/*
 * Created on Mar 9, 2012
 * Created by Paul Gardner
 *
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program 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
 * of the License, or (at your option) any later version.
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */


package com.biglybt.plugin.magnet;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.RandomAccessFile;
import java.net.InetSocketAddress;
import java.net.URL;
import java.util.*;

import com.biglybt.core.category.Category;
import com.biglybt.core.download.DownloadManagerState;
import com.biglybt.core.internat.MessageText;
import com.biglybt.core.peer.PEPeerManager;
import com.biglybt.core.torrent.*;
import com.biglybt.core.util.*;
import com.biglybt.pif.PluginInterface;
import com.biglybt.pif.disk.DiskManagerChannel;
import com.biglybt.pif.disk.DiskManagerEvent;
import com.biglybt.pif.disk.DiskManagerListener;
import com.biglybt.pif.disk.DiskManagerRequest;
import com.biglybt.pif.download.Download;
import com.biglybt.pif.download.DownloadManager;
import com.biglybt.pif.download.DownloadManagerListener;
import com.biglybt.pif.download.DownloadPeerListener;
import com.biglybt.pif.peers.*;
import com.biglybt.pif.utils.PooledByteBuffer;
import com.biglybt.pifimpl.local.PluginCoreUtils;

public class
MagnetPluginMDDownloader
{
	final private static Set<String>	active_set = new HashSet<>();

	final private PluginInterface		plugin_interface;
	final private MagnetPlugin			plugin;
	final private byte[]				hash;
	final private Set<String>			networks;
	final private InetSocketAddress[]	addresses;
	final private List<String>			tags;
	final private Map<String,Object>	initial_metadata;
	final private String				args;

	private volatile com.biglybt.core.download.DownloadManager		core_dm;
	
	private volatile boolean		started;
	private volatile boolean		cancelled;
	private volatile boolean		completed;

	private List<DiskManagerRequest>	requests = new ArrayList<>();

	private AESemaphore running_sem 	= new AESemaphore( "MPMDD:run" );
	private AESemaphore complete_sem 	= new AESemaphore( "MPMDD:comp" );

	protected
	MagnetPluginMDDownloader(
		MagnetPlugin		_plugin,
		PluginInterface		_plugin_interface,
		byte[]				_hash,
		Set<String>			_networks,
		InetSocketAddress[]	_addresses,
		List<String>		_tags,
		Map<String,Object>	_initial_metadata,
		String				_args )
	{
		plugin				= _plugin;
		plugin_interface	= _plugin_interface;
		hash				= _hash;
		networks			= _networks;
		addresses			= _addresses;
		tags				= _tags;
		initial_metadata	= _initial_metadata;
		args				= _args;
	}

	protected void
	start(
		final DownloadListener		listener )
	{
		synchronized( this ){

			if ( started ){

				listener.failed( false, new Exception( "Already started" ));

				return;
			}

			if ( cancelled || completed ){

				listener.failed( false, new Exception( "Already cancelled/completed" ));

				return;
			}

			started = true;

			new AEThread2( "MagnetPluginMDDownloader" )
			{
				@Override
				public void
				run()
				{
					startSupport( listener );
				}
			}.start();
		}
	}

	protected boolean
	cancel()
	{
		return( cancelSupport( false ));
	}

	private boolean
	cancelSupport(
		boolean	internal )
	{
		boolean	wait_for_complete 	= !internal;

		try{
			List<DiskManagerRequest>	to_cancel;

			synchronized( this ){

				if ( !started ){

					Debug.out( "Not started!" );

					wait_for_complete 	= false;
				}

				if ( cancelled || completed ){

					return( cancelled );
				}

				cancelled	= true;

				to_cancel = new ArrayList<>(requests);

				requests.clear();
			}

			for ( DiskManagerRequest request: to_cancel ){

				request.cancel();
			}
			
			return( true );
			
		}finally{

			running_sem.releaseForever();

			if ( wait_for_complete ){

				complete_sem.reserve();
			}
		}
	}

	protected com.biglybt.core.download.DownloadManager
	getDownloadManager()
	{
		return( core_dm );
	}
	
	private void
	startSupport(
		final DownloadListener		listener )
	{
		String	hash_str = ByteFormatter.encodeString( hash );

		File tmp_dir 		= null;
		File data_file 		= null;
		File torrent_file 	= null;

		DownloadManager download_manager = plugin_interface.getDownloadManager();

