<?php

/**
    SQL Table Schema Builder extension for the PHP Fat-Free Framework

    The contents of this file are subject to the terms of the GNU General
    Public License Version 3.0. You may not use this file except in
    compliance with the license. Any of the license terms and conditions
    can be waived if you get permission from the copyright holder.

    crafted by   __ __     __
                |__|  |--.|  |--.-----.-----.
                |  |    < |    <|  -__|-- __|
                |__|__|__||__|__|_____|_____|

    Copyright (c) 2014 by ikkez
    Christian Knuth <ikkez0n3@gmail.com>
    https://github.com/ikkez/F3-Sugar/

        @package DB
        @version 2.1.1
 **/


namespace DB\SQL;

use DB\SQL;

class Schema extends DB_Utils {

    public
        $dataTypes = array(
            'BOOLEAN' =>    array('mysql|sqlite2?' => 'BOOLEAN',
                                  'pgsql' => 'text',
                                  'mssql|sybase|dblib|odbc|sqlsrv' => 'bit',
                                  'ibm' => 'numeric(1,0)',
            ),
            'INT1' =>       array('mysql' => 'TINYINT UNSIGNED',
                                  'sqlite2?' => 'integer',
                                  'mssql|sybase|dblib|odbc|sqlsrv' => 'tinyint',
                                  'pgsql|ibm' => 'smallint',
            ),
            'INT2' =>       array('mysql' => 'SMALLINT',
                                  'sqlite2?' => 'integer',
                                  'pgsql|ibm|mssql|sybase|dblib|odbc|sqlsrv' => 'smallint',
            ),
            'INT4' =>       array('sqlite2?|pgsql|sybase|odbc|sqlsrv|imb' => 'integer',
                                  'mysql|mssql|dblib' => 'int',
            ),
            'INT8' =>       array('sqlite2?' => 'integer',
                                  'pgsql|mysql|mssql|sybase|dblib|odbc|sqlsrv|imb' => 'bigint',
            ),
            'FLOAT' =>      array('mysql|sqlite2?' => 'FLOAT',
                                  'pgsql' => 'double precision',
                                  'mssql|sybase|dblib|odbc|sqlsrv' => 'float',
                                  'imb' => 'decfloat'
            ),
            'DOUBLE' =>     array('mysql|sqlite2?|ibm' => 'DOUBLE',
                                  'pgsql|sybase|odbc|sqlsrv' => 'double precision',
                                  'mssql|dblib' => 'decimal',
            ),
            'VARCHAR128' => array('mysql|pgsql|sqlite2?|ibm|mssql|sybase|dblib|odbc|sqlsrv' => 'varchar(128)',
            ),
            'VARCHAR256' => array('mysql|pgsql|sqlite2?|ibm|mssql|sybase|dblib|odbc|sqlsrv' => 'varchar(255)',
            ),
            'VARCHAR512' => array('mysql|pgsql|sqlite2?|ibm|mssql|sybase|dblib|odbc|sqlsrv' => 'varchar(512)',
            ),
            'TEXT' =>       array('mysql|sqlite2?|pgsql|mssql|sybase|dblib|odbc|sqlsrv' => 'text',
                                  'ibm' => 'BLOB SUB_TYPE TEXT',
            ),
            'LONGTEXT' =>   array('mysql' => 'LONGTEXT',
                                  'sqlite2?|pgsql|mssql|sybase|dblib|odbc|sqlsrv' => 'text',
                                  'ibm' => 'CLOB(2000000000)',
            ),
            'DATE' =>       array('mysql|sqlite2?|pgsql|mssql|sybase|dblib|odbc|sqlsrv|ibm' => 'date',
            ),
            'DATETIME' =>   array('pgsql' => 'timestamp without time zone',
                                  'mysql|sqlite2?|mssql|sybase|dblib|odbc|sqlsrv' => 'datetime',
                                  'ibm' => 'timestamp',
            ),
            'TIMESTAMP' =>  array('mysql|ibm' => 'timestamp',
                                  'pgsql|odbc' => 'timestamp without time zone',
                                  'sqlite2?|mssql|sybase|dblib|sqlsrv'=>'DATETIME',
            ),
            'BLOB' =>       array('mysql|odbc|sqlite2?|ibm' => 'blob',
                                  'pgsql' => 'bytea',
                                  'mssql|sybase|dblib' => 'image',
                                  'sqlsrv' => 'varbinary(max)',
            ),
        ),
        $defaultTypes = array(
            'CUR_STAMP' =>  array('mysql' => 'CURRENT_TIMESTAMP',
                                  'mssql|sybase|dblib|odbc|sqlsrv' => 'getdate()',
                                  'pgsql' => 'LOCALTIMESTAMP(0)',
                                  'sqlite2?' => "(datetime('now','localtime'))",
            ),
        );

    public
        $name;

