/* ownCloud Android client application
 *   Copyright (C) 2012 Bartek Przybylski
 *   Copyright (C) 2012-2015 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.services;

import java.io.File;
import java.io.IOException;
import java.util.AbstractList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Vector;

import com.owncloud.android.R;
import com.owncloud.android.authentication.AuthenticatorActivity;
import com.owncloud.android.datamodel.FileDataStorageManager;
import com.owncloud.android.datamodel.OCFile;

import com.owncloud.android.lib.common.network.OnDatatransferProgressListener;
import com.owncloud.android.lib.common.OwnCloudAccount;
import com.owncloud.android.lib.common.OwnCloudClient;
import com.owncloud.android.lib.common.OwnCloudClientManagerFactory;
import com.owncloud.android.notifications.NotificationBuilderWithProgressBar;
import com.owncloud.android.notifications.NotificationDelayer;
import com.owncloud.android.lib.common.operations.RemoteOperationResult;
import com.owncloud.android.lib.common.operations.RemoteOperationResult.ResultCode;
import com.owncloud.android.lib.common.utils.Log_OC;
import com.owncloud.android.lib.resources.files.FileUtils;
import com.owncloud.android.operations.DownloadFileOperation;
import com.owncloud.android.ui.activity.FileActivity;
import com.owncloud.android.ui.activity.FileDisplayActivity;
import com.owncloud.android.ui.preview.PreviewImageActivity;
import com.owncloud.android.ui.preview.PreviewImageFragment;
import com.owncloud.android.utils.ErrorMessageAdapter;

import android.accounts.Account;
import android.accounts.AccountsException;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.Process;
import android.support.v4.app.NotificationCompat;
import android.util.Pair;

public class FileDownloader extends Service implements OnDatatransferProgressListener {
    
    public static final String EXTRA_ACCOUNT = "ACCOUNT";
    public static final String EXTRA_FILE = "FILE";

    private static final String DOWNLOAD_ADDED_MESSAGE = "DOWNLOAD_ADDED";
    private static final String DOWNLOAD_FINISH_MESSAGE = "DOWNLOAD_FINISH";
    public static final String EXTRA_DOWNLOAD_RESULT = "RESULT";    
    public static final String EXTRA_FILE_PATH = "FILE_PATH";
    public static final String EXTRA_REMOTE_PATH = "REMOTE_PATH";
    public static final String EXTRA_LINKED_TO_PATH = "LINKED_TO";
    public static final String ACCOUNT_NAME = "ACCOUNT_NAME";
    
    private static final String TAG = "FileDownloader";

    private Looper mServiceLooper;
    private ServiceHandler mServiceHandler;
    private IBinder mBinder;
    private OwnCloudClient mDownloadClient = null;
    private Account mCurrentAccount = null;
    private FileDataStorageManager mStorageManager;
    
    private IndexedForest<DownloadFileOperation> mPendingDownloads = new IndexedForest<DownloadFileOperation>();

    private DownloadFileOperation mCurrentDownload = null;
    
    private NotificationManager mNotificationManager;
    private NotificationCompat.Builder mNotificationBuilder;
    private int mLastPercent;

    
    public static String getDownloadAddedMessage() {
        return FileDownloader.class.getName() + DOWNLOAD_ADDED_MESSAGE;
    }
    
    public static String getDownloadFinishMessage() {
        return FileDownloader.class.getName() + DOWNLOAD_FINISH_MESSAGE;
    }
    
    /**
     * Service initialization
     */
    @Override
    public void onCreate() {
        super.onCreate();
        mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        HandlerThread thread = new HandlerThread("FileDownloaderThread",
                Process.THREAD_PRIORITY_BACKGROUND);
        thread.start();
        mServiceLooper = thread.getLooper();
        mServiceHandler = new ServiceHandler(mServiceLooper, this);
        mBinder = new FileDownloaderBinder();
    }

    /**
     * Entry point to add one or several files to the queue of downloads.
     *
     * New downloads are added calling to startService(), resulting in a call to this method.
     * This ensures the service will keep on working although the caller activity goes away.
     */
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (    !intent.hasExtra(EXTRA_ACCOUNT) ||
                !intent.hasExtra(EXTRA_FILE)
           ) {
            Log_OC.e(TAG, "Not enough information provided in intent");
            return START_NOT_STICKY;
        } else {
            final Account account = intent.getParcelableExtra(EXTRA_ACCOUNT);
            final OCFile file = intent.getParcelableExtra(EXTRA_FILE);

