/*
    Virtual base class for mail storage.

    This file is part of KMail.

    Copyright (c) 2004 Bo Thorsen <bo@sonofthor.dk>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.

    In addition, as a special exception, the copyright holders give
    permission to link the code of this program with any edition of
    the Qt library by Trolltech AS, Norway (or with modified versions
    of Qt that use the same license as Qt), and distribute linked
    combinations including the two.  You must obey the GNU General
    Public License in all respects for all of the code used other than
    Qt.  If you modify this file, you may extend this exception to
    your version of the file, but you are not obligated to do so.  If
    you do not wish to do so, delete this exception statement from
    your version.
*/

#ifndef FOLDERSTORAGE_H
#define FOLDERSTORAGE_H

// for large file support

#include "kmfoldernode.h"
#include "kmfoldertype.h"
#include "kmmsginfo.h"
#include "kmglobal.h"
#include "folderjob.h"
using KMail::FolderJob;

#include <QList>
#include <QByteArray>

#include "mimelib/string.h"

#include <sys/types.h>
#include <stdio.h>

class KMMessage;
class KMAccount;
class KMFolderDir;
class KMMsgDict; // for the rDict manipulations
class KMMsgDictREntry;
class QTimer;
class KMSearchPattern;

namespace KMail {
   class AttachmentStrategy;
}
using KMail::AttachmentStrategy;

typedef QList<quint32> SerNumList;

/**
 * @short The FolderStorage class is the bass class for the storage related
 * aspects of a collection of mail (a folder).
 *
 * @section Accounts
 *   The accounts (of KMail) that are fed into the folder are
 *   represented as the children of the folder. They are only stored here
 *   during runtime to have a reference for which accounts point to a
 *   specific folder.
 */

class FolderStorage : public QObject
{
  Q_OBJECT

public:


  /** Usually a parent is given. But in some cases there is no
    fitting parent object available. Then the name of the folder
    is used as the absolute path to the folder file. */
  explicit FolderStorage( KMFolder* folder, const char* name=0 );
  virtual ~FolderStorage();

  KMFolder* folder() const { return mFolder; }

  /** Returns the type of this folder */
  virtual KMFolderType folderType() const { return KMFolderTypeUnknown; }

  /** Returns the filename of the folder (reimplemented in KMFolderImap) */
  virtual QString fileName() const;
  /** Returns full path to folder file */
  QString location() const;

  /** Returns full path to index file */
  virtual QString indexLocation() const;

  /** Returns full path to 'ids' file */
  virtual QString idsLocation() const;

  /** Returns full path to 'sorted' file */
  virtual QString sortedLocation() const;

  /** Returns, if the folder can't contain mails, but only subfolder */
  virtual bool noContent() const { return mNoContent; }

  /** Specify, that the folder can't contain mails. */
  virtual void setNoContent(bool aNoContent);

  /** Returns, if the folder can't have children */
  virtual bool noChildren() const { return mNoChildren; }

  /** Specify, that the folder can't have children */
  virtual void setNoChildren( bool aNoChildren );

  enum ChildrenState {
    HasChildren,
    HasNoChildren,
    ChildrenUnknown
  };
  /** Returns if the folder has children,
   *  has no children or we don't know */
  virtual ChildrenState hasChildren() const { return mHasChildren; }

  /** Specify if the folder has children */
  virtual void setHasChildren( ChildrenState state )
    { mHasChildren = state; }

  /** Updates the hasChildren() state */
  virtual void updateChildrenState();

  /** Read message at given index. Indexing starts at zero */
  virtual KMMessage* getMsg(int idx);

  /** Replace KMMessage with KMMsgInfo and delete KMMessage  */
  virtual KMMsgInfo* unGetMsg(int idx);

  /** Checks if the message is already "gotten" with getMsg */
  virtual bool isMessage(int idx);

  /** Load message from file and do NOT store it, only return it.
      This is equivalent to, but faster than, getMsg+unGetMsg
      WARNING: the caller has to delete the returned value!
      WARNING: Use this only for messages which are local, never for remote
               messages, because remote messages could start a transfer, which
               would trigger an assert when the message is deleted by the caller.
  */
  virtual KMMessage* readTemporaryMsg(int idx);

  /** Read a message and returns a DwString */
  virtual DwString getDwString(int idx) = 0;

  /**
   * Removes and deletes all jobs associated with the particular message
   */
  virtual void ignoreJobsForMessage( KMMessage* );

