from __future__ import annotations

from difflib import SequenceMatcher
from typing import Callable, Iterator, Literal, Mapping, Sequence, Union, cast

from src.enums import ServiceType


__all__ = ["get_playlist_id", "compare_sequences"]


SERVICE_TYPE_ID_MAP = {ServiceType.spotify: lambda p_id: p_id.split(":")[-1]}

InsertActionType = Literal["insert"]
DeleteActionType = Literal["delete"]
ReplaceActionType = Literal["replace"]
ActionType = Union[InsertActionType, DeleteActionType, ReplaceActionType]

INSERT_ACTION: InsertActionType = "insert"
DELETE_ACTION: DeleteActionType = "delete"
REPLACE_ACTION: ReplaceActionType = "replace"

OPERATION_OFFSET_MAP: Mapping[ActionType, Callable[[int, int, int, int], int]] = {
    INSERT_ACTION: lambda t1, t2, s1, s2: s2 - s1,
    DELETE_ACTION: lambda t1, t2, s1, s2: -(t2 - t1),
    REPLACE_ACTION: lambda t1, t2, s1, s2: s2 - s1 - (t2 - t1),
}


def get_playlist_id(service_type: ServiceType, playlist_id: str) -> str:
    if not playlist_id:
        return playlist_id
    return SERVICE_TYPE_ID_MAP.get(service_type, lambda p_id: p_id)(playlist_id)


def compare_sequences(source: Sequence, target: Sequence) -> Iterator[tuple[ActionType, int, int, int, int]]:
    squeeze = SequenceMatcher(a=target, b=source)
    offset = 0
    for action, t1, t2, s1, s2 in squeeze.get_opcodes():
        action = cast(ActionType, action)
        if action not in OPERATION_OFFSET_MAP:
            continue

        yield action, t1 + offset, t2 + offset, s1, s2

        offset += OPERATION_OFFSET_MAP[action](t1, t2, s1, s2)