import yaml
from ee import EeException
from ee.part import Part, common_fact_types


def map_footprint(footprint_mappings, table, from_footprint_key):
    if footprint_mappings is None:
        return None

    mappings = {}
    with open(footprint_mappings, "r") as f:
        doc = yaml.load(f, Loader=yaml.SafeLoader)
        if not isinstance(doc, dict):
            raise EeException("The footprint mappings document must be a dict.")

        if table not in doc:
            raise EeException("The footprint mappings document must contain the key '{}'.".format(table))

        for k, v in doc[table].items():
            if not isinstance(v, str):
                raise EeException("Bad value for key {}, must be a string".format(k))

            mappings[k] = v

    def on_part(part: Part) -> Part:
        from_footprint = part.facts.get_value(from_footprint_key)

        if not from_footprint:
            return part

        footprint = mappings.get(from_footprint, None)

        if footprint:
            part.facts.add(common_fact_types.footprint, footprint)

        return part

    return on_part