  /**
   * These methods create respective FolderJob (You should derive FolderJob
   * for each derived KMFolder).
   */
  virtual FolderJob* createJob( KMMessage *msg, FolderJob::JobType jt = FolderJob::tGetMessage,
                                KMFolder *folder = 0, const QString &partSpecifier = QString(),
                                const AttachmentStrategy *as = 0 ) const;
  virtual FolderJob* createJob( QList<KMMessage*>& msgList, const QString& sets,
                                FolderJob::JobType jt = FolderJob::tGetMessage,
                                KMFolder *folder = 0 ) const;

  /** Provides access to the basic message fields that are also stored
    in the index. Whenever you only need subject, from, date, status
    you should use this method instead of getMsg() because getMsg()
    will load the message if necessary and this method does not. */
  virtual const KMMsgBase* getMsgBase(int idx) const = 0;
  virtual KMMsgBase* getMsgBase(int idx) = 0;

  /** Same as getMsgBase(int). */
  virtual const KMMsgBase* operator[](int idx) const { return getMsgBase(idx); }

  /** Same as getMsgBase(int). This time non-const. */
  virtual KMMsgBase* operator[](int idx) { return getMsgBase(idx); }

  /** Detach message from this folder. Usable to call addMsg() afterwards.
    Loads the message if it is not loaded up to now. */
  virtual KMMessage* take(int idx);
  virtual void takeMessages(const QList<KMMessage*>& msgList);

  /** Add the given message to the folder. Usually the message
    is added at the end of the folder. Returns zero on success and
    an errno error code on failure. The index of the new message
    is stored in index_return if given.
    Please note that the message is added as is to the folder and the folder
    takes ownership of the message (deleting it in the destructor).*/
  virtual int addMsg(KMMessage* msg, int* index_return = 0) = 0;

  /** (Note(bo): This needs to be fixed better at a later point.)
      This is overridden by dIMAP because addMsg strips the X-UID
      header from the mail. */
  virtual int addMsgKeepUID(KMMessage* msg, int* index_return = 0) {
    return addMsg(msg, index_return);
  }

  /**
   * Adds the given messages to the folder. Behaviour is identical
   * to addMsg(msg)
   */
  virtual int addMessages( QList<KMMessage*>&, QList<int>& index_return );

  /** Called by derived classes implementation of addMsg.
      Emits msgAdded signals */
  void emitMsgAddedSignals(int idx);

  /** Returns false, if the message has to be retrieved from an IMAP account
   * first. In this case this function does this and cares for the rest */
  virtual bool canAddMsgNow(KMMessage* aMsg, int* aIndex_ret);

  /** Remove (first occurrence of) given message from the folder. */
  virtual void removeMsg(int i, bool imapQuiet = false);
  virtual void removeMessages(const QList<KMMsgBase*>& msgList, bool imapQuiet = false);
  virtual void removeMessages(const QList<KMMessage*>& msgList, bool imapQuiet = false);

  /** Delete messages in the folder that are older than days. Return the
   * number of deleted messages. */
  virtual int expungeOldMsg(int days);

  /** Detaches the given message from it's current folder and
    adds it to this folder. Returns zero on success and an errno error
    code on failure. The index of the new message is stored in index_return
    if given. */
  virtual int moveMsg(KMMessage* msg, int* index_return = 0);
  virtual int moveMsg(QList<KMMessage*>, int* index_return = 0);

  /** Returns the index of the given message or -1 if not found. */
  virtual int find(const KMMsgBase* msg) const = 0;
  int find( const KMMessage * msg ) const;

  /** Number of messages in this folder. */
  virtual int count(bool cache = false) const;

  /** Number of new or unread messages in this folder. */
  virtual int countUnread();

  /** Total size of the contents of this folder. */
  qint64 folderSize() const;

  /** Return whether the folder is close to its quota limit, which can
   * be reflected in the UI.  */
  virtual bool isCloseToQuota() const;

  /** Called by KMMsgBase::setStatus when status of a message has changed
      required to keep the number unread messages variable current. */
  virtual void msgStatusChanged( const MessageStatus& oldStatus,
                                 const MessageStatus& newStatus,
                                 int idx);

  /** Open folder for access.
    open() and close() use reference counting.
    Returns zero on success and an error code equal to the c-library
    fopen call otherwise (errno).
    @p owner is for debugging.
    @see KMFolderOpener */
  virtual int open( const char *owner ) = 0;

  /** Check folder for permissions
    @return true if readable and writable. */
  virtual bool canAccess() const = 0;

  /** Close folder. If force is true the files are closed even if
    If @p force is TRUE the files are closed regardless of reference count,
    and the reference count will be set to zero.
    @p owner is for debugging. */
  virtual void close( const char *owner, bool force = false );
  virtual void reallyDoClose() = 0;

