/* SOGoCache.m - this file is part of SOGo
 *
 * Copyright (C) 2008-2010 Inverse inc.
 *
 * Author: Wolfgang Sourdeau <wsourdeau@inverse.ca>
 *         Ludovic Marcotte <lmarcotte@inverse.ca>
 *
 * This file 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, or (at your option)
 * any later version.
 *
 * This file 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; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * [ Cache Structure ]
 *
 * users                 value = instances of SOGoUser > flushed after the completion of every SOGo requests
 * groups                value = instances of SOGoGroup > flushed after the completion of every SOGo requests
 * imap4Connections      value = 
 * localCache            value = any value of what's in memcached - this is used to NOT query memcached within the same sogod instance
 * 
 * [ Distributed (using memcached) cache structure ]
 *
 * <uid>+defaults        value = NSDictionary instance > user's defaults
 * <uid>+settings        value = NSDictionary instance > user's settings
 * <uid>+attributes      value = NSMutableDictionary instance > user's LDAP attributes
 * <object path>+acl     value = NSDictionary instance > ACLs on an object at specified path
 * <groupname>+<domain>  value = NSString instance (array components separated by ",") or group member logins for a specific group in domain
 * cas-id:< >            value = 
 * cas-ticket:< >        value =
 * cas-pgtiou:< >        value =
 * session:< >           value =
 */


#import <Foundation/NSArray.h>
#import <Foundation/NSData.h>
#import <Foundation/NSDictionary.h>
#import <Foundation/NSLock.h>
#import <Foundation/NSString.h>
#import <Foundation/NSTimer.h>

#import <NGObjWeb/SoObject.h>
#import <NGExtensions/NSObject+Logs.h>

#import "NSDictionary+Utilities.h"
#import "NSString+Utilities.h"
#import "SOGoObject.h"
#import "SOGoSystemDefaults.h"
#import "SOGoUser.h"
#import "SOGoUserProfile.h"

#import "SOGoCache.h"

/* Those used to be ivars but were converted to static globals to work around
   a bug in GCC that prevent SOGo from using libmemcached > 0.37:

   "SOGoCache.m:409: internal compiler error: in encode_gnu_bitfield, at
   objc/objc-act.c:8218
   Please submit a full bug report,
   with preprocessed source if appropriate.
   See <file:///usr/share/doc/gcc-4.4/README.Bugs> for instructions." */

static memcached_server_st *servers = NULL;
static memcached_st *handle = NULL;

@implementation SOGoCache

+ (SOGoCache *) sharedCache
{
  static SOGoCache *sharedCache = nil;

  if (!sharedCache)
    sharedCache = [self new];

  return sharedCache;
}

- (id) init
{
  SOGoSystemDefaults *sd;

  if ((self = [super init]))
    {
      cache = [[NSMutableDictionary alloc] init];
      requestsCacheEnabled = YES;
      users = [[NSMutableDictionary alloc] init];
      groups = [[NSMutableDictionary alloc] init];
      imap4Connections = [[NSMutableDictionary alloc] init];

      // localCache is used to avoid going all the time to the memcached
      // server during each request. We'll cache the value we got from
      // memcached for the duration of the current request - which is good
      // enough for pretty much all cases. We surely don't want to get new
      // defaults/settings during the _same_ requests, it could produce
      // relatively strange behaviors
      localCache = [NSMutableDictionary new];

      if (!handle)
        {
          handle = memcached_create(NULL);
          if (handle)
            {
              sd = [SOGoSystemDefaults sharedSystemDefaults];
	      
	      // We define the default value for cleaning up cached users'
              // preferences. This value should be relatively high to avoid
              // useless database calls.
              cleanupInterval = [sd cacheCleanupInterval];
              ASSIGN(memcachedServerName, [sd memcachedHost]);

              [self logWithFormat: @"Cache cleanup interval set every %f seconds",
                    cleanupInterval];
              [self logWithFormat: @"Using host(s) '%@' as server(s)",
                    memcachedServerName];
              if (!servers)
                servers
		  = memcached_servers_parse([memcachedServerName UTF8String]);

              if ([memcachedServerName hasPrefix:@"/"])
                  memcached_server_add_unix_socket(handle, [memcachedServerName UTF8String]);
              else
                  memcached_server_push(handle, servers);
            }
        }
    }

  return self;
}

- (void) dealloc
{
  /* Commented out because of a bug in GCC:
     memcached_server_free (servers);
     memcached_free (handle); */
  [memcachedServerName release];
  [cache release];
  [users release];
  [groups release];
  [imap4Connections release];
  [localCache release];
  [super dealloc];
}

- (void) disableRequestsCache
{
  requestsCacheEnabled = NO;  
}

- (void) disableLocalCache
{
  [localCache release];
  localCache = nil;
}

- (void) killCache
{
  [cache removeAllObjects];
  [imap4Connections removeAllObjects];

  // This is essential for refetching the cached values in case something has changed
  // accross various sogod processes
  [users removeAllObjects];
  [groups removeAllObjects];
  [localCache removeAllObjects];
}

