/*
    QCommsy
    Copyright (C) 2020  niansa

    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 3 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 "ui_overview.h"
#include "ui_info.h"
#include "ui_login.h"
#include "ui_failure.h"
#include "ui_offline.h"
#include "ui_postView.h"
#include "libcommsy.hpp"
#include "libcommsyauth.hpp"

#include <limits.h>

#include <string>
#include <vector>
#include <functional>

#include <QMainWindow>
#include <QApplication>
#include <QPushButton>
#include <QString>
#include <QUrl>
#include <QDir>
#include <QFile>
#include <QTimer>
#include <QMainWindow>
#include <QListWidgetItem>
#include <QFont>
#include <QStyleFactory>
#include <QDesktopServices>
#include <QSettings>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QStandardPaths>

#define QCommsy_NAME "QCommsy"
#define QCommsy_VERSION "1.2-stable"

static QSettings *settings;
static QApplication *a;
static QMainWindow *w;


class _UILoader {
    libCommsy *connector = nullptr;
    libCommsyAuth *auther = nullptr;
    bool cacheInvalidate = true;

public:
    void failureWindow();
    void overviewWindow(bool catchInvalidRoomError = true);
    void loginWindow(const QString& failure = "");
    void infoWindow();
    void postViewWindow(commsyPost *thispost, QString description);
    void offlineWindow();

    _UILoader () {
        auther = new libCommsyAuth();
    }

    void reconnect() {
        // Destroy old connector
        if (connector != nullptr) {
            if (not cacheInvalidate) {
                return;
            }
            delete connector;
            connector = nullptr;
        }
        cacheInvalidate = false;
        // Connect to commsy
        connector = new libCommsy(settings->value("server_url").toString().toStdString(), settings->value("server_sid").toString().toStdString(), settings->value("server_room").toString().toStdString());
    }

    void logout() {
        settings->remove("server_sid");
    }

    void downloadAndOpenFile(QNetworkRequest mNetReq, const QString& filename) {
        auto mNetMan = new QNetworkAccessManager();

        // Set SID in request so we're authenticated  TODO: think about a cleaner way
        mNetReq.setRawHeader("Cookie", "SID=" + settings->value("server_sid").toString().toUtf8());

        // Connect to downloading
        w->connect(mNetMan, &QNetworkAccessManager::finished, [this, mNetMan, filename] (QNetworkReply *mNetReply) {
            // Save and open downloaded file
            {
                // Initialise
                QString destPath = QStandardPaths::writableLocation(QStandardPaths::DownloadLocation) + '/' + filename;
                QFile destFile(destPath);

                // Write downloaded data to file
                if (!destFile.open(QIODevice::WriteOnly)) {
                    return failureWindow();
                }
                destFile.write(mNetReply->readAll());
                destFile.close();

                // Open file in some application
                QDesktopServices::openUrl(QUrl::fromLocalFile(destPath));
            }

            // Clean up
            mNetMan->deleteLater();
        });

        // Start download
        mNetMan->get(mNetReq);
    }

};

void _UILoader::infoWindow() {
    Ui::infoWindow *thisui = new Ui::infoWindow;

    // Show initial UI
    thisui->setupUi(w);
    w->show();

    // Update version info
    thisui->versionInfo->setText(
                "<b>App frontend:</b> " QCommsy_NAME " version " QCommsy_VERSION "<br />"
                "<b>Authentication backend:</b> " libCommsyAuth_NAME " version " libCommsyAuth_VERSION "<br />"
                "<b>Scrapping backend:</b> " libCommsy_NAME " version " libCommsy_VERSION "<br />"
                "<b>Git version:</b> " GIT_CURRENT_SHA1 "<br />"
                "<b>Build ID:</b> " + QString::number(std::hash<std::string>{}(__DATE__ __TIME__)) + "<br />"
                );
    thisui->buildDateInfo->setText(
                "Build date:\n"
                __DATE__ " " __TIME__
                );

    // Add button handlers
    w->connect(thisui->backButton, &QPushButton::pressed, [this] () { loginWindow(); });
}

void _UILoader::failureWindow() {
    Ui::failureWindow *thisui = new Ui::failureWindow;

    // Show initial UI
    thisui->setupUi(w);
    w->show();

