<?php
/*
 * Helper functions for building a DataTables server-side processing SQL query
 *
 * The static functions in this class are just helper functions to help build
 * the SQL used in the DataTables demo server-side processing scripts. These
 * functions obviously do not represent all that can be done with server-side
 * processing, they are intentionally simple to show how it works. More complex
 * server-side processing operations will likely require a custom script.
 *
 * See http://datatables.net/usage/server-side for full details on the server-
 * side processing requirements of DataTables.
 *
 * @license MIT - http://datatables.net/license_mit
 *
 * @author Aleksey Shutiy<shutiy@ligthsoft.ru>
 */
class SSP {

	/**
	 * * 'Result condition' - This is applied to the result set, but not the
	 *   overall paging information query - i.e. it will not effect the number
	 *   of records that a user sees they can have access to. This should be
	 *   used when you want apply a filtering condition that the user has sent.
	 * * 'All condition' - This is applied to all queries that are made and
	 *   reduces the number of records that the user can access. This should be
	 *   used in conditions where you don't want the user to ever have access to
	 *   particular records (for example, restricting by a login id).
	 *
	 *  @param  array $request Data sent to server by DataTables
	 *  @param  PDO $db PDO connection resource
	 *  @param  string $table SQL table to query
	 *  @param  string $primaryKey Primary key of the table
	 *  @param  array $columns Column information array
	 *  @param  string $whereResult WHERE condition to apply to the result set
	 *  @param  string $whereAll WHERE condition to apply to all queries
	 *  @return array          Server-side processing response array
	 */
	static function complex ( $request, $db, $sub_select, $total_select, $from, $primaryKey, $columns, $whereResult=null, $whereAll=null )
	{
		$bindings = array();
		$localWhereResult = array();
		$localWhereAll = array();
		$whereAllSql = '';
		// Build the SQL query string from the request
		$limit = self::limit( $request, $columns );
		$order = self::order( $request, $columns );
		$where = self::filter( $request, $columns, $bindings );
		$whereResult = self::_flatten( $whereResult );
		$whereAll = self::_flatten( $whereAll );
		if ( $whereResult ) {
			$where = $where ?
				$where .' AND '.$whereResult :
				'WHERE '.$whereResult;
		}
		if ( $whereAll ) {
			$where = $where ?
				$where .' AND '.$whereAll :
				'WHERE '.$whereAll;
			$whereAllSql = 'WHERE '.$whereAll;
		}
		// Main query to actually get the data
		$sql = "SELECT `".implode("`, `", self::pluck($columns, 'db'))."`
			FROM ($sub_select
			$from
			$where
			$order
			$limit) as t";
		$data = $db->query(
			"SELECT `".implode("`, `", self::pluck($columns, 'db'))."`
			FROM ($sub_select
			$from
			$where
			$order
			$limit) as t",
			$bindings
		)->rows;

		$sum_row = $db->query("$total_select $from $where", $bindings);

		$total = array_fill_keys(array_column($columns, 'db'), '');
		
		$total['c_name']     = 'Total:';
		$total['total_cod']  = $sum_row->row['sum_cod'];
		$total['total_free'] = $sum_row->row['sum_free'];
		
		$data[] = $total;

		// Data set length after filtering
		$recordsFiltered = $db->query(
			"SELECT COUNT(`{$primaryKey}`) as total
			 FROM ($sub_select
			 $from
			 $where) as t",
			$bindings
		)->row['total'];

		// Total data set length
		$recordsTotal = $db->query(
			"SELECT COUNT(`{$primaryKey}`) as total
			 FROM ($sub_select
			 $from
			{$whereAllSql}) as t",
			$bindings
		)->row['total'];
		/*
		 * Output
		 */
		return array(
			"draw"            => isset ( $request['draw'] ) ?
				intval( $request['draw'] ) :
				0,
			"recordsTotal"    => intval( $recordsTotal ),
			"recordsFiltered" => intval( $recordsFiltered ),
			"data"            => self::data_output( $columns, $data )
		);
	}

	/**
	 * Create the data output array for the DataTables rows
	 *
	 *  @param  array $columns Column information array
	 *  @param  array $data    Data from the SQL get
	 *  @return array          Formatted data in a row based format
	 */
	static function data_output ( $columns, $data )
	{
		$out = array();
		for ( $i=0, $ien=count($data) ; $i<$ien ; $i++ ) {
			$row = array();
			for ( $j=0, $jen=count($columns) ; $j<$jen ; $j++ ) {
				$column = $columns[$j];
				// Is there a formatter?
				if ( isset( $column['formatter'] ) ) {
					$row[ $column['dt'] ] = $column['formatter']( $data[$i][ $column['db'] ], $data[$i] );
				}
				else {
					$row[ $column['dt'] ] = $data[$i][ $columns[$j]['db'] ];
				}
			}
			$out[] = $row;
		}
		return $out;
	}

	/**
	 * Paging
	 *
	 * Construct the LIMIT clause for server-side processing SQL query
	 *
	 *  @param  array $request Data sent to server by DataTables
	 *  @param  array $columns Column information array
	 *  @return string SQL limit clause
	 */
	static function limit ( $request, $columns )
	{
		$limit = '';
		if ( isset($request['start']) && $request['length'] != -1 ) {
			$limit = "LIMIT ".intval($request['start']).", ".intval($request['length']);
		}
		return $limit;
	}

