/*
 * Copyright (C) by Klaas Freitag <freitag@owncloud.com>
 * Copyright (C) by Daniel Molkentin <danimo@owncloud.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.
 */

#pragma once

#include "owncloudlib.h"
#include <QObject>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QPointer>
#include <QElapsedTimer>
#include <QDateTime>
#include <QTimer>
#include "accountfwd.h"
#include "common/asserts.h"

class QUrl;

namespace OCC {

class AbstractSslErrorHandler;

/**
 * @brief The AbstractNetworkJob class
 * @ingroup libsync
 */
class OWNCLOUDSYNC_EXPORT AbstractNetworkJob : public QObject
{
    Q_OBJECT
public:
    explicit AbstractNetworkJob(AccountPtr account, const QString &path, QObject *parent = 0);
    virtual ~AbstractNetworkJob();

    virtual void start();

    AccountPtr account() const { return _account; }

    void setPath(const QString &path);
    QString path() const { return _path; }

    void setReply(QNetworkReply *reply);
    QNetworkReply *reply() const { return _reply; }

    void setIgnoreCredentialFailure(bool ignore);
    bool ignoreCredentialFailure() const { return _ignoreCredentialFailure; }

    /** Whether to handle redirects transparently.
     *
     * If true, a follow-up request is issued automatically when
     * a redirect is encountered. The finished() function is only
     * called if there are no more redirects (or there are problems
     * with the redirect).
     *
     * The transparent redirect following may be disabled for some
     * requests where custom handling is necessary.
     */
    void setFollowRedirects(bool follow);
    bool followRedirects() const { return _followRedirects; }

    QByteArray responseTimestamp();
    /* Content of the X-Request-ID header. (Only set after the request is sent) */
    QByteArray requestId();

    qint64 timeoutMsec() const { return _timer.interval(); }
    bool timedOut() const { return _timedout; }

    /** Returns an error message, if any. */
    QString errorString() const;

    /** Like errorString, but also checking the reply body for information.
     *
     * Specifically, sometimes xml bodies have extra error information.
     * This function reads the body of the reply and parses out the
     * error information, if possible.
     *
     * \a body is optinally filled with the reply body.
     *
     * Warning: Needs to call reply()->readAll().
     */
    QString errorStringParsingBody(QByteArray *body = 0);

    /** Make a new request */
    void retry();

    /** static variable the HTTP timeout (in seconds). If set to 0, the default will be used
     */
    static int httpTimeout;

public slots:
    void setTimeout(qint64 msec);
    void resetTimeout();
signals:
    /** Emitted on network error.
     *
     * \a reply is never null
     */
    void networkError(QNetworkReply *reply);
    void networkActivity();

    /** Emitted when a redirect is followed.
     *
     * \a reply The "please redirect" reply
     * \a targetUrl Where to redirect to
     * \a redirectCount Counts redirect hops, first is 0.
     */
    void redirected(QNetworkReply *reply, const QUrl &targetUrl, int redirectCount);

protected:
    /** Initiate a network request, returning a QNetworkReply.
     *
     * Calls setReply() and setupConnections() on it.
     *
     * Takes ownership of the requestBody (to allow redirects).
     */
    QNetworkReply *sendRequest(const QByteArray &verb, const QUrl &url,
        QNetworkRequest req = QNetworkRequest(),
        QIODevice *requestBody = 0);

    // sendRequest does not take a relative path instead of an url,
    // but the old API allowed that. We have this undefined overload
    // to help catch usage errors
    QNetworkReply *sendRequest(const QByteArray &verb, const QString &relativePath,
        QNetworkRequest req = QNetworkRequest(),
        QIODevice *requestBody = 0);

    /** Makes this job drive a pre-made QNetworkReply
     *
     * This reply cannot have a QIODevice request body because we can't get
     * at it and thus not resend it in case of redirects.
     */
    void adoptRequest(QNetworkReply *reply);

    void setupConnections(QNetworkReply *reply);

    /** Can be used by derived classes to set up the network reply.
     *
     * Particularly useful when the request is redirected and reply()
     * changes. For things like setting up additional signal connections
     * on the new reply.
     */
    virtual void newReplyHook(QNetworkReply *) {}

    /// Creates a url for the account from a relative path
    QUrl makeAccountUrl(const QString &relativePath) const;

    /// Like makeAccountUrl() but uses the account's dav base path
    QUrl makeDavUrl(const QString &relativePath) const;

    int maxRedirects() const { return 10; }

    /** Called at the end of QNetworkReply::finished processing.
     *
     * Returning true triggers a deleteLater() of this job.
     */
    virtual bool finished() = 0;

    /** Called on timeout.
     *
     * The default implementation aborts the reply.
     */
    virtual void onTimedOut();

    QByteArray _responseTimestamp;
    bool _timedout; // set to true when the timeout slot is received

    // Automatically follows redirects. Note that this only works for
    // GET requests that don't set up any HTTP body or other flags.
    bool _followRedirects;

    QString replyStatusString();

private slots:
    void slotFinished();
    void slotTimeout();

protected:
    AccountPtr _account;

private:
    QNetworkReply *addTimer(QNetworkReply *reply);
    bool _ignoreCredentialFailure;
    QPointer<QNetworkReply> _reply; // (QPointer because the NetworkManager may be destroyed before the jobs at exit)
    QString _path;
    QTimer _timer;
    int _redirectCount = 0;
    int _http2ResendCount = 0;

    // Set by the xyzRequest() functions and needed to be able to redirect
    // requests, should it be required.
    //
    // Reparented to the currently running QNetworkReply.
    QPointer<QIODevice> _requestBody;
};

/**
 * @brief Internal Helper class
 */
class NetworkJobTimeoutPauser
{
public:
    NetworkJobTimeoutPauser(QNetworkReply *reply);
    ~NetworkJobTimeoutPauser();

private:
    QPointer<QTimer> _timer;
};


/** Gets the SabreDAV-style error message from an error response.
 *
 * This assumes the response is XML with a 'error' tag that has a
 * 'message' tag that contains the data to extract.
 *
 * Returns a null string if no message was found.
 */
QString OWNCLOUDSYNC_EXPORT extractErrorMessage(const QByteArray &errorResponse);

/** Builds a error message based on the error and the reply body. */
QString OWNCLOUDSYNC_EXPORT errorMessage(const QString &baseError, const QByteArray &body);

/** Helper to construct the HTTP verb used in the request
 *
 * Returns an empty QByteArray for UnknownOperation.
 */
QByteArray OWNCLOUDSYNC_EXPORT requestVerb(const QNetworkReply &reply);

/** Nicer errorString() for QNetworkReply
 *
 * By default QNetworkReply::errorString() often produces messages like
 *   "Error downloading <url> - server replied: <reason>"
 * but the "downloading" part invariably confuses people since the
 * error might very well have been produced by a PUT request.
 *
 * This function produces clearer error messages for HTTP errors.
 */
QString OWNCLOUDSYNC_EXPORT networkReplyErrorString(const QNetworkReply &reply);

} // namespace OCC
