from collections import namedtuple
from typing import List, Any
from utils.list_utils import map_dict_keys, flattern, unique
import csv
import io


ExportKey = namedtuple("ExportKey", ["order", "name"])


class ExportItem:
    def __init__(self, init=None):
        if init is not None:
            self.__dict__.update(init)

    def __getitem__(self, key):
        return self.__dict__[key]

    def __delitem__(self, key):
        del self.__dict__[key]

    def __contains__(self, key):
        return key in self.__dict__

    def __len__(self):
        return len(self.__dict__)

    def __repr__(self):
        return repr(self.__dict__)

    def add_item(self, key: str, order: int, value: Any):
        if value is not None:
            self.__dict__[ExportKey(order, key)] = value

    def to_dict(self):
        return map_dict_keys(self.__dict__, lambda key: key.name)

    def keys(self):
        return self.__dict__.keys()


class CSVExporter:
    def __init__(self, items: List[ExportItem] = []):
        self.export_items = []
        self.export_items.extend(items)

    def add_export_item(self, item: ExportItem):
        self.export_items.append(item)

    def export(self):
        with io.StringIO() as f:
            all_keys = flattern([list(item.keys()) for item in self.export_items])

            campaigns_to_export = [item.to_dict() for item in self.export_items]

            headers = list(map(lambda key: key.name, sorted(unique(all_keys), key=lambda x: (x.order, x.name))))

            writer = csv.DictWriter(f, fieldnames=headers)
            writer.writeheader()
            [writer.writerow(campaign_dict_repr) for campaign_dict_repr in campaigns_to_export]

            f.seek(0)
            doc = f.read()
            f.close()
            return doc