/*
Copyright (c) 2008  Franklin Schmidt <fschmidt@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package fschmidt.db.pool;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;
import java.util.List;
import java.util.ArrayList;
import java.util.Set;
import java.util.HashSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import fschmidt.db.DbDatabase;
import fschmidt.db.DbObject;
import fschmidt.db.DbKey;
import fschmidt.db.DbObjectFactory;
import fschmidt.db.SQLRuntimeException;
import fschmidt.db.extend.DbDatabaseExt;
import fschmidt.db.extend.DbTableExt;
import fschmidt.db.extend.DbTransaction;
import fschmidt.db.extend.DbRecordExt;
import fschmidt.db.extend.FilterDatabase;
import fschmidt.util.java.Stack;
import fschmidt.util.java.ArrayStack;


public final class PooledConnection {
	private static final Logger logger = LoggerFactory.getLogger(PooledConnection.class);

	private final Pool pool;
	private Connection con;
	private int trans = 0;
	final List<Runnable> beforeCommitList = new ArrayList<Runnable>();
	final List<Runnable> afterCommitList = new ArrayList<Runnable>();
	DbTransaction dbTrans = null;
	long lastUsed;
	boolean ignoreRunnablesInThisTransaction = false;
	private final Stack<NestedConnection> nesting = new ArrayStack<NestedConnection>();
	private volatile String user = null;

	PooledConnection(DbDatabaseImpl db)
		throws SQLException
	{
		this.pool = db.pool;
		this.con = db.database().getConnection();
	}

	protected void finalize() throws Throwable {
		super.finalize();
		if( con == null )
			return;
		if( !nesting.isEmpty() )
			logger.error("connection lost from pool: opened="+nesting.size()+" trans="+trans,nesting.peek().initException);
		try {
			this.con.close();
		} catch(SQLException e) {
		} finally {
			this.con = null;
		}
	}

	void setUser(String user) throws SQLException {
		if( this.user == user ) {
/*
			Statement stmt = con.createStatement();
			ResultSet rs = stmt.executeQuery("select CURRENT_USER");
			rs.next();
			String s = rs.getString("CURRENT_USER");
			rs.close();
			stmt.close();
			if( s.equals(user) )
				return;
			logger.error("setUser error, user should be "+user+" but is "+s,new Exception());
*/
			return;
		}
		this.user = null;
		Statement stmt = con.createStatement();
		stmt.executeUpdate(
			"set role " + user
		);
		stmt.close();
		this.user = user;
	}

	Connection nest(String user) {
		NestedConnection nc = new NestedConnection(this,user);
		nesting.push(nc);
		return nc.proxyCon;
	}

	private void transOver()
		throws SQLException
	{
		con.setAutoCommit(true);
		trans = 0;
		dbTrans = null;
		ignoreRunnablesInThisTransaction = false;
		beforeCommitList.clear();
		afterCommitList.clear();
	}

	void setAutoCommit(boolean autoCommit)
		throws SQLException
	{
		int opened = nesting.size();
		if( autoCommit==true ) {
			//logger.warn("setAutoCommit true not well supported");
			if( trans > 0 ) {
				if( trans != opened )
					throw new IllegalStateException("setAutoCommit to true with unclosed connections");
				transOver();
				return;
			}
		} else if( trans == 0 ) {
			trans = opened;
			dbTrans = new DbTransaction();
		}
		con.setAutoCommit(autoCommit);
	}

