/* ============================================================
* QupZilla - WebKit based browser
* Copyright (C) 2014  David Rosca <nowrep@gmail.com>
*
* 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 "adblockmatcher.h"
#include "adblockmanager.h"
#include "adblockrule.h"
#include "adblocksubscription.h"

AdBlockMatcher::AdBlockMatcher(AdBlockManager* manager)
    : QObject(manager)
    , m_manager(manager)
{
    connect(manager, SIGNAL(enabledChanged(bool)), this, SLOT(enabledChanged(bool)));
}

AdBlockMatcher::~AdBlockMatcher()
{
    clear();
}

const AdBlockRule* AdBlockMatcher::match(const QWebEngineUrlRequestInfo &request, const QString &urlDomain, const QString &urlString) const
{
    // Exception rules
    if (m_networkExceptionTree.find(request, urlDomain, urlString))
        return 0;

    int count = m_networkExceptionRules.count();
    for (int i = 0; i < count; ++i) {
        const AdBlockRule* rule = m_networkExceptionRules.at(i);
        if (rule->networkMatch(request, urlDomain, urlString))
            return 0;
    }

    // Block rules
    if (const AdBlockRule* rule = m_networkBlockTree.find(request, urlDomain, urlString))
        return rule;

    count = m_networkBlockRules.count();
    for (int i = 0; i < count; ++i) {
        const AdBlockRule* rule = m_networkBlockRules.at(i);
        if (rule->networkMatch(request, urlDomain, urlString))
            return rule;
    }

    return 0;
}

bool AdBlockMatcher::adBlockDisabledForUrl(const QUrl &url) const
{
    int count = m_documentRules.count();

    for (int i = 0; i < count; ++i)
        if (m_documentRules.at(i)->urlMatch(url))
            return true;

    return false;
}

bool AdBlockMatcher::elemHideDisabledForUrl(const QUrl &url) const
{
    if (adBlockDisabledForUrl(url))
        return true;

    int count = m_elemhideRules.count();

    for (int i = 0; i < count; ++i)
        if (m_elemhideRules.at(i)->urlMatch(url))
            return true;

    return false;
}

QString AdBlockMatcher::elementHidingRules() const
{
    return m_elementHidingRules;
}

QString AdBlockMatcher::elementHidingRulesForDomain(const QString &domain) const
{
    QString rules;
    int addedRulesCount = 0;
    int count = m_domainRestrictedCssRules.count();

    for (int i = 0; i < count; ++i) {
        const AdBlockRule* rule = m_domainRestrictedCssRules.at(i);
        if (!rule->matchDomain(domain))
            continue;

        if (Q_UNLIKELY(addedRulesCount == 1000)) {
            rules.append(rule->cssSelector());
            rules.append(QL1S("{display:none !important;}\n"));
            addedRulesCount = 0;
        }
        else {
            rules.append(rule->cssSelector() + QLatin1Char(','));
            addedRulesCount++;
        }
    }

    if (addedRulesCount != 0) {
        rules = rules.left(rules.size() - 1);
        rules.append(QL1S("{display:none !important;}\n"));
    }

    return rules;
}

void AdBlockMatcher::update()
{
    clear();

    QHash<QString, const AdBlockRule*> cssRulesHash;
    QVector<const AdBlockRule*> exceptionCssRules;

    foreach (AdBlockSubscription* subscription, m_manager->subscriptions()) {
        foreach (const AdBlockRule* rule, subscription->allRules()) {
            // Don't add internally disabled rules to cache
            if (rule->isInternalDisabled())
                continue;

            if (rule->isCssRule()) {
                // We will add only enabled css rules to cache, because there is no enabled/disabled
                // check on match. They are directly embedded to pages.
                if (!rule->isEnabled())
                    continue;

                if (rule->isException())
                    exceptionCssRules.append(rule);
                else
                    cssRulesHash.insert(rule->cssSelector(), rule);
            }
            else if (rule->isDocument()) {
                m_documentRules.append(rule);
            }
            else if (rule->isElemhide()) {
                m_elemhideRules.append(rule);
            }
            else if (rule->isException()) {
                if (!m_networkExceptionTree.add(rule))
                    m_networkExceptionRules.append(rule);
            }
            else {
                if (!m_networkBlockTree.add(rule))
                    m_networkBlockRules.append(rule);
            }
        }
    }

    foreach (const AdBlockRule* rule, exceptionCssRules) {
        const AdBlockRule* originalRule = cssRulesHash.value(rule->cssSelector());

        // If we don't have this selector, the exception does nothing
        if (!originalRule)
            continue;

        AdBlockRule* copiedRule = originalRule->copy();
        copiedRule->m_options |= AdBlockRule::DomainRestrictedOption;
        copiedRule->m_blockedDomains.append(rule->m_allowedDomains);

        cssRulesHash[rule->cssSelector()] = copiedRule;
        m_createdRules.append(copiedRule);
    }

    // Apparently, excessive amount of selectors for one CSS rule is not what WebKit likes.
    // (In my testings, 4931 is the number that makes it crash)
    // So let's split it by 1000 selectors...
    int hidingRulesCount = 0;

    QHashIterator<QString, const AdBlockRule*> it(cssRulesHash);
    while (it.hasNext()) {
        it.next();
        const AdBlockRule* rule = it.value();

        if (rule->isDomainRestricted()) {
            m_domainRestrictedCssRules.append(rule);
        }
        else if (Q_UNLIKELY(hidingRulesCount == 1000)) {
            m_elementHidingRules.append(rule->cssSelector());
            m_elementHidingRules.append(QL1S("{display:none !important;} "));
            hidingRulesCount = 0;
        }
        else {
            m_elementHidingRules.append(rule->cssSelector() + QLatin1Char(','));
            hidingRulesCount++;
        }
    }

    if (hidingRulesCount != 0) {
        m_elementHidingRules = m_elementHidingRules.left(m_elementHidingRules.size() - 1);
        m_elementHidingRules.append(QL1S("{display:none !important;} "));
    }
}

void AdBlockMatcher::clear()
{
    m_networkExceptionTree.clear();
    m_networkExceptionRules.clear();
    m_networkBlockTree.clear();
    m_networkBlockRules.clear();
    m_domainRestrictedCssRules.clear();
    m_elementHidingRules.clear();
    m_documentRules.clear();
    m_elemhideRules.clear();
    qDeleteAll(m_createdRules);
    m_createdRules.clear();
}

void AdBlockMatcher::enabledChanged(bool enabled)
{
    if (enabled)
        update();
    else
        clear();
}