<?php
/**
 * CPgsqlSchema class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CPgsqlSchema is the class for retrieving metadata information from a PostgreSQL database.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.db.schema.pgsql
 * @since 1.0
 */
class CPgsqlSchema extends CDbSchema
{
	const DEFAULT_SCHEMA='public';

	/**
	 * @var array the abstract column types mapped to physical column types.
	 * @since 1.1.6
	 */
	public $columnTypes=array(
		'pk' => 'serial NOT NULL PRIMARY KEY',
		'string' => 'character varying (255)',
		'text' => 'text',
		'integer' => 'integer',
		'float' => 'double precision',
		'decimal' => 'numeric',
		'datetime' => 'timestamp',
		'timestamp' => 'timestamp',
		'time' => 'time',
		'date' => 'date',
		'binary' => 'bytea',
		'boolean' => 'boolean',
		'money' => 'decimal(19,4)',
	);

	private $_sequences=array();

	/**
	 * Quotes a table name for use in a query.
	 * A simple table name does not schema prefix.
	 * @param string $name table name
	 * @return string the properly quoted table name
	 * @since 1.1.6
	 */
	public function quoteSimpleTableName($name)
	{
		return '"'.$name.'"';
	}

	/**
	 * Resets the sequence value of a table's primary key.
	 * The sequence will be reset such that the primary key of the next new row inserted
	 * will have the specified value or max value of a primary key plus one (i.e. sequence trimming).
	 * @param CDbTableSchema $table the table schema whose primary key sequence will be reset
	 * @param integer|null $value the value for the primary key of the next new row inserted.
	 * If this is not set, the next new row's primary key will have the max value of a primary
	 * key plus one (i.e. sequence trimming).
	 * @since 1.1
	 */
	public function resetSequence($table,$value=null)
	{
		if($table->sequenceName===null)
			return;
		$sequence='"'.$table->sequenceName.'"';
		if(strpos($sequence,'.')!==false)
			$sequence=str_replace('.','"."',$sequence);
		if($value!==null)
			$value=(int)$value;
		else
			$value="(SELECT COALESCE(MAX(\"{$table->primaryKey}\"),0) FROM {$table->rawName})+1";
		$this->getDbConnection()
			->createCommand("SELECT SETVAL('$sequence',$value,false)")
			->execute();
	}

	/**
	 * Enables or disables integrity check.
	 * @param boolean $check whether to turn on or off the integrity check.
	 * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
	 * @since 1.1
	 */
	public function checkIntegrity($check=true,$schema='')
	{
		$enable=$check ? 'ENABLE' : 'DISABLE';
		$tableNames=$this->getTableNames($schema);
		$db=$this->getDbConnection();
		foreach($tableNames as $tableName)
		{
			$tableName='"'.$tableName.'"';
			if(strpos($tableName,'.')!==false)
				$tableName=str_replace('.','"."',$tableName);
			$db->createCommand("ALTER TABLE $tableName $enable TRIGGER ALL")->execute();
		}
	}

	/**
	 * Loads the metadata for the specified table.
	 * @param string $name table name
	 * @return CDbTableSchema driver dependent table metadata.
	 */
	protected function loadTable($name)
	{
		$table=new CPgsqlTableSchema;
		$this->resolveTableNames($table,$name);
		if(!$this->findColumns($table))
			return null;
		$this->findConstraints($table);

		if(is_string($table->primaryKey) && isset($this->_sequences[$table->rawName.'.'.$table->primaryKey]))
			$table->sequenceName=$this->_sequences[$table->rawName.'.'.$table->primaryKey];
		elseif(is_array($table->primaryKey))
		{
			foreach($table->primaryKey as $pk)
			{
				if(isset($this->_sequences[$table->rawName.'.'.$pk]))
				{
					$table->sequenceName=$this->_sequences[$table->rawName.'.'.$pk];
					break;
				}
			}
		}

		return $table;
	}

	/**
	 * Generates various kinds of table names.
	 * @param CPgsqlTableSchema $table the table instance
	 * @param string $name the unquoted table name
	 */
	protected function resolveTableNames($table,$name)
	{
		$parts=explode('.',str_replace('"','',$name));
		if(isset($parts[1]))
		{
			$schemaName=$parts[0];
			$tableName=$parts[1];
		}
		else
		{
			$schemaName=self::DEFAULT_SCHEMA;
			$tableName=$parts[0];
		}

		$table->name=$tableName;
		$table->schemaName=$schemaName;
		if($schemaName===self::DEFAULT_SCHEMA)
			$table->rawName=$this->quoteTableName($tableName);
		else
			$table->rawName=$this->quoteTableName($schemaName).'.'.$this->quoteTableName($tableName);
	}