  /** Try releasing @p folder if possible, something is attempting an exclusive access to it.
      Currently used for KMFolderSearch and the background tasks like expiry. */
  virtual void tryReleasingFolder(KMFolder*) {}

  /** fsync buffers to disk */
  virtual void sync() = 0;

  /** Test if folder is opened, i.e. its reference count is greater than zero. */
  bool isOpened() const { return (mOpenCount>0); }

  /** Mark all new messages as unread. */
  virtual void markNewAsUnread();

  /** Mark all new and unread messages as read. */
  virtual void markUnreadAsRead();

  /** Create a new folder with the name of this object and open it.
      Returns zero on success and an error code equal to the
      c-library fopen call otherwise. */
  virtual int create() = 0;

  /** Removes the folder physically from disk and empties the contents
    of the folder in memory. Note that the folder is closed during this
    process, whether there are others using it or not.
    @see KMFolder::removeContents */
  virtual void remove();

  /** Delete entire folder. Forces a close *but* opens the
    folder again afterwards. Returns errno(3) error code or zero on
    success.  see KMFolder::expungeContents */
  virtual int expunge();

  /** Remove deleted messages from the folder. Returns zero on success
    and an errno on failure.
    A statusbar message will inform the user that the compaction worked,
    unless @p silent is set. */
  virtual int compact( bool silent ) = 0;

  /** Physically rename the folder. Returns zero on success and an errno
    on failure. */
  virtual int rename(const QString& newName, KMFolderDir *aParent = 0);

  /** Returns true if a table of contents file is automatically created. */
  bool autoCreateIndex() const { return mAutoCreateIndex; }

  /** Allow/disallow automatic creation of a table of contents file.
    Default is true. */
  virtual void setAutoCreateIndex(bool);

  /** Returns true if the table of contents is dirty. This happens when
    a message is deleted from the folder. The toc will then be re-created
    when the folder is closed. */
  bool dirty() const { return mDirty; }

  /** Change the dirty flag. */
  void setDirty(bool f);

  /** Returns true if the folder contains deleted messages */
  bool needsCompacting() const { return needsCompact; }
  virtual void setNeedsCompacting(bool f) { needsCompact = f; }

  /** If set to quiet the folder will not emit msgAdded(idx) signal.
    This is necessary because adding the messages to the listview
    one by one as they come in ( as happens on msgAdded(idx) ) is
    very slow for large ( >10000 ) folders. For pop, where whole
    bodies are downloaded this is not an issue, but for imap, where
    we only download headers it becomes a bottleneck. We therefore
    set the folder quiet() and rebuild the listview completely once
    the complete folder has been checked. */
  virtual void quiet(bool beQuiet);

  /** Is the folder read-only? */
  virtual bool isReadOnly() const = 0;

  /** Can messages in this folder be deleted? */
  virtual bool canDeleteMessages() const;

  /** Returns the label of the folder for visualization. */
  QString label() const;

  /** A cludge to help make sure the count of unread messges is kept in sync */
  virtual void correctUnreadMsgsCount();

  /** Write index to index-file. Returns 0 on success and errno error on
    failure. */
  virtual int writeIndex( bool createEmptyIndex = false ) = 0;

  /** Triggers registration with the message dict, which will cause the dict
   * to ask the FolderStorage to fill itself into it. */
  void registerWithMessageDict();

    /** Triggers deregistration from the message dict, which will cause the dict
     * to ask the FolderStorage to write the relevant data structures to disk.. */
  void deregisterFromMessageDict();

  /** Set the status of the message at index @p idx to @p status. */
  virtual void setStatus(int idx, const MessageStatus& status, bool toggle=false);

  /** Set the status of the message(s) in the QValueList @p ids to @p status. */
  virtual void setStatus(QList<int>& ids, const MessageStatus& status, bool toggle=false);

  void removeJobs();

  /** Escape a leading dot */
  static QString dotEscape(const QString&);

  /** Read the config file */
  virtual void readConfig();

  /** Write the config file */
  virtual void writeConfig();

  /**
   * If this folder has a special trash folder set, return it. Otherwise
   * return 0.
   */
  virtual KMFolder* trashFolder() const { return 0; }

  /**
   * Add job for this folder. This is done automatically by createJob.
   * This method is public only for other kind of FolderJob like ExpireJob.
   */
  void addJob( FolderJob* ) const;

  /** false if index file is out of sync with mbox file */
  bool compactable() const { return mCompactable; }

  /**
   * Enable compaction, even if it appears to be unsafe (see above).
   * Use at your own risk!!
   */
  void enableCompaction();

