/* ownCloud Android client application
 *   Copyright (C) 2012-2014 ownCloud Inc.
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License version 2,
 *   as published by the Free Software Foundation.
 *
 *   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.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package com.owncloud.android.files;

import java.io.File;
import java.util.HashMap;
import java.util.Map;

import android.accounts.Account;
import android.content.Context;
import android.content.Intent;
import android.os.FileObserver;

import com.owncloud.android.datamodel.FileDataStorageManager;
import com.owncloud.android.datamodel.OCFile;
import com.owncloud.android.lib.common.operations.RemoteOperationResult;
import com.owncloud.android.lib.common.operations.RemoteOperationResult.ResultCode;
import com.owncloud.android.operations.SynchronizeFileOperation;
import com.owncloud.android.ui.activity.ConflictsResolveActivity;
import com.owncloud.android.utils.Log_OC;

/**
 * Observer watching a folder to request the synchronization of kept-in-sync files
 * inside it.
 * 
 * Takes into account two possible update cases:
 *  - an editor directly updates the file;
 *  - an editor works on a temporal file, and later replaces the kept-in-sync file with the
 *  temporal.
 *  
 *  The second case requires to monitor the folder parent of the files, since a direct 
 *  {@link FileObserver} on it will not receive more events after the file is deleted to
 *  be replaced later.
 * 
 * @author David A. Velasco
 */
public class OwnCloudFolderObserver extends FileObserver {

    private static int UPDATE_MASK = (
            FileObserver.ATTRIB | FileObserver.MODIFY | 
            FileObserver.MOVED_TO | FileObserver.CLOSE_WRITE
    ); 
    /* 
    private static int ALL_EVENTS_EVEN_THOSE_NOT_DOCUMENTED = 0x7fffffff;   // NEVER use 0xffffffff
    */

    private static String TAG = OwnCloudFolderObserver.class.getSimpleName();

    private String mPath;
    private Account mAccount;
    private Context mContext;
    private Map<String, Boolean> mObservedChildren;

    public OwnCloudFolderObserver(String path, Account account, Context context) {
        super(path, UPDATE_MASK);
        
        if (path == null)
            throw new IllegalArgumentException("NULL path argument received");
        if (account == null)
            throw new IllegalArgumentException("NULL account argument received");
        if (context == null)
            throw new IllegalArgumentException("NULL context argument received");
        
        mPath = path;
        mAccount = account;
        mContext = context;
        mObservedChildren = new HashMap<String, Boolean>();
    }

    
    @Override
    public void onEvent(int event, String path) {
        Log_OC.d(TAG, "Got event " + event + " on FOLDER " + mPath + " about "
                + ((path != null) ? path : ""));
        
        boolean shouldSynchronize = false;
        synchronized(mObservedChildren) {
            if (path != null && path.length() > 0 && mObservedChildren.containsKey(path)) {
                
                if ((event & FileObserver.MODIFY) != 0) {
                    if (!mObservedChildren.get(path)) {
                        mObservedChildren.put(path, Boolean.valueOf(true));
                    }
                }
        
                /*
                if ((event & FileObserver.ATTRIB) != 0) {
                    if (mObservedChildren.get(path) != true) {
                        mObservedChildren.put(path, Boolean.valueOf(true));
                    }
                }
                */
                
                /*
                if ((event & FileObserver.MOVED_TO) != 0) {
                    if (mObservedChildren.get(path) != true) {
                        mObservedChildren.put(path, Boolean.valueOf(true));
                    }
                }
                */
                
                if ((event & FileObserver.CLOSE_WRITE) != 0) {
                    mObservedChildren.put(path, Boolean.valueOf(false));
                    shouldSynchronize = true;
                }
            }
        }
        if (shouldSynchronize) {
            startSyncOperation(path);
        }
        
        if ((event & OwnCloudFileObserver.IN_IGNORE) != 0 &&
                (path == null || path.length() == 0)) {
            Log_OC.d(TAG, "Stopping the observance on " + mPath);
        }
        
    }
    

    public void startWatching(String localPath) {
        synchronized (mObservedChildren) {
            if (!mObservedChildren.containsKey(localPath)) {
                mObservedChildren.put(localPath, Boolean.valueOf(false));
            }
        }
        
        if (new File(mPath).exists()) {
            startWatching();
            Log_OC.d(TAG, "Started watching parent folder " + mPath + "/");
        }
        // else - the observance can't be started on a file not existing;
    }

    public void stopWatching(String localPath) {
        synchronized (mObservedChildren) {
            mObservedChildren.remove(localPath);
            if (mObservedChildren.isEmpty()) {
                stopWatching();
                Log_OC.d(TAG, "Stopped watching parent folder " + mPath + "/");
            }
        }
    }

    public boolean isEmpty() {
        synchronized (mObservedChildren) {
            return mObservedChildren.isEmpty();
        }
    }
    
    
    private void startSyncOperation(String childName) {
        FileDataStorageManager storageManager = 
                new FileDataStorageManager(mAccount, mContext.getContentResolver());
        // a fresh object is needed; many things could have occurred to the file
        // since it was registered to observe again, assuming that local files
        // are linked to a remote file AT MOST, SOMETHING TO BE DONE;
        OCFile file = storageManager.getFileByLocalPath(mPath + File.separator + childName);
        SynchronizeFileOperation sfo = 
                new SynchronizeFileOperation(file, null, mAccount, true, mContext);
        RemoteOperationResult result = sfo.execute(storageManager, mContext);
        if (result.getCode() == ResultCode.SYNC_CONFLICT) {
            // ISSUE 5: if the user is not running the app (this is a service!),
            // this can be very intrusive; a notification should be preferred
            Intent i = new Intent(mContext, ConflictsResolveActivity.class);
            i.setFlags(i.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
            i.putExtra(ConflictsResolveActivity.EXTRA_FILE, file);
            i.putExtra(ConflictsResolveActivity.EXTRA_ACCOUNT, mAccount);
            mContext.startActivity(i);
        }
        // TODO save other errors in some point where the user can inspect them later;
        // or maybe just toast them;
        // or nothing, very strange fails
    }

}