<?php

/**
 * This file contains the SQLDataListSource child class
 * that uses the PEAR DB object to talk to the DB.
 *
 * @author Walter A. Boring IV <waboring@newsblob.com>
 * @package phpHtmlLib
 */

/**
 * This requires the SQLDataListSource
 * parent class
 *
 */
include_once(PHPHTMLLIB_ABSPATH . "/widgets/data_list/SQLDataListSource.inc");

/**
 * Have to have PEAR and DB included
 * the pear dir must be in the
 * include path.
 */
require_once("PEAR.php");
require_once("DB.php");

/**
 * This SQLDataListSource child class interacts with
 * with the specific DB via the php PEAR DB abstraction
 * objects.
 *
 * How to use?
 * in the DataList child's get_data_source() method
 * you pass in the already connected PEAR DB object
 * in to the constructor.  PEARSQLDataListSource
 * takes care of the rest.
 *
 * @author Walter A. Boring IV <waboring@newsblob.com>
 * @package phpHtmlLib
 */
class PEARSQLDataListSource extends SQLDataListSource {

	/**
	 * This var holds the Database object
	 * that is used to do the sql queries
	 * It is assumed that the db is already
	 * connected to, and the object provides
	 * 2 methods:
	 * query() - execute a sql query
	 */
	var $_db = NULL;

	/**
	 * this holds the query result from the
	 * PEAR::DB->query() call
	 *
	 */
	var $_result = NULL;


	/**
	 * The constructor is used to pass in the
	 * PEAR DB object that has already been
	 * created and connected to the db.
	 *
	 * @param PEAR::DB object - MUST BE CONNECTED
	 */
	function PEARSQLDataListSource( &$db ) {
		$this->set_db_object( $db );
	}
	
	/**
     * Set the DB object we will use
     * to talk to the DB.
     *
     * @param  object - $db the babw_db object.
     */
    function set_db_object( &$db ) {
        $this->_db = &$db;
    }

    /**
	 * This is the function that does the data fetching,
	 * and sorting if needed.
	 * If the source is a sql database, this is where the
	 * query gets called.  This function doesn't actually read the
	 * data from the DB yet.  That is what get_next_data_row()
	 * does.
     *
	 * @return boolean - the query passed/failed.
	 */
	function do_query() {
		$this->_result = $this->_db->query($this->_query);
		if (DB::isError($this->_result)) {
			$msg = $this->_result->getMessage();
            $query = $this->_query;
			user_error("PEARSQLDataListSource::do_query($query) - query failed : ".$msg);
            return false;
		} else {
            return true;
        }
	}

	
	/**
	 * This function gets the next data row
	 * from the query()
	 *
	 * @return array()
	 */
	function get_next_data_row() {
		return $this->_result->fetchRow(DB_FETCHMODE_ASSOC);
	}

	/**
     * This function builds the limit
     * clause portion of a DB query.
     *
     * @return string - the limit portion of
     *                  the query.
     */
    function build_limit_clause($offset, $limit) {
        if ($this->get_limit() != -1 ) {
			if ($offset == '' || $offset == "none") {
				$offset = 0;
			}
			switch(get_class($this->_db)) {
			case "db_mysql":
				$clause = " LIMIT $offset, $limit ";
				break;
			case "db_pgsql":
				$clause = " LIMIT $limit OFFSET $offset ";
				break;
			default:
				$clause = " LIMIT $offset, $limit ";
				break;
			}
            return $clause;
        } else {
            return NULL;
        }
    }

    /**
     * find the number of rows to be returned
     * from a query from a table and where clause
     *
     * @param string $table - the table to count from
     * @param string $where_clause - a where clause
     *
     * @return int the # of rows
     */
    function count($tables, $where_clause='', $count_clause='*') {
		$query = "select count(".$count_clause.") as xxCOUNTxx from ".$tables." ".$where_clause;
        $result = $this->_db->getOne($query);
		if (DB::isError($result)) {
			$msg = $result->getMessage();
			user_error("PEARSQLDataListSource::count() - query failed : ".$msg);
            return 0;
		} else {
            return $result;
        }		
    }

}

?>