import django_tables2 as tables

from dcim.tables import DeviceTable, RackTable
from utilities.tables import register_table_column


COLUMN_NAME = "site_prefix"


def first_word(value):
    """Return the first whitespace-delimited word of a value."""
    words = str(value or "").split()
    return words[0] if words else None


class SitePrefixColumn(tables.Column):
    """Render the first word of a record's site name."""

    def render(self, value):
        if value is None:
            return None
        return first_word(value.name)


site_prefix = SitePrefixColumn(
    accessor=tables.A("site"),
    verbose_name="Prefix",
    empty_values=(),
    orderable=False,
)

register_table_column(site_prefix, COLUMN_NAME, DeviceTable, RackTable)


def _prepend_to_defaults(table):
    """Show the registered column first for users without saved preferences."""
    defaults = tuple(table.Meta.default_columns)
    table.Meta.default_columns = (
        "pk",
        COLUMN_NAME,
        *(name for name in defaults if name not in {"pk", COLUMN_NAME}),
    )


_prepend_to_defaults(DeviceTable)
_prepend_to_defaults(RackTable)