/***************************************************************************
 *   Copyright (C) 2010 Matthias Fuchs <mat69@gmx.net>                     *
 *                                                                         *
 *   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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA .        *
 ***************************************************************************/

#ifndef KGET_URL_CHECKER_H
#define KGET_URL_CHECKER_H

#include "kget_export.h"

#include <QHash>
#include <QList>
#include <QUrl>

class Transfer;
class TransferHandler;

/**
 * This class provides static methods to check if urls are valid, and if not
 * provides enums to see what is not valid and provides translated error messages
 */
class KGET_EXPORT UrlChecker
{
public:
    enum UrlType { Source, Destination, Folder };

    /**
     * Before using UrlChecker you have to specify a type
     * You can either do that in the constructor and later
     * via setType
     *
     * @see setType
     */
    explicit UrlChecker(UrlType type);
    ~UrlChecker();

    /**
     * Removes duplicates of a list of urls
     */
    static void removeDuplicates(QList<QUrl> &urls);

    // NOTE only first found error is reported, i.e. NotWriteable before ExistingFile if both are the case
    enum UrlError {
        // General
        NoError = 0,
        Empty,
        Invalid,

        // Source only
        NoProtocol,
        NoHost,

        // Destination and Folder only
        NotWriteable
    };

    enum UrlWarning {
        NoWarning = 0,
        // Source and Destination only
        ExistingFinishedTransfer,
        ExistingTransfer,

        // Destination only
        ExistingFile
    };

    /**
     * Folder:
     * Checks if the destination url points to is a folder that is writeable and existent.
     *
     * Destination:
     * Checks if url points to a file (can be non-existent) and if the
     * directory this file is (would) be in is existent and writeable
     *
     * @param url the URL
     * @param type all types supported here
     * @param showNotification true shows a notification if an error is found
     * @note checkExisting is not done within this method
     * @note you can use the convenience methods checkSource, checkDestination, checkFolder
     * directly
     * @see checkExisting
     */
    static UrlError checkUrl(const QUrl &url, const UrlType type, bool showNotification = false);

    /**
     * Convenience method of checkUrl
     * @param source the URL
     * @param showNotification true shows a notification if an error is found
     */
    static UrlError checkSource(const QUrl &source, bool showNotification = false);

    /**
     * Convenience method of checkUrl
     * @param destination the URL
     * @param showNotification true shows a notification if an error is found
     */
    static UrlError checkDestination(const QUrl &destination, bool showNotification = false);

    /**
     * Convenience method of checkUrl
     * @param folder the folder
     * @param showNotification true shows a notification if an error is found
     */
    static UrlError checkFolder(const QUrl &folder, bool showNotification = false);

    /**
     * Checks if source is local and exists already
     * @note If both @p dest and @p source are the same and local, then @c false will be returned
     * since it is assumed, that local files are either not handled by any
     * transfer plugin or are e.g. metalink or torrent files otherwise and thus
     * can have the same @p source / @p dest.
     * Also keep in mind that false will be returned if @p dest is being removed
     * at the moment. Avoid to ask a user twice in worst case.
     */
    static bool wouldOverwrite(const QUrl &source, const QUrl &dest);

    /**
     * Checks if there is an existing transfer for url with type
     * @param url the URL
     * @param type Source checks if there is a transfer with the same source
     * destination checks if there is a transfer with the same destination
     * @param warning the warning type
     * @return if an existing transfer is found it will be returned,
     * otherwise @c nullptr will be returned
     * @note checkUrl check is not done and UrlType Folder is not supported
     * Keep in mind, that the same transfers could be found via Source and Destination!
     * @see checkUrl
     */
    static TransferHandler *existingTransfer(const QUrl &url, const UrlType type, UrlWarning *warning = nullptr);

    /**
     * @note UrlType folder is not supported, the result then is undefined!
     */
    static QList<QUrl> hasExistingTransferMessages(const QList<QUrl> &urls, const UrlType type);

    /**
     * Get a describing message for UrlError
     * @param url is only needed here to include it in some error messages,
     * if url is empty, then it won't be used.
     * @param type the URL type
     * @param error the error type
     * @note this method does no checks, it only creates messages based on the error code
     * @see checkUrl
     */
    static QString message(const QUrl &url, const UrlType type, const UrlError error);

    /**
     * Get a describing message for UrlWarning
     * @param url is only needed here to include it in some error messages,
     * if @p url is empty, then it won't be used.
     * @param type the URL type
     * @param warning the warning type
     * @note this method does no checks, it only creates messages based on the warning code
     * @see existingTransfer fileExists
     */
    static QString message(const QUrl &url, const UrlType type, const UrlWarning warning);

