package eu.siacs.conversations.services;

import android.util.Log;

import java.math.BigInteger;
import java.util.HashSet;
import java.util.List;

import eu.siacs.conversations.Config;
import eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.entities.Conversation;
import eu.siacs.conversations.generator.AbstractGenerator;
import eu.siacs.conversations.parser.AbstractParser;
import eu.siacs.conversations.xml.Element;
import eu.siacs.conversations.xmpp.OnAdvancedStreamFeaturesLoaded;
import eu.siacs.conversations.xmpp.OnIqPacketReceived;
import eu.siacs.conversations.xmpp.jid.Jid;
import eu.siacs.conversations.xmpp.stanzas.IqPacket;

public class MessageArchiveService implements OnAdvancedStreamFeaturesLoaded {

	private final XmppConnectionService mXmppConnectionService;

	private final HashSet<Query> queries = new HashSet<Query>();

	public MessageArchiveService(final XmppConnectionService service) {
		this.mXmppConnectionService = service;
	}

	public void catchup(final Account account) {
		long startCatchup = getLastMessageTransmitted(account);
		long endCatchup = account.getXmppConnection().getLastSessionEstablished();
		if (startCatchup == 0) {
			return;
		} else if (endCatchup - startCatchup >= Config.MAX_CATCHUP) {
			startCatchup = endCatchup - Config.MAX_CATCHUP;
			List<Conversation> conversations = mXmppConnectionService.getConversations();
			for (Conversation conversation : conversations) {
				if (conversation.getMode() == Conversation.MODE_SINGLE && conversation.getAccount() == account && startCatchup > conversation.getLastMessageTransmitted()) {
					this.query(conversation,startCatchup);
				}
			}
		}
		final Query query = new Query(account, startCatchup, endCatchup);
		this.queries.add(query);
		this.execute(query);
	}

	private long getLastMessageTransmitted(final Account account) {
		long timestamp = 0;
		for(final Conversation conversation : mXmppConnectionService.getConversations()) {
			if (conversation.getAccount() == account) {
				long tmp = conversation.getLastMessageTransmitted();
				if (tmp > timestamp) {
					timestamp = tmp;
				}
			}
		}
		return timestamp;
	}

	public void query(final Conversation conversation) {
		query(conversation,conversation.getAccount().getXmppConnection().getLastSessionEstablished());
	}

	public void query(final Conversation conversation, long end) {
		synchronized (this.queries) {
			final Account account = conversation.getAccount();
			long start = conversation.getLastMessageTransmitted();
			if (start > end) {
				return;
			} else if (end - start >= Config.MAX_HISTORY_AGE) {
				start = end - Config.MAX_HISTORY_AGE;
			}
			final Query query = new Query(conversation, start, end);
			this.queries.add(query);
			this.execute(query);
		}
	}

	private void execute(final Query query) {
		Log.d(Config.LOGTAG,query.getAccount().getJid().toBareJid().toString()+": running mam query "+query.toString());
		IqPacket packet = this.mXmppConnectionService.getIqGenerator().queryMessageArchiveManagement(query);
			this.mXmppConnectionService.sendIqPacket(query.getAccount(), packet, new OnIqPacketReceived() {
				@Override
				public void onIqPacketReceived(Account account, IqPacket packet) {
					if (packet.getType() == IqPacket.TYPE_ERROR) {
						Log.d(Config.LOGTAG,account.getJid().toBareJid().toString()+": error executing mam: "+packet.toString());
						finalizeQuery(query);
					}
				}
			});
	}

	private void finalizeQuery(Query query) {
		synchronized (this.queries) {
			this.queries.remove(query);
		}
		final Conversation conversation = query.getConversation();
		if (conversation != null) {
			conversation.sort();
			if (conversation.setLastMessageTransmitted(query.getEnd())) {
				this.mXmppConnectionService.databaseBackend.updateConversation(conversation);
			}
			this.mXmppConnectionService.updateConversationUi();
		} else {
			for(Conversation tmp : this.mXmppConnectionService.getConversations()) {
				if (tmp.getAccount() == query.getAccount()) {
					tmp.sort();
					if (tmp.setLastMessageTransmitted(query.getEnd())) {
						this.mXmppConnectionService.databaseBackend.updateConversation(tmp);
					}
				}
			}
		}
	}

	public void processFin(Element fin) {
		if (fin == null) {
			return;
		}
		Query query = findQuery(fin.getAttribute("queryid"));
		if (query == null) {
			return;
		}
		boolean complete = fin.getAttributeAsBoolean("complete");
		Element set = fin.findChild("set","http://jabber.org/protocol/rsm");
		Element last = set == null ? null : set.findChild("last");
		if (complete || last == null) {
			this.finalizeQuery(query);
		} else {
			final Query nextQuery = query.next(last == null ? null : last.getContent());
			this.execute(nextQuery);
			synchronized (this.queries) {
				this.queries.remove(query);
				this.queries.add(nextQuery);
			}
		}
	}

	public Query findQuery(String id) {
		if (id == null) {
			return null;
		}
		synchronized (this.queries) {
			for(Query query : this.queries) {
				if (query.getQueryId().equals(id)) {
					return query;
				}
			}
			return null;
		}
	}

	@Override
	public void onAdvancedStreamFeaturesAvailable(Account account) {
		if (account.getXmppConnection() != null && account.getXmppConnection().getFeatures().mam()) {
			this.catchup(account);
		}
	}

	public class Query {
		private long start;
		private long end;
		private Jid with = null;
		private String queryId;
		private String after = null;
		private Account account;
		private Conversation conversation;

		public Query(Conversation conversation, long start, long end) {
			this(conversation.getAccount(), start, end);
			this.conversation = conversation;
			this.with = conversation.getContactJid().toBareJid();
		}

		public Query(Account account, long start, long end) {
			this.account = account;
			this.start = start;
			this.end = end;
			this.queryId = new BigInteger(50, mXmppConnectionService.getRNG()).toString(32);
		}

		public Query next(String after) {
			Query query = new Query(this.account,this.start,this.end);
			query.after = after;
			query.conversation = conversation;
			query.with = with;
			return query;
		}

		public String getAfter() {
			return after;
		}

		public String getQueryId() {
			return queryId;
		}

		public Jid getWith() {
			return with;
		}

		public long getStart() {
			return start;
		}

		public long getEnd() {
			return end;
		}

		public Conversation getConversation() {
			return conversation;
		}

		public Account getAccount() {
			return this.account;
		}

		@Override
		public String toString() {
			StringBuilder builder = new StringBuilder();
			builder.append("with=");
			if (this.with==null) {
				builder.append("*");
			} else {
				builder.append(with.toString());
			}
			builder.append(", start=");
			builder.append(AbstractGenerator.getTimestamp(this.start));
			builder.append(", end=");
			builder.append(AbstractGenerator.getTimestamp(this.end));
			if (this.after!=null) {
				builder.append(", after=");
				builder.append(this.after);
			}
			return builder.toString();
		}
	}
}