    /** @var \Base */
    protected $fw;

    const
        // DataTypes and Aliases
        DT_BOOL = 'BOOLEAN',
        DT_BOOLEAN = 'BOOLEAN',
        DT_INT1 = 'INT1',
        DT_TINYINT = 'INT1',
        DT_INT2 = 'INT2',
        DT_SMALLINT = 'INT2',
        DT_INT4 = 'INT4',
        DT_INT = 'INT4',
        DT_INT8 = 'INT8',
        DT_BIGINT = 'INT8',
        DT_FLOAT = 'FLOAT',
        DT_DOUBLE = 'DOUBLE',
        DT_DECIMAL = 'DOUBLE',
        DT_VARCHAR128 = 'VARCHAR128',
        DT_VARCHAR256 = 'VARCHAR256',
        DT_VARCHAR512 = 'VARCHAR512',
        DT_TEXT = 'TEXT',
        DT_LONGTEXT = 'LONGTEXT',
        DT_DATE = 'DATE',
        DT_DATETIME = 'DATETIME',
        DT_TIMESTAMP = 'TIMESTAMP',
        DT_BLOB = 'BLOB',
        DT_BINARY = 'BLOB',

        // column default values
        DF_CURRENT_TIMESTAMP = 'CUR_STAMP';


    public function __construct(\DB\SQL $db)
    {
        $this->fw = \Base::instance();
        parent::__construct($db);
    }

    /**
     * get a list of all databases
     * @return array|bool
     */
    public function getDatabases()
    {
        $cmd = array(
            'mysql' => 'SHOW DATABASES',
            'pgsql' => 'SELECT datname FROM pg_catalog.pg_database',
            'mssql|sybase|dblib|sqlsrv|odbc' => 'EXEC SP_HELPDB',
        );
        $query = $this->findQuery($cmd);
        if (!$query) return false;
        $result = $this->db->exec($query);
        if (!is_array($result)) return false;
        foreach($result as &$db)
            if (is_array($db)) $db = array_shift($db);
        return $result;
    }

    /**
     * get all tables of current DB
     * @return bool|array list of tables, or false
     */
    public function getTables()
    {
        $cmd = array(
            'mysql' => array(
                "show tables"),
            'sqlite2?' => array(
                "SELECT name FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'"),
            'pgsql|sybase|dblib' => array(
                "select table_name from information_schema.tables where table_schema = 'public'"),
            'mssql|sqlsrv|odbc' => array(
                "select table_name from information_schema.tables"),
            'ibm' => array("select TABLE_NAME from sysibm.tables"),
        );
        $query = $this->findQuery($cmd);
        if (!$query[0]) return false;
        $tables = $this->db->exec($query[0]);
        if ($tables && is_array($tables) && count($tables) > 0)
            foreach ($tables as &$table)
                $table = array_shift($table);
        return $tables;
    }

    /**
     * returns a table object for creation
     * @param $name
     * @return bool|TableCreator
     */
    public function createTable($name)
    {
        return new TableCreator($name,$this);
    }

    /**
     * returns a table object for altering operations
     * @param $name
     * @return bool|TableModifier
     */
    public function alterTable($name)
    {
        return new TableModifier($name,$this);
    }

    /**
     * rename a table
     * @param string $name
     * @param string $new_name
     * @param bool $exec
     * @return bool
     */
    public function renameTable($name, $new_name, $exec = true)
    {
        $name = $this->db->quotekey($name);
        $new_name = $this->db->quotekey($new_name);
        if (preg_match('/odbc/', $this->db->driver())) {
            $queries = array();
            $queries[] = "SELECT * INTO $new_name FROM $name;";
            $queries[] = $this->dropTable($name, false);
            return ($exec) ? $this->db->exec($queries) : implode("\n",$queries);
        } else {
            $cmd = array(
                'sqlite2?|pgsql' =>
                    "ALTER TABLE $name RENAME TO $new_name;",
                'mysql|ibm' =>
                    "RENAME TABLE $name TO $new_name;",
                'mssql|sqlsrv|sybase|dblib|odbc' =>
                    "sp_rename {$name}, $new_name"
            );
            $query = $this->findQuery($cmd);
            if (!$exec) return $query;
            return (preg_match('/mssql|sybase|dblib|sqlsrv/', $this->db->driver()))
                ? @$this->db->exec($query) : $this->db->exec($query);
        }
    }

    /**
     * drop a table
     * @param \DB\SQL\TableBuilder|string $name
     * @param bool $exec
     * @return bool
     */
    public function dropTable($name, $exec = true)
    {
        if (is_object($name) && $name instanceof TableBuilder)
            $name = $name->name;
        $cmd = array(
            'mysql|ibm|sqlite2?|pgsql|sybase|dblib' =>
                'DROP TABLE IF EXISTS '.$this->db->quotekey($name).';',
            'mssql|sqlsrv|odbc' =>
                "IF OBJECT_ID('[$name]', 'U') IS NOT NULL DROP TABLE [$name];"
        );
        $query = $this->findQuery($cmd);
        return ($exec) ? $this->db->exec($query) : $query;
    }

}

abstract class TableBuilder extends DB_Utils {

    protected   $columns, $pkeys, $queries, $increments, $rebuild_cmd, $suppress;
    public      $name, $schema;

    const
        TEXT_NoDefaultForTEXT = "Column `%s` of type TEXT can't have a default value.",
        TEXT_ColumnExists = "Cannot add the column `%s`. It already exists.";

    /**
     * @param string $name
     * @param Schema $schema
     * @return \DB\SQL\TableBuilder
     */
    public function __construct($name, Schema $schema)
    {
        $this->name = $name;
        $this->schema = $schema;
        $this->columns = array();
        $this->queries = array();
        $this->pkeys = array('id');
        $this->increments = 'id';
        parent::__construct($schema->db);
    }

