use message system in exception handler

resources/lib/UnityHTTPD.php

@@ -2,6 +2,7 @@
 
 namespace UnityWebPortal\lib;
 
+use stdClass;
 use UnityWebPortal\lib\exceptions\NoDieException;
 use UnityWebPortal\lib\exceptions\ArrayKeyException;
 use RuntimeException;
@@ -43,6 +44,31 @@ public static function redirect(?string $dest = null): never
         self::die();
     }
 
+    // assumes that a session is started and has a good unique session_id
+    public static function errorID(?\Throwable $e = null): string
+    {
+        $e ??= new stdClass();
+        return md5(strval(session_id()) . spl_object_id($e));
+    }
+
+    public static function logThrowableAndMessageUser(
+        \Throwable $error,
+        string $log_title,
+        string $log_message,
+        string $user_message_title,
+        string $user_message_body,
+    ) {
+        $errorid = self::errorID($error);
+        $data = [];
+        self::errorLog($log_title, $log_message, error: $error, errorid: $errorid, data: $data);
+        if (strlen($user_message_body) == 0) {
+            $user_message_body = "error ID: $errorid";
+        } else {
+            $user_message_body .= " error ID: $errorid";
+        }
+        self::messageError($user_message_title, $user_message_body);
+    }
+
     // $data must be JSON serializable
     public static function errorLog(
         string $title,
@@ -72,8 +98,9 @@ public static function errorLog(
         }
         $output["REMOTE_USER"] = $_SERVER["REMOTE_USER"] ?? null;
         $output["REMOTE_ADDR"] = $_SERVER["REMOTE_ADDR"] ?? null;
-        if (!is_null($errorid)) {
-            $output["errorid"] = $errorid;
+        $output["_REQUEST"] = $_REQUEST;
+        if (!is_null($errorid) || !is_null($error)) {
+            $output["errorid"] = self::errorID($error);
         }
         error_log("$title: " . \jsonEncode($output));
     }
@@ -119,7 +146,7 @@ public static function badRequest(
         ?\Throwable $error = null,
         ?array $data = null,
     ): never {
-        $errorid = uniqid();
+        $errorid = self::errorID($error);
         self::errorToUser("Invalid requested action or submitted data.", 400, $errorid);
         self::errorLog("bad request", $message, $errorid, $error, $data);
         self::die($message);
@@ -130,7 +157,7 @@ public static function forbidden(
         ?\Throwable $error = null,
         ?array $data = null,
     ): never {
-        $errorid = uniqid();
+        $errorid = self::errorID($error);
         self::errorToUser("Permission denied.", 403, $errorid);
         self::errorLog("forbidden", $message, $errorid, $error, $data);
         self::die($message);
@@ -141,7 +168,7 @@ public static function internalServerError(
         ?\Throwable $error = null,
         ?array $data = null,
     ): never {
-        $errorid = uniqid();
+        $errorid = self::errorID($error);
         self::errorToUser("An internal server error has occurred.", 500, $errorid);
         self::errorLog("internal server error", $message, $errorid, $error, $data);
         if (!is_null($error) && ini_get("display_errors") && ini_get("html_errors")) {
@@ -155,8 +182,23 @@ public static function internalServerError(
     // https://www.php.net/manual/en/function.set-exception-handler.php
     public static function exceptionHandler(\Throwable $e): void
     {
-        ini_set("log_errors", true); // in case something goes wrong and error is not logged
-        self::internalServerError("An internal server error has occurred.", error: $e);
+        // we disable log_errors before we enable this exception handler to avoid duplicate logging
+        // if this exception handler itself fails, information will be lost unless we re-enable it
+        ini_set("log_errors", true);
+        // if the user was doing HTTP POST, then make a pretty error and redirect
+        // else, a redirect may cause an infinite loop, so fall back on the old ugly error
+        if ($_SERVER["REQUEST_METHOD"] == "POST") {
+            self::logThrowableAndMessageUser(
+                $e,
+                "uncaught exception",
+                strval($e),
+                "An internal server error has occurred.",
+                "",
+            );
+            self::redirect();
+        } else {
+            self::internalServerError("", error: $e);
+        }
     }
 
     public static function errorHandler(int $severity, string $message, string $file, int $line)