	/**
	 * Collects the table column metadata.
	 * @param CPgsqlTableSchema $table the table metadata
	 * @return boolean whether the table exists in the database
	 */
	protected function findColumns($table)
	{
		$sql=<<<EOD
SELECT a.attname, LOWER(format_type(a.atttypid, a.atttypmod)) AS type, d.adsrc, a.attnotnull, a.atthasdef,
	pg_catalog.col_description(a.attrelid, a.attnum) AS comment
FROM pg_attribute a LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attnum > 0 AND NOT a.attisdropped
	AND a.attrelid = (SELECT oid FROM pg_catalog.pg_class WHERE relname=:table
		AND relnamespace = (SELECT oid FROM pg_catalog.pg_namespace WHERE nspname = :schema))
ORDER BY a.attnum
EOD;
		$command=$this->getDbConnection()->createCommand($sql);
		$command->bindValue(':table',$table->name);
		$command->bindValue(':schema',$table->schemaName);

		if(($columns=$command->queryAll())===array())
			return false;

		foreach($columns as $column)
		{
			$c=$this->createColumn($column);
			$table->columns[$c->name]=$c;

			if(stripos($column['adsrc'],'nextval')===0 && preg_match('/nextval\([^\']*\'([^\']+)\'[^\)]*\)/i',$column['adsrc'],$matches))
			{
				if(strpos($matches[1],'.')!==false || $table->schemaName===self::DEFAULT_SCHEMA)
					$this->_sequences[$table->rawName.'.'.$c->name]=$matches[1];
				else
					$this->_sequences[$table->rawName.'.'.$c->name]=$table->schemaName.'.'.$matches[1];
				$c->autoIncrement=true;
			}
		}
		return true;
	}

	/**
	 * Creates a table column.
	 * @param array $column column metadata
	 * @return CDbColumnSchema normalized column metadata
	 */
	protected function createColumn($column)
	{
		$c=new CPgsqlColumnSchema;
		$c->name=$column['attname'];
		$c->rawName=$this->quoteColumnName($c->name);
		$c->allowNull=!$column['attnotnull'];
		$c->isPrimaryKey=false;
		$c->isForeignKey=false;
		$c->comment=$column['comment']===null ? '' : $column['comment'];

		$c->init($column['type'],$column['atthasdef'] ? $column['adsrc'] : null);

		return $c;
	}

	/**
	 * Collects the primary and foreign key column details for the given table.
	 * @param CPgsqlTableSchema $table the table metadata
	 */
	protected function findConstraints($table)
	{
		$sql=<<<EOD
SELECT conname, consrc, contype, indkey FROM (
	SELECT
		conname,
		CASE WHEN contype='f' THEN
			pg_catalog.pg_get_constraintdef(oid)
		ELSE
			'CHECK (' || consrc || ')'
		END AS consrc,
		contype,
		conrelid AS relid,
		NULL AS indkey
	FROM
		pg_catalog.pg_constraint
	WHERE
		contype IN ('f', 'c')
	UNION ALL
	SELECT
		pc.relname,
		NULL,
		CASE WHEN indisprimary THEN
				'p'
		ELSE
				'u'
		END,
		pi.indrelid,
		indkey
	FROM
		pg_catalog.pg_class pc,
		pg_catalog.pg_index pi
	WHERE
		pc.oid=pi.indexrelid
		AND EXISTS (
			SELECT 1 FROM pg_catalog.pg_depend d JOIN pg_catalog.pg_constraint c
			ON (d.refclassid = c.tableoid AND d.refobjid = c.oid)
			WHERE d.classid = pc.tableoid AND d.objid = pc.oid AND d.deptype = 'i' AND c.contype IN ('u', 'p')
	)
) AS sub
WHERE relid = (SELECT oid FROM pg_catalog.pg_class WHERE relname=:table
	AND relnamespace = (SELECT oid FROM pg_catalog.pg_namespace
	WHERE nspname=:schema))
EOD;
		$command=$this->getDbConnection()->createCommand($sql);
		$command->bindValue(':table',$table->name);
		$command->bindValue(':schema',$table->schemaName);
		foreach($command->queryAll() as $row)
		{
			if($row['contype']==='p') // primary key
				$this->findPrimaryKey($table,$row['indkey']);
			elseif($row['contype']==='f') // foreign key
				$this->findForeignKey($table,$row['consrc']);
		}
	}

	/**
	 * Collects primary key information.
	 * @param CPgsqlTableSchema $table the table metadata
	 * @param string $indices pgsql primary key index list
	 */
	protected function findPrimaryKey($table,$indices)
	{
		$indices=implode(', ',preg_split('/\s+/',$indices));
		$sql=<<<EOD
SELECT attnum, attname FROM pg_catalog.pg_attribute WHERE
	attrelid=(
		SELECT oid FROM pg_catalog.pg_class WHERE relname=:table AND relnamespace=(
			SELECT oid FROM pg_catalog.pg_namespace WHERE nspname=:schema
		)
	)
	AND attnum IN ({$indices})
EOD;
		$command=$this->getDbConnection()->createCommand($sql);
		$command->bindValue(':table',$table->name);
		$command->bindValue(':schema',$table->schemaName);
		foreach($command->queryAll() as $row)
		{
			$name=$row['attname'];
			if(isset($table->columns[$name]))
			{
				$table->columns[$name]->isPrimaryKey=true;
				if($table->primaryKey===null)
					$table->primaryKey=$name;
				elseif(is_string($table->primaryKey))
					$table->primaryKey=array($table->primaryKey,$name);
				else
					$table->primaryKey[]=$name;
			}
		}
	}