            /*Log_OC.v(
                    "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                    "Received request to download file"
            );*/

                AbstractList<String> requestedDownloads = new Vector<String>();
                try {
                    DownloadFileOperation newDownload = new DownloadFileOperation(account, file);
                    newDownload.addDatatransferProgressListener(this);
                    newDownload.addDatatransferProgressListener((FileDownloaderBinder) mBinder);
                    Pair<String, String> putResult = mPendingDownloads.putIfAbsent(
                        account, file.getRemotePath(), newDownload
                    );
                    String downloadKey = putResult.first;
                    requestedDownloads.add(downloadKey);
                    /*Log_OC.v(
                        "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                        "Download on " + file.getRemotePath() + " added to queue"
                    );*/

                    // Store file on db with state 'downloading'
                    /*
                    TODO - check if helps with UI responsiveness, letting only folders use FileDownloaderBinder to check
                    FileDataStorageManager storageManager = new FileDataStorageManager(account, getContentResolver());
                    file.setDownloading(true);
                    storageManager.saveFile(file);
                    */

                    sendBroadcastNewDownload(newDownload, putResult.second);

                } catch (IllegalArgumentException e) {
                    Log_OC.e(TAG, "Not enough information provided in intent: " + e.getMessage());
                    return START_NOT_STICKY;
                }

                if (requestedDownloads.size() > 0) {
                    Message msg = mServiceHandler.obtainMessage();
                    msg.arg1 = startId;
                    msg.obj = requestedDownloads;
                    mServiceHandler.sendMessage(msg);
                }
            //}
        }

        return START_NOT_STICKY;
    }


    /**
     * Provides a binder object that clients can use to perform operations on the queue of downloads,
     * excepting the addition of new files.
     *
     * Implemented to perform cancellation, pause and resume of existing downloads.
     */
    @Override
    public IBinder onBind(Intent arg0) {
        return mBinder;
    }


    /**
     * Called when ALL the bound clients were onbound.
     */
    @Override
    public boolean onUnbind(Intent intent) {
        ((FileDownloaderBinder)mBinder).clearListeners();
        return false;   // not accepting rebinding (default behaviour)
    }


    /**
     *  Binder to let client components to perform operations on the queue of downloads.
     *
     *  It provides by itself the available operations.
     */
    public class FileDownloaderBinder extends Binder implements OnDatatransferProgressListener {
        
        /** 
         * Map of listeners that will be reported about progress of downloads from a {@link FileDownloaderBinder}
         * instance.
         */
        private Map<Long, OnDatatransferProgressListener> mBoundListeners =
                new HashMap<Long, OnDatatransferProgressListener>();


        /**
         * Cancels a pending or current download of a remote file.
         *
         * @param account       ownCloud account where the remote file is stored.
         * @param file          A file in the queue of pending downloads
         */
        public void cancel(Account account, OCFile file) {
            /*Log_OC.v(
                    "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                    "Received request to cancel download of " + file.getRemotePath()
            );
            Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                    "Removing download of " + file.getRemotePath());*/
            Pair<DownloadFileOperation, String> removeResult = mPendingDownloads.remove(account, file.getRemotePath());
            DownloadFileOperation download = removeResult.first;
            if (download != null) {
                /*Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                        "Canceling returned download of " + file.getRemotePath());*/
                download.cancel();
            } else {
                if (mCurrentDownload != null && mCurrentAccount != null &&
                        mCurrentDownload.getRemotePath().startsWith(file.getRemotePath()) &&
                        account.name.equals(mCurrentAccount.name)) {
                    /*Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                            "Canceling current sync as descendant: " + mCurrentDownload.getRemotePath());*/
                    mCurrentDownload.cancel();
                }
            }
        }
        
        
        public void clearListeners() {
            mBoundListeners.clear();
        }


        /**
         * Returns True when the file described by 'file' in the ownCloud account 'account' is downloading or
         * waiting to download.
         * 
         * If 'file' is a directory, returns 'true' if any of its descendant files is downloading or
         * waiting to download.
         * 
         * @param account       ownCloud account where the remote file is stored.
         * @param file          A file that could be in the queue of downloads.
         */
        public boolean isDownloading(Account account, OCFile file) {
            if (account == null || file == null) return false;
            return (mPendingDownloads.contains(account, file.getRemotePath()));
        }

