/*
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.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 Pool {
	private static final Logger logger = LoggerFactory.getLogger(Pool.class);

	final Stack<PooledConnection> stack = new ArrayStack<PooledConnection>();
	private long idleTimeout = 0L;
	private long idleExpires;
	final ThreadLocal<PooledConnection> localCon = new ThreadLocal<PooledConnection>();

	public long getIdleTimeout() {
		return idleTimeout;
	}

	public void setIdleTimeout(long idleTimeout) {
		this.idleTimeout = idleTimeout;
	}

	boolean isInTransaction() {
		PooledConnection con = localCon.get();
		return con!=null && con.isInTransaction();
	}

	void commitTransaction() {
		localCon.get().commitTransaction();
	}

	void endTransaction() {
		PooledConnection con = localCon.get();
		if( con==null )
			throw new IllegalStateException("endTransaction called without beginTransaction"); 
		con.endTransaction();
	}

	void runBeforeCommit(Runnable r) {
		PooledConnection con = localCon.get();
		if( !con.ignoreRunnablesInThisTransaction )
			con.beforeCommitList.add(r);
	}

	void runJustAfterCommit(Runnable r) {
		PooledConnection con = localCon.get();
		if( !con.ignoreRunnablesInThisTransaction )
			con.afterCommitList.add(0,r);
	}

	void runAfterCommit(Runnable r) {
		PooledConnection con = localCon.get();
		if( !con.ignoreRunnablesInThisTransaction )
			con.afterCommitList.add(r);
	}

	void ignoreRunnablesInThisTransaction() {
		if( !isInTransaction() )
			throw new IllegalStateException("not in transaction");
		localCon.get().ignoreRunnablesInThisTransaction = true;
	}

	DbTransaction getTransaction() {
		if( isInTransaction() ) {
			return localCon.get().dbTrans;
		} else {
			return null;
		}
	}

	Connection getConnection(DbDatabaseImpl db)
		throws SQLException
	{
		PooledConnection con = localCon.get();
		if( con==null || con.con().isClosed() ) {
			con = getConnection2(db);
			localCon.set(con);
			pools.get().add(this);
		}
		return con.nest(db.user);
	}

	private static final long timeout = 1000L*60*60;  // 1 hour

	private synchronized PooledConnection getConnection2(DbDatabaseImpl db)
		throws SQLException
	{
		long now = System.currentTimeMillis();
		while( !stack.isEmpty() ) {
			PooledConnection con = stack.pop();
			Connection realCon = con.con();
			if( realCon.isClosed() )
				continue;
			try {
				if( now - con.lastUsed > timeout ) {
					Statement stmt = realCon.createStatement();
					stmt.executeQuery("select 1");
					stmt.close();
				}
			} catch(SQLException e) {
				logger.info("corrupt connection dropped from pool");
				continue;
			}
			return con;
		}
		idleExpires = now + idleTimeout;
		return new PooledConnection(db);
	}

	boolean isExpired(long lastUsed) {
		return idleTimeout > 0 && lastUsed > idleExpires;
	}

	private static ThreadLocal<Set<Pool>> pools = new ThreadLocal<Set<Pool>>() {
		protected Set<Pool> initialValue() {
			return new HashSet<Pool>();
		}
	};

	public static void threadReset() {
		Set<Pool> set = pools.get();
		for( Pool pool : set ) {
			PooledConnection con = pool.localCon.get();
			if( con != null ) {
				con.forceClose();
			}
		}
		set.clear();
	}

	public Connection getNativeConnection() {
		return localCon.get().con();
	}

}