/*
 * 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://library.iserlohn-fortress.net/aqua/smolbote.git
 *
 * SPDX-License-Identifier: GPL-3.0
 */

#include "filterlist.h"
#include "rule.h"
#include <QRegularExpression>
#include <QTextStream>

/**
 * Documentation:
 *
 * https://adblockplus.org/filter-cheatsheet
 * https://help.eyeo.com/adblockplus/how-to-write-filters
 *
 * https://github.com/gorhill/uBlock/wiki/Introduction-to-basic-filtering-syntax
 * https://github.com/gorhill/uBlock/wiki/Static-filter-syntax
 *
 */

const QLatin1String comment_lastModified("! Last modified: ");
const QLatin1String comment_expires("! Expires: ");

using namespace AdblockPlus;

FilterList::~FilterList()
{
    qDeleteAll(m_rules);
}

FilterList::ParseResult FilterList::parse(QTextStream &stream)
{
    FilterList::ParseResult result;

    if(stream.readLine().trimmed() != "[Adblock Plus 2.0]") {
        result.state = FilterList::InvalidFormat;
        return result;
    }

    QString line;
    while(stream.readLineInto(&line)) {

        if(!line.isEmpty()) {
            ++result.lines_total;

            if(line.startsWith('!')) {
                ++result.lines_comments;
                parseComment(line);

            } else if(line.contains("##") || line.contains("#@#")) {
                // ## is element hiding rule
                // #@# is element hiding exception rule
                if(qgetenv("PRINT_IGNORED") == "1")
                    qDebug("ignored: >%s<", qUtf8Printable(line));
                ++result.lines_ignored;

            } else {
                if(parseRule(line))
                    ++result.lines_parsed;
                else {
                    if(qgetenv("PRINT_FAILED") == "1")
                        qDebug("failed: >%s<", qUtf8Printable(line));
                    ++result.lines_failed;
                }
            }
        }
    }

    result.state = FilterList::Ok;
    return result;
}

void FilterList::parseComment(QString &line)
{
    if(line.startsWith(comment_lastModified)) {
        lastModified = QDateTime::fromString(line.mid(comment_lastModified.size()), "dd MMM yyyy HH:mm 'UTC'");
        expires = lastModified;

    } else if(line.startsWith(comment_expires)) {
        const QRegularExpression time_re("(?:(\\d+) days)|(?:(\\d+) hours)");
        const auto match = time_re.match(line);
        if(match.hasMatch()) {
            expires = expires.addDays(match.captured(1).toInt());
            expires = expires.addSecs(match.captured(2).toInt() * 60 * 60);
        }
    }
}

bool FilterList::parseRule(const QString &line)
{
    QString pattern = line;
    Options opt;

    if(pattern.startsWith(QLatin1String("@@"))) {
        pattern.remove(0, 2);
        opt.exception = true;
    }

    // parse options
    if(pattern.contains('$')) {
        const auto list = pattern.split('$');
        pattern = list.at(0);
        const auto options = list.at(1).split(',');

        for(const auto &option : options) {
            if(!opt.set(option))
                return false;
        }
    }

    if(pattern.startsWith("||") && pattern.endsWith("^")) {
        // domain match
        pattern = pattern.mid(2, pattern.length() - 3);
        m_rules.append(new MatcherRule(pattern, opt));

    } else if(pattern.startsWith("|") && pattern.endsWith("|")) {
        // string equals
        pattern = pattern.mid(1, pattern.length() - 2);
        m_rules.append(new MatcherRule(pattern, opt));

    } else if(pattern.startsWith("||")) {
        // string starts with
        pattern = pattern.mid(2, pattern.length() - 2);
        m_rules.append(new MatcherRule(pattern, opt));

    } else if(pattern.endsWith("|")) {
        // string ends with
        pattern = pattern.mid(0, pattern.length() - 1);
        m_rules.append(new MatcherRule(pattern, opt));

    } else if(pattern.startsWith("/") && pattern.endsWith("/")) {
        // regular expression
        pattern = pattern.mid(1, pattern.length() - 2);
        m_rules.append(new RegexRule(pattern, opt));

    } else {
        // wildcard pattern
        pattern = QRegularExpression::wildcardToRegularExpression(pattern);
        m_rules.append(new RegexRule(pattern, opt));
    }

    return true;
}

void FilterList::filter(QWebEngineUrlRequestInfo &info) const
{
}

bool FilterList::isUpToDate() const
{
    const auto current = QDateTime::currentDateTime();
    return expires > current;
}