    /**
     * generate SQL query and execute it if $exec is true
     * @param bool $exec
     */
    abstract public function build($exec = TRUE);

    /**
     * add a new column to this table
     * @param string|Column $key column name or object
     * @param null|array $args optional config array
     * @return \DB\SQL\Column
     */
    public function addColumn($key,$args = null)
    {
        if ($key instanceof Column) {
            $args = $key->getColumnArray();
            $key = $key->name;
        }
        if (array_key_exists($key,$this->columns))
            trigger_error(sprintf(self::TEXT_ColumnExists,$key));
        $column = new Column($key, $this);
        if ($args)
            foreach ($args as $arg => $val)
                $column->{$arg} = $val;
        // skip default pkey field
        if (count($this->pkeys) == 1 && in_array($key,$this->pkeys))
            return $column;
        return $this->columns[$key] =& $column;
    }

    /**
     * create index on one or more columns
     * @param string|array $index_cols Column(s) to be indexed
     * @param              $search_cols
     * @param bool         $unique     Unique index
     * @param int          $length     index length for text fields in mysql
     */
    protected function _addIndex($index_cols, $search_cols, $unique, $length)
    {
        if (!is_array($index_cols))
            $index_cols = array($index_cols);
        $quotedCols = array_map(array($this->db, 'quotekey'), $index_cols);
        if (preg_match('/mysql/', $this->db->driver()))
            foreach($quotedCols as $i=>&$col)
                if(strtoupper($search_cols[$index_cols[$i]]['type']) == 'TEXT')
                    $col.='('.$length.')';
        $cols = implode(',', $quotedCols);
        $name = $this->db->quotekey($this->name.'___'.implode('__', $index_cols));
        $table = $this->db->quotekey($this->name);
        $index = $unique ? 'UNIQUE INDEX' : 'INDEX';
        $cmd = array(
            'pgsql|sqlite2?|ibm|mssql|sybase|dblib|odbc|sqlsrv' =>
                "CREATE $index $name ON $table ($cols);",
            'mysql' => //ALTER TABLE is used because of MySQL bug #48875
                "ALTER TABLE $table ADD $index $name ($cols);",
        );
        $query = $this->findQuery($cmd);
        $this->queries[] = $query;
    }

    /**
     * set primary / composite key to table
     * @param string|array $pkeys
     * @return bool
     */
    public function primary($pkeys) {
        if (empty($pkeys))
            return false;
        if (!is_array($pkeys))
            $pkeys = array($pkeys);
        // single pkey
        $this->increments = $pkeys[0];
        $this->pkeys = $pkeys;
        // drop duplicate pkey definition
        if (array_key_exists($this->increments,$this->columns))
            unset($this->columns[$this->increments]);
        // set flag on new fields
        foreach ($pkeys as $name)
            if(array_key_exists($name,$this->columns))
                $this->columns[$name]->pkey = true;
        // composite key
        if (count($pkeys) > 1) {
            $pkeys_quoted = array_map(array($this->db,'quotekey'), $pkeys);
            $pk_string = implode(', ', $pkeys_quoted);
            if (preg_match('/sqlite2?/', $this->db->driver())) {
                // rebuild table with new primary keys
                $this->rebuild_cmd['pkeys'] = $pkeys;
                return;
            } else {
                $table = $this->db->quotekey($this->name);
                $table_key = $this->db->quotekey($this->name.'_pkey');
                $cmd = array(
                    'odbc' =>
                        "CREATE INDEX $table_key ON $table ( $pk_string );",
                    'mysql' =>
                        "ALTER TABLE $table DROP PRIMARY KEY, ADD PRIMARY KEY ( $pk_string );",
                    'mssql|sybase|dblib|sqlsrv' => array(
                        "ALTER TABLE $table DROP CONSTRAINT PK_".$this->name."_ID;",
                        "ALTER TABLE $table ADD CONSTRAINT $table_key PRIMARY KEY ( $pk_string );",
                    ),
                    'pgsql' => array(
                        "ALTER TABLE $table DROP CONSTRAINT $table_key;",
                        "ALTER TABLE $table ADD CONSTRAINT $table_key PRIMARY KEY ( $pk_string );",
                    ),
                );
                $query = $this->findQuery($cmd);
                if (!is_array($query))
                    $query = array($query);
                foreach ($query as $q)
                    $this->queries[] = $q;
            }
        }
    }

}

class TableCreator extends TableBuilder {

    const
        TEXT_TableAlreadyExists = "Table `%s` already exists. Cannot create it.";