    /**
     * Convenience method for multiple urls (urls can be empty)
     * @see message
     */
    static QString message(const QList<QUrl> &urls, const UrlType type, const UrlError error);

    /**
     * Convenience method for multiple urls (urls can be empty)
     * @see message
     */
    static QString message(const QList<QUrl> &urls, const UrlType type, const UrlWarning warning);

    /**
     * Takes an url to a source and an url to either the destination or a folder
     *  and returns a destination url.
     *
     * @param destOrFolder An existing folder then a file name derived from source
     * will be appended to it and returned
     * otherwise no modification will be done and destOrFolder will be returned
     * @param source the source
     * @param fileName the filename
     * @note no checkUrl check happens!
     * @see checkUrl
     */
    static QUrl destUrl(const QUrl &destOrFolder, const QUrl &source, const QString &fileName = QString());

    /// Non static methods following

    UrlType type() const;

    /**
     * Sets the type for the following operations to type
     * @note calls clear
     * @see clear
     */
    void setType(UrlType type);

    /**
     * Clears all data, like correctUrls, errorUrls, responses from checkExistingFile ...
     */
    void clear();

    /**
     * Checks url of type()
     * @return UrlError, None if no error has been found
     * @note checkExisting is not done within this method
     * @note both this method and checkUrls() will store all correct
     * urls in correctUrls() and the others in errorUrls() and
     * splitErrorUrls()
     */
    UrlError addUrl(const QUrl &url);

    /**
     * Does checkUrl for a list of urls.
     * @return true if all urls are valid, false, if at least one url is invalid
     * @note checkExisting is not done within this method
     * @note both this method and checkUrl() will store all correct
     * urls in correctUrls() and the others in errorUrls() and
     * splitErrorUrls()
     * @see addUrl
     */
    bool addUrls(const QList<QUrl> &urls);

    /**
     * Displays error messages for the collected urls if any are needed
     */
    void displayErrorMessages();

    /**
     * Returns the correct urls collected with the last call to urlCollectErrors
     * @see urlCollectErrors
     */
    QList<QUrl> correctUrls() const;

    /**
     * Checks all correctUrls() if there are existing Transfers
     * for the specified UrlType and asks the user how to proceed.
     *
     * After this urls where the user decided that they should not be downloaded
     * won't be in correctUrls anymore.
     * @note UrlType folder is not supported, the result then is undefined!
     * @return urls to download, after user interaction
     * @see correctUrls errorUrls splitErrorUrls
     */
    void existingTransfers();

    /**
     * Checks if the file at destination exists already, source needs to be defined
     * to have a nice dialog and to make sure that both source and destination aren't
     * the same
     * @note This method does _not_ affect other methods like correctUrls or existingTransfers
     * etc., though responses like overwrite all files are stored in case you call this method
     * again you can clear that with clear.
     * @return returns the destination to download the file to, if empty then the file
     * should not be downloaded
     * @see clear
     */
    QUrl checkExistingFile(const QUrl &source, const QUrl &destination);

    /**
     * Returns all wrong urls
     * @note the order of the urls is not guaranteed to be the same as it initially was
     * @see urlCollectErrors splitErrorUrls existingTransfers
     */
    QList<QUrl> errorUrls() const;

    /**
     * Returns all wrong urls collected with the last call to urlCollectErrors
     * or existingTransfers categorized by their errors
     * @note urls without an error (UrlError == None) are not included
     * @see urlCollectErrors correctUrls errorUrls existingTransfers
     */
    QHash<UrlError, QList<QUrl>> splitErrorUrls() const;

private:
    static TransferHandler *existingSource(const QUrl &url, UrlWarning &warning);
    static TransferHandler *existingDestination(const QUrl &url, UrlWarning &warning);
    static int hasExistingDialog(const QUrl &url, const UrlChecker::UrlType type, const UrlWarning warning); // TODO description --> returncode etc.!
    static void removeTransfers(const QList<TransferHandler *> &toRemove);

private:
    UrlType m_type;
    QList<QUrl> m_correctUrls;
    QHash<UrlError, QList<QUrl>> m_splitErrorUrls;

    QHash<UrlWarning, QPair<QUrl, Transfer *>> m_existingTransfers;
    QList<QUrl> m_nonExistingUrls;

    // Existing files stuff
    bool m_cancel;
    bool m_overwriteAll;
    bool m_autoRenameAll;
    bool m_skipAll;
};

#endif
