import schema_salad.schema
import schema_salad.ref_resolver
import logging
import pkg_resources
import logging
import traceback

class CustomFetcher(schema_salad.ref_resolver.DefaultFetcher):
    def check_exists(sup, url):
        if url.startswith("keep:"):
            return True
        else:
            return super().check_exists(url)

    def supported_schemes(self):  # type: () -> List[str]
        return ["file", "http", "https", "mailto", "keep"]


def qc_metadata(metadatafile):
    schema_resource = pkg_resources.resource_stream(__name__, "bh20seq-schema.yml")
    cache = {"https://raw.githubusercontent.com/arvados/bh20-seq-resource/master/bh20sequploader/bh20seq-schema.yml": schema_resource.read().decode("utf-8")}
    (loader,
     avsc_names,
     schema_metadata,
     metaschema_loader) = schema_salad.schema.load_schema("https://raw.githubusercontent.com/arvados/bh20-seq-resource/master/bh20sequploader/bh20seq-schema.yml", cache=cache)

    if not isinstance(avsc_names, schema_salad.avro.schema.Names):
        print(avsc_names)
        return False

    document_loader = schema_salad.ref_resolver.Loader(
        loader.ctx,
        schemagraph=loader.graph,
        foreign_properties=loader.foreign_properties,
        idx=loader.idx,
        cache=loader.cache,
        fetcher_constructor=CustomFetcher,
        skip_schemas=loader.skip_schemas,
        url_fields=loader.url_fields,
        allow_attachments=loader.allow_attachments,
        session=loader.session,
        )

    try:
        doc, metadata = schema_salad.schema.load_and_validate(document_loader, avsc_names, metadatafile, True)
        return True
    except Exception as e:
        traceback.print_exc()
        logging.warn(e)
    return False