"""Bounded parsing for explicit message-read acknowledgements."""
import json
import uuid

from django.core.exceptions import ValidationError


def message_read_ids(request):
    if request.content_type == 'application/json':
        try:
            payload = json.loads(request.body or b'{}')
        except (TypeError, ValueError):
            raise ValidationError('invalid_json')
        if not isinstance(payload, dict):
            raise ValidationError('invalid_json')
        values = payload.get('message_ids', [])
    else:
        values = request.POST.getlist('message_ids')
    if not isinstance(values, list) or len(values) > 100:
        raise ValidationError('invalid_message_ids')
    identifiers = set()
    for value in values:
        if not isinstance(value, str) or len(value) > 45:
            continue
        try:
            identifiers.add(uuid.UUID(value))
        except ValueError:
            continue
    return identifiers