  /// Set the type of contents held in this folder (mail, calendar, etc.)
  // If quiet is true, the KMailIcalIface is not informed of the changed.
  // That's useful for folder that are being copied around, should retain
  // their type, but not cause conflicts on copy because events are identical
  // in two folders.
  virtual void setContentsType( KMail::FolderContentsType type, bool quiet = false );
  /// @return the type of contents held in this folder (mail, calendar, etc.)
  KMail::FolderContentsType contentsType() const { return mContentsType; }

  /**
   * Search for messages
   * The end is signaled with searchDone()
   */
  virtual void search( const KMSearchPattern* );

  /**
   * Check if the message matches the search criteria
   * The end is signaled with searchDone()
   */
  virtual void search( const KMSearchPattern*, quint32 serNum );

  /** Returns true if this folder can be moved */
  virtual bool isMoveable() const;

  virtual KMAccount* account() const;

signals:
  /** Emitted when the status, name, or associated accounts of this
    folder changed. */
  void changed();

  /** Emitted when the contents of a folder have been cleared
     (new search in a search folder, for example) */
  void cleared();

  /** Emitted at the end of a compaction job step.
   *  in order to reload the views. */

  void compacted();
  /** Emitted after an expunge. If not quiet, changed() will be
      emmitted first. */
  void expunged( KMFolder* );

  /** Emitted when the folder was closed and ticket owners have to reopen */
  void closed( KMFolder* );

  /** Emitted when the serial numbers of this folder were invalidated. */
  void invalidated( KMFolder* );

  /** Emitted when the name of the folder changes. */
  void nameChanged();

  /** Emitted when the location on disk of the folder changes. This
   * is used by all code which uses the locatio on disk of the folder storage
   * ( or the cache storage ) as an identifier for the folder. */
  void locationChanged( const QString &, const QString & );

  /** Emitted when the contents type (calendar, mail, tasks, ..) of the
   * folderstorage changes. */
  void contentsTypeChanged( KMail::FolderContentsType type );

  /** Emitted when the readonly status of the folder changes. */
  void readOnlyChanged(KMFolder*);

  /** Emitted when the no content state of the folder changes. */
  void noContentChanged();

  /** Emitted before a message is removed from the folder. */
  void msgRemoved(KMFolder*, quint32 sernum);

  /** Emitted after a message is removed from the folder. */
  void msgRemoved( int idx, const QString &msgIdMD5 );
  void msgRemoved( KMFolder* );

  /** Emitted when a message is added from the folder. */
  void msgAdded(int idx);
  void msgAdded(KMFolder*, quint32 sernum);

  /** Emitted, when the status of a message is changed */
  void msgChanged(KMFolder*, quint32 sernum, int delta);

  /** Emitted when a field of the header of a specific message changed. */
  void msgHeaderChanged(KMFolder*, int);

  /** Emmited to display a message somewhere in a status line. */
  void statusMsg(const QString&);

  /** Emitted when number of unread messages has changed. */
  void numUnreadMsgsChanged( KMFolder* );

  /** Emitted when a folder was removed */
  void removed(KMFolder*, bool);

  /**
   * Emitted when a search delivers results
   * The matching serial numbers are included
   * If @p complete is true the search is done
   */
  void searchResult( KMFolder*, QList<quint32>,
                     const KMSearchPattern*, bool complete );

  /**
   * Emitted when a search for a single message is completed
   * The serial number and a bool matching yes/no is included
   */
  void searchDone( KMFolder*, quint32, const KMSearchPattern*, bool );

  /** Emitted when the folder's size changes. */
  void folderSizeChanged();


public slots:
  /** Incrementally update the index if possible else call writeIndex */
  virtual int updateIndex() = 0;

  /** Add the message to the folder after it has been retrieved from an IMAP
      server */
  virtual void reallyAddMsg(KMMessage* aMsg);

  /** Add a copy of the message to the folder after it has been retrieved
      from an IMAP server */
  virtual void reallyAddCopyOfMsg(KMMessage* aMsg);

  /** Emit changed signal if mQuite <=0 */
  void slotEmitChangedTimer();

protected slots:
  virtual void removeJob( QObject* );

  /** Process the next search batch */
  void slotProcessNextSearchBatch();

protected:

  /**
   * These two methods actually create the jobs. They have to be implemented
   * in all folders.
   * @see createJob
   */
  virtual FolderJob* doCreateJob( KMMessage *msg, FolderJob::JobType jt, KMFolder *folder,
                                  const QString &partSpecifier, const AttachmentStrategy *as ) const = 0;
  virtual FolderJob* doCreateJob( QList<KMMessage*>& msgList, const QString& sets,
                                  FolderJob::JobType jt, KMFolder *folder ) const = 0;

