"""Bounded multipart reader for image edit requests."""
import base64
from email import policy
from email.parser import BytesParser

MAX_IMAGE=10*1024*1024
MAX_BODY=4*MAX_IMAGE+65536

def read_image_upload(handler,profile_field='model'):
 handler.connection.settimeout(45)
 if handler.headers.get('Transfer-Encoding'):raise ValueError('Chunked Upload wird nicht unterstützt.')
 try:length=int(handler.headers.get('Content-Length','0'))
 except ValueError:raise ValueError('Ungültige Upload-Länge.') from None
 content_type=handler.headers.get('Content-Type','')
 if not 0<length<=MAX_BODY or not content_type.lower().startswith('multipart/form-data;'):raise ValueError('Multipart-Upload mit höchstens vier Bildern zu je 10 MiB erforderlich.')
 raw=handler.rfile.read(length)
 if len(raw)!=length:raise ValueError('Upload unvollständig.')
 message=BytesParser(policy=policy.default).parsebytes(b'Content-Type: '+content_type.encode()+b'\r\nMIME-Version: 1.0\r\n\r\n'+raw)
 if not message.is_multipart() or message.defects:raise ValueError('Ungültiger Multipart-Upload.')
 fields={};images=[]
 for part in message.iter_parts():
  name=part.get_param('name',header='content-disposition');data=part.get_payload(decode=True)
  if not isinstance(data,bytes):raise ValueError('Ungültiges Upload-Feld.')
  if name in ('image','image[]'):
   if len(images)>=4 or not 0<len(data)<=MAX_IMAGE:raise ValueError('Höchstens vier Referenzbilder bis je 10 MiB erlaubt.')
   mime=part.get_content_type().lower()
   if mime not in ('image/png','image/jpeg','image/webp'):raise ValueError('Nur PNG, JPEG oder WebP erlaubt.')
   images.append('data:'+mime+';base64,'+base64.b64encode(data).decode('ascii'))
  else:
   if name not in (profile_field,'prompt','size','n','response_format','skip_enhancer') or name in fields or len(data)>4096:raise ValueError('Ungültiges oder doppeltes Formularfeld.')
   try:fields[name]=data.decode('utf-8')
   except UnicodeError:raise ValueError('Ungültiges Textfeld.') from None
 if profile_field not in fields:raise ValueError('Bildprofil fehlt.')
 return fields,images