/*
  Controller.cpp

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

  Copyright (C) 2007-2018 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com

  Author: Mirko Boehm <mirko.boehm@kdab.com>
  Author: Frank Osterfeld <frank.osterfeld@kdab.com>
  Author: Olivier JG <olivier.de.gaalon@kdab.com>
  Author: Guillermo A. Amaral <gamaral@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 "Controller.h"
#include "CharmCommand.h"
#include "CharmConstants.h"
#include "CharmExceptions.h"
#include "Configuration.h"
#include "Event.h"
#include "SqLiteStorage.h"
#include "SqlRaiiTransactor.h"
#include "SqlStorage.h"
#include "Task.h"

#include <QtDebug>

Controller::Controller(QObject *parent_)
    : QObject(parent_)
{
}

Controller::~Controller()
{
}

Event Controller::makeEvent(const Task &task)
{
    Event event = m_storage->makeEvent();
    Q_ASSERT(event.isValid());

    event.setTaskId(task.id());
    if (m_storage->modifyEvent(event)) {
        emit eventAdded(event);
    } else {
        event = Event();
    }
    return event;
}

Event Controller::cloneEvent(const Event &e)
{
    Event event = m_storage->makeEvent();
    Q_ASSERT(event.isValid());

    int id = event.id();
    event = e;
    event.setId(id);
    if (m_storage->modifyEvent(event)) {
        emit eventAdded(event);
    } else {
        event = Event();
    }
    return event;
}

bool Controller::modifyEvent(const Event &e)
{
    if (m_storage->modifyEvent(e)) {
        emit eventModified(e);
        return true;
    } else {
        return false;
    }
}

bool Controller::deleteEvent(const Event &e)
{
    if (m_storage->deleteEvent(e)) {
        emit eventDeleted(e);
        return true;
    } else {
        return false;
    }
}

bool Controller::addTask(const Task &task)
{
    if (m_storage->addTask(task)) {
        updateSubscriptionForTask(task);
        emit taskAdded(task);

        return true;
    } else {
        Q_ASSERT(false);   // impossible
        return false;
    }
}

bool Controller::modifyTask(const Task &task)
{
    // modify the task itself:
    bool result = m_storage->modifyTask(task);
    Q_ASSERT(result);
    if (!result) {
        qCritical() << Q_FUNC_INFO << "modifyTask failed!";
        return result;
    }

    updateSubscriptionForTask(task);
    emit(taskUpdated(task));

    return true;
}

bool Controller::deleteTask(const Task &task)
{
    if (m_storage->deleteTask(task)) {
        m_storage->deleteSubscription(CONFIGURATION.user, task);
        emit taskDeleted(task);
        return true;
    } else {
        Q_ASSERT(false);   // impossible
        return false;
    }
}

bool Controller::setAllTasks(const TaskList &tasks)
{
    if (m_storage->setAllTasks(CONFIGURATION.user, tasks)) {
        const TaskList newTasks = m_storage->getAllTasks();
        // tell the view about the existing tasks;
        emit definedTasks(newTasks);
        return true;
    } else {
        return false;
    }
}

void Controller::updateSubscriptionForTask(const Task &task)
{
    if (task.subscribed()) {
        bool result = m_storage->addSubscription(CONFIGURATION.user, task);
        Q_ASSERT(result);
        Q_UNUSED(result);
    } else {
        bool result = m_storage->deleteSubscription(CONFIGURATION.user, task);
        Q_ASSERT(result);
        Q_UNUSED(result);
    }
}

void Controller::stateChanged(State previous, State next)
{
    Q_UNUSED(previous);

    switch (next) {
    case Connected:
    {   // yes, it is that simple:
        TaskList tasks = m_storage->getAllTasks();
        // tell the view about the existing tasks;
        if (!Task::checkForUniqueTaskIds(tasks)) {
            throw CharmException(tr(
                                     "The Charm database is corrupted, it contains duplicate task ids. "
                                     "Please have it looked after by a professional."));
        }
        if (!Task::checkForTreeness(tasks)) {
            throw CharmException(tr(
                                     "The Charm database is corrupted, the tasks do not form a tree. "
                                     "Please have it looked after by a professional."));
        }
        emit definedTasks(tasks);
        EventList events = m_storage->getAllEvents();
        emit allEvents(events);
        break;
    }
    case Disconnecting:
    {
        emit readyToQuit();
        if (m_storage) {
// this will still leave Qt complaining about a repeated connection
            m_storage->disconnect();
            delete m_storage;
            m_storage = nullptr;
        }
        break;
    }
    default:
        break;
    }

    if (m_storage) {
        emit currentBackendStatus(m_storage->description());
        m_storage->stateChanged(previous);
    }
}

