from __future__ import annotations
import stat
from typing import TYPE_CHECKING
import curses
from ..items.Symlink import Symlink
from ..items.AItems import AItem

if TYPE_CHECKING:
    from .App import App


class UI:
    def __init__(self, app: App):
        self._app = app

    HEADER_ROWS = 2
    ERROR_COLOR = 5

    def _get_attr(self, item: any, index: int) -> str:
        attr = curses.color_pair(item.color_pair)
        if index == self.app.navigator.cursor.pos:
            attr |= curses.A_REVERSE
        return attr

    def render(self, stdscr: curses.window) -> None:
        stdscr.erase()
        height, width = stdscr.getmaxyx()
        navigator = self.app.navigator

        stdscr.addstr(0, 0, str(navigator.history[-1])[:width - 1])
        if navigator.error:
            stdscr.addstr(1, 0, navigator.error[:width - 1],
                          curses.color_pair(self.ERROR_COLOR))

        items = navigator.items
        available = max(0, height - self.HEADER_ROWS)
        for index in range(min(available, len(items))):
            item = items[index]
            self._render_item(stdscr, item, index, index + self.HEADER_ROWS, width)

    SIZE_UNITS = ("", "K", "M", "G", "T", "P")

    @staticmethod
    def _format_size(size: int) -> str:
        value = float(size)
        for unit in UI.SIZE_UNITS:
            if value < 1024:
                return str(int(value)) if unit == "" else f"{value:.1f}{unit}"
            value /= 1024
        return f"{value:.1f}E"

    ARROW = " -> "
    ARROW_LEN = len(ARROW)

    def _render_item(self, stdscr: curses.window, item: AItem, index: int,
                      row: int, width: int) -> None:
        name, size, perm = item.fields()
        name_len = len(name)
        col_width = int(width / 3)

        attr = self._get_attr(item, index)
        stdscr.addstr(row, 0, name.ljust(col_width), attr)

        if type(item) is Symlink:
            attr_arrow = curses.color_pair(0)
            attr_target = curses.color_pair(Symlink.target_color(item.point_to))
            if index == self.app.navigator.cursor.pos:
                attr_arrow |= curses.A_REVERSE
                attr_target |= curses.A_REVERSE
            stdscr.addstr(row, name_len, self.ARROW, attr_arrow)
            stdscr.addstr(row, name_len + self.ARROW_LEN, str(item.point_to), attr_target)

        stdscr.addstr(row, col_width, self._format_size(size).ljust(col_width * 2), attr)
        stdscr.addstr(row, col_width * 2, stat.filemode(perm), attr)

    @property
    def app(self) -> App:
        return self._app