"""
Sync implementation module
"""
import datetime
from collections import defaultdict

from peeringdb.util import group_fields


def _field_resource(B, concrete, field):
    return B.get_resource(B.get_field_concrete(concrete, field))


def clean_helper(B, obj, clean_func):
    """
    Clean object, intercepting and collecting any missing-relation or
    unique-constraint errors and returning the relevant resource ids/fields.

    Returns:
        - tuple: (<dict of non-unique fields>, <dict of missing refs>)
    """
    try:
        clean_func(obj)
    except B.validation_error() as e:
        # _debug.log_validation_errors(B, e, obj, k)

        # Check if it's a uniqueness or missing relation error
        fields = B.detect_uniqueness_error(e)
        missing = B.detect_missing_relations(obj, e)
        return fields, missing
    return ({}, {})


def initialize_object(B, res, row):
    """
    Do a shallow initialization of an object

    Arguments:
        - row<dict>: dict of data like depth=1, i.e. many_refs are only ids
    """
    group_fields(B.get_concrete(res))

    try:
        obj = B.get_object(B.get_concrete(res), row["id"])
    except B.object_missing_error(B.get_concrete(res)):
        tbl = B.get_concrete(res)
        obj = tbl()
    return obj


def set_scalars(B, res, obj, row):
    field_groups = group_fields(B.get_concrete(res))
    # Set attributes, refs
    for fname, field in field_groups["scalars"].items():
        value = row.get(fname, getattr(obj, fname, None))
        value = B.convert_field(obj.__class__, fname, value)
        setattr(obj, fname, value)
    # _debug('res, row: %s, %s', res, row)


def _get_subrow(row, fname, field):
    key = field.column
    subrow = row.get(key)
    if subrow is None:  # e.g. use "org" if "org_id" is missing
        key = fname
        subrow = row[key]
    return key, subrow


def extract_relations(B, res, row):
    field_groups = group_fields(B.get_concrete(res))
    # Already-fetched, and id-only refs
    fetched, dangling = defaultdict(dict), defaultdict(set)

    # Handle subrows that might be shallow (id) or deep (dict)
    def _handle_subrow(R, subrow):
        if isinstance(subrow, dict):
            pk = subrow["id"]
            fetched[R][pk] = subrow
        else:
            pk = subrow
            dangling[R].add(pk)
        return pk

    for fname, field in field_groups["single_refs"].items():
        fieldres = _field_resource(B, B.get_concrete(res), fname)
        _, subrow = _get_subrow(row, fname, field)
        _handle_subrow(fieldres, subrow)

    for fname, field in field_groups["many_refs"].items():
        fieldres = _field_resource(B, B.get_concrete(res), fname)
        for subrow in row.get(fname, []):
            _handle_subrow(fieldres, subrow)

    return fetched, dangling


def set_single_relations(B, res, obj, row):
    field_groups = group_fields(B.get_concrete(res))
    for fname, field in field_groups["single_refs"].items():
        key, subrow = _get_subrow(row, fname, field)
        if isinstance(subrow, dict):
            pk = subrow["id"]
        else:
            pk = subrow
        setattr(obj, key, pk)


def set_many_relations(B, res, obj, row):
    field_groups = group_fields(B.get_concrete(res))
    for fname, field in field_groups["many_refs"].items():
        fieldres = _field_resource(B, B.get_concrete(res), fname)
        pks = row.get(fname, [])
        objs = [B.get_object(B.get_concrete(fieldres), pk) for pk in pks]
        B.set_relation_many_to_many(obj, fname, objs)


def patch_object(B, res, obj, strip_tz):
    field_groups = group_fields(B.get_concrete(res))

    for fname in field_groups["scalars"]:
        value = getattr(obj, fname)
        if strip_tz and isinstance(value, datetime.datetime):
            value = value.replace(tzinfo=None)
        B.update(obj, fname, value)