        
        /**
         * Adds a listener interested in the progress of the download for a concrete file.
         * 
         * @param listener      Object to notify about progress of transfer.    
         * @param account       ownCloud account holding the file of interest.
         * @param file          {@link OCFile} of interest for listener.
         */
        public void addDatatransferProgressListener (
                OnDatatransferProgressListener listener, Account account, OCFile file
        ) {
            if (account == null || file == null || listener == null) return;
            //String targetKey = buildKey(account, file.getRemotePath());
            mBoundListeners.put(file.getFileId(), listener);
        }
        
        
        /**
         * Removes a listener interested in the progress of the download for a concrete file.
         * 
         * @param listener      Object to notify about progress of transfer.    
         * @param account       ownCloud account holding the file of interest.
         * @param file          {@link OCFile} of interest for listener.
         */
        public void removeDatatransferProgressListener (
                OnDatatransferProgressListener listener, Account account, OCFile file
        ) {
            if (account == null || file == null || listener == null) return;
            //String targetKey = buildKey(account, file.getRemotePath());
            Long fileId = file.getFileId();
            if (mBoundListeners.get(fileId) == listener) {
                mBoundListeners.remove(fileId);
            }
        }

        @Override
        public void onTransferProgress(long progressRate, long totalTransferredSoFar, long totalToTransfer,
                String fileName) {
            //String key = buildKey(mCurrentDownload.getAccount(), mCurrentDownload.getFile().getRemotePath());
            OnDatatransferProgressListener boundListener = mBoundListeners.get(mCurrentDownload.getFile().getFileId());
            if (boundListener != null) {
                boundListener.onTransferProgress(progressRate, totalTransferredSoFar, totalToTransfer, fileName);
            }
        }
        
    }
    
    
    /** 
     * Download worker. Performs the pending downloads in the order they were requested. 
     * 
     * Created with the Looper of a new thread, started in {@link FileUploader#onCreate()}. 
     */
    private static class ServiceHandler extends Handler {
        // don't make it a final class, and don't remove the static ; lint will warn about a possible memory leak
        FileDownloader mService;
        public ServiceHandler(Looper looper, FileDownloader service) {
            super(looper);
            if (service == null)
                throw new IllegalArgumentException("Received invalid NULL in parameter 'service'");
            mService = service;
        }

        @Override
        public void handleMessage(Message msg) {
            @SuppressWarnings("unchecked")
            AbstractList<String> requestedDownloads = (AbstractList<String>) msg.obj;
            if (msg.obj != null) {
                Iterator<String> it = requestedDownloads.iterator();
                while (it.hasNext()) {
                    String next = it.next();
                    /*Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                            "Handling download file " + next);*/
                    mService.downloadFile(next);
                }
            }
            mService.stopSelf(msg.arg1);
        }
    }
    

    /**
     * Core download method: requests a file to download and stores it.
     * 
     * @param downloadKey   Key to access the download to perform, contained in mPendingDownloads 
     */
    private void downloadFile(String downloadKey) {

        /*Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                "Getting download of " + downloadKey);*/
        mCurrentDownload = mPendingDownloads.get(downloadKey);

        if (mCurrentDownload != null) {
            
            notifyDownloadStart(mCurrentDownload);

            RemoteOperationResult downloadResult = null;
            try {
                /// prepare client object to send the request to the ownCloud server
                if (mCurrentAccount == null || !mCurrentAccount.equals(mCurrentDownload.getAccount())) {
                    mCurrentAccount = mCurrentDownload.getAccount();
                    mStorageManager = new FileDataStorageManager(
                            mCurrentAccount,
                            getContentResolver()
                    );
                }   // else, reuse storage manager from previous operation

                // always get client from client manager, to get fresh credentials in case of update
                OwnCloudAccount ocAccount = new OwnCloudAccount(mCurrentAccount, this);
                mDownloadClient = OwnCloudClientManagerFactory.getDefaultSingleton().
                        getClientFor(ocAccount, this);


                /// perform the download
                /*Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                        "Executing download of " + mCurrentDownload.getRemotePath());*/
                downloadResult = mCurrentDownload.execute(mDownloadClient);
                if (downloadResult.isSuccess()) {
                    saveDownloadedFile();
                }
            
            } catch (AccountsException e) {
                Log_OC.e(TAG, "Error while trying to get authorization for " + mCurrentAccount.name, e);
                downloadResult = new RemoteOperationResult(e);
            } catch (IOException e) {
                Log_OC.e(TAG, "Error while trying to get authorization for " + mCurrentAccount.name, e);
                downloadResult = new RemoteOperationResult(e);
                