    /**
     * generate SQL query for creating a basic table, containing an ID serial field
     * and execute it if $exec is true, otherwise just return the generated query string
     * @param bool $exec
     * @return bool|TableModifier|string
     */
    public function build($exec = TRUE)
    {
        // check if already existing
        if ($exec && in_array($this->name, $this->schema->getTables())) {
            trigger_error(sprintf(self::TEXT_TableAlreadyExists,$this->name));
            return false;
        }
        $cols = '';
        if (!empty($this->columns))
            foreach ($this->columns as $cname => $column) {
                // no defaults for TEXT type
                if ($column->default !== false && is_int(strpos(strtoupper($column->type),'TEXT'))) {
                    trigger_error(sprintf(self::TEXT_NoDefaultForTEXT, $column->name));
                    return false;
                }
                $cols .= ', '.$column->getColumnQuery();
            }
        $table = $this->db->quotekey($this->name);
        $id = $this->db->quotekey($this->increments);
        $cmd = array(
            'sqlite2?|sybase|dblib' =>
                "CREATE TABLE $table ($id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT".$cols.");",
            'mysql' =>
                "CREATE TABLE $table ($id INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT".$cols.") DEFAULT CHARSET=utf8 COLLATE utf8_unicode_ci;",
            'pgsql' =>
                "CREATE TABLE $table ($id SERIAL PRIMARY KEY".$cols.");",
            'mssql|odbc|sqlsrv' =>
                "CREATE TABLE $table ($id INT IDENTITY CONSTRAINT PK_".$this->name."_ID PRIMARY KEY".$cols.");",
            'ibm' =>
                "CREATE TABLE $table ($id INTEGER AS IDENTITY NOT NULL $cols, PRIMARY KEY($id));",
        );
        $query = $this->findQuery($cmd);
        // composite key for sqlite
        if (count($this->pkeys) > 1 && preg_match('/sqlite2?/', $this->db->driver())) {
            $pk_string = implode(', ', $this->pkeys);
            $query = "CREATE TABLE $table ($id INTEGER NULL".$cols.", PRIMARY KEY ($pk_string) );";
            $newTable = new TableModifier($this->name, $this->schema);
            // auto-incrementation in composite primary keys
            $pk_queries = $newTable->_sqlite_increment_trigger($this->increments);
            $this->queries = array_merge($this->queries, $pk_queries);
        }
        array_unshift($this->queries, $query);
        // indexes
        foreach ($this->columns as $cname => $column)
            if ($column->index)
                $this->addIndex($cname, $column->unique);
        if (!$exec)
            return $this->queries;
        $this->db->exec($this->queries);
        return isset($newTable) ? $newTable : new TableModifier($this->name,$this->schema);
    }

    /**
     * create index on one or more columns
     * @param string|array $columns Column(s) to be indexed
     * @param bool         $unique  Unique index
     * @param int          $length  index length for text fields in mysql
     */
    public function addIndex($columns, $unique = FALSE, $length = 20)
    {
        if (!is_array($columns))
            $columns = array($columns);
        $cols = $this->columns;
        foreach ($cols as &$col)
            $col = $col->getColumnArray();
        parent::_addIndex($columns,$cols,$unique,$length);
    }

}


class TableModifier extends TableBuilder {

    protected
        $colTypes, $rebuild_cmd;

    const
        // error messages
        TEXT_TableNotExisting = "Unable to alter table `%s`. It does not exist.",
        TEXT_NotNullFieldNeedsDefault = 'You cannot add the not nullable column `%s` without specifying a default value',
        TEXT_ENGINE_NOT_SUPPORTED = 'DB Engine `%s` is not supported for this action.';

    /**
     * generate SQL queries for altering the table and execute it if $exec is true,
     * otherwise return the generated query string
     */
    public function build($exec = TRUE)
    {
        // check if table exists
        if (!in_array($this->name, $this->schema->getTables()))
            trigger_error(sprintf(self::TEXT_TableNotExisting, $this->name));

        if ($sqlite = preg_match('/sqlite2?/', $this->db->driver())) {
            $sqlite_queries = array();
        }
        $rebuild = false;
        $additional_queries = $this->queries;
        $this->queries = array();
        // add new columns
        foreach ($this->columns as $cname => $column) {
            // not nullable fields should have a default value, when altering a table
            if ($column->default === false && $column->nullable === false) {
                trigger_error(sprintf(self::TEXT_NotNullFieldNeedsDefault, $column->name));
                return false;
            }
            // no defaults for TEXT type
            if($column->default !== false && is_int(strpos(strtoupper($column->type),'TEXT'))) {
                trigger_error(sprintf(self::TEXT_NoDefaultForTEXT, $column->name));
                return false;
            }
            $table = $this->db->quotekey($this->name);
            $col_query = $column->getColumnQuery();
            if ($sqlite) {
                // sqlite: dynamic column default only works when rebuilding the table
                if($column->default === Schema::DF_CURRENT_TIMESTAMP) {
                    $rebuild = true;
                    break;
                } else
                    $sqlite_queries[] = "ALTER TABLE $table ADD $col_query;";
            } else {
                $cmd = array(
                    'mysql|pgsql|mssql|sybase|dblib|odbc|sqlsrv' =>
                        "ALTER TABLE $table ADD $col_query;",
                    'ibm' =>
                        "ALTER TABLE $table ADD COLUMN $col_query;",
                );
                $this->queries[] = $this->findQuery($cmd);
            }
        }
        if ($sqlite)
            if ($rebuild || !empty($this->rebuild_cmd)) $this->_sqlite_rebuild($exec);
            else $this->queries += $sqlite_queries;
        $this->queries = array_merge($this->queries,$additional_queries);
        // add new indexes
        foreach ($this->columns as $cname => $column)
            if ($column->index)
                $this->addIndex($cname, $column->unique);
        if (empty($this->queries))
            return false;
        if (is_array($this->queries) && count($this->queries) == 1)
            $this->queries = $this->queries[0];
        if (!$exec) return $this->queries;
        $result = ($this->suppress)
            ? @$this->db->exec($this->queries) : $this->db->exec($this->queries);
        $this->queries = $this->columns = $this->rebuild_cmd = array();
        return $result;
    }

