package com.j256.db;

import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;

import javax.sql.DataSource;

/**
 * Connection that doesn't actually allocate the connection until it sees the first call. If the first call is to set
 * read-only to be true then it will use the read-only connection pool otherwise read-write. For the read-only
 * connections, it does not send any changes to read-only to the delegate.
 * 
 * @see http://256.com/gray/docs/misc/performance_optimizing_spring_hibernate_transactions/
 *
 * @author graywatson
 */
public class ReadOnlyDetectingConnection implements Connection {

	private final DataSource readOnlyDataSource;
	private final DataSource readWriteDataSource;
	private final String username;
	private final String password;

	private Connection delegate;
	private boolean isReadOnlyDataSource;

	public ReadOnlyDetectingConnection(DataSource readOnlyDataSource, DataSource readWriteDataSource, String username,
			String password) {
		this.readOnlyDataSource = readOnlyDataSource;
		this.readWriteDataSource = readWriteDataSource;
		this.username = username;
		this.password = password;
	}

	@Override
	public <T> T unwrap(Class<T> iface) throws SQLException {
		return getConnection(false).unwrap(iface);
	}

	@Override
	public boolean isWrapperFor(Class<?> iface) throws SQLException {
		return getConnection(false).isWrapperFor(iface);
	}

	@Override
	public Statement createStatement() throws SQLException {
		return getConnection(false).createStatement();
	}

	@Override
	public PreparedStatement prepareStatement(String sql) throws SQLException {
		return getConnection(false).prepareStatement(sql);
	}

	@Override
	public CallableStatement prepareCall(String sql) throws SQLException {
		return getConnection(false).prepareCall(sql);
	}

	@Override
	public String nativeSQL(String sql) throws SQLException {
		return getConnection(false).nativeSQL(sql);
	}

	@Override
	public void setAutoCommit(boolean autoCommit) throws SQLException {
		getConnection(false).setAutoCommit(autoCommit);
	}

	@Override
	public boolean getAutoCommit() throws SQLException {
		return getConnection(false).getAutoCommit();
	}

	@Override
	public void commit() throws SQLException {
		getConnection(false).commit();
	}

	@Override
	public void rollback() throws SQLException {
		getConnection(false).rollback();
	}

	@Override
	public void close() throws SQLException {
		getConnection(false).close();
	}

	@Override
	public boolean isClosed() throws SQLException {
		return getConnection(false).isClosed();
	}

	@Override
	public DatabaseMetaData getMetaData() throws SQLException {
		return getConnection(false).getMetaData();
	}

	@Override
	public void setReadOnly(boolean readOnly) throws SQLException {
		// if we don't have a delegate yet
		if (delegate == null) {
			/*
			 * Then we use the first set read-only call to determine whether to get the connection from the read-only
			 * data-source or the read-write one.
			 */
			if (readOnly) {
				// assign the delegate but don't do the set read-only because the connection should be alreadyq
				// read-only
				getConnection(true);
				isReadOnlyDataSource = true;
			} else {
				getConnection(false).setReadOnly(false);
			}
		} else if (isReadOnlyDataSource) {
			// ignore setting read-only if the connection is always read-only
		} else {
			delegate.setReadOnly(readOnly);
		}
	}

	@Override
	public boolean isReadOnly() throws SQLException {
		return getConnection(false).isReadOnly();
	}

	@Override
	public void setCatalog(String catalog) throws SQLException {
		getConnection(false).setCatalog(catalog);
	}

	@Override
	public String getCatalog() throws SQLException {
		return getConnection(false).getCatalog();
	}

	@Override
	public void setTransactionIsolation(int level) throws SQLException {
		getConnection(false).setTransactionIsolation(level);
	}

	@Override
	public int getTransactionIsolation() throws SQLException {
		return getConnection(false).getTransactionIsolation();
	}

	@Override
	public SQLWarning getWarnings() throws SQLException {
		return getConnection(false).getWarnings();
	}

	@Override
	public void clearWarnings() throws SQLException {
		getConnection(false).clearWarnings();
	}

	@Override
	public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
		return getConnection(false).createStatement(resultSetType, resultSetConcurrency);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
			throws SQLException {
		return getConnection(false).prepareStatement(sql, resultSetType, resultSetConcurrency);
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
		return getConnection(false).prepareCall(sql, resultSetType, resultSetConcurrency);
	}

