// This file Copyright © Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.

#include <QAbstractTextDocumentLayout>
#include <QApplication>
#include <QPainter>
#include <QPixmap>
#include <QTextDocument>

#include <libtransmission/web-utils.h>
#include <libtransmission/favicon-cache.h>

#include "Formatter.h"
#include "Torrent.h"
#include "TrackerDelegate.h"
#include "TrackerModel.h"
#include "Utils.h"

/***
****
***/

namespace
{
auto constexpr Spacing = 6;

auto constexpr Margin = QSize{ 10, 10 };

class ItemLayout
{
public:
    QRect icon_rect;
    QRect text_rect;

    ItemLayout(QString const& text, bool suppress_colors, Qt::LayoutDirection direction, QPoint const& top_left, int width);

    [[nodiscard]] QSize size() const
    {
        return (icon_rect | text_rect).size();
    }

    [[nodiscard]] QAbstractTextDocumentLayout* textLayout() const
    {
        return text_document_.documentLayout();
    }

private:
    QTextDocument text_document_;
};

ItemLayout::ItemLayout(
    QString const& text,
    bool suppress_colors,
    Qt::LayoutDirection direction,
    QPoint const& top_left,
    int width)
{
    auto const icon_size = QSize{ FaviconCache<QPixmap>::Width, FaviconCache<QPixmap>::Height };

    QRect base_rect{ top_left, QSize{ width, 0 } };

    icon_rect = QStyle::alignedRect(direction, Qt::AlignLeft | Qt::AlignTop, icon_size, base_rect);
    Utils::narrowRect(base_rect, icon_size.width() + Spacing, 0, direction);

    text_document_.setDocumentMargin(0);
    text_document_.setTextWidth(base_rect.width());

    QTextOption text_option;
    text_option.setTextDirection(direction);

    if (suppress_colors)
    {
        text_option.setFlags(QTextOption::SuppressColors);
    }

    text_document_.setDefaultTextOption(text_option);
    text_document_.setHtml(text);

    text_rect = base_rect;
    text_rect.setSize(text_document_.size().toSize());
}

} // namespace

/***
****
***/

QSize TrackerDelegate::sizeHint(QStyleOptionViewItem const& option, TrackerInfo const& info) const
{
    ItemLayout const layout{ getText(info), true, option.direction, QPoint{ 0, 0 }, option.rect.width() - Margin.width() * 2 };
    return layout.size() + Margin * 2;
}

QSize TrackerDelegate::sizeHint(QStyleOptionViewItem const& option, QModelIndex const& index) const
{
    auto const tracker_info = index.data(TrackerModel::TrackerRole).value<TrackerInfo>();
    return sizeHint(option, tracker_info);
}

void TrackerDelegate::paint(QPainter* painter, QStyleOptionViewItem const& option, QModelIndex const& index) const
{
    auto const tracker_info = index.data(TrackerModel::TrackerRole).value<TrackerInfo>();
    painter->save();
    painter->setClipRect(option.rect);
    drawBackground(painter, option, index);
    drawTracker(painter, option, tracker_info);
    drawFocus(painter, option, option.rect);
    painter->restore();
}

void TrackerDelegate::drawTracker(QPainter* painter, QStyleOptionViewItem const& option, TrackerInfo const& inf) const
{
    bool const is_item_selected((option.state & QStyle::State_Selected) != 0);
    bool const is_item_enabled((option.state & QStyle::State_Enabled) != 0);
    bool const is_item_active((option.state & QStyle::State_Active) != 0);

    QIcon const tracker_icon(inf.st.getFavicon());

    QRect const content_rect(option.rect.adjusted(Margin.width(), Margin.height(), -Margin.width(), -Margin.height()));
    ItemLayout const layout(getText(inf), is_item_selected, option.direction, content_rect.topLeft(), content_rect.width());

    painter->save();

    if (is_item_selected)
    {
        QPalette::ColorGroup cg = is_item_enabled ? QPalette::Normal : QPalette::Disabled;

        if (cg == QPalette::Normal && !is_item_active)
        {
            cg = QPalette::Inactive;
        }

        painter->fillRect(option.rect, option.palette.brush(cg, QPalette::Highlight));
    }

    tracker_icon
        .paint(painter, layout.icon_rect, Qt::AlignCenter, is_item_selected ? QIcon::Selected : QIcon::Normal, QIcon::On);

    QAbstractTextDocumentLayout::PaintContext paint_context;
    paint_context.clip = layout.text_rect.translated(-layout.text_rect.topLeft());
    paint_context.palette.setColor(
        QPalette::Text,
        option.palette.color(is_item_selected ? QPalette::HighlightedText : QPalette::Text));
    painter->translate(layout.text_rect.topLeft());
    layout.textLayout()->draw(painter, paint_context);

    painter->restore();
}

void TrackerDelegate::setShowMore(bool b)
{
    show_more_ = b;
}

namespace
{
QString timeToRoundedString(int seconds)
{
    if (seconds > 60)
    {
        seconds -= seconds % 60;
    }

    return Formatter::time_to_string(seconds);
}
} // namespace

QString TrackerDelegate::getText(TrackerInfo const& inf) const
{
    QString str;
    auto const err_markup_begin = QStringLiteral("<span style=\"color:red\">");
    auto const err_markup_end = QStringLiteral("</span>");
    auto const timeout_markup_begin = QStringLiteral("<span style=\"color:#224466\">");
    auto const timeout_markup_end = QStringLiteral("</span>");
    auto const success_markup_begin = QStringLiteral("<span style=\"color:#008B00\">");
    auto const success_markup_end = QStringLiteral("</span>");

    auto const now = time(nullptr);
    auto const time_until = [&now](auto t)
    {
        return timeToRoundedString(static_cast<int>(t - now));
    };
    auto const time_since = [&now](auto t)
    {
        return timeToRoundedString(static_cast<int>(now - t));
    };

