Transforms raw HADS metadata into a dictionary (station code -> props)

def _parse_metadata(self, metadata):
        """
        Transforms raw HADS metadata into a dictionary (station code -> props)
        """
        retval = {}

        # these are the first keys, afterwards follows a var-len list of variables/props
        # first key always blank so skip it
        field_keys = [
            "nesdis_id",
            "nwsli",
            "location_text",
            "latitude",
            "longitude",
            "hsa",
            "state",
            "owner",
            "manufacturer",
            "channel",
            "init_transmit",  # HHMM
            "trans_interval",
        ]  # min

        # repeat in blocks of 7 after field_keys
        var_keys = [
            "pe_code",
            "data_interval",  # min
            "coefficient",
            "constant",
            "time_offset",  # min
            "base_elevation",  # ft
            "gauge_correction",
        ]  # ft

        lines = metadata.splitlines()
        for line in lines:
            if len(line) == 0:
                continue

            raw_fields = line.split("|")

            fields = dict(zip(field_keys, raw_fields[1 : len(field_keys)]))

            # how many blocks of var_keys after initial fields
            var_offset = len(field_keys) + 1
            var_blocks = (len(raw_fields) - var_offset) // len(
                var_keys
            )  # how many variables
            vars_only = raw_fields[var_offset:]
            variables = {}

            for offset in range(var_blocks):
                var_dict = dict(
                    zip(
                        var_keys,
                        vars_only[
                            offset
                            * len(var_keys) : (offset + 1)
                            * len(var_keys)
                        ],
                    )
                )
                variables[var_dict["pe_code"]] = var_dict

                var_dict["base_elevation"] = float(var_dict["base_elevation"])
                var_dict["gauge_correction"] = float(
                    var_dict["gauge_correction"]
                )
                del var_dict["pe_code"]  # no need to duplicate

            line_val = {"variables": variables}
            line_val.update(fields)

            # conversions
            def dms_to_dd(dms):
                parts = dms.split(" ")
                sec = int(parts[1]) * 60 + int(parts[2])
                return float(parts[0]) + (
                    sec / 3600.0
                )  # negative already in first portion

            line_val["latitude"] = dms_to_dd(line_val["latitude"])
            line_val["longitude"] = dms_to_dd(line_val["longitude"])

            retval[line_val["nesdis_id"]] = line_val

        return retval