    /**
     * rebuild a sqlite table with additional schema changes
     */
    protected function _sqlite_rebuild($exec=true)
    {
        $new_columns = $this->columns;
        $existing_columns = $this->getCols(true);
        // find after sorts
        $after = array();
        foreach ($new_columns as $cname => $column)
            if(!empty($column->after))
                $after[$column->after][] = $cname;
        // find rename commands
        $rename = (!empty($this->rebuild_cmd) && array_key_exists('rename',$this->rebuild_cmd))
                  ? $this->rebuild_cmd['rename'] : array();
        // get primary-key fields
        foreach ($existing_columns as $key => $col)
            if ($col['pkey'])
                $pkeys[array_key_exists($key,$rename) ? $rename[$key] : $key] = $col;
        foreach ($new_columns as $key => $col)
            if ($col->pkey)
                $pkeys[$key] = $col;
        // indexes
        $indexes = $this->listIndex();
        // drop fields
        if (!empty($this->rebuild_cmd) && array_key_exists('drop', $this->rebuild_cmd))
            foreach ($this->rebuild_cmd['drop'] as $name)
                if (array_key_exists($name, $existing_columns)) {
                    if (array_key_exists($name, $pkeys)) {
                        unset($pkeys[$name]);
                        // drop composite key
                        if(count($pkeys) == 1) {
                            $incrementTrigger = $this->db->quotekey($this->name.'_insert');
                            $this->queries[] = 'DROP TRIGGER IF EXISTS '.$incrementTrigger;
                        }
                    }
                    unset($existing_columns[$name]);
                    // drop index
                    foreach (array_keys($indexes) as $col) {
                        // for backward compatibility
                        if ($col == $name)
                            unset($indexes[$name]);
                        // new index names
                        if ($col == $this->name.'___'.$name)
                            unset($indexes[$this->name.'___'.$name]);
                        // check if column is part of an existing combined index
                        if (is_int(strpos($col, '__'))) {
                            if (is_int(strpos($col, '___'))) {
                                $col = explode('___', $col);
                                $ci = explode('__', $col[1]);
                                $col = implode('___',$col);
                            } else // for backward compatibility
                                $ci = explode('__', $col);
                            // drop combined index
                            if (in_array($name, $ci))
                                unset($indexes[$col]);
                        }
                    }
                }       
        // create new table
        $oname = $this->name;
        $this->queries[] = $this->rename($oname.'_temp', false);
        $newTable = $this->schema->createTable($oname);
        // add existing fields
        foreach ($existing_columns as $name => $col) {
            $colName = array_key_exists($name, $rename) ? $rename[$name] : $name;
            // update column datatype
            if (array_key_exists('update',$this->rebuild_cmd)
                && in_array($name,array_keys($this->rebuild_cmd['update'])))
                $col['type']=$this->rebuild_cmd['update'][$name];
            $newTable->addColumn($colName, $col)->passThrough();
            // add new fields with after flag
            if (array_key_exists($name,$after))
                foreach (array_reverse($after[$name]) as $acol) {
                    $newTable->addColumn($new_columns[$acol]);
                    unset($new_columns[$acol]);
                }
        }
        // add remaining new fields
        foreach ($new_columns as $ncol)
            $newTable->addColumn($ncol);
        $newTable->primary(array_keys($pkeys));
        // add existing indexes
        foreach (array_reverse($indexes) as $name=>$conf) {
            if (is_int(strpos($name, '___')))
               list($tname,$name) = explode('___', $name);
            if (is_int(strpos($name, '__')))
                $name = explode('__', $name);
            if ($exec) {
                $t = $this->schema->alterTable($oname);
                $t->dropIndex($name);
                $t->build();
            }
            $newTable->addIndex($name,$conf['unique']);
        }
        // build new table
        $newTableQueries = $newTable->build(false);
        $this->queries = array_merge($this->queries,$newTableQueries);
        // copy data
        if (!empty($existing_columns)) {
            foreach (array_keys($existing_columns) as $name) {
                $fields_from[] = $this->db->quotekey($name);
                $toName = array_key_exists($name, $rename) ? $rename[$name] : $name;
                $fields_to[] = $this->db->quotekey($toName);
            }
            $this->queries[] =
                'INSERT INTO '.$this->db->quotekey($newTable->name).' ('.implode(', ', $fields_to).') '.
                'SELECT '.implode(', ', $fields_from).' FROM '.$this->db->quotekey($this->name).';';
        }
        $this->queries[] = $this->drop(false);
        $this->name = $oname;
    }

    /**
     * create an insert trigger to work-a-round auto-incrementation in composite primary keys
     * @param $pkey
     * @return array
     */
    public function _sqlite_increment_trigger($pkey) {
        $table = $this->db->quotekey($this->name);
        $pkey = $this->db->quotekey($pkey);
        $triggerName = $this->db->quotekey($this->name.'_insert');
        $queries[] = "DROP TRIGGER IF EXISTS $triggerName;";
        $queries[] = 'CREATE TRIGGER '.$triggerName.' AFTER INSERT ON '.$table.
                     ' WHEN (NEW.'.$pkey.' IS NULL) BEGIN'.
                     ' UPDATE '.$table.' SET '.$pkey.' = ('.
                     ' select coalesce( max( '.$pkey.' ), 0 ) + 1 from '.$table.
                     ') WHERE ROWID = NEW.ROWID;'.
                     ' END;';
        return $queries;
    }

