/*
 * 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: https://neueland.iserlohn-fortress.net/smolbote.hg
 *
 * SPDX-License-Identifier: GPL-3.0
 */

#include "urlinterceptor.h"
#include "web/urlfilter/adblockrule.h"
#include <QDir>
#include <QJsonArray>
#include <QJsonDocument>
#include <QTextStream>
#include <boost/algorithm/string.hpp>
#include <configuration/configuration.h>

inline std::vector<FilterRule> parseAdBlockList(const QString &filename)
{
    std::vector<FilterRule> rules;
    QFile list(filename);

    if(list.open(QIODevice::ReadOnly | QIODevice::Text), true) {
        QTextStream l(&list);
        QString line;
        while(l.readLineInto(&line)) {
            AdBlockRule rule(line);
            if(rule.isEnabled()) {
                rules.emplace_back(std::move(rule));
                //qDebug("added rule: %s", qUtf8Printable(line));
            }
        }
        list.close();
    }

    return rules;
}

UrlRequestInterceptor::UrlRequestInterceptor(const std::unique_ptr<Configuration> &config, QObject *parent)
    : QWebEngineUrlRequestInterceptor(parent)
{
    QDir hostsD(config->value<QString>("filter.path").value());
    const QStringList hostFiles = hostsD.entryList(QDir::Files);
    for(const QString &file : hostFiles) {
        const QString absPath = hostsD.absoluteFilePath(file);
        auto r = parse(absPath);
#ifdef QT_DEBUG
        qDebug("Parsed %i rules from %s", r.count(), qUtf8Printable(absPath));
#endif

        rules.unite(r);
    }

    const auto header = config->value<std::vector<std::string>>("filter.header");
    if(header) {
        for(const std::string &h : header.value()) {
            std::vector<std::string> s;
            boost::split(s, h, boost::is_any_of(":="));
            auto pair = std::make_pair(s.at(0), s.at(1));
            m_headers.emplace_back(pair);
        }
    }

    auto filtersPath = config->value<QString>("filter.adblock");
    if(filtersPath)
        filters = std::move(parseAdBlockList(filtersPath.value()));
}

// test DNT on https://browserleaks.com/donottrack
void UrlRequestInterceptor::interceptRequest(QWebEngineUrlRequestInfo &info)
{
    for(const Header &header : m_headers) {
        info.setHttpHeader(QByteArray::fromStdString(header.first), QByteArray::fromStdString(header.second));
    }

    if(rules.contains(info.requestUrl().host())) {
        info.block(rules.value(info.requestUrl().host()).isBlocking);
        return;
    }

    for(const FilterRule &rule : filters) {
        if(rule.matchesDomain(info.firstPartyUrl().host()) && rule.matchesType(info.resourceType()) && rule.matchesUrl(info.requestUrl())) {
            info.block(rule.isBlocking());
#ifdef QT_DEBUG
            qDebug("--> blocked %s", qUtf8Printable(info.requestUrl().toString()));
            qDebug("- %s", qUtf8Printable(rule.toString()));
#endif
            break;
        }
    }
}

QHash<QString, UrlRequestInterceptor::HostRule> parse(const QString &filename)
{
    QHash<QString, UrlRequestInterceptor::HostRule> rules;

    QFile hostfile(filename);
    if(hostfile.open(QIODevice::ReadOnly | QIODevice::Text)) {

        // with a QTextStream we can read lines without getting linebreaks at the end
        QTextStream hostfile_stream(&hostfile);

        while(!hostfile_stream.atEnd()) {

            // read line and remove any whitespace at the end
            const QString &line = hostfile_stream.readLine().trimmed();

            // skip comments and empty lines
            if(line.isEmpty() || line.startsWith('#'))
                continue;

            // everything else should be a rule
            // format is <redirect> <host>
            // 0.0.0.0 hostname
            const QStringList &parts = line.split(' ');
            const QString &redirect = parts.at(0);

            for(auto i = parts.constBegin() + 1; i != parts.constEnd(); ++i) {
                if(!rules.contains(*i)) {
                    UrlRequestInterceptor::HostRule rule{};
                    rule.isBlocking = (redirect == "0.0.0.0");
                    rules.insert(*i, rule);
                }
            }

            //            for(const QString &host : parts.mid(1)) {
            //                if(!rules.contains(host)) {
            //                    UrlRequestInterceptor::HostRule rule{};
            //                    rule.isBlocking = redirect == "0.0.0.0";
            //                    rules.insert(host, rule);
            //                }
            //            }
        }

        hostfile.close();
    }

    return rules;
}