struct Setting {
    QString key;
    QString value;
};

void Controller::persistMetaData(Configuration &configuration)
{
    Q_ASSERT_X(m_storage != nullptr, Q_FUNC_INFO, "No storage interface available");
    Setting settings[] = {
        { MetaKey_Key_UserName,
          configuration.user.name() },
        { MetaKey_Key_SubscribedTasksOnly,
          QString().setNum(configuration.taskPrefilteringMode) },
        { MetaKey_Key_TimeTrackerFontSize,
          QString().setNum(configuration.timeTrackerFontSize) },
        { MetaKey_Key_DurationFormat,
          QString::number(configuration.durationFormat) },
        { MetaKey_Key_IdleDetection,
          stringForBool(configuration.detectIdling) },
        { MetaKey_Key_WarnUnuploadedTimesheets,
          stringForBool(configuration.warnUnuploadedTimesheets) },
        { MetaKey_Key_RequestEventComment,
          stringForBool(configuration.requestEventComment) },
        { MetaKey_Key_ToolButtonStyle,
          QString().setNum(configuration.toolButtonStyle) },
        { MetaKey_Key_ShowStatusBar,
          stringForBool(configuration.showStatusBar) },
        { MetaKey_Key_EnableCommandInterface,
          stringForBool(configuration.enableCommandInterface) },
        { MetaKey_Key_NumberOfTaskSelectorEntries,
          QString::number(configuration.numberOfTaskSelectorEntries) }
    };
    int NumberOfSettings = sizeof settings / sizeof settings[0];

    bool good = true;
    for (int i = 0; i < NumberOfSettings; ++i)
        good = good && m_storage->setMetaData(settings[i].key, settings[i].value);
    Q_ASSERT_X(good, Q_FUNC_INFO, "Controller assumes write "
                                  "permissions in meta data table if persistMetaData is called");
    CONFIGURATION.dump();
}

template<class T>
void Controller::loadConfigValue(const QString &key, T &configValue) const
{
    const QString storedValue = m_storage->getMetaData(key);
    if (storedValue.isNull())
        return;
    configValue = strToT<T>(storedValue);
}

void Controller::provideMetaData(Configuration &configuration)
{
    Q_ASSERT_X(m_storage != nullptr, Q_FUNC_INFO, "No storage interface available");
    configuration.user.setName(m_storage->getMetaData(MetaKey_Key_UserName));

    loadConfigValue(MetaKey_Key_TimeTrackerFontSize, configuration.timeTrackerFontSize);
    loadConfigValue(MetaKey_Key_DurationFormat, configuration.durationFormat);
    loadConfigValue(MetaKey_Key_SubscribedTasksOnly, configuration.taskPrefilteringMode);
    loadConfigValue(MetaKey_Key_IdleDetection, configuration.detectIdling);
    loadConfigValue(MetaKey_Key_WarnUnuploadedTimesheets, configuration.warnUnuploadedTimesheets);
    loadConfigValue(MetaKey_Key_RequestEventComment, configuration.requestEventComment);
    loadConfigValue(MetaKey_Key_ToolButtonStyle, configuration.toolButtonStyle);
    loadConfigValue(MetaKey_Key_ShowStatusBar, configuration.showStatusBar);
    loadConfigValue(MetaKey_Key_EnableCommandInterface, configuration.enableCommandInterface);
    loadConfigValue(MetaKey_Key_NumberOfTaskSelectorEntries, configuration.numberOfTaskSelectorEntries);
    configuration.numberOfTaskSelectorEntries = qMax(0, configuration.numberOfTaskSelectorEntries);

    CONFIGURATION.dump();
}

bool Controller::initializeBackEnd(const QString &name)
{
    // make storage interface according to configuration
    // this is our local storage backend factory and may have to be
    // factored out into a factory method (now that is some serious
    // refucktoring):
    if (name == CHARM_SQLITE_BACKEND_DESCRIPTOR) {
        m_storage = new SqLiteStorage;
        return true;
    } else {
        Q_ASSERT_X(false, Q_FUNC_INFO, "Unknown local storage backend type");
        return false;
    }
}

bool Controller::connectToBackend()
{
    bool result = m_storage->connect(CONFIGURATION);

    // the user id in the database, and the installation id, do not
    // have to be 1 and 1, as we have guessed --> persist configuration
    if (result && !CONFIGURATION.newDatabase)
        provideMetaData(CONFIGURATION);

    return result;
}

bool Controller::disconnectFromBackend()
{
    return m_storage->disconnect();
}

void Controller::executeCommand(CharmCommand *command)
{
    command->execute(this);
    // send it back to the view:
    emit commandCompleted(command);
}

void Controller::rollbackCommand(CharmCommand *command)
{
    command->rollback(this);
    // send it back to the view:
    emit commandCompleted(command);
}