            } finally {
                /*Log_OC.v(   "NOW " + TAG + ", thread " + Thread.currentThread().getName(),
                        "Removing payload " + mCurrentDownload.getRemotePath());*/

                Pair<DownloadFileOperation, String> removeResult =
                        mPendingDownloads.removePayload(mCurrentAccount, mCurrentDownload.getRemotePath());

                /// notify result
                notifyDownloadResult(mCurrentDownload, downloadResult);

                sendBroadcastDownloadFinished(mCurrentDownload, downloadResult, removeResult.second);
            }

        }
    }


    /**
     * Updates the OC File after a successful download.
     */
    private void saveDownloadedFile() {
        OCFile file = mStorageManager.getFileById(mCurrentDownload.getFile().getFileId());
        long syncDate = System.currentTimeMillis();
        file.setLastSyncDateForProperties(syncDate);
        file.setLastSyncDateForData(syncDate);
        file.setNeedsUpdateThumbnail(true);
        file.setModificationTimestamp(mCurrentDownload.getModificationTimestamp());
        file.setModificationTimestampAtLastSyncForData(mCurrentDownload.getModificationTimestamp());
        // file.setEtag(mCurrentDownload.getEtag());    // TODO Etag, where available
        file.setMimetype(mCurrentDownload.getMimeType());
        file.setStoragePath(mCurrentDownload.getSavePath());
        file.setFileLength((new File(mCurrentDownload.getSavePath()).length()));
        file.setRemoteId(mCurrentDownload.getFile().getRemoteId());
        mStorageManager.saveFile(file);
        mStorageManager.triggerMediaScan(file.getStoragePath());
    }

    /**
     * Update the OC File after a unsuccessful download
     */
    private void updateUnsuccessfulDownloadedFile() {
        OCFile file = mStorageManager.getFileById(mCurrentDownload.getFile().getFileId());
        file.setDownloading(false);
        mStorageManager.saveFile(file);
    }


    /**
     * Creates a status notification to show the download progress
     * 
     * @param download  Download operation starting.
     */
    private void notifyDownloadStart(DownloadFileOperation download) {
        /// create status notification with a progress bar
        mLastPercent = 0;
        mNotificationBuilder = 
                NotificationBuilderWithProgressBar.newNotificationBuilderWithProgressBar(this);
        mNotificationBuilder
                .setSmallIcon(R.drawable.notification_icon)
                .setTicker(getString(R.string.downloader_download_in_progress_ticker))
                .setContentTitle(getString(R.string.downloader_download_in_progress_ticker))
                .setOngoing(true)
                .setProgress(100, 0, download.getSize() < 0)
                .setContentText(
                        String.format(getString(R.string.downloader_download_in_progress_content), 0,
                                new File(download.getSavePath()).getName())
                );
                
        /// includes a pending intent in the notification showing the details view of the file
        Intent showDetailsIntent = null;
        if (PreviewImageFragment.canBePreviewed(download.getFile())) {
            showDetailsIntent = new Intent(this, PreviewImageActivity.class);
        } else {
            showDetailsIntent = new Intent(this, FileDisplayActivity.class);
        }
        showDetailsIntent.putExtra(FileActivity.EXTRA_FILE, download.getFile());
        showDetailsIntent.putExtra(FileActivity.EXTRA_ACCOUNT, download.getAccount());
        showDetailsIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        
        mNotificationBuilder.setContentIntent(PendingIntent.getActivity(
            this, (int) System.currentTimeMillis(), showDetailsIntent, 0
        ));

        mNotificationManager.notify(R.string.downloader_download_in_progress_ticker, mNotificationBuilder.build());
    }

    
    /**
     * Callback method to update the progress bar in the status notification.
     */
    @Override
    public void onTransferProgress(long progressRate, long totalTransferredSoFar, long totalToTransfer, String filePath)
    {
        int percent = (int)(100.0*((double)totalTransferredSoFar)/((double)totalToTransfer));
        if (percent != mLastPercent) {
            mNotificationBuilder.setProgress(100, percent, totalToTransfer < 0);
            String fileName = filePath.substring(filePath.lastIndexOf(FileUtils.PATH_SEPARATOR) + 1);
            String text = String.format(getString(R.string.downloader_download_in_progress_content), percent, fileName);
            mNotificationBuilder.setContentText(text);
            mNotificationManager.notify(R.string.downloader_download_in_progress_ticker, mNotificationBuilder.build());
        }
        mLastPercent = percent;
    }
    
