QString pattern = rule;

    // Empty rule or comment
    if(pattern.trimmed().isEmpty() || pattern.startsWith("!")) {
        m_type = RuleType::Invalid;
        return;
    }

    // Exception
    if(pattern.startsWith("@@")) {
        m_exception = true;
        pattern.remove(0, 2);
    }

    // Options
    if(pattern.contains("$")) {
        QString opts = pattern.mid(pattern.indexOf("$")+1);
        for(QString opt : opts.split(',')) {
            if(opt.endsWith("script")) {
                m_blacklistOptions.setFlag(RuleOption::script, true);
                m_whitelistOptions.setFlag(RuleOption::script, opt.startsWith("~"));
            } else if(opt.endsWith("image")) {
                m_blacklistOptions.setFlag(RuleOption::image, true);
                m_whitelistOptions.setFlag(RuleOption::image, opt.startsWith("~"));
            }
        }

        pattern.remove(pattern.indexOf("$"), pattern.length());
    }

    // Domain
    if(pattern.startsWith("||")) {
        m_type = RuleType::DomainMatch;
        m_domain = pattern.mid(2, pattern.indexOf("^")-2);
        return;
    }

    // Regular expression
    if(rule.startsWith("/") && rule.endsWith("/")) {
        m_type = RuleType::RegularExpressionMatch;
        ruleExpression.setPattern(pattern);
        return;
    }

    // Regular rule
    ruleExpression.setPattern(fromWildcardMatch(pattern));
    m_type = RuleType::WildcardMatch;
}

bool BlockerRule::match(const QWebEngineUrlRequestInfo &info)
{
    bool shouldBlock = false;

    switch (m_type) {
    case RuleType::Invalid:
        shouldBlock = false;
        break;

    case DomainMatch:
        if(info.requestUrl().host() == m_domain) {
            shouldBlock = true;
        }
        break;

    case RegularExpressionMatch:
    case WildcardMatch:
        shouldBlock = ruleExpression.match(info.requestUrl().toString()).hasMatch();
        break;
    }

    if(shouldBlock) {
        if(m_whitelistOptions.testFlag(RuleOption::image) && info.resourceType() == QWebEngineUrlRequestInfo::ResourceTypeImage) {
            shouldBlock = false;
        }
    }
    if(shouldBlock) {
        if(m_blacklistOptions.testFlag(RuleOption::image) && info.resourceType() == QWebEngineUrlRequestInfo::ResourceTypeImage) {
            shouldBlock = true;
        } else {
            shouldBlock = false;
        }
    }

    return shouldBlock;
}

bool BlockerRule::isValid()
{
    if(m_type == RuleType::Invalid) {
        return false;
    } else {
        return true;
    }
}
bool BlockerRule::isException()
{
    return m_exception;
}

QString BlockerRule::toString() const
{
    return m_rule;
}

QString BlockerRule::fromWildcardMatch(const QString &pattern)
{
    QString parsed;

    for(int i=0; i<pattern.length(); i++) {
        const QChar c = pattern.at(i);
        switch (c.toLatin1()) {
        case '*':
            parsed.append(".*");
            break;
        case '^':
            parsed.append("(?:[^\\w\\d\\_\\-\\.\\%]|$)");
            break;
        case '|':
            if(i == 0) {
                // beginning of string
                parsed.append('^');
            } else {
                // end of string
                parsed.append('$');
            }
            break;
        default:
            parsed.append(c);
            break;
        }
    }

    return parsed;
}