from __future__ import annotations
import os
import sys
import tomllib
from pathlib import Path
from . import Sort

DEFAULT_KEYBINDS: dict[str, list[str]] = {
    "quit": ["q"],
    "down": ["j", "KEY_DOWN"],
    "up": ["k", "KEY_UP"],
    "enter": ["l", "KEY_RIGHT", "\n", "KEY_ENTER"],
    "back": ["-", "KEY_LEFT", "KEY_BACKSPACE", "\x7f", "\x08"],
    "parent": ["h"],
    "sort": ["i"],
}

DEFAULT_CURSOR_RESET = "top"


class Config:
    def __init__(self, keybinds: dict[str, list[str]], cursor_reset: str,
                 sort_mode: str) -> None:
        self._keybinds = keybinds
        self._cursor_reset = cursor_reset
        self._sort_mode = sort_mode
        self._key_to_action: dict[str, str] = {
            key: action
            for action, keys in keybinds.items()
            for key in keys
        }

    @classmethod
    def load(cls, path: Path | None = None) -> Config:
        path = path or cls._default_path()
        data: dict = {}
        if path.is_file():
            try:
                with path.open("rb") as f:
                    data = tomllib.load(f)
            except tomllib.TOMLDecodeError as e:
                print(f"pyexplorer: ignoring invalid config {path}: {e}",
                      file=sys.stderr)
                data = {}

        keybinds = dict(DEFAULT_KEYBINDS)
        keybinds.update(data.get("keybinds", {}))
        cursor_reset = data.get("cursor", {}).get("reset", DEFAULT_CURSOR_RESET)
        sort_mode = data.get("sort", {}).get("mode", Sort.DEFAULT_MODE)
        if sort_mode not in Sort.MODES:
            print(f"pyexplorer: unknown sort mode {sort_mode!r}, "
                  f"falling back to {Sort.DEFAULT_MODE!r}", file=sys.stderr)
            sort_mode = Sort.DEFAULT_MODE
        return cls(keybinds, cursor_reset, sort_mode)

    @staticmethod
    def _default_path() -> Path:
        base = os.environ.get("XDG_CONFIG_HOME") or str(Path.home() / ".config")
        return Path(base) / "pyexplorer" / "config.toml"

    def keys_for(self, action: str) -> list[str]:
        return self._keybinds.get(action, [])

    def action_for(self, key: str) -> str | None:
        return self._key_to_action.get(key)

    @property
    def cursor_reset(self) -> str:
        return self._cursor_reset

    @property
    def sort_mode(self) -> str:
        return self._sort_mode