    
    /**
     * Updates the status notification with the result of a download operation.
     * 
     * @param downloadResult    Result of the download operation.
     * @param download          Finished download operation
     */
    private void notifyDownloadResult(DownloadFileOperation download, RemoteOperationResult downloadResult) {
        mNotificationManager.cancel(R.string.downloader_download_in_progress_ticker);
        if (!downloadResult.isCancelled()) {
            int tickerId = (downloadResult.isSuccess()) ? R.string.downloader_download_succeeded_ticker : 
                R.string.downloader_download_failed_ticker;
            
            boolean needsToUpdateCredentials = (
                    downloadResult.getCode() == ResultCode.UNAUTHORIZED ||
                    downloadResult.isIdPRedirection()
            );
            tickerId = (needsToUpdateCredentials) ? 
                    R.string.downloader_download_failed_credentials_error : tickerId;
            
            mNotificationBuilder
            .setTicker(getString(tickerId))
            .setContentTitle(getString(tickerId))
            .setAutoCancel(true)
            .setOngoing(false)
            .setProgress(0, 0, false);
            
            if (needsToUpdateCredentials) {
                
                // let the user update credentials with one click
                Intent updateAccountCredentials = new Intent(this, AuthenticatorActivity.class);
                updateAccountCredentials.putExtra(AuthenticatorActivity.EXTRA_ACCOUNT, download.getAccount());
                updateAccountCredentials.putExtra(
                        AuthenticatorActivity.EXTRA_ACTION, AuthenticatorActivity.ACTION_UPDATE_EXPIRED_TOKEN
                );
                updateAccountCredentials.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                updateAccountCredentials.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
                updateAccountCredentials.addFlags(Intent.FLAG_FROM_BACKGROUND);
                mNotificationBuilder
                    .setContentIntent(PendingIntent.getActivity(
                        this, (int) System.currentTimeMillis(), updateAccountCredentials, PendingIntent.FLAG_ONE_SHOT));
                
            } else {
                // TODO put something smart in showDetailsIntent
                Intent   showDetailsIntent = new Intent();
                mNotificationBuilder
                    .setContentIntent(PendingIntent.getActivity(
                        this, (int) System.currentTimeMillis(), showDetailsIntent, 0));
            }
            
            mNotificationBuilder.setContentText(
                    ErrorMessageAdapter.getErrorCauseMessage(downloadResult, download, getResources())
            );
            mNotificationManager.notify(tickerId, mNotificationBuilder.build());
            
            // Remove success notification
            if (downloadResult.isSuccess()) {   
                // Sleep 2 seconds, so show the notification before remove it
                NotificationDelayer.cancelWithDelay(
                        mNotificationManager, 
                        R.string.downloader_download_succeeded_ticker, 
                        2000);
            }
                
        }
    }
    
    
    /**
     * Sends a broadcast when a download finishes in order to the interested activities can update their view
     * 
     * @param download                  Finished download operation
     * @param downloadResult            Result of the download operation
     * @param unlinkedFromRemotePath    Path in the downloads tree where the download was unlinked from
     */
    private void sendBroadcastDownloadFinished(
            DownloadFileOperation download,
            RemoteOperationResult downloadResult,
            String unlinkedFromRemotePath) {
        Intent end = new Intent(getDownloadFinishMessage());
        end.putExtra(EXTRA_DOWNLOAD_RESULT, downloadResult.isSuccess());
        end.putExtra(ACCOUNT_NAME, download.getAccount().name);
        end.putExtra(EXTRA_REMOTE_PATH, download.getRemotePath());
        end.putExtra(EXTRA_FILE_PATH, download.getSavePath());
        if (unlinkedFromRemotePath != null) {
            end.putExtra(EXTRA_LINKED_TO_PATH, unlinkedFromRemotePath);
        }
        sendStickyBroadcast(end);
    }
    
    
    /**
     * Sends a broadcast when a new download is added to the queue.
     * 
     * @param download              Added download operation
     * @param linkedToRemotePath    Path in the downloads tree where the download was linked to
     */
    private void sendBroadcastNewDownload(DownloadFileOperation download, String linkedToRemotePath) {
        Intent added = new Intent(getDownloadAddedMessage());
        added.putExtra(ACCOUNT_NAME, download.getAccount().name);
        added.putExtra(EXTRA_REMOTE_PATH, download.getRemotePath());
        added.putExtra(EXTRA_FILE_PATH, download.getSavePath());
        added.putExtra(EXTRA_LINKED_TO_PATH, linkedToRemotePath);
        sendStickyBroadcast(added);
    }

}