    // Show error message
    thisui->descriptionText->setText("<b>Verbindung fehlgeschlagen</b><br />"
                                     "Ein interner Fehler ist aufgetreten<br />"
                                     "<i>Dies ist sehr wahrscheinlich ein Programmfehler. Sollte das zu häufig passieren, kontaktiere bitte den Entwickler</i>");

    // Add button handlers
    w->connect(thisui->retryButton, &QPushButton::pressed, [this] () { loginWindow(); });
    w->connect(thisui->logoutButton, &QPushButton::pressed, [this] () { logout(); loginWindow(); });
}

void _UILoader::offlineWindow() {
    Ui::offlineWindow *thisui = new Ui::offlineWindow;

    // Show initial UI
    thisui->setupUi(w);
    w->show();
    // Add button handlers
    w->connect(thisui->logoutButton, &QPushButton::pressed, [this] () { logout(); loginWindow(); });
}

void _UILoader::loginWindow(const QString& failure) {
    Ui::loginWindow *thisui = new Ui::loginWindow;

    // Check if logged in already
    if (settings->contains("server_sid")) {
        return overviewWindow();
    }

    // Show initial UI
    thisui->setupUi(w);
    w->show();

    // Restore login data if wanted
    bool restoreForm = settings->value("server_save", false).toBool();
    if (restoreForm) {
        thisui->saveBox->setCheckState(Qt::Checked);
        thisui->adressLine->setText(settings->value("server_url", thisui->adressLine->text()).toString());
        thisui->roomLine->setText(settings->value("server_room", "").toString());
        thisui->usernameLine->setText(settings->value("server_username", "").toString());
        thisui->passwordLine->setText(settings->value("server_password", "").toString());
    }

    // Set failure text
    thisui->failureText->setText(failure);

    // Connect connection handlers
    w->connect(auther, &libCommsyAuth::authDone, [thisui] (QNetworkReply *) { // Finished authentication; reenable login button
        thisui->loginButton->setDisabled(false);
    });
    w->connect(auther, &libCommsyAuth::authDone, [this, thisui] (QNetworkReply *netReply) { // Finished authentication; try to login
        // Login
        try {
            settings->setValue("server_sid", auther->getSID(netReply));
            cacheInvalidate = true;
            overviewWindow(false);
            auther->deleteLater();
        } catch (authFailureError&) {
            thisui->failureText->setText("Die eingegebenen Anmeldedaten sind ungültig");
        } catch (libCommsy::invalidRoomError&) {
            thisui->failureText->setText("Der angegebene Raum existiert nicht");
        }
    });
    w->connect(auther, &libCommsyAuth::connectionDone, [this, thisui] (QNetworkReply *netReply) { // Finished test connection
        auther->sendAuth(auther->getAuthUrl(netReply), thisui->usernameLine->text(), thisui->passwordLine->text());
    });

    // Add button handlers
    w->connect(thisui->loginButton, &QPushButton::pressed, [this, thisui] () {
        // Check input lines
        if (thisui->adressLine->text().isEmpty() or thisui->usernameLine->text().isEmpty() or thisui->roomLine->text().isEmpty() or thisui->passwordLine->text().isEmpty()) {
            return;
        }

        // Make sure the adressLine doesn't end with /
        if (thisui->adressLine->text().endsWith("/")) {
            thisui->adressLine->backspace();
        }

        // Save basic server credentials
        bool saveAllData = thisui->saveBox->checkState() == Qt::Checked;
        settings->setValue("server_save", saveAllData);
        settings->setValue("server_url", thisui->adressLine->text());
        settings->setValue("server_room", thisui->roomLine->text());
        if (saveAllData) {
            settings->setValue("server_username", thisui->usernameLine->text());
            settings->setValue("server_password", thisui->passwordLine->text());
        }

        // Disable login button
        thisui->loginButton->setDisabled(true);

        // Connect
        auther->connectionInit(thisui->adressLine->text());
    });
}

void _UILoader::postViewWindow(commsyPost *thispost, QString description) {
    Ui::postViewWindow *thisui = new Ui::postViewWindow;

    // Show initial UI
    thisui->setupUi(w);
    w->show();
    thisui->statusText->setVisible(false);

    // Remove trailing space from description
    if (description.size() != 0 and description.back() == '\n') {
        description.chop(1);
    }