    /**
     * get columns of a table
     * @param bool $types
     * @return array
     */
    public function getCols($types = false)
    {
        $schema = $this->db->schema($this->name, null, 0);
        if (!$types)
            return array_keys($schema);
        else
            foreach ($schema as $name => &$cols) {
                $default = ($cols['default'] === '') ? null : $cols['default'];
                if (!is_null($default) && (
                    (is_int(strpos($curdef=$this->findQuery($this->schema->defaultTypes['CUR_STAMP']),
                    $default)) || is_int(strpos($default,$curdef)))
                    || $default == "('now'::text)::timestamp(0) without time zone"))
                {
                    $default = 'CUR_STAMP';
                } elseif (!is_null($default)) {
                    // remove single-qoutes
                    if (preg_match('/sqlite2?/', $this->db->driver()))
                        $default=preg_replace('/^\s*([\'"])(.*)\1\s*$/','\2',$default);
                    elseif (preg_match('/mssql|sybase|dblib|odbc|sqlsrv/', $this->db->driver()))
                        $default=preg_replace('/^\s*(\(\')(.*)(\'\))\s*$/','\2',$default);
                    // extract value from character_data in postgre
                    elseif (preg_match('/pgsql/', $this->db->driver()))
                        if (is_int(strpos($default, 'nextval')))
                            $default = null; // drop autoincrement default
                        elseif (preg_match("/^\'*(.*)\'*::(\s*\w)+/", $default, $match))
                            $default = $match[1];
                } else
                    $default=false;
                $cols['default'] = $default;
            }
        return $schema;
    }

    /**
     * removes a column from a table
     * @param string $name
     * @return bool
     */
    public function dropColumn($name)
    {
        $colTypes = $this->getCols(true);
        // check if column exists
        if (!in_array($name, array_keys($colTypes))) return true;
        if (preg_match('/sqlite2?/', $this->db->driver())) {
            // SQlite does not support drop column directly
            $this->rebuild_cmd['drop'][] = $name;
        } else {
            $quotedTable = $this->db->quotekey($this->name);
            $quotedColumn = $this->db->quotekey($name);
            $cmd = array(
                'mysql' =>
                    "ALTER TABLE $quotedTable DROP $quotedColumn;",
                'pgsql|odbc|ibm|mssql|sybase|dblib|sqlsrv' =>
                    "ALTER TABLE $quotedTable DROP COLUMN $quotedColumn;",
            );
            if (preg_match('/mssql|sybase|dblib|sqlsrv/', $this->db->driver()))
                $this->suppress=true;
            $this->queries[] = $this->findQuery($cmd);
        }
    }

    /**
     * rename a column
     * @param $name
     * @param $new_name
     * @return void
     */
    public function renameColumn($name, $new_name)
    {
        $existing_columns = $this->getCols(true);
        // check if column is already existing
        if (!in_array($name, array_keys($existing_columns)))
            trigger_error('cannot rename column. it does not exist.');
        if (in_array($new_name, array_keys($existing_columns)))
            trigger_error('cannot rename column. new column already exist.');
        
        if (preg_match('/sqlite2?/', $this->db->driver()))
            // SQlite does not support drop or rename column directly
            $this->rebuild_cmd['rename'][$name] = $new_name;
        elseif (preg_match('/odbc/', $this->db->driver())) {
            // no rename column for odbc, create temp column
            $this->addColumn($new_name, $existing_columns[$name])->passThrough();
            $this->queries[] = "UPDATE $this->name SET $new_name = $name";
            $this->dropColumn($name);
        } else {
            $existing_columns = $this->getCols(true);
            $quotedTable = $this->db->quotekey($this->name);
            $quotedColumn = $this->db->quotekey($name);
            $quotedColumnNew = $this->db->quotekey($new_name);
            $cmd = array(
                'mysql' =>
                    "ALTER TABLE $quotedTable CHANGE $quotedColumn $quotedColumnNew ".$existing_columns[$name]['type'].";",
                'pgsql|ibm' =>
                    "ALTER TABLE $quotedTable RENAME COLUMN $quotedColumn TO $quotedColumnNew;",
                'mssql|sybase|dblib|sqlsrv' =>
                    "sp_rename [$this->name.$name], '$new_name', 'Column'",
            );
            if (preg_match('/mssql|sybase|dblib|sqlsrv/', $this->db->driver()))
                $this->suppress = true;
            $this->queries[] = $this->findQuery($cmd);
        }
    }

    /**
     * modifies column datatype
     * @param      $name
     * @param      $datatype
     * @param bool $force
     * @return bool
     */
    public function updateColumn($name, $datatype, $force = false)
    {
        if(!$force)
            $datatype = $this->findQuery($this->schema->dataTypes[strtoupper($datatype)]);
        $table = $this->db->quotekey($this->name);
        $column = $this->db->quotekey($name);
        if (preg_match('/sqlite2?/', $this->db->driver())){
            $this->rebuild_cmd['update'][$name] = $datatype;
        } else {
            $cmd = array(
            'mysql' =>
                "ALTER TABLE $table MODIFY COLUMN $column $datatype;",
            'pgsql' =>
                "ALTER TABLE $table ALTER COLUMN $column TYPE $datatype;",
            'sqlsrv|mssql|sybase|dblib|ibm' =>
                "ALTER TABLE $table ALTER COLUMN $column $datatype;",
            );
            $this->queries[] = $this->findQuery($cmd);
        }
    }

