"""Terminal multi-select UI for skills."""

from __future__ import annotations

from dataclasses import dataclass
from typing import Callable, Iterable


@dataclass(frozen=True)
class SkillChoice:
    name: str
    kind: str
    description: str = ""
    installed: bool = False


def filter_choices(choices: Iterable[SkillChoice], query: str) -> list[SkillChoice]:
    needle = query.casefold().strip()
    if not needle:
        return list(choices)
    return [
        choice
        for choice in choices
        if needle in choice.name.casefold()
        or needle in choice.kind.casefold()
        or needle in choice.description.casefold()
    ]


def select_skills(
    choices: list[SkillChoice],
    *,
    wrapper: Callable[..., set[str] | None] | None = None,
) -> set[str] | None:
    """Open the selector. Return names, or None when cancelled."""
    if not choices:
        return set()

    try:
        import curses
    except ImportError as exc:
        raise RuntimeError("当前 Python 环境不支持 curses，无法打开交互界面") from exc

    selected = {choice.name for choice in choices if choice.installed}

    def draw(stdscr: object) -> set[str] | None:
        curses.curs_set(0)
        stdscr.keypad(True)
        current = 0
        query = ""

        while True:
            visible = filter_choices(choices, query)
            current = min(current, max(0, len(visible) - 1))
            stdscr.erase()
            height, width = stdscr.getmaxyx()
            header = "↑/↓ 移动  Space 勾选  / 搜索  Enter 安装  q 取消"
            stdscr.addnstr(0, 0, header, max(0, width - 1))
            if query:
                stdscr.addnstr(1, 0, f"搜索: {query}", max(0, width - 1))

            rows = max(1, height - 4)
            start = max(0, current - rows + 1)
            for row, choice in enumerate(visible[start : start + rows], start=2):
                index = start + row - 2
                mark = "x" if choice.name in selected else " "
                suffix = f" · {choice.description}" if choice.description else ""
                line = f"[{mark}] {choice.name}  {choice.kind}{suffix}"
                attr = curses.A_REVERSE if index == current else curses.A_NORMAL
                stdscr.addnstr(row, 0, line, max(0, width - 1), attr)

            footer = f"已选择 {len(selected)} 项"
            stdscr.addnstr(height - 1, 0, footer, max(0, width - 1))
            stdscr.refresh()
            key = stdscr.get_wch()

            if key in ("q", "Q", "\x1b"):
                return None
            if key in ("\n", "\r") or key == curses.KEY_ENTER:
                return set(selected)
            if key == curses.KEY_UP and visible:
                current = (current - 1) % len(visible)
            elif key == curses.KEY_DOWN and visible:
                current = (current + 1) % len(visible)
            elif key == " " and visible:
                name = visible[current].name
                selected.symmetric_difference_update({name})
            elif key == "/":
                curses.curs_set(1)
                query = _read_query(stdscr, curses, width)
                curses.curs_set(0)
                current = 0

    runner = wrapper or curses.wrapper
    return runner(draw)


def _read_query(stdscr: object, curses: object, width: int) -> str:
    query = ""
    while True:
        stdscr.move(1, 0)
        stdscr.clrtoeol()
        stdscr.addnstr(1, 0, f"搜索: {query}", max(0, width - 1))
        stdscr.refresh()
        key = stdscr.get_wch()
        if key in ("\n", "\r") or key == curses.KEY_ENTER:
            return query
        if key == "\x1b":
            return ""
        if key in ("\b", "\x7f") or key == curses.KEY_BACKSPACE:
            query = query[:-1]
        elif isinstance(key, str) and key.isprintable():
            query += key