"""Shared navigation helpers (home, menu, popups, back/escape)."""

# The mailbox/cafe/shop-style header bar renders a plain light background
# here; the home screen shows character art instead.
SUBSCREEN_HEADER_PROBE = (500, 10)
SUBSCREEN_HEADER_MIN_CHANNEL = 200

# Any modal dialog dims the screen behind it to roughly this darkness.
MODAL_DIM_PROBE = (960, 200)
MODAL_DIM_MAX_CHANNEL = 150

# Shared top-left back-arrow position -- every subscreen calibrated so far
# (mailbox, cafe, shop, lesson, event) puts its own back button here
# (confirmed identical across config.py's LESSON_BACK_BUTTON/
# SHOP_BACK_BUTTON/EVENT_BACK_BUTTON). Used by return_to_home below as a
# generic recovery affordance, independent of which task got stuck.
BACK_BUTTON = (85, 55)
RETURN_HOME_MAX_ROUNDS = 6


def is_on_subscreen(driver):
    r, g, b = driver.color_at(*SUBSCREEN_HEADER_PROBE)
    return r > SUBSCREEN_HEADER_MIN_CHANNEL and g > SUBSCREEN_HEADER_MIN_CHANNEL and b > SUBSCREEN_HEADER_MIN_CHANNEL


def is_modal_open(driver):
    r, g, b = driver.color_at(*MODAL_DIM_PROBE)
    return r < MODAL_DIM_MAX_CHANNEL and g < MODAL_DIM_MAX_CHANNEL and b < MODAL_DIM_MAX_CHANNEL


def return_to_home(driver):
    """Bounded "press back until the home screen is reached" loop -- the
    shared recovery path for any task that ends up on an unexpected or wrong
    subscreen (e.g. event_sweep landing on a stale/finished event's page
    instead of the current one, see plan.md's Event sweep phase). Generic
    across tasks: it only depends on is_on_subscreen and the shared
    BACK_BUTTON position above, not on any task-specific state.

    Checks is_on_subscreen before every single press and stops the instant
    it reads False -- never presses Escape/clicks back while already on the
    home screen. This matters: CLAUDE.md documents a real hazard where a
    blind Escape press on the home screen itself raises Blue Archive's own
    "exit the game?" confirmation, which is exactly the failure mode a
    naive fixed-count blind-press loop could cause here.

    Tries Escape first each round (works for most subscreens, confirmed for
    mailbox/cafe/event's own stage modal) and falls back to clicking
    BACK_BUTTON if Escape didn't clear it, re-checking after each.

    Returns True once home is confirmed reached, False if still not home
    after RETURN_HOME_MAX_ROUNDS -- callers should treat False as "abort,
    don't guess further" rather than assume home was reached.
    """
    for _ in range(RETURN_HOME_MAX_ROUNDS):
        if not is_on_subscreen(driver):
            return True
        driver.keypress("Escape")
        driver.wait(1)
        if not is_on_subscreen(driver):
            return True
        driver.click(*BACK_BUTTON)
        driver.wait(1)
    return not is_on_subscreen(driver)


def wait_for_state(driver, config, reactions, ends, max_iterations=30, poll_interval=1.0):
    """Generic "watch the screen, react to anything recognized, stop once a
    recognized destination is reached" loop -- the local equivalent of the
    reference's core/picture.py::co_detect, scoped to what this project
    actually needs (a handful of named checks) rather than co_detect's full
    generality (which spans the whole reference project via ~20 image
    template assets this project doesn't have).

    `ends`: {check_fn(driver, config) -> bool: outcome_name}. Checked first,
    every iteration; the first match stops the loop and returns its name.

    `reactions`: {check_fn(driver, config) -> bool: action(driver)}. Checked
    if no end matched; the first match runs its action (a click, a keypress,
    whatever the recognized state calls for) and the loop continues.

    If neither an end nor a reaction matches, the loop just waits and retries
    -- it never falls back to a blind click/keypress guess (see CLAUDE.md's
    exit-game-dialog writeup for why that was a real bug elsewhere).

    Returns the matched end's outcome name, or None once max_iterations is
    exhausted without reaching a recognized end -- callers should treat None
    as "unrecognized state, abort safely."
    """
    for _ in range(max_iterations):
        for check_fn, outcome_name in ends.items():
            if check_fn(driver, config):
                return outcome_name
        for check_fn, action in reactions.items():
            if check_fn(driver, config):
                action(driver)
                break
        else:
            driver.wait(poll_interval)
    return None