	/**
	 * Collects foreign key information.
	 * @param CPgsqlTableSchema $table the table metadata
	 * @param string $src pgsql foreign key definition
	 */
	protected function findForeignKey($table,$src)
	{
		$matches=array();
		$brackets='\(([^\)]+)\)';
		$pattern="/FOREIGN\s+KEY\s+{$brackets}\s+REFERENCES\s+([^\(]+){$brackets}/i";
		if(preg_match($pattern,str_replace('"','',$src),$matches))
		{
			$keys=preg_split('/,\s+/', $matches[1]);
			$tableName=$matches[2];
			$fkeys=preg_split('/,\s+/', $matches[3]);
			foreach($keys as $i=>$key)
			{
				$table->foreignKeys[$key]=array($tableName,$fkeys[$i]);
				if(isset($table->columns[$key]))
					$table->columns[$key]->isForeignKey=true;
			}
		}
	}

	/**
	 * Returns all table names in the database.
	 * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
	 * If not empty, the returned table names will be prefixed with the schema name.
	 * @return array all table names in the database.
	 */
	protected function findTableNames($schema='')
	{
		if($schema==='')
			$schema=self::DEFAULT_SCHEMA;
		$sql=<<<EOD
SELECT table_name, table_schema FROM information_schema.tables
WHERE table_schema=:schema AND table_type='BASE TABLE'
EOD;
		$command=$this->getDbConnection()->createCommand($sql);
		$command->bindParam(':schema',$schema);
		$rows=$command->queryAll();
		$names=array();
		foreach($rows as $row)
		{
			if($schema===self::DEFAULT_SCHEMA)
				$names[]=$row['table_name'];
			else
				$names[]=$row['table_schema'].'.'.$row['table_name'];
		}
		return $names;
	}

	/**
	 * Builds a SQL statement for renaming a DB table.
	 * @param string $table the table to be renamed. The name will be properly quoted by the method.
	 * @param string $newName the new table name. The name will be properly quoted by the method.
	 * @return string the SQL statement for renaming a DB table.
	 * @since 1.1.6
	 */
	public function renameTable($table, $newName)
	{
		return 'ALTER TABLE ' . $this->quoteTableName($table) . ' RENAME TO ' . $this->quoteTableName($newName);
	}

	/**
	 * Builds a SQL statement for adding a new DB column.
	 * @param string $table the table that the new column will be added to. The table name will be properly quoted by the method.
	 * @param string $column the name of the new column. The name will be properly quoted by the method.
	 * @param string $type the column type. The {@link getColumnType} method will be invoked to convert abstract column type (if any)
	 * into the physical one. Anything that is not recognized as abstract type will be kept in the generated SQL.
	 * For example, 'string' will be turned into 'varchar(255)', while 'string not null' will become 'varchar(255) not null'.
	 * @return string the SQL statement for adding a new column.
	 * @since 1.1.6
	 */
	public function addColumn($table, $column, $type)
	{
		$type=$this->getColumnType($type);
		$sql='ALTER TABLE ' . $this->quoteTableName($table)
			. ' ADD COLUMN ' . $this->quoteColumnName($column) . ' '
			. $this->getColumnType($type);
		return $sql;
	}

	/**
	 * Builds a SQL statement for changing the definition of a column.
	 * @param string $table the table whose column is to be changed. The table name will be properly quoted by the method.
	 * @param string $column the name of the column to be changed. The name will be properly quoted by the method.
	 * @param string $type the new column type. The {@link getColumnType} method will be invoked to convert abstract column type (if any)
	 * into the physical one. Anything that is not recognized as abstract type will be kept in the generated SQL.
	 * For example, 'string' will be turned into 'varchar(255)', while 'string not null' will become 'varchar(255) not null'.
	 * @return string the SQL statement for changing the definition of a column.
	 * @since 1.1.6
	 */
	public function alterColumn($table, $column, $type)
	{
		$type=$this->getColumnType($type);
		$sql='ALTER TABLE ' . $this->quoteTableName($table) . ' ALTER COLUMN '
			. $this->quoteColumnName($column) . ' TYPE ' . $this->getColumnType($type);
		return $sql;
	}

	/**
	 * Builds a SQL statement for dropping an index.
	 * @param string $name the name of the index to be dropped. The name will be properly quoted by the method.
	 * @param string $table the table whose index is to be dropped. The name will be properly quoted by the method.
	 * @return string the SQL statement for dropping an index.
	 * @since 1.1.6
	 */
	public function dropIndex($name, $table)
	{
		return 'DROP INDEX '.$this->quoteTableName($name);
	}

	/**
	 * Creates a command builder for the database.
	 * This method may be overridden by child classes to create a DBMS-specific command builder.
	 * @return CPgsqlCommandBuilder command builder instance.
	 */
	protected function createCommandBuilder()
	{
		return new CPgsqlCommandBuilder($this);
	}
}