	void commit()
		throws SQLException
	{
		int opened = nesting.size();
		if( trans != opened )
			throw new IllegalStateException("commit failed: trans="+trans+" opened="+opened);
		final int opened2 = opened;
		while( !beforeCommitList.isEmpty() ) {
			Runnable[] a = beforeCommitList.toArray(new Runnable[0]);
			beforeCommitList.clear();
			for( int i=0; i<a.length; i++ ) {
				a[i].run();
				if( opened != opened2 ) {
					logger.error("before commit opened="+opened+" opened2="+opened2+" runnable="+a[i]);
					opened = opened2;
				}
				a[i] = null;
			}
		}
		{	// for now, to catch aborted transactions
			Statement stmt = con.createStatement();
			stmt.executeQuery("select 1");
			stmt.close();
		}
		con.commit();
		if( afterCommitList.isEmpty() ) {
			dbTrans = new DbTransaction();
		} else {
			Runnable[] a = afterCommitList.toArray(new Runnable[0]);
			setAutoCommit(true);
			for( int i=0; i<a.length; i++ ) {
				a[i].run();
				if( opened != opened2 ) {
					logger.error("after commit opened="+opened+" opened2="+opened2+" runnable="+a[i]);
					opened = opened2;
				}
				a[i] = null;
			}
			setAutoCommit(false);
		}
	}

	void rollback()
		throws SQLException
	{
		int opened = nesting.size();
		if( trans != opened )
			logger.warn("rollback called in nested transaction");
		con.rollback();
		beforeCommitList.clear();
		afterCommitList.clear();
	}

	void close(NestedConnection nestedCon)
		throws SQLException
	{
		int i = nesting.indexOf(nestedCon);
		if( trans==nesting.size() ) {
			if( i != trans - 1 )
				logger.error("closing connection outside of transaction: i="+i+" trans="+trans,new Exception(nestedCon.initException));
			con.rollback();  // rollback everything since last commit
			transOver();
		}
		if( i < trans )
			logger.error("closing connection outside of transaction: i="+i+" trans="+trans,new Exception(nestedCon.initException));
		nesting.remove(nestedCon);
		if( !nesting.isEmpty() ) {
			nesting.get(nesting.size()-1).setUser();  // best guess
			return;
		}
		if( trans != 0 )
			logger.error("trans = "+trans,new Exception());
		pool.localCon.remove();
		if( !beforeCommitList.isEmpty() ) {
			logger.error("beforeCommitList = "+beforeCommitList,new Exception());
			beforeCommitList.clear();
		}
		if( !afterCommitList.isEmpty() ) {
			logger.error("afterCommitList = "+afterCommitList,new Exception());
			afterCommitList.clear();
		}
		lastUsed = System.currentTimeMillis();
		synchronized(pool) {
			if( pool.isExpired(lastUsed) ) {
				con.close();
				con = null;
			} else {
				if( con.getAutoCommit() == false ) {
					logger.error("autoCommit is false at close",new Exception());
					con.setAutoCommit(true);
				}
				pool.stack.push(this);
			}
		}
	}

	Connection con() {
		return con;
	}

	boolean isInTransaction() {
		return dbTrans!=null;
	}

	void commitTransaction() {
		if( !isInTransaction() )
			throw new IllegalStateException("commitTransaction called outside of transaction"); 
		try {
			if( con.getAutoCommit()==true )
				throw new IllegalStateException("commitTransaction called outside of transaction"); 
			int opened = nesting.size();
			if( opened < trans )
				throw new IllegalStateException(); 
			if( opened > trans )
				throw new IllegalStateException("commitTransaction called with unclosed connections"); 
			commit();
			setAutoCommit(true);
		} catch(SQLException e) {
			throw new SQLRuntimeException(e);
		}
	}

	void endTransaction() {
		try {
			if( con.getAutoCommit()==false && nesting.size() > trans ) {
				logger.error("endTransaction called with unclosed connections, closing them now",new Exception(nesting.peek().initException));
				while( nesting.size() > trans ) {
					nesting.peek().close();
				}
			}
			nesting.peek().close();
		} catch(SQLException e) {
			throw new SQLRuntimeException(e);
		}
	}

	void forceClose() {
		logger.error("connection never closed: opened="+nesting.size()+" trans="+trans+" user="+user,nesting.peek().initException);
		pool.localCon.remove();
		try {
			con.close();
		} catch(SQLException e) {
			logger.error("",e);
		}
		con = null;
	}

}