		Download download	= null;
			
		final Throwable[] 	error 				= { null };
		final boolean[]		manually_removed 	= { false };
		
		final ByteArrayOutputStream	result = new ByteArrayOutputStream(32*1024);

		TOTorrentAnnounceURLSet[]	url_sets = null;

		try{
			synchronized( active_set ){

				if ( active_set.contains( hash_str )){

					throw( new Exception( "Download already active for hash " + hash_str ));
				}

				active_set.add( hash_str );
			}

			Download existing_download = download_manager.getDownload( hash );

			if ( existing_download != null ){

				throw( new Exception( "download already exists" ));
			}

			tmp_dir = AETemporaryFileHandler.createTempDir();

			int	 rand = RandomUtils.generateRandomIntUpto( 10000 );

			data_file 		= FileUtil.newFile( tmp_dir, hash_str + "_" + rand + ".torrent" );
			torrent_file 	= FileUtil.newFile( tmp_dir, hash_str + "_" + rand + ".metatorrent" );

			RandomAccessFile raf = new RandomAccessFile( data_file, "rw" );

			try{
				byte[] buffer = new byte[512*1024];

				Arrays.fill( buffer, (byte)0xff );

				for (long i=0;i<64*1024*1024;i+=buffer.length){

					raf.write( buffer );
				}
			}finally{

				raf.close();
			}

			URL announce_url = TorrentUtils.getDecentralisedURL( hash );

			TOTorrentCreator creator =
				TOTorrentFactory.createFromFileOrDirWithFixedPieceLength(
						data_file,
						announce_url,
						16*1024 );

			TOTorrent meta_torrent = creator.create();

			String[] bits = args.split( "&" );

			List<String>	trackers 	= new ArrayList<>();

			String	name = "magnet:" + Base32.encode( hash );

			Map<String,String>	magnet_args = new HashMap<>();

			for ( String bit: bits ){

				String[] x = bit.split( "=" );

				if ( x.length == 2 ){

					String lhs = x[0].toLowerCase();
					String rhs =  UrlUtils.decode( x[1] );

					magnet_args.put( lhs, rhs );

					if ( lhs.equals( "tr" )){

						String tracker = rhs;

						trackers.add( tracker );

					}else if ( lhs.equals( "dn" )){

						name = rhs;
					}
				}
			}

			if ( trackers.size() > 0 ){

					// stick the decentralised one we created above in position 0 - this will be
					// removed later if the torrent is downloaded

				trackers.add( 0, announce_url.toExternalForm());

				TOTorrentAnnounceURLGroup ag = meta_torrent.getAnnounceURLGroup();

				List<TOTorrentAnnounceURLSet> sets = new ArrayList<>();

				for ( String tracker: trackers ){

					try{
						URL tracker_url =  new URL( tracker );

						sets.add( ag.createAnnounceURLSet(new URL[]{ tracker_url }));

					}catch( Throwable e ){

						Debug.out( e );
					}
				}

				if ( sets.size() > 0 ){

					url_sets = sets.toArray( new TOTorrentAnnounceURLSet[ sets.size()]);

					ag.setAnnounceURLSets( url_sets );
				}
			}

			if ( !data_file.delete()){

				throw( new Exception( "Failed to delete " + data_file ));
			}

			meta_torrent.setHashOverride( hash );

			TorrentUtils.setFlag( meta_torrent, TorrentUtils.TORRENT_FLAG_METADATA_TORRENT, true );

			TorrentUtils.setFlag( meta_torrent, TorrentUtils.TORRENT_FLAG_LOW_NOISE, true );

			meta_torrent.serialiseToBEncodedFile( torrent_file );

			download_manager.clearNonPersistentDownloadState( hash );

			download = download_manager.addNonPersistentDownloadStopped( PluginCoreUtils.wrap( meta_torrent ), torrent_file, data_file);

			final String	display_name = MessageText.getString( "MagnetPlugin.use.md.download.name", new String[]{ name }) + ".torrent";

			core_dm = PluginCoreUtils.unwrap( download );
			
			DownloadManagerState state = core_dm.getDownloadState();
			
			state.setDisplayName( display_name );

			if (	 networks.size() == 0 ||
					( networks.size() == 1 && networks.contains( AENetworkClassifier.AT_PUBLIC ))){

