feat: provide a helpful error message if no DB access

If unable to access the database provide a helpful error message.

Now the error message will say:
  Unable to connect to the database.

  Ask the website administrator to verify that the database has been
  created/initialized.

  They should also verify that the config/config.php database
  configuration is correct.

Previously it said:
  Unknown Error

Author: JohnVillalovos

lang/en_us.php

@@ -94,6 +94,8 @@ protected function _LoadStrings()
         $strings['Error'] = 'Error';
         $strings['ReturnToPreviousPage'] = 'Return to the last page that you were on';
         $strings['UnknownError'] = 'Unknown Error';
+        $strings['DatabaseConnectionError'] = 'Unable to connect to the database server.<br/>Ask the website administrator to verify the database host, username, and password in <code>config/config.php</code>.';
+        $strings['DatabaseNotFoundError'] = 'Unable to select the configured database.<br/>Ask the website administrator to verify the database name in <code>config/config.php</code> and confirm the database has been created/initialized.';
         $strings['InsufficientPermissionsError'] = 'You do not have permission to access this resource';
         $strings['MissingReservationResourceError'] = 'A resource was not selected';
         $strings['MissingReservationScheduleError'] = 'A schedule was not selected';

lib/Common/ErrorMessages.php

@@ -8,6 +8,8 @@ class ErrorMessages
     public const MISSING_SCHEDULE = 3;
     public const RESERVATION_NOT_FOUND = 4;
     public const RESERVATION_NOT_AVAILABLE = 5;
+    public const DATABASE_CONNECTION = 6;
+    public const DATABASE_NOT_FOUND = 7;
 
     private $_resourceKeys = [];
     private static $_instance;
@@ -19,6 +21,8 @@ private function __construct()
         $this->SetKey(ErrorMessages::MISSING_SCHEDULE, 'MissingReservationScheduleError');
         $this->SetKey(ErrorMessages::RESERVATION_NOT_FOUND, 'ReservationNotFoundError');
         $this->SetKey(ErrorMessages::RESERVATION_NOT_AVAILABLE, 'ReservationNotAvailable');
+        $this->SetKey(ErrorMessages::DATABASE_CONNECTION, 'DatabaseConnectionError');
+        $this->SetKey(ErrorMessages::DATABASE_NOT_FOUND, 'DatabaseNotFoundError');
     }
 
     /**

lib/Common/Logging/ExceptionHandler.php

@@ -42,7 +42,14 @@ public function HandleException($exception)
         ob_start();
         debug_print_backtrace();
         error_log(ob_get_clean());
-        call_user_func($this->callback);
+        $errorMessageId = ErrorMessages::UNKNOWN_ERROR;
+        if (is_a($exception, 'DatabaseConnectionException')) {
+            $errorMessageId = ErrorMessages::DATABASE_CONNECTION;
+        } elseif (is_a($exception, 'DatabaseNotFoundException')) {
+            $errorMessageId = ErrorMessages::DATABASE_NOT_FOUND;
+        }
+
+        call_user_func($this->callback, $errorMessageId);
     }
 }
 

lib/Database/DatabaseExceptions.php

@@ -0,0 +1,13 @@
+<?php
+
+class DatabaseException extends Exception
+{
+}
+
+class DatabaseConnectionException extends DatabaseException
+{
+}
+
+class DatabaseNotFoundException extends DatabaseException
+{
+}

lib/Database/MySQL/MySqlConnection.php

@@ -43,14 +43,14 @@ public function Connect()
         if (!$this->_db) {
             $connectError = mysqli_connect_error();
             Log::Error("Error connecting to database\nCheck your database settings in the config file\n%s", $connectError);
-            throw new Exception("Error connecting to database\nError: " . $connectError);
+            throw new DatabaseConnectionException("Error connecting to database\nError: " . $connectError);
         }
 
         $selected = mysqli_select_db($this->_db, $this->_dbName);
 
         if (!$selected) {
             Log::Error("Error selecting database '%s'\nCheck your database settings in the config file\n%s", $this->_dbName, mysqli_error($this->_db));
-            throw new Exception("Error selecting database\nError: " . mysqli_error($this->_db));
+            throw new DatabaseNotFoundException("Error selecting database\nError: " . mysqli_error($this->_db));
         }
         mysqli_set_charset($this->_db, 'utf8mb4');
 

lib/Database/namespace.php

@@ -5,6 +5,7 @@
 require_once(ROOT_DIR . 'lib/Database/IReader.php');
 require_once(ROOT_DIR . 'lib/Database/Parameter.php');
 require_once(ROOT_DIR . 'lib/Database/Parameters.php');
+require_once(ROOT_DIR . 'lib/Database/DatabaseExceptions.php');
 require_once(ROOT_DIR . 'lib/Database/SqlCommand.php');
 require_once(ROOT_DIR . 'lib/Database/Database.php');
 require_once(ROOT_DIR . 'lib/Database/DatabaseFactory.php');