<?php defined('SYSPATH') or die('No direct access allowed.');

/**
 * DB2 database connection.
 *
 * @package    Kohana/Database
 * @category   Drivers
 * @author     Deon George
 * @copyright  (c) 2010-2014 Deon George
 * @license    http://dev.leenooks.net/license.html
 */
class Kohana_Database_DB2 extends Database {
	// Database in use by each connection
	protected static $_current_databases = array();

	// Identifier for this connection within the PHP driver
	protected $_connection_id;

	// DB2 doesnt use identifies identifiers
	protected $_identifier = '';

	// Required Abstract Classes
	public function begin($mode = NULL) {}
	public function commit() {}
	public function rollback() {}
	public function list_tables($like = NULL) {}

	public function connect() {
		if ($this->_connection)
			return;

		// Extract the connection parameters, adding required variabels
		extract($this->_config['connection'] + array(
			'database'   => '',
			'hostname'   => '',
			'username'   => '',
			'port'       => '',
			'password'   => '',
			'persistent' => FALSE,
		));

		// Get user login details from user session - these are set by login
		if (! $username)
			$username = Session::instance()->get_once(Kohana::$config->load('auth')->session_key);
		if (! $password)
			$password = Session::instance()->get_once('password');

		// Prevent this information from showing up in traces
		unset($this->_config['connection']['username'], $this->_config['connection']['password']);

		if (! $username OR ! $password)
			HTTP::redirect('login');

		try {
			if ($persistent) {
				// Create a persistent connection
				throw new Kohana_Exception('Cant do persistant connections');

			} else {
				// Create a connection and force it to be a new link
				$constring = sprintf('DATABASE=%s;HOSTNAME=%s;PORT=%s;PROTOCOL=%s;UID=%s;PWD=%s',
					$database,$hostname,$port,'TCPIP',$username,$password);

				$this->_connection = db2_connect($constring,NULL,NULL);
			}

		} catch (ErrorException $e) {
			// No connection exists
			$this->_connection = NULL;

			throw new Database_Exception(':error', array(
					':error' => sprintf('%s error in %s (%s)',$e->getMessage(),$e->getFile(),$e->getLine()),
				),
				$e->getCode());
		}

		if (! $this->_connection)
			throw new Database_Exception('Connection failed (:error)',array(':error'=>db2_conn_errormsg()),db2_conn_error());

		// \xFF is a better delimiter, but the PHP driver uses underscore
		$this->_connection_id = sha1($hostname.'_'.$username.'_'.$password);

		if ( ! empty($this->_config['charset'])) {
			// Set the character set
			$this->set_charset($this->_config['charset']);
		}
	}

	// @todo
	public function disconnect() {}

	public function escape($value)
	{
		// SQL standard is to use single-quotes for all values
		return "'$value'";
	}

	public function set_charset($charset) {}

	public function query($type, $sql, $as_object = FALSE, array $params = NULL)
	{
		// Make sure the database is connected
		$this->_connection OR $this->connect();

		if (Kohana::$profiling)
		{
			// Benchmark this query for the current instance
			$benchmark = Profiler::start("Database ({$this->_instance})", $sql);
		}

		if ( ! empty($this->_config['connection']['persistent']) AND $this->_config['connection']['database'] !== Database_DB2::$_current_databases[$this->_connection_id])
		{
			// Select database on persistent connections
			$this->_select_db($this->_config['connection']['database']);
		}

		// Execute the query
		try
		{
			$result = db2_exec($this->_connection,$sql,array('cursor'=>DB2_SCROLLABLE));
		}
		catch (Exception $e)
		{
			if (isset($benchmark))
			{
				// This benchmark is worthless
				Profiler::delete($benchmark);
			}

			throw new Database_Exception(':error [ :query ]',array(':error' => db2_stmt_errormsg(), ':query' => $sql),db2_stmt_error());
		}

		if (isset($benchmark))
			Profiler::stop($benchmark);

		// Set the last query
		$this->last_query = $sql;

		if ($type === Database::SELECT)
		{
			// Return an iterator of results
			return new Database_DB2_Result($result, $sql, $as_object, $params);
		}
		elseif ($type === Database::INSERT)
		{
			throw new Kohana_Exception('Not Implemented (:type).',array(':type'=>$type));
		}
		else
		{
			throw new Kohana_Exception('Not Implemented (:type).',array(':type'=>$type));
		}
	}

	public function list_columns($table, $like = NULL, $add_prefix = FALSE) {
		// If caching is on, cache the tables
		if ($this->_config['caching']) {
			$cache_key = __METHOD__.':'.$table.':'.$like.':'.$add_prefix;

			$columns = Kohana::cache($cache_key);

			if ($columns) {
				return $columns;
			}
		}

		// Make sure the database is connected
		$this->_connection or $this->connect();

		$table = strtoupper($table);

		// Quote the table name
		$table = ($add_prefix === TRUE) ? $this->quote_table($table) : $table;

		// Find all column names
		try {
			$result = db2_columns($this->_connection,NULL,$this->_config['connection']['schema'] ? $this->_config['connection']['schema'] : '%',$table,$like);