					// no clues in the magnet link, or just public
					// start off by enabling all networks, public will be disabled later
					// if off by default

				for ( String network: AENetworkClassifier.AT_NETWORKS ){

					state.setNetworkEnabled( network, true );
				}

			}else{

				for ( String network: networks ){

					state.setNetworkEnabled( network, true );
				}

					// disable public network if no explicit trackers are public ones

				if ( !networks.contains( AENetworkClassifier.AT_PUBLIC )){

					state.setNetworkEnabled( AENetworkClassifier.AT_PUBLIC, false );
				}
			}

				// if user has specifically disabled the public network then remove this too
				// as this gives them a way to control metadata download network usage

			if ( !plugin.isNetworkEnabled( AENetworkClassifier.AT_PUBLIC )){

				state.setNetworkEnabled( AENetworkClassifier.AT_PUBLIC, false );
			}

			final List<InetSocketAddress>	peers_to_inject = new ArrayList<>();

			if ( addresses != null && addresses.length > 0 ){

				String[] enabled_nets = state.getNetworks();

				for ( InetSocketAddress address: addresses ){

					String host = AddressUtils.getHostAddress( address );

					String net = AENetworkClassifier.categoriseAddress( host );

					for ( String n: enabled_nets ){

						if ( n == net ){

							peers_to_inject.add( address );

							break;
						}
					}
				}
			}

			plugin.setInitialMetadata( core_dm, tags, initial_metadata );
			
			final Set<String> peer_networks = new HashSet<>();

			final List<Map<String,Object>> peers_for_cache = new ArrayList<>();

			download.addPeerListener(
				new DownloadPeerListener()
				{
					@Override
					public void
					peerManagerAdded(
						final Download			download,
						final PeerManager		peer_manager )
					{
						if ( cancelled || completed ){

							download.removePeerListener( this );

							return;
						}

						final PEPeerManager pm = PluginCoreUtils.unwrap( peer_manager );

						peer_manager.addListener(
							new PeerManagerListener2()
							{
								private PeerManagerListener2	pm_listener = this;

								private int	md_size;

								@Override
								public void
								eventOccurred(
									PeerManagerEvent	event )
								{
									if ( cancelled || completed ){

										peer_manager.removeListener( this );

										return;
									}

									if ( event.getType() != PeerManagerEvent.ET_PEER_ADDED ){

										return;
									}

									final Peer peer = event.getPeer();

									try{
										String	peer_ip = peer.getIp();

										String network = AENetworkClassifier.categoriseAddress( peer_ip );

										synchronized( peer_networks ){

											peer_networks.add( network );

											Map<String,Object> map = new HashMap<>();

											peers_for_cache.add( map );

											map.put( "ip", peer_ip.getBytes( "UTF-8" ));

											map.put( "port", new Long(peer.getPort()));
										}
									}catch( Throwable e ){

										Debug.out( e );
									}

									peer.addListener(
										new PeerListener2()
										{
											@Override
											public void
											eventOccurred(
												PeerEvent	event )
											{
												if ( cancelled || completed || md_size > 0 ){

													peer.removeListener( this );

													return;
												}

												if ( event.getType() != PeerEvent.ET_STATE_CHANGED ){

													return;
												}

												if ( (Integer)event.getData() != Peer.TRANSFERING ){

													return;
												}

												synchronized( pm_listener ){

													if ( md_size > 0 ){

														return;
													}

													md_size = pm.getTorrentInfoDictSize();

													if ( md_size > 0 ){

														peer_manager.removeListener( pm_listener );

													}else{

														return;
													}
												}

												listener.reportProgress( 0, md_size );

												new AEThread2( "" )
												{
													@Override
													public void
													run()
													{
														DiskManagerChannel channel = null;

														try{
															channel = download.getDiskManagerFileInfo()[0].createChannel();

															final DiskManagerRequest request = channel.createRequest();

															request.setType( DiskManagerRequest.REQUEST_READ );
															request.setOffset( 0 );
															request.setLength( md_size );

															request.setMaximumReadChunkSize( 16*1024 );

															request.addListener(
																new DiskManagerListener()
																{
																	@Override
																	public void
																	eventOccurred(
																		DiskManagerEvent	event )
																	{
																		int	type = event.getType();

																		if ( type == DiskManagerEvent.EVENT_TYPE_FAILED ){

																			error[0]	= event.getFailure();

																			running_sem.releaseForever();

