Improve header field generation

CHANGELOG.md

@@ -16,6 +16,7 @@ All Notable changes to `Csv` will be documented in this file
 
 - `JsonConverter::withPrettyPrint` now accepts the `$identSize` as its unique parameter.
 - Adding support for `callable` in the `Query\Constraint` namespace.
+- `HttpHeaders::forFileDownload` to be inline with RFC2183 and Header name and value best practices.
 
 ### Remove
 

src/AbstractCsvTest.php

@@ -141,7 +141,7 @@ public function testOutputHeaders(): void
         self::assertStringContainsString('content-type: text/csv', strtolower($headers[0]));
         self::assertSame('content-transfer-encoding: binary', strtolower($headers[1]));
         self::assertSame('content-description: File Transfer', $headers[2]);
-        self::assertStringContainsString('content-disposition: attachment; filename="tst.csv"; filename*=utf-8\'\'t%C3%A9st.csv', $headers[3]);
+        self::assertStringContainsString('content-disposition: attachment; filename="tst.csv"; filename*=UTF-8\'\'t%c3%a9st.csv', $headers[3]);
     }
 
     public function testChunkDoesNotTimeoutAfterReading(): void

src/HttpHeaders.php

@@ -40,14 +40,20 @@ final class HttpHeaders
      */
     public static function forFileDownload(string $filename, string $contentType): void
     {
-        !(str_contains($filename, '/') || str_contains($filename, '\\')) || throw new InvalidArgumentException('The filename `'.$filename.'` cannot contain the "/" and "\" characters.');
+        if (str_contains($filename, '/') || str_contains($filename, '\\')) {
+            throw new InvalidArgumentException('The filename `'.$filename.'` cannot contain the "/" or "\" characters.');
+        }
 
         /** @var string $filteredName */
         $filteredName = filter_var($filename, FILTER_UNSAFE_RAW, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH);
         $fallbackName = str_replace('%', '', $filteredName);
-        $disposition = 'attachment; filename="'.str_replace('"', '\\"', $fallbackName).'"';
+        $disposition = 'attachment;filename="'.str_replace('"', '\\"', $fallbackName).'"';
         if ($filename !== $fallbackName) {
-            $disposition .= "; filename*=utf-8''".rawurlencode($filename);
+            $disposition .= ";filename*=UTF-8''".preg_replace_callback(
+                '/[%"\x00-\x1F\x7F-\xFF]/',
+                static fn (array $matches): string => strtolower(rawurlencode($matches[0])),
+                $filename
+            );
         }
 
         header('content-type: '.$contentType);