	@Override
	public Map<String, Class<?>> getTypeMap() throws SQLException {
		return getConnection(false).getTypeMap();
	}

	@Override
	public void setTypeMap(Map<String, Class<?>> map) throws SQLException {
		getConnection(false).setTypeMap(map);
	}

	@Override
	public void setHoldability(int holdability) throws SQLException {
		getConnection(false).setHoldability(holdability);
	}

	@Override
	public int getHoldability() throws SQLException {
		return getConnection(false).getHoldability();
	}

	@Override
	public Savepoint setSavepoint() throws SQLException {
		return getConnection(false).setSavepoint();
	}

	@Override
	public Savepoint setSavepoint(String name) throws SQLException {
		return getConnection(false).setSavepoint(name);
	}

	@Override
	public void rollback(Savepoint savepoint) throws SQLException {
		getConnection(false).rollback(savepoint);
	}

	@Override
	public void releaseSavepoint(Savepoint savepoint) throws SQLException {
		getConnection(false).releaseSavepoint(savepoint);
	}

	@Override
	public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
			throws SQLException {
		return getConnection(false).createStatement(resultSetType, resultSetConcurrency, resultSetHoldability);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency,
			int resultSetHoldability) throws SQLException {
		return getConnection(false).prepareStatement(sql, resultSetType, resultSetConcurrency, resultSetHoldability);
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency,
			int resultSetHoldability) throws SQLException {
		return getConnection(false).prepareCall(sql, resultSetType, resultSetConcurrency, resultSetHoldability);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
		return getConnection(false).prepareStatement(sql, autoGeneratedKeys);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
		return getConnection(false).prepareStatement(sql, columnIndexes);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
		return getConnection(false).prepareStatement(sql, columnNames);
	}

	@Override
	public Clob createClob() throws SQLException {
		return getConnection(false).createClob();
	}

	@Override
	public Blob createBlob() throws SQLException {
		return getConnection(false).createBlob();
	}

	@Override
	public NClob createNClob() throws SQLException {
		return getConnection(false).createNClob();
	}

	@Override
	public SQLXML createSQLXML() throws SQLException {
		return getConnection(false).createSQLXML();
	}

	@Override
	public boolean isValid(int timeout) throws SQLException {
		return getConnection(false).isValid(timeout);
	}

	@Override
	public void setClientInfo(String name, String value) throws SQLClientInfoException {
		try {
			getConnection(false).setClientInfo(name, value);
		} catch (SQLClientInfoException e) {
			throw e;
		} catch (SQLException e) {
			SQLClientInfoException scie = new SQLClientInfoException();
			scie.initCause(e);
			throw scie;
		}
	}

	@Override
	public void setClientInfo(Properties properties) throws SQLClientInfoException {
		try {
			getConnection(false).setClientInfo(properties);
		} catch (SQLClientInfoException e) {
			throw e;
		} catch (SQLException e) {
			SQLClientInfoException scie = new SQLClientInfoException();
			scie.initCause(e);
			throw scie;
		}
	}

	@Override
	public String getClientInfo(String name) throws SQLException {
		return getConnection(false).getClientInfo(name);
	}

	@Override
	public Properties getClientInfo() throws SQLException {
		return getConnection(false).getClientInfo();
	}

	@Override
	public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
		return getConnection(false).createArrayOf(typeName, elements);
	}

	@Override
	public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
		return getConnection(false).createStruct(typeName, attributes);
	}

	@Override
	public void setSchema(String schema) throws SQLException {
		getConnection(false).setSchema(schema);
	}

	@Override
	public String getSchema() throws SQLException {
		return getConnection(false).getSchema();
	}

	@Override
	public void abort(Executor executor) throws SQLException {
		getConnection(false).abort(executor);
	}

	@Override
	public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {
		getConnection(false).setNetworkTimeout(executor, milliseconds);
	}

	@Override
	public int getNetworkTimeout() throws SQLException {
		return getConnection(false).getNetworkTimeout();
	}

	private Connection getConnection(boolean readOnlyCandidate) throws SQLException {
		if (delegate == null) {
			DataSource dataSource = (readOnlyCandidate ? readOnlyDataSource : readWriteDataSource);
			if (username == null) {
				delegate = dataSource.getConnection();
			} else {
				delegate = dataSource.getConnection(username, password);
			}
		}
		return delegate;
	}
}