																		}else if ( type == DiskManagerEvent.EVENT_TYPE_SUCCESS ){

																			PooledByteBuffer	buffer = null;

																			try{
																				buffer	= event.getBuffer();

																				byte[]	bytes = buffer.toByteArray();

																				int	dl_size;

																				synchronized( MagnetPluginMDDownloader.this ){

																					result.write( bytes );

																					dl_size = result.size();

																					if ( dl_size == md_size ){

																						completed	= true;

																						listener.reportProgress( md_size, md_size );

																						running_sem.releaseForever();
																					}
																				}

																				if ( !completed ){

																					listener.reportProgress( dl_size, md_size );
																				}

																			}catch( Throwable e ){

																				error[0] = e;

																				request.cancel();

																				running_sem.releaseForever();

																			}finally{

																				if ( buffer != null ){

																					buffer.returnToPool();
																				}
																			}
																		}else if ( type == DiskManagerEvent.EVENT_TYPE_BLOCKED ){

																			//System.out.println( "Waiting..." );
																		}
																	}
																});

															synchronized( MagnetPluginMDDownloader.this ){

																if ( cancelled ){

																	return;
																}

																requests.add( request );
															}

															request.run();

															synchronized( MagnetPluginMDDownloader.this ){

																requests.remove( request );
															}
														}catch( Throwable e ){

															error[0] = e;

															running_sem.releaseForever();

														}finally{

															if ( channel != null ){

																channel.destroy();
															}
														}
													}
												}.start();
											}
										});
								}
							});
					}

					@Override
					public void
					peerManagerRemoved(
						Download		download,
						PeerManager		peer_manager )
					{
					}
				});

			final Download f_download = download;

			DownloadManagerListener dl_listener =
				new DownloadManagerListener()
				{
					private Object				lock  = this;

					private TimerEventPeriodic	timer_event;
					private boolean				removed;

					@Override
					public void
					downloadAdded(
						final Download	download )
					{
						if ( download == f_download ){

							synchronized( lock ){

								if ( !removed ){

									if ( timer_event == null ){

										timer_event =
											SimpleTimer.addPeriodicEvent(
												"announcer",
												30*1000,
												new TimerEventPerformer()
												{
													@Override
													public void
													perform(
														TimerEvent event)
													{
														synchronized( lock ){

															if ( removed ){

																return;
															}

																// it is possible for the running_sem to be released before
																// the downloadRemoved event is fired and the listener removed
																// so the removed event never fires...

															if ( running_sem.isReleasedForever()){

																if ( timer_event != null ){

																	timer_event.cancel();

																	timer_event = null;
																}

																return;
															}
														}

														download.requestTrackerAnnounce( true );

														injectPeers( download );
													}
												});
									}

									if ( peers_to_inject.size() > 0 ){

										SimpleTimer.addEvent(
											"injecter",
											SystemTime.getOffsetTime( 5*1000 ),
											new TimerEventPerformer(){
												@Override
												public void perform(TimerEvent event ){
													injectPeers( download );
												}
											});
									}
								}
							}
						}
					}

					private void
					injectPeers(
						Download	download )
					{
						PeerManager pm = download.getPeerManager();

						if ( pm != null ){

							for ( InetSocketAddress address: peers_to_inject ){

								pm.addPeer(
									AddressUtils.getHostAddress( address ),
									address.getPort());
							}
						}
					}

					@Override
					public void
					downloadRemoved(
						Download	dl )
					{
						if ( dl == f_download ){

							synchronized( lock ){

								removed = true;

								if ( timer_event != null ){

									timer_event.cancel();

									timer_event = null;
								}
							}

							if ( !( cancelled || completed )){

								error[0] = new Exception( "Download manually removed" );

								manually_removed[0] = true;
								
								running_sem.releaseForever();
							}
						}
					}
				};

			download_manager.addListener( dl_listener, true );

			try{
				download.moveTo(1);

				download.setForceStart( true );

				download.setFlag( Download.FLAG_DISABLE_AUTO_FILE_MOVE, true );

				running_sem.reserve();

			}finally{

				download_manager.removeListener( dl_listener );
			}

			if ( completed ){

				byte[]	bytes = result.toByteArray();

				Map	info = BDecoder.decode( bytes );

				Map	map = new HashMap();

				map.put( "info", info );

				TOTorrent torrent = TOTorrentFactory.deserialiseFromMap( map );

				byte[] torrent_hash = torrent.getHash();

				if ( !Arrays.equals( hash, torrent_hash )){

					byte[] v2_hash = torrent.getV2Hash();
					
					boolean ok = false;
					
					if ( v2_hash != null ){
					
						byte[]	trunc = new byte[20];
						
