finish q4

question_2.php

@@ -21,6 +21,66 @@ public function get_balance() {
 
 
 // Write your code below
+class Database {
+    protected $DB_HOST;
+    protected $DB_NAME;
+    protected $DB_USER;
+    protected $DB_PASS;
+    private $mysqli;
+
+    /**
+     * database constructor.
+     */
+    public function __construct() {
+        $this->DB_HOST = 'localhost';
+        $this->DB_NAME = 'test';
+        $this->DB_USER = 'test';
+        $this->DB_PASS = 'test';
+        $this->mysqli = new \mysqli($this->DB_HOST, $this->DB_USER, $this->DB_PASS, $this->DB_NAME);
+        /* check connection */
+        if (mysqli_connect_errno()) {
+            printf("Connect failed: %s\n", mysqli_connect_error());
+            exit();
+        }
+    }
+
+    public function check_username($username){
+        $username = mysqli_real_escape_string($this->mysqli, $username);
+        $sql = 'SELECT first_name FROM customer WHERE username = "'.$username.'"';
+        $result = $this->mysqli->query($sql);
+        return ($result->num_rows > 0) ? $result : false;
+    }
+
+    /**
+     * Close database connection
+     * @return bool
+     */
+    public function close(){
+        return mysqli_close($this->mysqli);
+    }
+
+
+    /**
+     * Generate Random string
+     * @param int $length maximum string generate
+     * @param int $min minimum string generate
+     * @return string
+     */
+    public function randomString($length = 30, $min=8) {
+        $str = "";
+        $characters = array_merge(range('a','z'), range('0','9'));
+        $max = count($characters) - 1;
+        $randomLength = mt_rand($min, $length);
+        for ($i = 0; $i < $randomLength; $i++) {
+            $rand = mt_rand(0, $max);
+            $str .= $characters[$rand];
+        }
+        return $str;
+    }
+
+}
+
+
 /**
  * Class Bronze_Customer
  * @package SoftwareEngineerTest
@@ -35,7 +95,6 @@ public function deposit($amount){
 		$this->balance = $this->get_balance() + $amount;
 	}
 
-
 	/**
 	 * Instantiate the correct object for customer ID
 	 * @return bool
@@ -49,6 +108,26 @@ public function get_instance(){
 			throw new \InvalidArgumentException('Invalid customer ID');
 		}
 	}
+
+    /**
+     *  Generate unique random username
+     * @return string
+     */
+    public function generate_username(){
+        $flag = true;
+        $db = new Database();
+        $username = '';
+        while($flag){
+            $username = 'B'.$db->randomString();
+            $result = $db->check_username($username);
+            if (!$result){
+                //username is unique now
+                $flag = false;
+            }
+        }
+        $db->close();
+        return $username;
+    }
 }
 
 /**
@@ -78,6 +157,27 @@ public function get_instance(){
             throw new \InvalidArgumentException('Invalid customer ID');
         }
     }
+
+    /**
+     *  Generate unique random username
+     * @return string
+     */
+    public function generate_username(){
+        $flag = true;
+        $db = new Database();
+        $username = '';
+        while($flag){
+            $username = 'S'.$db->randomString();
+            $result = $db->check_username($username);
+            if (!$result){
+                //username is unique now
+                $flag = false;
+            }
+        }
+        $db->close();
+        return $username;
+    }
+
 }
 
 /**
@@ -107,4 +207,25 @@ public function get_instance(){
             throw new \InvalidArgumentException('Invalid customer ID');
         }
     }
+
+    /**
+     *  Generate unique random username
+     * @return string
+     */
+    public function generate_username(){
+        $flag = true;
+        $db = new Database();
+        $username = '';
+        while($flag){
+            $username = 'G'.$db->randomString();
+            $result = $db->check_username($username);
+            if (!$result){
+                //username is unique now
+                $flag = false;
+            }
+        }
+        $db->close();
+        return $username;
+    }
+
 }