/*
 * This file is part of smolbote. It's copyrighted by the contributors recorded
 * in the version control history of the file, available from its original
 * location: git://neueland.iserlohn-fortress.net/smolbote.git
 * 
 * SPDX-License-Identifier: GPL-3.0
 */

#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_filter = rule;
    QString pattern = rule;

    // Empty rule or comment
    if(pattern.trimmed().isEmpty() || pattern.startsWith("!")) {
        m_valid = false;
        return;
    }

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

    // Ignore element hiding rules for now
    if(pattern.contains("##") || pattern.contains("#@#")) {
        m_valid = false;
        return;
    }

    // Options
    if(pattern.contains("$")) {
        QString opts = pattern.mid(pattern.indexOf("$")+1);
        pattern.remove(pattern.indexOf("$"), pattern.length());

        const QStringList optList = opts.split(',');
        QStringList::const_iterator i;
        for(i = optList.constBegin(); i != optList.constEnd(); ++i) {
            parseOption(*i);
        }
    }

    // Regular expression
    if(rule.startsWith("/") && rule.endsWith("/")) {
        m_valid = true;
        ruleExpression.setPattern(pattern);
        return;
    }

    // Domain rules
    if(pattern.startsWith("||")) {
        pattern.remove(0, 2);
        // find the end point for the domain
        int end = pattern.indexOf(QRegularExpression("(?:[^\\w\\d\\_\\-\\.\\%]|$)"), 0);
        domainExpression.setPattern(pattern.mid(0, end));
        pattern.remove(0, end+1);
    } else if(pattern.startsWith("|") && pattern.endsWith("|")) {
        pattern.remove(0, 1);
        pattern.chop(1);
        domainExpression.setPattern(pattern);
    } else {
        domainExpression.setPattern(".*");
    }

    // Regular rule
    ruleExpression.setWildcardPattern(pattern);
    m_valid = true;
}

bool BlockerRule::match(const QWebEngineUrlRequestInfo &info)
{
    if(!m_valid) {
        return false;
    }

    // if both domain and rule match
    if(domainExpression.match(info.requestUrl().host()) && ruleExpression.match(info.requestUrl().toString())) {

        // option explicitly allows
        if(matchOptions(info, m_whitelistOptions)) {
            return false;
        }

        // option explicitly bans
        if(matchOptions(info, m_blacklistOptions)) {
            return true;
        }

        // no options, but both domain and rule match --> rule matches
        return true;
    }

    // domain and/or rule do not match
    return false;
}

bool BlockerRule::isValid()
{
    return m_valid;
}
bool BlockerRule::isException()
{
    return m_exception;
}

QString BlockerRule::filter() const
{
    return m_filter;
}

void BlockerRule::parseOption(const QString &opt)
{
    if(opt.startsWith("script")) {
        m_blacklistOptions.setFlag(RuleOption::script, true);
    } else if(opt.startsWith("~script")) {
        m_whitelistOptions.setFlag(RuleOption::script, true);

    } else if(opt.startsWith("image")) {
        m_blacklistOptions.setFlag(RuleOption::image, true);
    } else if(opt.startsWith("~image")) {
        m_whitelistOptions.setFlag(RuleOption::image, true);

    } else if(opt.startsWith("stylesheet")) {
        m_blacklistOptions.setFlag(RuleOption::stylesheet, true);
    } else if(opt.startsWith("~stylesheet")) {
        m_whitelistOptions.setFlag(RuleOption::stylesheet, true);

    } else if(opt.startsWith("object")) {
        m_blacklistOptions.setFlag(RuleOption::object, true);
    } else if(opt.startsWith("~object")) {
        m_whitelistOptions.setFlag(RuleOption::object, true);

    } else if(opt.startsWith("object-subrequest")) {
        m_blacklistOptions.setFlag(RuleOption::objectsubrequest, true);
    } else if(opt.startsWith("~object-subrequest")) {
        m_whitelistOptions.setFlag(RuleOption::objectsubrequest, true);

    } else if(opt.startsWith("subdocument")) {
        m_blacklistOptions.setFlag(RuleOption::subdocument, true);
    } else if(opt.startsWith("~subdocument")) {
        m_whitelistOptions.setFlag(RuleOption::subdocument, true);
    }
}

bool BlockerRule::matchOptions(const QWebEngineUrlRequestInfo &info, const RuleOptions &options)
{
    // no options are defined
    if(options == 0) {
        return false;
    }

    bool hasOption = false;
    switch (info.resourceType()) {
    case QWebEngineUrlRequestInfo::ResourceTypeScript:
        if(options.testFlag(RuleOption::script)) {
            hasOption = true;
        }
        break;
    case QWebEngineUrlRequestInfo::ResourceTypeImage:
        if(options.testFlag(RuleOption::image)) {
            hasOption = true;
        }
        break;
    case QWebEngineUrlRequestInfo::ResourceTypeStylesheet:
        if(options.testFlag(RuleOption::stylesheet)) {
            hasOption = true;
        }
        break;
    case QWebEngineUrlRequestInfo::ResourceTypeObject:
        if(options.testFlag(RuleOption::object)) {
            hasOption = true;
        }
        break;
    case QWebEngineUrlRequestInfo::ResourceTypePluginResource:
        if(options.testFlag(RuleOption::objectsubrequest)) {
            hasOption = true;
        }
        break;
    case QWebEngineUrlRequestInfo::ResourceTypeSubFrame:
        if(options.testFlag(RuleOption::subdocument)) {
            hasOption = true;
        }
        break;
    default:
        break;
    }

    return hasOption;
}