    // Update informations
    thisui->titleText->setText(QString::fromStdString(thispost->name));
    thisui->metaText->setText(QString::fromStdString(thispost->meta));
    thisui->descriptionText->setText(description);

    // Update file list if required
    if (thispost->files.size() != 0) {
        for (const auto& thisfile : thispost->files) {
            thisui->fileList->addItem(QString::fromStdString(thisfile.name));
        }
    } else { // If no files exist, hide the list
        thisui->filesInfo->setHidden(true);
        thisui->fileList->setHidden(true);
    }

    // Add button handlers
    w->connect(thisui->fileList, &QListWidget::activated, [this, thisui, thispost] (QModelIndex index) {
        // Get full file URL
        commsyFile *thisfile = &thispost->files[static_cast<unsigned long>(index.row())];
        QUrl fullFileUrl(settings->value("server_url").toString() + QString::fromStdString(thisfile->url));

        // Start download
        downloadAndOpenFile(QNetworkRequest(fullFileUrl), QString::fromStdString(thisfile->name));

        // Show download status für 5 seconds
        thisui->statusText->setVisible(true);
        QTimer::singleShot(5 * 1000, thisui->statusText, &QLabel::hide);
    });
    w->connect(thisui->backButton, &QPushButton::pressed, [this] () { loginWindow(); });
}

void _UILoader::overviewWindow(bool catchInvalidRoomError) {
    Ui::overviewWindow *thisui = new Ui::overviewWindow;

    // Following code is blocking
    a->processEvents();

    // Connect if required
    try {
        reconnect();
    } catch (libCommsy::invalidSIDError&) {
        logout();
        return loginWindow("Die Sitzung ist abgelaufen - bitte erneut anmelden");
    } catch (libCommsy::invalidRoomError& exception) {

        if (catchInvalidRoomError) {
            logout();
            return loginWindow("Der Raum existiert nicht mehr");
        } else {
            throw exception;
        }

    } catch (libCommsy::connectionFailError&) {
        return offlineWindow();
    } catch (std::exception&) {
        return failureWindow();
    }

    // Show initial UI
    thisui->setupUi(w);
    w->show();

    // Add button handlers
    w->connect(thisui->postList, &QListWidget::activated, [this, thisui] (QModelIndex index) {
        auto postID = static_cast<unsigned long>(index.row());
        commsyPost *thispost = connector->getPost(postID);
        thisui->centralwidget->setDisabled(true);
        thispost->unread = false; // Mark post as read locally

        // Run blocking code
        a->processEvents();
        postViewWindow(thispost, QString::fromStdString(*connector->getDescription(postID)));
    });

    w->connect(thisui->logoutButton, &QPushButton::pressed, [this] () { logout(); loginWindow(); });
    w->connect(thisui->infoButton, &QPushButton::pressed, [this] () { infoWindow(); });

    // Get font used for unread posts
    QFont unreadFont = QFont();
    unreadFont.setBold(true);

    // Refresh view
    thisui->postCounter->setText(QString::number(connector->numposts) + " Einträge");
    thisui->postList->clear();
    for (const auto& thispost : connector->posts) {
        QListWidgetItem *thisitem = new QListWidgetItem(QString::fromStdString(thispost.name), thisui->postList);

        if (thispost.unread) {
            thisitem->setFont(unreadFont);
        }

        QString postIcon;
        switch(thispost.taskState) {
            case taskState::done:
                postIcon = "checkbox-checked-symbolic";
                break;
            case taskState::inProgress:
                postIcon = "clock";
                break;
            case taskState::todo:
                postIcon = "emblem-important-symbolic";
                break;
            default:
                postIcon = "arrow-right";
                break;
        }
        thisitem->setIcon(QIcon::fromTheme(postIcon));
    }
}




int main(int argc, char *argv[]) {
    // Initalise settings storage
    QCoreApplication::setOrganizationName("QCommsy");
    QCoreApplication::setOrganizationDomain("qcommsy.github.io");
    QCoreApplication::setApplicationName("QCommsy");
    settings = new QSettings();

    //Initialise variables
    a = new QApplication(argc, argv);
    w = new QMainWindow;
    _UILoader UILoader;

    // Set theme
    //a->setStyle(QStyleFactory::create("android"));

    // Load initial window
    UILoader.loginWindow();

    // Run forever
    return a->exec();
}