	/**
	 * Ordering
	 *
	 * Construct the ORDER BY clause for server-side processing SQL query
	 *
	 *  @param  array $request Data sent to server by DataTables
	 *  @param  array $columns Column information array
	 *  @return string SQL order by clause
	 */
	static function order ( $request, $columns )
	{
		$order = '';
		if ( isset($request['order']) && count($request['order']) ) {
			$orderBy = array();
			$dtColumns = self::pluck( $columns, 'dt' );
			for ( $i=0, $ien=count($request['order']) ; $i<$ien ; $i++ ) {
				// Convert the column index into the column data property
				$columnIdx = intval($request['order'][$i]['column']);
				$requestColumn = $request['columns'][$columnIdx];
				$columnIdx = array_search( $requestColumn['data'], $dtColumns );
				$column = $columns[ $columnIdx ];
				if ( $requestColumn['orderable'] == 'true' ) {
					$dir = $request['order'][$i]['dir'] === 'asc' ?
						'ASC' :
						'DESC';
					$orderBy[] = '`'.$column['db'].'` '.$dir;
				}
			}
			$order = 'ORDER BY '.implode(', ', $orderBy);
		}
		return $order;
	}

	/**
	 * Searching / Filtering
	 *
	 * Construct the WHERE clause for server-side processing SQL query.
	 *
	 * NOTE this does not match the built-in DataTables filtering which does it
	 * word by word on any field. It's possible to do here performance on large
	 * databases would be very poor
	 *
	 *  @param  array $request Data sent to server by DataTables
	 *  @param  array $columns Column information array
	 *  @param  array $bindings Array of values for PDO bindings, used in the
	 *    sql_exec() function
	 *  @return string SQL where clause
	 */
	static function filter ( $request, $columns, &$bindings )
	{
		$globalSearch = array();
		$columnSearch = array();
		$dtColumns = self::pluck( $columns, 'dt' );
		if ( isset($request['search']) && $request['search']['value'] != '' ) {
			$str = $request['search']['value'];
			for ( $i=0, $ien=count($request['columns']) ; $i<$ien ; $i++ ) {
				$requestColumn = $request['columns'][$i];
				$columnIdx = array_search( $requestColumn['data'], $dtColumns );
				$column = $columns[ $columnIdx ];
				if ( $requestColumn['searchable'] == 'true' ) {
					$binding = self::bind( $bindings, '%'.$str.'%', PDO::PARAM_STR );
					$globalSearch[] = "`".$column['db']."` LIKE ".$binding;
				}
			}
		}
		// Individual column filtering
		if ( isset( $request['columns'] ) ) {
			for ( $i=0, $ien=count($request['columns']) ; $i<$ien ; $i++ ) {
				$requestColumn = $request['columns'][$i];
				$columnIdx = array_search( $requestColumn['data'], $dtColumns );
				$column = $columns[ $columnIdx ];
				$str = $requestColumn['search']['value'];
				if ( $requestColumn['searchable'] == 'true' &&
				 $str != '' ) {
					$binding = self::bind( $bindings, '%'.$str.'%', PDO::PARAM_STR );
					$columnSearch[] = "`".$column['db']."` LIKE ".$binding;
				}
			}
		}
		// Combine the filters into a single string
		$where = '';
		if ( count( $globalSearch ) ) {
			$where = '('.implode(' OR ', $globalSearch).')';
		}
		if ( count( $columnSearch ) ) {
			$where = $where === '' ?
				implode(' AND ', $columnSearch) :
				$where .' AND '. implode(' AND ', $columnSearch);
		}
		if ( $where !== '' ) {
			$where = 'WHERE '.$where;
		}
		return $where;
	}

	/**
	 * Create a PDO binding key which can be used for escaping variables safely
	 * when executing a query with sql_exec()
	 *
	 * @param  array &$a    Array of bindings
	 * @param  *      $val  Value to bind
	 * @param  int    $type PDO field type
	 * @return string       Bound key to be used in the SQL where this parameter
	 *   would be used.
	 */
	static function bind ( &$a, $val, $type )
	{
		$key = ':binding_'.count( $a );
		
		$a[$key] = $val;
		/*
		$a[] = array(
			'key' => $key,
			'val' => $val,
			'type' => $type
		);
		 *
		 */
		return $key;
	}

	/**
	 * Pull a particular property from each assoc. array in a numeric array,
	 * returning and array of the property values from each item.
	 *
	 *  @param  array  $a    Array to get data from
	 *  @param  string $prop Property to read
	 *  @return array        Array of property values
	 */
	static function pluck ( $a, $prop )
	{
		$out = array();
		for ( $i=0, $len=count($a) ; $i<$len ; $i++ ) {
			$out[] = $a[$i][$prop];
		}
		return $out;
	}

	/**
	 * Return a string from an array or a string
	 *
	 * @param  array|string $a Array to join
	 * @param  string $join Glue for the concatenation
	 * @return string Joined string
	 */
	static function _flatten ( $a, $join = ' AND ' )
	{
		if ( ! $a ) {
			return '';
		}
		else if ( $a && is_array($a) ) {
			return implode( $join, $a );
		}
		return $a;
	}
}
