import urllib.parse

class Concept(object):

    def __init__(self, context, data):
        self.context = context
        self.data = {self.canonical_key(k):v for (k, v) in data.items()}

    def get(self, key, *args, **kwargs):
        return self.data.get(self.canonical_key(key, *args, **kwargs))

    def __getitem__(self, key):
        return self.data[self.canonical_key(key)]

    def __setitem__(self, key, value):
        self.data[self.canonical_key(key)] = value

    def __contains__(self, key):
        return self.canonical_key(key) in self.data

    def __delitem__(self, key):
        del self.data[self.canonical_key(key)]

    def canonical_key(self, key):
        if not isinstance(key, str):
            return key
        elif key.startswith('@'):
            return key
        elif key.startswith(self.context):
            return key
        return self.context + key

def determine_concepts_internal(json, context, outputs):
    if isinstance(json, list):
        for m in json:
            determine_concepts_internal(m, context, outputs)
        return

    assert isinstance(json, dict)
    context = json.get('@context', context)
    assert urllib.parse.urlparse(context).netloc == 'schema.org'
    if '@graph' in json:
        determine_concepts_internal(json['@graph'], context, outputs)
    else:
        outputs.append(Concept(context, json))

def determine_concepts(json):
    concepts = []
    determine_concepts_internal(json, '', concepts)
    return concepts