		} catch (Exception $e) {
			throw new Database_Exception('Unable to obtain Columns for :table [:error] (:like)',array(':like'=>$like,':table'=>$table,':error' => db2_stmt_errormsg()),db2_stmt_error());
		}

		$count = 0;
		$columns = array();
		while ($row = db2_fetch_assoc($result)) {
			list($type, $length) = $this->_parse_type($row['TYPE_NAME']);

			$column = $this->datatype($type);

			$column['column_name']      = $row['COLUMN_NAME'];
			$column['data_type']        = $type;
			$column['is_nullable']      = ($row['IS_NULLABLE'] == 'YES');
			$column['ordinal_position'] = ++$count;

			switch (strtolower($column['data_type'])) {
				case 'float':
					if (isset($length))
						list($column['numeric_precision'], $column['numeric_scale']) = explode(',', $length);
					break;

				case 'int':
					if (isset($length))
						// MySQL attribute
						$column['display'] = $length;
					break;

				case 'string':
					switch ($column['data_type']) {
						case 'binary':
						case 'varbinary':
							$column['character_maximum_length'] = $length;
							break;

						case 'char':
						case 'varchar':
							$column['character_maximum_length'] = $length;
						case 'text':
						case 'tinytext':
						case 'mediumtext':
						case 'longtext':
							$column['collation_name'] = $row['Collation'];
							break;

						case 'enum':
						case 'set':
							$column['collation_name'] = $row['Collation'];
							$column['options'] = explode('\',\'', substr($length, 1, -1));
							break;
					}

					break;
			}

			$columns[$row['COLUMN_NAME']] = $column;
		}

		if (! $columns)
			throw new Database_Exception('Unable to obtain Columns for :table [:error] (:like)',
				array(':like'=>$like,':table'=>$table,':error' => db2_conn_errormsg()),db2_conn_error());

		// Save our cache data for next call
		if ($this->_config['caching']) {
			Kohana::cache($cache_key,$columns);
		}

		return $columns;
	}

	public function quote_column($column)
	{
		// Identifiers are escaped by repeating them
		$escaped_identifier = $this->_identifier.$this->_identifier;

		if (is_array($column)) {
			list($column, $alias) = $column;
			$alias = str_replace($this->_identifier, $escaped_identifier, $alias);
		}

		if ($column instanceof Database_Query) {
			// Create a sub-query
			$column = '('.$column->compile($this).')';

		} elseif ($column instanceof Database_Expression) {
			// Compile the expression
			$column = $column->compile($this);

		} else {
			// Convert to a string
			$column = (string) $column;

			$column = str_replace($this->_identifier, $escaped_identifier, $column);

			if ($column === '*') {
				return $column;

			} elseif (strpos($column, '.') !== FALSE) {
				$parts = explode('.', $column);

				if ($prefix = $this->table_prefix()) {
					// Get the offset of the table name, 2nd-to-last part
					$offset = count($parts) - 2;

					// Add the table prefix to the table name
					$parts[$offset] = $prefix.$parts[$offset];
				}

				foreach ($parts as & $part) {
					if ($part !== '*') {
						// Quote each of the parts
						$part = $this->_identifier.$part.$this->_identifier;
					}
				}

				$column = implode('.', $parts);

			} else {
				$column = $this->_identifier.$column.$this->_identifier;
			}
		}

		if (isset($alias))
			$column .= ' AS '.$this->_identifier.$alias.$this->_identifier;

		return $column;
	}

	public function quote_table($table)
	{
		// Identifiers are escaped by repeating them
		$escaped_identifier = $this->_identifier.$this->_identifier;

		if (is_array($table))
		{
			list($table, $alias) = $table;
			$alias = str_replace($this->_identifier, $escaped_identifier, $alias);
		}

		if ($table instanceof Database_Query)
		{
			// Create a sub-query
			$table = '('.$table->compile($this).')';
		}
		elseif ($table instanceof Database_Expression)
		{
			// Compile the expression
			$table = $table->compile($this);
		}
		else
		{
			// Convert to a string
			$table = (string) $table;

			$table = str_replace($this->_identifier, $escaped_identifier, $table);

			if (strpos($table, '.') !== FALSE)
			{
				$parts = explode('.', $table);

				if ($prefix = $this->table_prefix())
				{
					// Get the offset of the table name, last part
					$offset = count($parts) - 1;

					// Add the table prefix to the table name
					$parts[$offset] = $prefix.$parts[$offset];
				}

				foreach ($parts as & $part)
				{
					// Quote each of the parts
					$part = $this->_identifier.$part.$this->_identifier;
				}

				$table = implode('.', $parts);
			}
			else
			{
				// Add the table prefix
				$table = $this->table_prefix(TRUE).$table;
			}
		}

		if (isset($alias))
		{
			// Attach table prefix to alias
			$table .= ' AS '.$this->table_prefix().$alias;
		}

		return $table;
	}

	public function table_prefix($schema=FALSE)
	{
		return ($schema === TRUE ? $this->_config['connection']['schema'].'.' : '').$this->_config['table_prefix'];
	}
}
?>