"""State handling functions."""

from __future__ import annotations

import tcod.console

import tcod.event

import g

from game.state import Pop, Push, Reset, State, StateResult

def main_draw() -> None:

"""Render and present the active state."""

if not g.states:

return

g.console.clear()

g.states[-1].on_draw(g.console)

g.context.present(g.console)

def apply_state_result(result: StateResult) -> None:

"""Apply a StateResult to `g.states`."""

match result:

case Push(state=state):

g.states.append(state)

case Pop():

g.states.pop()

case Reset(state=state):

while g.states:

apply_state_result(Pop())

apply_state_result(Push(state))

case None:

pass

case _:

raise TypeError(result)

def main_loop() -> None:

"""Run the active state forever."""

while g.states:

main_draw()

for event in tcod.event.wait():

tile_event = g.context.convert_event(event)

if g.states:

apply_state_result(g.states[-1].on_event(tile_event))

def get_previous_state(state: State) -> State | None:

"""Return the state before `state` in the stack if it exists."""

current_index = next(index for index, value in enumerate(g.states) if value is state)

return g.states[current_index - 1] if current_index > 0 else None

def draw_previous_state(state: State, console: tcod.console.Console, *, dim: bool = True) -> None:

"""Draw previous states, optionally dimming all but the active state."""

prev_state = get_previous_state(state)

if prev_state is None:

return

prev_state.on_draw(console)

if dim and state is g.states[-1]:

console.rgb["fg"] //= 4

console.rgb["bg"] //= 4