from collections.abc import MutableMapping, MutableSequence
from typing import TypeVar

from . import events as e
from .container import HookedContainer, HookFunction, MutableNesting

T = TypeVar("T")


class HookedMapping(HookedContainer[T], MutableMapping[T, MutableNesting[T]]):
    _data: MutableMapping[T, MutableNesting[T]]

    def __init__(
        self,
        existing: MutableMapping[T, MutableNesting[T]],
        hook: HookFunction | None = None,
        path: MutableSequence[int] | None = None,
    ):
        self.hook = hook
        match existing:
            case HookedMapping(_data=seq):
                self._data = seq
            case MutableMapping() as seq:
                self._data = seq
            case _ as it:
                self._data = dict(it)
        self._data = existing
        self._path = list(path) if path is not None else []

    # MutableMapping Methods

    def __iter__(self):
        return iter(self._data)

    def insert(self, key: T, value: MutableNesting[T]) -> None:
        self._data[key] = value
        if self.hook:
            self.hook(e.AddItemEvent(self.new_path(key), value))

    # HookedContainer methods

    def __getitem__(self, key: T) -> MutableNesting[T]:
        if key not in self._data:
            self.insert(key, {})
            return HookedMapping(self._data[key], hook=self.hook, path=self.new_path(key))
        value = self._data[key]
        match value:
            case HookedMapping(_data=seq):
                return type(self)(seq, hook=self.hook, path=self.new_path(key))
            case MutableMapping() as mapping:
                return HookedMapping(mapping, hook=self.hook, path=self.new_path(key))
            case _ as item:
                return item

    def __setitem__(self, key: T, value: MutableNesting[T]) -> None:
        if key not in self._data:
            self.insert(key, value)
        else:
            self._data[key] = value
            if self.hook:
                self.hook(e.SetItemEvent(self.new_path(key), value))

    def __delitem__(self, key: T) -> None:
        item = self._data[key]
        del self._data[key]
        if self.hook:
            self.hook(e.RemoveItemEvent(self.new_path(key), item))