    /**
     * create index on one or more columns
     * @param string|array $columns Column(s) to be indexed
     * @param bool         $unique  Unique index
     * @param int          $length  index length for text fields in mysql
     */
    public function addIndex($columns, $unique = FALSE, $length = 20)
    {
        if (!is_array($columns))
            $columns = array($columns);
        $existingCol = $this->columns;
        foreach ($existingCol as &$col)
            $col = $col->getColumnArray();
        $allCols = array_merge($this->getCols(true), $existingCol);
        parent::_addIndex($columns, $allCols, $unique, $length);
    }

    /**
     * drop a column index
     * @param string|array $name
     */
    public function dropIndex($name)
    {
        if (is_array($name))
            $name = $this->name.'___'.implode('__', $name);
        elseif(!is_int(strpos($name,'___')))
            $name = $this->name.'___'.$name;
        $name = $this->db->quotekey($name);
        $table = $this->db->quotekey($this->name);
        $cmd = array(
            'pgsql|sqlite2?|ibm' =>
                "DROP INDEX $name;",
            'mssql|sybase|dblib|odbc|sqlsrv' =>
                "DROP INDEX $table.$name;",
            'mysql'=>
                "ALTER TABLE $table DROP INDEX $name;",
        );
        $query = $this->findQuery($cmd);
        $this->queries[] = $query;
    }

    /**
     * returns table indexes as assoc array
     * @return array
     */
    public function listIndex()
    {
        $table = $this->db->quotekey($this->name);
        $cmd = array(
            'sqlite2?' =>
                "PRAGMA index_list($table);",
            'mysql' =>
                "SHOW INDEX FROM $table;",
            'mssql|sybase|dblib|sqlsrv' =>
                "select * from sys.indexes ".
                "where object_id = (select object_id from sys.objects where name = '$this->name')",
            'pgsql' =>
                "select i.relname as name, ix.indisunique as unique ".
                "from pg_class t, pg_class i, pg_index ix ".
                "where t.oid = ix.indrelid and i.oid = ix.indexrelid ".
                "and t.relkind = 'r' and t.relname = '$this->name'".
                "group by t.relname, i.relname, ix.indisunique;",
        );
        $result = $this->db->exec($this->findQuery($cmd));
        $indexes = array();
        if (preg_match('/pgsql|sqlite2?/', $this->db->driver())) {
            foreach($result as $row)
                $indexes[$row['name']] = array('unique' => $row['unique']);
        } elseif (preg_match('/mssql|sybase|dblib|sqlsrv/', $this->db->driver())) {
            foreach ($result as $row)
                $indexes[$row['name']] = array('unique' => $row['is_unique']);
        } elseif (preg_match('/mysql/', $this->db->driver())) {
            foreach($result as $row)
                $indexes[$row['Key_name']] = array('unique' => !(bool)$row['Non_unique']);
        } else
            trigger_error(sprintf(self::TEXT_ENGINE_NOT_SUPPORTED, $this->db->driver()));
        return $indexes;
    }

    /**
     * rename this table
     * @param string $new_name
     * @param bool $exec
     * @return $this|bool
     */
    public function rename($new_name, $exec = true) {
        $query = $this->schema->renameTable($this->name, $new_name, $exec);
        $this->name = $new_name;
        return ($exec) ? $this : $query;
    }

    /**
     * drop this table
     * @param bool $exec
     * @return mixed
     */
    public function drop($exec = true) {
        return $this->schema->dropTable($this,$exec);
    }

}

/**
 * defines a table column configuration
 * Class Column
 * @package DB\SQL
 */
class Column extends DB_Utils {

    public      $name, $type, $nullable, $default, $after, $index, $unique, $passThrough, $pkey;
    protected   $table, $schema;

    const
        TEXT_NoDataType = 'The specified datatype %s is not defined in %s driver',
        TEXT_CurrentStampDataType = 'Current timestamp as column default is only possible for TIMESTAMP datatype';

    /**
     * @param string $name
     * @param TableBuilder $table
     */
    public function __construct($name, TableBuilder $table) {
        $this->name = $name;
        $this->nullable = true;
        $this->default = false;
        $this->after = false;
        $this->index = false;
        $this->unique = false;
        $this->passThrough = false;
        $this->pkey = false;

        $this->table = $table;
        $this->schema = $table->schema;
        parent::__construct($this->schema->db);
    }

