"""Scrollable help page backed by a bundled markdown file."""

from __future__ import annotations

from importlib.resources import files

from unicurses import (  # type: ignore[import-untyped]
	KEY_DOWN,
	KEY_RESIZE,
	KEY_UP,
)

from pygittools.tui.draw import draw_line
from pygittools.tui.types import PageAction, PageContext, PageResult


def _load_help_lines() -> list[str]:
	text = files("pygittools").joinpath("help.md").read_text(encoding="utf-8")
	return text.splitlines()


class HelpPage:
	title = "help"

	def __init__(self) -> None:
		self._lines = _load_help_lines()
		self._offset = 0

	def on_enter(self, ctx: PageContext) -> None:
		del ctx

	def status_text(self) -> str:
		total = len(self._lines)
		if total == 0:
			return "Help"
		visible_end = min(self._offset + 1, total)
		return f"Help {visible_end}/{total} — J/K or arrows to scroll, Q or Esc to go back"

	def draw(self, stdscr: int, height: int, width: int) -> None:
		del stdscr
		if height <= 0:
			return
		max_offset = max(0, len(self._lines) - height)
		self._offset = min(self._offset, max_offset)
		for row in range(height):
			line_index = self._offset + row
			if line_index >= len(self._lines):
				break
			draw_line(row, 0, self._lines[line_index], width)

	def handle_key(self, key: int) -> PageResult:
		if key in (ord("q"), ord("Q"), 27):
			return PageResult(action=PageAction.POP)
		if key == KEY_RESIZE:
			return PageResult()
		if key in (KEY_UP, ord("k"), ord("K")):
			self._offset = max(0, self._offset - 1)
			return PageResult()
		if key in (KEY_DOWN, ord("j"), ord("J")):
			self._offset += 1
			return PageResult()
		return PageResult()


def help_page() -> HelpPage:
	return HelpPage()