- (NSString *) _pathFromObject: (SOGoObject *) container
                      withName: (NSString *) name
{
  NSString *fullPath, *nameInContainer;
  NSMutableArray *names;
  id currentObject;

  if ([name length])
    {
      names = [NSMutableArray array];

      [names addObject: name];
      currentObject = container;
      while ((nameInContainer = [currentObject nameInContainer]))
        {
          [names addObject: nameInContainer];
          currentObject = [currentObject container];
        }

      fullPath = [names componentsJoinedByString: @"/"];
    }
  else
    fullPath = nil;

  return fullPath;
}

- (void) registerObject: (id) object
	       withName: (NSString *) name
	    inContainer: (SOGoObject *) container
{
  NSString *fullPath;

  if (requestsCacheEnabled && object && name)
    {
      [self registerObject: container
	    withName: [container nameInContainer]
	    inContainer: [container container]];
      fullPath = [self _pathFromObject: container
		       withName: name];
      if (fullPath && ![cache objectForKey: fullPath])
	{
	  [cache setObject: object forKey: fullPath];
	}
    }
}

- (void) unregisterObjectWithName: (NSString *) name
                      inContainer: (SOGoObject *) container
{
  NSString *fullPath;

  if (requestsCacheEnabled && name)
    {
      fullPath = [self _pathFromObject: container
                              withName: name];
      [cache removeObjectForKey: fullPath];
    }
}

- (id) objectNamed: (NSString *) name
       inContainer: (SOGoObject *) container
{
  NSString *fullPath;
  id cacheObject;

  if (requestsCacheEnabled)
    {
      fullPath = [self _pathFromObject: container
                              withName: name];
      cacheObject = [cache objectForKey: fullPath];
    }
  else
    cacheObject = nil;

  return cacheObject;
}

- (void) registerUser: (SOGoUser *) user
             withName: (NSString *) userName
{ 
  [users setObject: user forKey: userName];
}

- (id) userNamed: (NSString *) name
{
  return [users objectForKey: name];
}

- (void) registerGroup: (SOGoGroup *) group
              withName: (NSString *) groupName
	      inDomain: (NSString *) domainName

{
  if (group)
    [groups setObject: group forKey: [NSString stringWithFormat: @"%@+%@", groupName, domainName]];
}

- (id) groupNamed: (NSString *) groupName
	 inDomain: (NSString *) domainName

{
  return [groups objectForKey: [NSString stringWithFormat: @"%@+%@", groupName, domainName]];
}

- (void) registerIMAP4Connection: (NGImap4Connection *) connection
                          forKey: (NSString *) key
{
  if (connection)
    [imap4Connections setObject: connection forKey: key];
  else
    [imap4Connections removeObjectForKey: key];
}

- (NGImap4Connection *) imap4ConnectionForKey: (NSString *) key
{
  return [imap4Connections objectForKey: key];
}

//
// For non-blocking cache method, see memcached_behavior_set and MEMCACHED_BEHAVIOR_NO_BLOCK
// memcached is thread-safe so no need to lock here.
//
- (void) setValue: (NSString *) value
           forKey: (NSString *) key
           expire: (float) expiration
{
  NSData *keyData, *valueData;
  memcached_return error;

  // [self logWithFormat: @"setValue: '%@' forKey: '%@'", value, key];
  if (handle)
    {
      keyData = [key dataUsingEncoding: NSUTF8StringEncoding];
      valueData = [value dataUsingEncoding: NSUTF8StringEncoding];
      error = memcached_set(handle,
			    [keyData bytes], [keyData length],
			    [valueData bytes], [valueData length],
			    expiration, 0);
      if (error != MEMCACHED_SUCCESS)
        [self logWithFormat:
                @"an error occurred when caching value for key '%@':"
              @" \"%s\"", key, memcached_strerror(handle, error)];
      //else
      //[self logWithFormat: @"memcached: cached values (%s) with subtype %@
      //for user %@", value, theType, theLogin];
    }
   else
     [self errorWithFormat: (@"attempting to cache value for key '%@' while"
                             " no handle exists"), key];
}

- (void) setValue: (NSString *) value
           forKey: (NSString *) key
{
  [self setValue: value forKey: key
          expire: cleanupInterval];
}

- (NSString *) valueForKey: (NSString *) key
{
  NSString *valueString;
  NSData *keyData;
  char *value;
  size_t vlen;
  memcached_return rc;
  unsigned int flags;
  
  if (handle)
    {
      keyData = [key dataUsingEncoding: NSUTF8StringEncoding];
      value = memcached_get (handle, [keyData bytes], [keyData length],
                             &vlen, &flags, &rc);
      if (rc == MEMCACHED_SUCCESS && value)
        {
          valueString
            = [[NSString alloc] initWithBytesNoCopy: value
                                             length: vlen
                                           encoding: NSUTF8StringEncoding
                                       freeWhenDone: YES];
          [valueString autorelease];
        }
      else
        valueString = nil;
    }
  else
    {
      valueString = nil;
      [self errorWithFormat: @"attempting to retrieved cached value for key"
            @" '%@' while no handle exists", key];
    }

