//

//  MYDirectoryWatcher.m

//  Murky

//

//  Copyright 2008 Jens Alfke. All rights reserved.

//

#import "MYDirectoryWatcher.h"

#import <CoreServices/CoreServices.h>

static void directoryWatcherCallback(ConstFSEventStreamRef streamRef,

                                     void *clientCallBackInfo,

                                     size_t numEvents,

                                     void *eventPaths,

                                     const FSEventStreamEventFlags eventFlags[],

                                     const FSEventStreamEventId eventIds[]);

@interface MYDirectoryEvent ()

- (id) _initWithWatcher: (MYDirectoryWatcher*)itsWatcher

                   path: (NSString*)itsPath 

                  flags: (FSEventStreamEventFlags)itsFlags

                eventID: (FSEventStreamEventId)itsEventID;

@end

@implementation MYDirectoryWatcher

- (id) initWithDirectory: (NSString*)path target: (id)target action: (SEL)action

{

    NSParameterAssert(path);

    self = [super init];

    if (self != nil) {

        _path = path.copy;

        _target = target;

        _action = action;

        _latency = 5.0;

        _lastEventID = kFSEventStreamEventIdSinceNow;

    }

    return self;

}

- (void) dealloc

{

    [self stop];

    [_path release];

    [super dealloc];

}

- (void) finalize

{

    [self stop];

    [super finalize];

}

@synthesize path=_path, latency=_latency, lastEventID=_lastEventID;

- (BOOL) start

{

    if( ! _stream ) {

        FSEventStreamContext context = {0,self,NULL,NULL,NULL};

        _stream = FSEventStreamCreate(NULL, 

                                      &directoryWatcherCallback, &context,

                                      (CFArrayRef)[NSArray arrayWithObject: _path], 

                                      _lastEventID, 

                                      _latency, 

                                      kFSEventStreamCreateFlagUseCFTypes);

        if( ! _stream )

            return NO;

        FSEventStreamScheduleWithRunLoop(_stream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);

        if( ! FSEventStreamStart(_stream) ) {

            [self stop];

            return NO;

        }

        _historyDone = (_lastEventID == kFSEventStreamEventIdSinceNow);

        Log(@"MYDirectoryWatcher: Started on %@ (latency=%g, lastEvent=%llu)",_path,_latency,_lastEventID);

    }

    return YES;

}

- (void) pause

{

    if( _stream ) {

        FSEventStreamStop(_stream);

        FSEventStreamInvalidate(_stream);

        FSEventStreamRelease(_stream);

        _stream = NULL;

        Log(@"MYDirectoryWatcher: Stopped on %@ (lastEvent=%llu)",_path,_lastEventID);

    }

}

- (void) stop

{

    [self pause];

    _lastEventID = kFSEventStreamEventIdSinceNow;   // so events from now till next start will be dropped

    [NSObject cancelPreviousPerformRequestsWithTarget: self selector: @selector(start) object: nil];

}

- (void) stopTemporarily

{

    if( _stream ) {

        [self stop];

        [self performSelector: @selector(start) withObject: nil afterDelay: 0.0];

    }

}

- (void) _notifyEvents: (size_t)numEvents

                 paths: (NSArray*)paths

                 flags: (const FSEventStreamEventFlags[])eventFlags

              eventIDs: (const FSEventStreamEventId[])eventIDs

{

    for (size_t i=0; i<numEvents; i++) {

        NSString *path = [paths objectAtIndex: i];

        FSEventStreamEventFlags flags = eventFlags[i];

        FSEventStreamEventId eventID = eventIDs[i];

        if( flags & (kFSEventStreamEventFlagMount | kFSEventStreamEventFlagUnmount) ) {

            if( flags & kFSEventStreamEventFlagMount )

                Log(@"MYDirectoryWatcher: Volume mounted: %@",path);

            else

                Log(@"MYDirectoryWatcher: Volume unmounted: %@",path);

        } else if( flags & kFSEventStreamEventFlagHistoryDone ) {

            Log(@"MYDirectoryWatcher: Event #%llu History done",eventID);

            _historyDone = YES;

        } else {

            Log(@"MYDirectoryWatcher: Event #%llu flags=%02x path=%@",eventID,flags,path);

            if( _historyDone )

                flags |= kFSEventStreamEventFlagHistoryDone;

            MYDirectoryEvent *event = [[MYDirectoryEvent alloc] _initWithWatcher: self

                                                                        path: path 

                                                                       flags: flags

                                                                     eventID: eventID];

            [_target performSelector: _action withObject: event];

            [event release];

        }

        _lastEventID = eventIDs[i];

    }

}

static void directoryWatcherCallback(ConstFSEventStreamRef streamRef,

                                     void *watcher,

                                     size_t numEvents,

                                     void *eventPaths,

                                     const FSEventStreamEventFlags eventFlags[],

                                     const FSEventStreamEventId eventIDs[])

{

    [(MYDirectoryWatcher*)watcher _notifyEvents: numEvents

                                          paths: (NSArray*)eventPaths

                                          flags: eventFlags

                                       eventIDs: eventIDs];

}

@end

@implementation MYDirectoryEvent

- (id) _initWithWatcher: (MYDirectoryWatcher*)itsWatcher

                   path: (NSString*)itsPath 

                  flags: (FSEventStreamEventFlags)itsFlags

                eventID: (FSEventStreamEventId)itsEventID

{

    self = [super init];

    if (self != nil) {

        watcher = itsWatcher;

        path = itsPath.copy;

        flags = itsFlags;

        eventID = itsEventID;

    }

    return self;

}

- (void) dealloc

{

    [path release];

    [super dealloc];

}

@synthesize watcher,path,flags,eventID;

- (NSString*) relativePath

{

    NSString *base = watcher.path;

    if( ! [path hasPrefix: base] )

        return nil;

    int length = base.length;

    while( length < path.length && [path characterAtIndex: length]=='/' )

        length++;

    return [path substringFromIndex: length];

}

- (BOOL) mustScanSubdirectories     {return (flags & kFSEventStreamEventFlagMustScanSubDirs) != 0;}

- (BOOL) eventsWereDropped          {return (flags & (kFSEventStreamEventFlagUserDropped|kFSEventStreamEventFlagKernelDropped)) != 0;}

- (BOOL) isHistorical               {return (flags & kFSEventStreamEventFlagHistoryDone)==0;}

- (BOOL) rootChanged                {return (flags & kFSEventStreamEventFlagRootChanged)!=0;}

@end