import json

from django.forms import widgets
from apps.files.models import File


class CommaSeparatedTextInput(widgets.HiddenInput):
    def format_value(self, value):
        try:
            value = ','.join(value)
        except TypeError:
            value = ''
        return super().format_value(value)

    def value_from_datadict(self, data, files, name):
        value = super().value_from_datadict(data, files, name)

        if value == '':
            return None

        try:
            return value.split(',')
        except AttributeError:
            return None


def idToDict(id):
    file = File.objects.get(pk=id)
    return dict(id=id, name=file.name())


# For clarity:
# the canonical format is a list of integers (IDs of files)
# the input/display format is a string containing a JSON list of {id=x, name=y} objects
class JSONFileListWidget(widgets.HiddenInput):

    def format_value(self, value):
        try:
            value = [ idToDict(id) for id in value ]
            value = json.dumps(value)
        except TypeError:
            value = ''
        return super().format_value(value)

    def value_from_datadict(self, data, files, name):
        value = super().value_from_datadict(data, files, name)

        if value == '':
            return None

        try:
            filelist = json.loads(value)
            return [ file['id'] for file in filelist ]
        except JSONDecodeError:
            return None