  // [self logWithFormat: @"valueForKey: '%@' -> '%@'", key, valueString];

  return valueString;
}

- (void) removeValueForKey: (NSString *) key
{
  NSData *keyData;
  memcached_return rc;

  [localCache removeObjectForKey: key];

  if (handle)
    {
      keyData = [key dataUsingEncoding: NSUTF8StringEncoding];
      rc = memcached_delete (handle, [keyData bytes], [keyData length],
                             0);
      if (rc != MEMCACHED_SUCCESS)
        [self errorWithFormat: (@"failure deleting cached value for key"
                                @" '%@'"),
              key];
    }
  else
    [self errorWithFormat: (@"attempting to delete cached value for key"
                            @" '%@' while no handle exists"),
          key];
}


//
// This method is used to cache a specific value (represented as a
// string, usually JSON stuff) using the specified key and type-suffix
//
// The final key will aways be of the form: <key>+<type suffix>
//
// This method will insert the value in the localCache and also
// in memcached.
//
- (void) _cacheValues: (NSString *) theAttributes
	       ofType: (NSString *) theType
	       forKey: (NSString *) theKey
{
  NSString *keyName;

  keyName = [NSString stringWithFormat: @"%@+%@", theKey, theType];

  if (theAttributes)
    {
      [self setValue: theAttributes forKey: keyName];
      [localCache setObject: theAttributes forKey: keyName];
    }
}

- (NSString *) _valuesOfType: (NSString *) theType
                      forKey: (NSString *) theKey
{
  NSString *valueString, *keyName;

  valueString = nil;

  keyName = [NSString stringWithFormat: @"%@+%@", theKey, theType];
  valueString = [localCache objectForKey: keyName];
  if (!valueString)
    {
      valueString = [self valueForKey: keyName];
      if (valueString)
        [localCache setObject: valueString forKey: keyName];
    }

  return valueString;
}

- (void) setUserAttributes: (NSString *) theAttributes
                  forLogin: (NSString *) login
{
  [self _cacheValues: theAttributes ofType: @"attributes"
	forKey: login];
}

- (NSString *) userAttributesForLogin: (NSString *) theLogin
{
  return [self _valuesOfType: @"attributes" forKey: theLogin];
}

- (void) setUserDefaults: (NSString *) theAttributes
                forLogin: (NSString *) login
{
  [self _cacheValues: theAttributes ofType: @"defaults"
	forKey: login];
}

- (NSString *) userDefaultsForLogin: (NSString *) theLogin
{
  return [self _valuesOfType: @"defaults" forKey: theLogin];
}

- (void) setUserSettings: (NSString *) theAttributes
                forLogin: (NSString *) login
{
  [self _cacheValues: theAttributes ofType: @"settings"
	forKey: login];
}

- (NSString *) userSettingsForLogin: (NSString *) theLogin
{
  return [self _valuesOfType: @"settings" forKey: theLogin];
}

//
// CAS session support
//
- (NSString *) CASTicketFromIdentifier: (NSString *) identifier
{
  return [self valueForKey: [NSString stringWithFormat: @"cas-id:%@",
                                      identifier]];
}

- (NSString *) CASSessionWithTicket: (NSString *) ticket
{
  return [self valueForKey: [NSString stringWithFormat: @"cas-ticket:%@",
                                        ticket]];
}

- (void) setCASSession: (NSString *) casSession
            withTicket: (NSString *) ticket
         forIdentifier: (NSString *) identifier
{
  [self setValue: ticket
          forKey: [NSString stringWithFormat: @"cas-id:%@", identifier]];
  [self setValue: casSession
          forKey: [NSString stringWithFormat: @"cas-ticket:%@", ticket]];
}

- (NSString *) CASPGTIdFromPGTIOU: (NSString *) pgtIou
{
  NSString *casPgtId, *key;

  key = [NSString stringWithFormat: @"cas-pgtiou:%@", pgtIou];
  casPgtId = [self valueForKey: key];
  /* we directly remove the value as it can only be used once anyway */
  if (casPgtId)
    [self removeValueForKey: key];

  return casPgtId;
}

- (void) setCASPGTId: (NSString *) pgtId
           forPGTIOU: (NSString *) pgtIou
{
  [self setValue: pgtId
          forKey: [NSString stringWithFormat: @"cas-pgtiou:%@", pgtIou]];
}

//
// ACL caching code
//
- (void) setACLs: (NSDictionary *) theACLs
	 forPath: (NSString *) thePath
{
  if (theACLs)
    [self _cacheValues: [theACLs jsonRepresentation]
	  ofType: @"acl"
	  forKey: thePath];
  else
    [self removeValueForKey: [NSString stringWithFormat: @"%@+acl", thePath]];
}

- (NSMutableDictionary *) aclsForPath: (NSString *) thePath
{
  NSString *s;
  
  s = [self _valuesOfType: @"acl"  forKey: thePath];

  if (s)
    return [s objectFromJSONString];

  return nil;
}



@end