/*
  EventEditorDelegate.cpp

  This file is part of Charm, a task-based time tracking application.

  Copyright (C) 2014-2018 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com

  Author: Frank Osterfeld <frank.osterfeld@kdab.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 2 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 "EventEditorDelegate.h"
#include "Data.h"
#include "EventModelFilter.h"
#include "ViewHelpers.h"

#include "Core/CharmConstants.h"
#include "Core/Event.h"

#include <QPainter>

#include <cmath>

EventEditorDelegate::EventEditorDelegate(EventModelFilter *model, QObject *parent)
    : QItemDelegate(parent)
    , m_model(model)
{
}

QSize EventEditorDelegate::sizeHint(const QStyleOptionViewItem &option,
                                    const QModelIndex &index) const
{
    // to have the size hint recalculated, simply set m_cachedSizeHint
    // to an invalid value (m_cachedSizeHint = QSize();)
    if (!m_cachedSizeHint.isValid()) {
        const Event &event = m_model->eventForIndex(index);
        Q_ASSERT(event.isValid());
        const TaskTreeItem &item = DATAMODEL->taskTreeItem(event.taskId());

        QPixmap pixmap(option.rect.size());   // temp
        QPainter painter(&pixmap);
        m_cachedSizeHint = paint(&painter, option,
                                 taskName(item),
                                 dateAndDuration(event),
                                 42, EventState_Locked).size();
    }
    return m_cachedSizeHint;
}

void EventEditorDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
                                const QModelIndex &index) const
{
    const Event &event = m_model->eventForIndex(index);
    Q_ASSERT(event.isValid());
    const TaskTreeItem &item = DATAMODEL->taskTreeItem(event.taskId());

    if (event.isValid()) {
        bool locked = DATAMODEL->isEventActive(event.id());

        paint(painter, option,
              taskName(item),
              dateAndDuration(event),
              logDuration(event.duration()),
              locked ? EventState_Locked : EventState_Default);
    }
}

QString EventEditorDelegate::taskName(const TaskTreeItem &item) const
{
    QString taskName;
    QTextStream taskStream(&taskName);
    // print leading zeroes for the TaskId
    const int taskIdLength = CONFIGURATION.taskPaddingLength;
    taskStream << QStringLiteral("%1").arg(item.task().id(), taskIdLength, 10, QLatin1Char('0'))
               << " " << DATAMODEL->smartTaskName(item.task());
    return taskName;
}

QString EventEditorDelegate::dateAndDuration(const Event &event) const
{
    QString dateAndDuration;
    QTextStream dateStream(&dateAndDuration);
    QDate date = event.startDateTime().date();
    QTime time = event.startDateTime().time();
    QTime endTime = event.endDateTime().time();
    dateStream << date.toString(Qt::SystemLocaleDate)
               << " " << time.toString(QStringLiteral("h:mm"))
               << " - " << endTime.toString(QStringLiteral("h:mm"))
               << " (" << hoursAndMinutes(event.duration()) << ") Week "
               << date.weekNumber();
    return dateAndDuration;
}

QRect EventEditorDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
                                 const QString &taskName, const QString &timespan,
                                 double logDuration, EventState state) const
{
    painter->save();
    const QPalette &palette = option.palette;
    const QFont &mainFont = option.font;
    painter->setFont(mainFont);
    QFont detailFont(mainFont);
    detailFont.setPointSizeF(mainFont.pointSizeF() * 0.8);
    QPixmap decoration;
    QColor foreground;
    QColor background;

    switch (state) {
    case EventState_Locked:
        decoration = Data::editorLockedPixmap();
        foreground = palette.color(QPalette::Disabled, QPalette::WindowText);
        background = palette.color(QPalette::Disabled, QPalette::Window);
        break;
    case EventState_Dirty:
        decoration = Data::editorDirtyPixmap();
        foreground = palette.color(QPalette::Active, QPalette::WindowText);
        background = palette.color(QPalette::Active, QPalette::Window);
        break;
    case EventState_Default:
        foreground = palette.color(QPalette::Active, QPalette::WindowText);
        background = palette.color(QPalette::Active, QPalette::Window);
        break;
    }

    if (option.state & QStyle::State_Selected) {
        QBrush brush(palette.color(QPalette::Active, QPalette::Highlight));
        painter->fillRect(option.rect, brush);
        if (state != EventState_Locked) {
            foreground = palette.color(
                QPalette::Active, QPalette::HighlightedText);
        }
    }

    painter->setPen(foreground);

    // draw line 1 and decoration:
    painter->setFont(mainFont);
    QRect taskRect(option.rect);
    taskRect.setWidth(option.rect.width() - decoration.width());
    QPoint decorationPoint(option.rect.width() - decoration.width(),
                           option.rect.center().y()  - decoration.height() / 2);

    QRect boundingRect;
    QString elidedTask = Charm::elidedTaskName(taskName, mainFont, taskRect.width());
    painter->drawText(taskRect, Qt::AlignLeft | Qt::AlignTop, elidedTask,
                      &boundingRect);
    taskRect = boundingRect;
    taskRect.setHeight(qMax(taskRect.height(), decoration.height()));
    // now taskRect tells us where to start line 2
    painter->drawPixmap(decorationPoint, decoration);

    // draw line 2 (timespan and comment, partly):
    painter->setFont(detailFont);
    QRect detailsRect(option.rect);
    detailsRect.setTop(taskRect.bottom());
    detailsRect.setHeight(option.rect.height() - taskRect.height());
    painter->drawText(detailsRect, Qt::AlignLeft | Qt::AlignTop,
                      timespan, &boundingRect);
    detailsRect = boundingRect;

    // draw the duration line:
    const int Margin = 2;
    QRect durationRect(option.rect.left() + 1, detailsRect.bottom(),
                       static_cast<int>(logDuration * (option.rect.width() - 2)), Margin);
    painter->fillRect(durationRect, palette.dark());

    painter->restore();
    return QRect(0, 0,
                 qMax(taskRect.width(), detailsRect.width()),
                 durationRect.bottom() + 1 - option.rect.top());
}

double EventEditorDelegate::logDuration(int duration) const
{   // we rely on the compiler to optimize at compile time :-)
    if (duration <= 0)
        return 0;
    if (duration <= 3600) {
        return 0.2 * 1.0 / 3600.0 * duration;
    } else {
        const double log2 = std::log(2.0);
        const double hours = 1.0 / 3600 * duration;
        const double value = log(hours) / log2;
        return 0.2 * (1.0 + value);
    }
}
