from abc import ABC, abstractmethod
import json
from pathlib import Path
import pickle
from typing import Type

from pfbudget.common.types import ExportFormat
from pfbudget.db.client import Client
from pfbudget.db.model import Serializable


class Command(ABC):
    @abstractmethod
    def execute(self) -> None:
        raise NotImplementedError

    def undo(self) -> None:
        raise NotImplementedError


class ExportCommand(Command):
    def __init__(
        self, client: Client, what: Type[Serializable], fn: Path, format: ExportFormat
    ):
        self.__client = client
        self.what = what
        self.fn = fn
        self.format = format

    def execute(self) -> None:
        values = self.__client.select(self.what)
        match self.format:
            case ExportFormat.JSON:
                with open(self.fn, "w", newline="") as f:
                    json.dump([e.serialize() for e in values], f, indent=4)
            case ExportFormat.pickle:
                raise AttributeError("pickle export not working at the moment!")
                with open(self.fn, "wb") as f:
                    pickle.dump(values, f)


class ImportCommand(Command):
    def __init__(
        self, client: Client, what: Type[Serializable], fn: Path, format: ExportFormat
    ):
        self.__client = client
        self.what = what
        self.fn = fn
        self.format = format

    def execute(self) -> None:
        match self.format:
            case ExportFormat.JSON:
                with open(self.fn, "r") as f:
                    try:
                        values = json.load(f)
                        values = [self.what.deserialize(v) for v in values]
                    except json.JSONDecodeError as e:
                        raise ImportFailedError(e)

            case ExportFormat.pickle:
                raise AttributeError("pickle import not working at the moment!")
                with open(self.fn, "rb") as f:
                    values = pickle.load(f)

        self.__client.insert(values)


class ImportFailedError(Exception):
    pass