    // hostname
    str += inf.st.is_backup ? QStringLiteral("<i>") : QStringLiteral("<b>");
    auto const announce_url = inf.st.announce.toStdString();
    if (auto const parsed = tr_urlParse(announce_url); parsed)
    {
        str += QStringLiteral("%1:%2")
                   .arg(QString::fromUtf8(std::data(parsed->host), std::size(parsed->host)))
                   .arg(parsed->port);
    }
    str += inf.st.is_backup ? QStringLiteral("</i>") : QStringLiteral("</b>");

    // announce & scrape info
    if (!inf.st.is_backup)
    {
        if (inf.st.has_announced && inf.st.announce_state != TR_TRACKER_INACTIVE)
        {
            auto const tstr = time_since(inf.st.last_announce_time);
            str += QStringLiteral("<br/>\n");

            if (inf.st.last_announce_succeeded)
            {
                //: %1 and %2 are replaced with HTML markup, %3 is duration
                str += tr("Got a list of%1 %Ln peer(s)%2 %3 ago", nullptr, inf.st.last_announce_peer_count)
                           .arg(success_markup_begin)
                           .arg(success_markup_end)
                           .arg(tstr);
            }
            else if (inf.st.last_announce_timed_out)
            {
                //: %1 and %2 are replaced with HTML markup, %3 is duration
                str += tr("Peer list request %1timed out%2 %3 ago; will retry")
                           .arg(timeout_markup_begin)
                           .arg(timeout_markup_end)
                           .arg(tstr);
            }
            else
            {
                //: %1 and %3 are replaced with HTML markup, %2 is error message, %4 is duration
                str += tr("Got an error %1\"%2\"%3 %4 ago")
                           .arg(err_markup_begin)
                           .arg(inf.st.last_announce_result)
                           .arg(err_markup_end)
                           .arg(tstr);
            }
        }

        switch (inf.st.announce_state)
        {
        case TR_TRACKER_INACTIVE:
            str += QStringLiteral("<br/>\n");
            str += tr("No updates scheduled");
            break;

        case TR_TRACKER_WAITING:
            str += QStringLiteral("<br/>\n");
            //: %1 is duration
            str += tr("Asking for more peers in %1").arg(time_until(inf.st.next_announce_time));
            break;

        case TR_TRACKER_QUEUED:
            str += QStringLiteral("<br/>\n");
            str += tr("Queued to ask for more peers");
            break;

        case TR_TRACKER_ACTIVE:
            str += QStringLiteral("<br/>\n");
            //: %1 is duration
            str += tr("Asking for more peers now… <small>%1</small>").arg(time_since(inf.st.last_announce_start_time));
            break;

        default:
            break;
        }

        if (!show_more_)
        {
            return str;
        }

        if (inf.st.has_scraped)
        {
            str += QStringLiteral("<br/>\n");
            auto const tstr = time_since(inf.st.last_scrape_time);

            if (!inf.st.last_scrape_succeeded)
            {
                //: %1 and %3 are replaced with HTML markup, %2 is error message, %4 is duration
                str += tr("Got a scrape error %1\"%2\"%3 %4 ago")
                           .arg(err_markup_begin)
                           .arg(inf.st.last_scrape_result)
                           .arg(err_markup_end)
                           .arg(tstr);
            }
            else if (inf.st.seeder_count >= 0 && inf.st.leecher_count >= 0)
            {
                //: First part of phrase "Tracker had ... seeder(s) and ... leecher(s) ... ago",
                //: %1 and %2 are replaced with HTML markup
                str += tr("Tracker had%1 %Ln seeder(s)%2", nullptr, inf.st.seeder_count)
                           .arg(success_markup_begin)
                           .arg(success_markup_end);
                //: Second part of phrase "Tracker had ... seeder(s) and ... leecher(s) ... ago",
                //: %1 and %2 are replaced with HTML markup, %3 is duration;
                //: notice that leading space (before "and") is included here
                str += tr(" and%1 %Ln leecher(s)%2 %3 ago", nullptr, inf.st.leecher_count)
                           .arg(success_markup_begin)
                           .arg(success_markup_end)
                           .arg(tstr);
            }
            else
            {
                //: %1 and %2 are replaced with HTML markup, %3 is duration
                str += tr("Tracker had %1no information%2 on peer counts %3 ago")
                           .arg(success_markup_begin)
                           .arg(success_markup_end)
                           .arg(tstr);
            }
        }

        switch (inf.st.scrape_state)
        {
        case TR_TRACKER_WAITING:
            str += QStringLiteral("<br/>\n");
            //: %1 is duration
            str += tr("Asking for peer counts in %1").arg(time_until(inf.st.next_scrape_time));
            break;

        case TR_TRACKER_QUEUED:
            str += QStringLiteral("<br/>\n");
            str += tr("Queued to ask for peer counts");
            break;

        case TR_TRACKER_ACTIVE:
            str += QStringLiteral("<br/>\n");
            //: %1 is duration
            str += tr("Asking for peer counts now… <small>%1</small>").arg(time_since(inf.st.last_scrape_start_time));
            break;

        default: // TR_TRACKER_INACTIVE
            break;
        }
    }

    return str;
}