import json
from django import forms
from django.core.exceptions import ValidationError

    
def validate_file(value):
    if value.size > 10**6:
        raise ValidationError("File too large")

    try:
        data = json.loads(value.read())
    except json.JSONDecodeError:
        raise ValidationError("Not a GCS file - json decode")

    try:
        version = data['version']
    except KeyError:
        import bpdb;bpdb.set_trace()
        raise ValidationError("Not a GCS file - key error")

    if version < 4:
        raise ValidationError(
                f"The file version ({version}) is too old. Please use a newer version (5.20.3) of GCS."
                )


class UploadFileForm(forms.Form):
    file = forms.FileField(validators=[validate_file])