/**
 * Copyright 2020 Tobias Fella <fella@posteo.de>
 *
 * 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 2 of
 * the License or (at your option) version 3 or any later version
 * accepted by the membership of KDE e.V. (or its successor approved
 * by the membership of KDE e.V.), which shall act as a proxy
 * defined in Section 14 of version 3 of the license.
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

#include <QDateTime>
#include <QFile>
#include <QFileInfo>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QStandardPaths>
#include <QTextDocumentFragment>

#include <Syndication/Syndication>

#include "database.h"
#include "fetcher.h"

Fetcher::Fetcher()
{
    manager = new QNetworkAccessManager(this);
    manager->setRedirectPolicy(QNetworkRequest::NoLessSafeRedirectPolicy);
    manager->setStrictTransportSecurityEnabled(true);
    manager->enableStrictTransportSecurityStore(true);
}

void Fetcher::fetch(QString url)
{
    qDebug() << "Starting to fetch" << url;

    Q_EMIT startedFetchingFeed(url);

    QNetworkRequest request((QUrl(url)));
    QNetworkReply *reply = get(request);
    connect(reply, &QNetworkReply::finished, this, [this, url, reply]() {
        QByteArray data = reply->readAll();
        Syndication::DocumentSource *document = new Syndication::DocumentSource(data, url);
        Syndication::FeedPtr feed = Syndication::parserCollection()->parse(*document, QStringLiteral("Atom"));

        processFeed(feed, url);

        delete reply;
    });
}

void Fetcher::fetchAll()
{
    QSqlQuery query;
    query.prepare(QStringLiteral("SELECT url FROM Feeds;"));
    Database::instance().execute(query);
    while (query.next()) {
        fetch(query.value(0).toString());
    }
}

void Fetcher::processFeed(Syndication::FeedPtr feed, QString url)
{
    if (feed.isNull())
        return;

    QSqlQuery query;
    query.prepare(QStringLiteral("UPDATE Feeds SET name=:name, image=:image, link=:link, description=:description, lastUpdated=:lastUpdated WHERE url=:url;"));
    query.bindValue(QStringLiteral(":name"), feed->title());
    query.bindValue(QStringLiteral(":url"), url);
    query.bindValue(QStringLiteral(":link"), feed->link());
    query.bindValue(QStringLiteral(":description"), feed->description());

    QDateTime current = QDateTime::currentDateTime();
    query.bindValue(QStringLiteral(":lastUpdated"), current.toSecsSinceEpoch());

    for (auto &author : feed->authors()) {
        processAuthor(author, QLatin1String(""), url);
    }

    QString image;
    if (feed->image()->url().startsWith(QStringLiteral("/")))
        image = QUrl(url).adjusted(QUrl::RemovePath).toString() + feed->image()->url();
    else
        image = feed->image()->url();
    query.bindValue(QStringLiteral(":image"), image);
    Database::instance().execute(query);

    qDebug() << "Updated feed title:" << feed->title();

    Q_EMIT feedDetailsUpdated(url, feed->title(), image, feed->link(), feed->description(), current);

    for (const auto &entry : feed->items()) {
        processEntry(entry, url);
    }

    Q_EMIT feedUpdated(url);
}

void Fetcher::processEntry(Syndication::ItemPtr entry, QString url)
{
    qDebug() << "Processing" << entry->title();
    QSqlQuery query;
    query.prepare(QStringLiteral("SELECT COUNT (id) FROM Entries WHERE id=:id;"));
    query.bindValue(QStringLiteral(":id"), entry->id());
    Database::instance().execute(query);
    query.next();

    if (query.value(0).toInt() != 0)
        return;

    query.prepare(QStringLiteral("INSERT INTO Entries VALUES (:feed, :id, :title, :content, :created, :updated, :link, false);"));
    query.bindValue(QStringLiteral(":feed"), url);
    query.bindValue(QStringLiteral(":id"), entry->id());
    query.bindValue(QStringLiteral(":title"), QTextDocumentFragment::fromHtml(entry->title()).toPlainText());
    query.bindValue(QStringLiteral(":created"), static_cast<int>(entry->datePublished()));
    query.bindValue(QStringLiteral(":updated"), static_cast<int>(entry->dateUpdated()));
    query.bindValue(QStringLiteral(":link"), entry->link());

    if (!entry->content().isEmpty())
        query.bindValue(QStringLiteral(":content"), entry->content());
    else
        query.bindValue(QStringLiteral(":content"), entry->description());

    Database::instance().execute(query);

    for (const auto &author : entry->authors()) {
        processAuthor(author, entry->id(), url);
    }

    for (const auto &enclosure : entry->enclosures()) {
        processEnclosure(enclosure, entry, url);
    }
}

void Fetcher::processAuthor(Syndication::PersonPtr author, QString entryId, QString url)
{
    QSqlQuery query;
    query.prepare(QStringLiteral("INSERT INTO Authors VALUES(:feed, :id, :name, :uri, :email);"));
    query.bindValue(QStringLiteral(":feed"), url);
    query.bindValue(QStringLiteral(":id"), entryId);
    query.bindValue(QStringLiteral(":name"), author->name());
    query.bindValue(QStringLiteral(":uri"), author->uri());
    query.bindValue(QStringLiteral(":email"), author->email());
    Database::instance().execute(query);
}

void Fetcher::processEnclosure(Syndication::EnclosurePtr enclosure, Syndication::ItemPtr entry, QString feedUrl)
{
    QSqlQuery query;
    query.prepare(QStringLiteral("INSERT INTO Enclosures VALUES (:feed, :id, :duration, :size, :title, :type, :url);"));
    query.bindValue(QStringLiteral(":feed"), feedUrl);
    query.bindValue(QStringLiteral(":id"), entry->id());
    query.bindValue(QStringLiteral(":duration"), enclosure->duration());
    query.bindValue(QStringLiteral(":size"), enclosure->length());
    query.bindValue(QStringLiteral(":title"), enclosure->title());
    query.bindValue(QStringLiteral(":type"), enclosure->type());
    query.bindValue(QStringLiteral(":url"), enclosure->url());
    Database::instance().execute(query);
}

QString Fetcher::image(QString url)
{
    QString path = filePath(url);
    if (QFileInfo::exists(path)) {
        return path;
    }

    download(url);

    return QLatin1String("");
}

void Fetcher::download(QString url)
{
    QNetworkRequest request((QUrl(url)));
    QNetworkReply *reply = get(request);
    connect(reply, &QNetworkReply::finished, this, [this, url, reply]() {
        QByteArray data = reply->readAll();
        QFile file(filePath(url));
        file.open(QIODevice::WriteOnly);
        file.write(data);
        file.close();

        delete reply;
    });
}

void Fetcher::removeImage(QString url)
{
    qDebug() << filePath(url);
    QFile(filePath(url)).remove();
}

QString Fetcher::filePath(QString url)
{
    return QStandardPaths::writableLocation(QStandardPaths::AppDataLocation) + QStringLiteral("/") + QString::fromStdString(QCryptographicHash::hash(url.toUtf8(), QCryptographicHash::Md5).toHex().toStdString());
}

QNetworkReply *Fetcher::get(QNetworkRequest &request)
{
    request.setRawHeader("User-Agent", "Alligator/0.1; Syndication");
    return manager->get(request);
}