"""Shutdown projection and the one-line i3blocks summary.

Split out of :mod:`screen_locker._status_data` to keep every file under the
250-line cap. ``format_summary_line`` is re-exported from there, so
``status_view`` and the i3blocks CLI are unaffected.

Projects what time the PC will shut down on each remaining day of the week,
and renders the compact status line.
"""

from __future__ import annotations

from datetime import date, datetime, timedelta
from typing import TYPE_CHECKING

from screen_locker._earned import hhmm
from screen_locker._shutdown import read_shutdown_config
from screen_locker._shutdown_base import base_minutes
from screen_locker._status_types import ShutdownProjection, ShutdownProjectionDay

if TYPE_CHECKING:
    from pathlib import Path

    from screen_locker._status_types import StatusSnapshot

_RELAXED_DAY_EXPLANATION = (
    "Shutdown time and the screen lock are two separate systems: the lock "
    "decides whether you must log a workout right now; shutdown time only "
    "controls how late the PC stays on tonight."
)
_WEEKDAY_LABELS = ("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")
_MON_WED_WEEKDAYS = frozenset({0, 1, 2})


def _week_rows(monday: date, *, speculative: bool) -> tuple[ShutdownProjectionDay, ...]:
    """Build 7 labeled rows, Mon-Sun from ``monday``, each on its own day's base.

    Each row asks ``base_minutes`` for its own date, so a registry cut dated
    mid-week (or next week) shows on the day it lands, not from today's base.
    """
    return tuple(
        ShutdownProjectionDay(
            label=label,
            minutes=base_minutes(monday + timedelta(days=weekday)),
            speculative=speculative,
        )
        for weekday, label in enumerate(_WEEKDAY_LABELS)
    )


def _shutdown_projection(
    *,
    shutdown_config_file: Path,
    today_local: datetime,
) -> ShutdownProjection:
    """Build the shutdown-time projection: tonight, rest of week, next week.

    Every row is the plain per-day base: no week carries a banked shutdown
    bonus (dropped 2026-10-10).
    """
    tonight = read_shutdown_config(shutdown_config_file)
    monday = today_local.date() - timedelta(days=today_local.weekday())
    rest_of_week = _week_rows(monday, speculative=False)
    next_week_preview = _week_rows(monday + timedelta(weeks=1), speculative=True)

    return ShutdownProjection(
        tonight=tonight,
        rest_of_week=rest_of_week,
        next_week_preview=next_week_preview,
        explanation=_RELAXED_DAY_EXPLANATION,
    )


def _tonight_minutes(snapshot: StatusSnapshot) -> int | None:
    """Pick the shutdown band (Mon-Wed vs Thu-Sun) matching today, in minutes.

    Uses ``snapshot.generated_at`` (not a fresh ``datetime.now()``) so the
    summary line is a pure function of the snapshot it was handed.
    """
    if snapshot.shutdown.tonight is None:
        return None
    mon_wed, thu_sun, _morning = snapshot.shutdown.tonight
    generated_weekday = (
        datetime.fromisoformat(snapshot.generated_at).astimezone().weekday()
    )
    return mon_wed if generated_weekday in _MON_WED_WEEKDAYS else thu_sun


def format_summary_line(snapshot: StatusSnapshot) -> str:
    """Cheap one-liner for the i3blocks summary (e.g. before/after a click)."""
    week = snapshot.week
    mark = "✓" if week.remaining == 0 else "…"
    tonight = _tonight_minutes(snapshot)
    tonight_str = hhmm(tonight) if tonight is not None else "?"
    sick = snapshot.sick_budget
    return (
        f"{mark} {week.counted_count}/{week.minimum} workouts · "
        f"{tonight_str} tonight · sick {sick.used_7d}/{sick.budget_7d}"
    )


def compliance_state_word(snapshot: StatusSnapshot) -> str:
    """One-word compliance state for the tray icon: ``ok`` / ``warn`` / ``lock``.

    ``lock`` — the lock would fire right now (no skip condition applies).
    ``warn`` — not locked, but this week's minimum isn't met yet.
    ``ok`` — not locked and the weekly minimum is already met.
    """
    if snapshot.lock_explanation.fired:
        return "lock"
    if snapshot.week.remaining > 0:
        return "warn"
    return "ok"