SqlStorage *Controller::storage()
{
    return m_storage;
}

const QString MetaDataElement(QStringLiteral("metadata"));
const QString ExportRootElement(QStringLiteral("charmdatabase"));
const QString VersionElement(QStringLiteral("version"));
const QString TasksElement(QStringLiteral("tasks"));
const QString EventsElement(QStringLiteral("events"));

QDomDocument Controller::exportDatabasetoXml() const
{
    QDomDocument document(QStringLiteral("charmdatabase"));
    // root element:
    QDomElement root = document.createElement(ExportRootElement);
    root.setAttribute(VersionElement, CHARM_DATABASE_VERSION);
    document.appendChild(root);
    // metadata:
    QDomElement metadata = document.createElement(MetaDataElement);
    // I am not so sure what kind of metadata needs to be stored
    root.appendChild(metadata);
    // tasks element:
    QDomElement tasksElement = document.createElement(TasksElement);
    // FIXME there are generic methods for that now, in Task.h
    TaskList tasks = m_storage->getAllTasks();
    Q_FOREACH (const Task &task, tasks) {
        QDomElement element = task.toXml(document);
        tasksElement.appendChild(element);
    }
    root.appendChild(tasksElement);
    // events element:
    QDomElement eventsElement = document.createElement(EventsElement);
    EventList events = m_storage->getAllEvents();
    Q_FOREACH (const Event &event, events) {
        QDomElement element = event.toXml(document);
        eventsElement.appendChild(element);
    }
    root.appendChild(eventsElement);
    return document;
}

class MakeSureTheModelIsUpdated
{
public:
    explicit MakeSureTheModelIsUpdated(Controller *controller)
        : m_controller(controller)
    {
    }

    ~MakeSureTheModelIsUpdated()
    {
        // now tell the data model that things have changed:
        m_controller->updateModelEventsAndTasks();
    }

private:
    Controller *m_controller;
};

QString Controller::importDatabaseFromXml(const QDomDocument &document)
{
    MakeSureTheModelIsUpdated m(this);

    // first, parse the XML document, and break if there is an error
    // (not touching the DB contents):
    TaskList importedTasks;
    EventList importedEvents;
    int databaseSchemaVersion;

    // FIXME test for the file to be a database export, not (for example) a task definitions export
    try {
        QDomElement rootElement = document.documentElement();
        bool ok;
        databaseSchemaVersion = rootElement.attribute(QStringLiteral("version")).toInt(&ok);
        if (!ok) throw XmlSerializationException(QObject::tr(
                                                     "Syntax error, no version attribute found."));

        QDomElement tasksElement = rootElement.firstChildElement(TasksElement);
        for (QDomElement element = tasksElement.firstChildElement(Task::tagName());
             !element.isNull(); element = element.nextSiblingElement(Task::tagName())) {
            Task task = Task::fromXml(element, databaseSchemaVersion);
            if (!task.isValid()) {
                qDebug() << "The following task is invalid and will not be added:";
                task.dump();
                // return tr( "The Export file contains at least one invalid task." );
            } else {
                importedTasks.append(task);
            }
        }
        QDomElement eventsElement = rootElement.firstChildElement(EventsElement);
        for (QDomElement element = eventsElement.firstChildElement(Event::tagName());
             !element.isNull(); element = element.nextSiblingElement(Event::tagName())) {
            Event event = Event::fromXml(element, databaseSchemaVersion);
            if (!event.isValid()) {
                qDebug() << "The following event is invalid and will not be added:";
                event.dump();
                // return tr( "The Export file contains at least one invalid event." );
            } else {
                importedEvents.append(event);
            }
        }
    } catch (const XmlSerializationException &e) {
        qDebug() << "Controller::importDatabaseFromXml: things fucked up:" << e.what();
        return tr("The export file is invalid: %1").arg(e.what());
    }

    const QString error = m_storage->setAllTasksAndEvents(CONFIGURATION.user, importedTasks,
                                                          importedEvents);
    if (!error.isEmpty()) {
        // the database should be unchanged, and the model will update on return
        return tr("Error importing tasks and events from the file:<br />%1")
               .arg(error);
    }

    // FIXME needed?

    // tell the model that the tasks and events have vanished:
    emit allEvents(EventList());
    emit definedTasks(TaskList());

    return QString();
}

void Controller::updateModelEventsAndTasks()
{
    TaskList tasks = m_storage->getAllTasks();
    // tell the view about the existing tasks;
    emit definedTasks(tasks);
    EventList events = m_storage->getAllEvents();
    emit allEvents(events);
}