/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is nsCacheEntryDescriptor.h, released February 22, 2001.
 * 
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 2001 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s): 
 *    Gordon Sheridan, 22-February-2001
 */


#ifndef _nsCacheEntryDescriptor_h_
#define _nsCacheEntryDescriptor_h_

#include "nsICacheEntryDescriptor.h"
#include "nsCacheEntry.h"
#include "nsIInputStream.h"
#include "nsIOutputStream.h"

/******************************************************************************
* nsCacheEntryDescriptor
*******************************************************************************/
class nsCacheEntryDescriptor :
    public PRCList,
    public nsICacheEntryDescriptor
{
public:
    NS_DECL_ISUPPORTS
    NS_DECL_NSICACHEENTRYDESCRIPTOR
    NS_DECL_NSICACHEENTRYINFO
    
    nsCacheEntryDescriptor(nsCacheEntry * entry, nsCacheAccessMode  mode);
    virtual ~nsCacheEntryDescriptor();
    
    static nsresult Create(nsCacheEntry * entry, nsCacheAccessMode  accessGranted,
                           nsICacheEntryDescriptor ** result);


    /**
     * utility method to attempt changing data size of associated entry
     */
    nsresult  RequestDataSizeChange(PRInt32 deltaSize);
    
    /**
     * methods callbacks for nsCacheService
     */
    nsCacheEntry * CacheEntry(void)      { return mCacheEntry; }
    void           ClearCacheEntry(void) { mCacheEntry = nsnull; }

private:


     /*************************************************************************
      * input stream wrapper class -
      *
      * The input stream wrapper references the descriptor, but the descriptor
      * doesn't need any references to the stream wrapper.
      *************************************************************************/
     class nsInputStreamWrapper : public nsIInputStream {
     private:
         nsCacheEntryDescriptor    * mDescriptor;
         nsCOMPtr<nsIInputStream>    mInput;
         PRUint32                    mStartOffset;
         PRBool                      mInitialized;
     public:
         NS_DECL_ISUPPORTS
         NS_DECL_NSIINPUTSTREAM

         nsInputStreamWrapper(nsCacheEntryDescriptor * desc, PRUint32 off)
             : mDescriptor(desc)
             , mStartOffset(off)
             , mInitialized(PR_FALSE)
         {
             NS_ADDREF(mDescriptor);
         }
         virtual ~nsInputStreamWrapper()
         {
             NS_RELEASE(mDescriptor);
         }

     private:
         nsresult LazyInit();
         nsresult EnsureInit() { return mInitialized ? NS_OK : LazyInit(); }
     };
     friend class nsInputStreamWrapper;


     /*************************************************************************
      * output stream wrapper class -
      *
      * The output stream wrapper references the descriptor, but the descriptor
      * doesn't need any references to the stream wrapper.
      *************************************************************************/
     class nsOutputStreamWrapper : public nsIOutputStream {
     private:
         nsCacheEntryDescriptor *    mDescriptor;
         nsCOMPtr<nsIOutputStream>   mOutput;
         PRUint32                    mStartOffset;
         PRBool                      mInitialized;
     public:
         NS_DECL_ISUPPORTS
         NS_DECL_NSIOUTPUTSTREAM

         nsOutputStreamWrapper(nsCacheEntryDescriptor * desc, PRUint32 off)
             : mDescriptor(desc)
             , mStartOffset(off)
             , mInitialized(PR_FALSE)
         {
             NS_ADDREF(mDescriptor); // owning ref
         }
         virtual ~nsOutputStreamWrapper()
         { 
             // XXX _HACK_ the storage stream needs this!
             Close();
             NS_RELEASE(mDescriptor);
         }

     private:
         nsresult LazyInit();
         nsresult EnsureInit() { return mInitialized ? NS_OK : LazyInit(); }
         nsresult OnWrite(PRUint32 count);
     };
     friend class nsOutputStreamWrapper;

 private:
     /**
      * nsCacheEntryDescriptor data members
      */
     nsCacheEntry          * mCacheEntry; // we are a child of the entry
     nsCacheAccessMode       mAccessGranted;
};


#endif // _nsCacheEntryDescriptor_h_