<?php

	// Helper class containing database-related methods. 
	// Does not close links or free results. 
	class SQLHelper
	{
		private $hostName = null;
		private $userName = null;
		private $password = null; 
		private $databaseName = null; 
		private $linkConnection = null;

		// Constructor, takes args used in connecting to a database.
		public function __construct($hostName, $userName, $password)
		{
			$this->hostName = $hostName; 
			$this->userName = $userName; 
			$this->password = $password; 
		}
		
		// Attempts to create and save a link_connection with the passed database name. 
		// Returns true on success, otherwise false. 
		public function ConnectToDatabase($databaseName)
		{
			$this->databaseName = $databaseName; 
			$this->linkConnection = mysqli_connect($this->hostName, $this->userName, $this->password, $databaseName); 
			return ($this->linkConnection == true); 
		}
		
		// Sends the passed query to the current database.
		// Returns the result on success, dies on failure. 
		public function SendQuery($query)
		{
			$retVal = mysqli_query($this->linkConnection, $query) or die("Query failed in ".__METHOD__."()\n"); 
			return $retVal; 
		}
		
		// Uses the currently-connected database and the passed tableName to get the column headers of said table. 
		// Returns an array of column header names on success, dies on failure. 
		public function GetColumnHeaders($tableName)
		{
			if(is_null($this->linkConnection))
			{
				die("Attempt to access database before connecting to it in ".__METHOD__."\n"); 
			}
			
			$query = "SHOW COLUMNS FROM $tableName"; 
			$result = mysqli_query($this->linkConnection, $query) or die("Query failed in ".__METHOD__."()\n"); 
			
			$i = 0; 
			$ar = array(); 
			while ($row = mysqli_fetch_array($result)) 
			{
				$ar[$i++] = $row[0]; 
			}
			
			return $ar; 
		}
	}
?>