  /** Tell the folder that a header field that is usually used for
    the index (subject, from, ...) has changed of given message.
    This method is usually called from within KMMessage::setSubject/set... */
  void headerOfMsgChanged(const KMMsgBase*, int idx);

  /** Load message from file and store it at given index. Returns 0
    on failure. */
  virtual KMMessage* readMsg(int idx) = 0;

  //--------- Message Dict manipulation
friend class KMMsgDict;
  /** Inserts messages into the message dictionary. The messages will get
   * new serial numbers. This is only used on newly appeared folders, where
   * there is no .ids file yet, or when that has been invalidated. */
  virtual void fillMessageDict() {}

  /** Read the on-disk cache of serial numbers  of messages in this store
   * and fill those into the global message dict, such that the messages
   * we hold can be looked up there. */
  void readFolderIdsFile();

  /** Writes the message serial number file. */
  int writeFolderIdsFile() const;

  /** Touches the message serial number file. */
  int touchFolderIdsFile();

  /** Append message to end of message serial number file. */
  int appendToFolderIdsFile( int idx = -1 );

  /** Sets the reverse-dictionary for this folder. const, because the mRDict
   * is mutable, since it is not part of the (conceptually) const-relevant state
   * of the object. */
  void setRDict(KMMsgDictREntry *rentry) const;

  /** Returns the reverse-dictionary for this folder. */
  KMMsgDictREntry *rDict() const { return mRDict; }


  /** Replaces the serial number for the message @p msg at index @p idx with
   * @p sernum */
  void replaceMsgSerNum( unsigned long sernum, KMMsgBase* msg, int idx );

   /** Called when serial numbers for a folder are invalidated,
  invalidates/recreates data structures dependent on the
  serial numbers for this folder */
  void invalidateFolder();

  /** Called by KMFolder::remove() to delete the actual contents.
    At the time of the call the folder has already been closed, and
    the various index files deleted.  Returns 0 on success. */
  virtual int removeContents() = 0;

  /** Called by KMFolder::expunge() to delete the actual contents.
    At the time of the call the folder has already been closed, and
    the various index files deleted.  Returns 0 on success. */
  virtual int expungeContents() = 0;

  /** Read index file and fill the message-info list mMsgList. */
  virtual bool readIndex() = 0;
  virtual KMMsgBase* takeIndexEntry( int idx ) = 0;
  virtual KMMsgInfo* setIndexEntry( int idx, KMMessage *msg ) = 0;
  virtual void clearIndex(bool autoDelete=true, bool syncDict = false) = 0;
  virtual void truncateIndex() = 0;

  /**
   * Compute the size of the folder storage.
   * Return -1 if the value is meaningless.
   */
  virtual qint64 doFolderSize() const { return -1; };

  /** Returns full path to .index, .index.ids or .index.sorted file (depending on @a suffix).
   The former path (in case of mmap-based implementation) is returned when @a suffix is empty. */
  virtual QString location(const QString& suffix) const;

  int mOpenCount;
  int mQuiet;
  bool mChanged :1;
  /** is the automatic creation of a index file allowed ? */
  bool mAutoCreateIndex :1;
  /** Has this storage exported its serial numbers to the global message
   * dict for lookup? */
  bool mExportsSernums :1;
  /** if the index is dirty it will be recreated upon close() */
  bool mDirty :1;
  /** true if the files of the folder are locked (writable) */
  bool mFilesLocked :1;

  /** number of unread messages, -1 if not yet set */
  int mUnreadMsgs, mGuessedUnreadMsgs;
  int mTotalMsgs;
  mutable qint64 mCachedSize;
  bool mWriteConfigEnabled :1;
  /** sven: true if on destruct folder needs to be compacted. */
  bool needsCompact :1;
  /** false if index file is out of sync with mbox file */
  bool mCompactable :1;
  bool mNoContent :1;
  bool mNoChildren :1;
  bool mConvertToUtf8 :1;

  /** Points at the reverse dictionary for this folder. */
  mutable KMMsgDictREntry *mRDict;
  /** List of jobs created by this folder. */
  mutable QList<FolderJob*> mJobList;

  QTimer *mDirtyTimer;
  enum { mDirtyTimerInterval = 600000 }; // 10 minutes

  ChildrenState mHasChildren;

  /** Type of contents in this folder. */
  KMail::FolderContentsType mContentsType;

  KMFolder* mFolder;

  QTimer * mEmitChangedTimer;

  int mCurrentSearchedMsg;
  const KMSearchPattern* mSearchPattern;
};

#endif // FOLDERSTORAGE_H