    /**
     * @param string $datatype
     * @param bool $force don't match datatype against DT array
     * @return $this
     */
    public function type($datatype, $force = FALSE) {
        $this->type = $datatype;
        $this->passThrough = $force;
        return $this;
    }

    public function type_tinyint() {
        $this->type = Schema::DT_INT1;
        return $this;
    }

    public function type_smallint() {
        $this->type = Schema::DT_INT2;
        return $this;
    }

    public function type_int() {
        $this->type = Schema::DT_INT4;
        return $this;
    }

    public function type_bigint() {
        $this->type = Schema::DT_INT8;
        return $this;
    }

    public function type_float() {
        $this->type = Schema::DT_FLOAT;
        return $this;
    }

    public function type_decimal() {
        $this->type = Schema::DT_DOUBLE;
        return $this;
    }

    public function type_text() {
        $this->type = Schema::DT_TEXT;
        return $this;
    }

    public function type_longtext() {
        $this->type = Schema::DT_LONGTEXT;
        return $this;
    }

    public function type_varchar($length = 255) {
        $this->type = "varchar($length)";
        $this->passThrough = true;
        return $this;
    }

    public function type_date() {
        $this->type = Schema::DT_DATE;
        return $this;
    }

    public function type_datetime() {
        $this->type = Schema::DT_DATETIME;
        return $this;
    }

    public function type_timestamp($asDefault=false) {
        $this->type = Schema::DT_TIMESTAMP;
        if ($asDefault)
            $this->default = Schema::DF_CURRENT_TIMESTAMP;
        return $this;
    }

    public function type_blob() {
        $this->type = Schema::DT_BLOB;
        return $this;
    }

    public function type_bool() {
        $this->type = Schema::DT_BOOLEAN;
        return $this;
    }

    public function passThrough($state = TRUE) {
        $this->passThrough = $state;
        return $this;
    }

    public function nullable($nullable) {
        $this->nullable = $nullable;
        return $this;
    }

    public function defaults($default) {
        $this->default = $default;
        return $this;
    }

    public function after($name) {
        $this->after = $name;
        return $this;
    }

    public function index($unique = FALSE) {
        $this->index = true;
        $this->unique = $unique;
        return $this;
    }

    /**
     * returns an array of this column configuration
     * @return array
     */
    public function getColumnArray()
    {
        $fields = array('name','type','passThrough','default','nullable',
                        'index','unique','after','pkey');
        $fields = array_flip($fields);
        foreach($fields as $key => &$val)
            $val = $this->{$key};
        unset($val);
        return $fields;
    }

    /**
     * generate SQL column definition query
     * @return bool|string
     */
    public function getColumnQuery()
    {
        if (!$this->type)
            trigger_error(sprintf('Cannot build a column query for `%s`: no column type set',$this->name));
        // prepare column types
        if ($this->passThrough)
            $type_val = $this->type;
        else {
            $type_val = $this->findQuery($this->schema->dataTypes[strtoupper($this->type)]);
            if (!$type_val) {
                trigger_error(sprintf(self::TEXT_NoDataType, strtoupper($this->type),
                    $this->db->driver()));
                return FALSE;
            }
        }
        // build query
        $query = $this->db->quotekey($this->name).' '.$type_val.' '.
            ($this->nullable ? 'NULL' : 'NOT NULL');
        // default value
        if ($this->default !== false) {
            $def_cmds = array(
                'sqlite2?|mysql|pgsql|mssql|sybase|dblib|odbc|sqlsrv' => 'DEFAULT',
                'ibm' => 'WITH DEFAULT',
            );
            $def_cmd = $this->findQuery($def_cmds).' ';
            // timestamp default
            if ($this->default === Schema::DF_CURRENT_TIMESTAMP) {
                // check for right datatpye
                $stamp_type = $this->findQuery($this->schema->dataTypes['TIMESTAMP']);
                if ($this->type != 'TIMESTAMP' && // TODO: check that condition
                    ($this->passThrough && strtoupper($this->type) != strtoupper($stamp_type))
                )
                    trigger_error(self::TEXT_CurrentStampDataType);
                $def_cmd .= $this->findQuery($this->schema->defaultTypes[strtoupper($this->default)]);
            } else {
                // static defaults
                $pdo_type = preg_match('/int|bool/i', $type_val, $parts) ?
                    constant('\PDO::PARAM_'.strtoupper($parts[0])) : \PDO::PARAM_STR;
                $def_cmd .= ($this->default === NULL ? 'NULL' :
                    $this->db->quote(htmlspecialchars($this->default, ENT_QUOTES,
                        $this->f3->get('ENCODING')), $pdo_type));
            }
            $query .= ' '.$def_cmd;
        }
        if (!empty($this->after)) {
            // `after` feature only works for mysql
            if (preg_match('/mysql/', $this->db->driver())) {
                $after_cmd = 'AFTER '.$this->db->quotekey($this->after);
                $query .= ' '.$after_cmd;
            }
        }
        return $query;
    }
}


class DB_Utils {

    /** @var \DB\SQL */
    protected $db;

    /** @var \BASE */
    protected $f3;

    const
        TEXT_ENGINE_NOT_SUPPORTED = 'DB Engine `%s` is not supported for this action.';

    /**
     * parse command array and return backend specific query
     * @param $cmd
     * @param $cmd array
     * @return bool|string
     */
    protected function findQuery($cmd)
    {
        $match = FALSE;
        foreach ($cmd as $backend => $val)
            if (preg_match('/'.$backend.'/', $this->db->driver())) {
                $match = TRUE;
                break;
            }
        if (!$match) {
            trigger_error(sprintf(self::TEXT_ENGINE_NOT_SUPPORTED, $this->db->driver()));
            return FALSE;
        }
        return $val;
    }

    public function __construct(SQL $db) {
        $this->db = $db;
        $this->f3 = \Base::instance();
    }
}