						System.arraycopy( v2_hash, 0, trunc, 0, 20 );
						
						ok = Arrays.equals( hash, trunc );
					}
					
					if ( !ok ){
					
						throw( new Exception( "Metadata torrent hash mismatch: expected=" + ByteFormatter.encodeString( hash ) + ", actual=" + ByteFormatter.encodeString( torrent_hash )));
					}
				}

				if ( url_sets != null ){

						// first entry should be the decentralised one that we want to remove now

					List<TOTorrentAnnounceURLSet> updated = new ArrayList<>();

					for ( TOTorrentAnnounceURLSet set: url_sets ){

						if ( !TorrentUtils.isDecentralised( set.getAnnounceURLs()[0] )){

							updated.add( set );
						}
					}

					if ( updated.size() == 0 ){

						url_sets = null;

					}else{

						url_sets = updated.toArray( new TOTorrentAnnounceURLSet[updated.size()]);
					}
				}

				if ( url_sets != null ){

					torrent.setAnnounceURL( url_sets[0].getAnnounceURLs()[0] );

					torrent.getAnnounceURLGroup().setAnnounceURLSets( url_sets );

				}else{

					torrent.setAnnounceURL( TorrentUtils.getDecentralisedURL( hash ));
				}

				if ( peers_for_cache.size() > 0 ){

					Map<String,List<Map<String,Object>>> peer_cache = new HashMap<>();

					peer_cache.put( "tracker_peers", peers_for_cache );

					TorrentUtils.setPeerCache( torrent, peer_cache );
				}
				
				String current_dn = state.getDisplayName();
				
				if ( !current_dn.equals( display_name )){
					
					TorrentUtils.setDisplayName( torrent, current_dn );
				}

				try{
					String dn		= magnet_args.get( "dn" );

					if ( dn != null ){

						PlatformTorrentUtils.setContentTitle( torrent, dn );
					}

					String pfi_str = magnet_args.get( "pfi" );

					if ( pfi_str != null ){

						PlatformTorrentUtils.setContentPrimaryFileIndex( torrent, Integer.parseInt( pfi_str ));
					}
				}catch( Throwable e ){
				}
				
				listener.complete( torrent, peer_networks );

			}else{
					
				if ( cancelled ){

					throw( new Exception( "Download cancelled" ));

				}else{

					cancelSupport( true );

					try{
						if ( error[0] != null ){

							throw( error[0] );

						}else{

							throw( new Exception( "Download terminated prematurely" ));
						}
					}catch( Throwable e ){

						listener.failed( manually_removed[0],  e );

						Debug.out( e );

						throw( e );
					}
				}
			}
		}catch( Throwable e ){

			boolean	was_cancelled = cancelled;

			cancelSupport( true );

			if ( !was_cancelled ){

				listener.failed( manually_removed[0], e );

				Debug.out( e );
			}
		}finally{

			try{
				if ( download != null ){

						// unfortunately the tags and category get lost on download removal so cache them
					
					List<String> latest_tags =  plugin.getInitialTags( core_dm );
					
					if ( !latest_tags.isEmpty()){
					
						core_dm.setUserData( MagnetPlugin.DM_TAG_CACHE, latest_tags );
					}
					
					Category cat = core_dm.getDownloadState().getCategory();
					
					if ( cat != null ){
						
						if ( cat.getType() == Category.TYPE_USER ){

							core_dm.setUserData( MagnetPlugin.DM_CATEGORY_CACHE, cat.getName());
						}
					}
					
					try{
						download.stop();

					}catch( Throwable e ){
					}

					try{
						download.remove();

					}catch( Throwable e ){

						Debug.out( e );
					}
				}

				List<DiskManagerRequest>	to_cancel;

				synchronized( this ){

					to_cancel = new ArrayList<>(requests);

					requests.clear();
				}

				for ( DiskManagerRequest request: to_cancel ){

					request.cancel();
				}

				if ( torrent_file != null ){

					torrent_file.delete();
				}

				if ( data_file != null ){

					data_file.delete();
				}

				if ( tmp_dir != null ){

					tmp_dir.delete();
				}
			}catch( Throwable e ){

				Debug.out( e );

			}finally{

				synchronized( active_set ){

					active_set.remove( hash_str );
				}

				complete_sem.releaseForever();
			}
		}
	}

	protected interface
	DownloadListener
	{
		public void
		reportProgress(
			int		downloaded,
			int		total_size );
		
		public void
		complete(
			TOTorrent		torrent,
			Set<String>		peer_networks );

		public void
		failed(
			boolean		manually_cancelled,
			Throwable 	e );
	}
}
