"""The challenge arc (SPEC.md §8).

Five challenges, two of them generalization beats (SPEC §5 requires at least
two). Each win condition is a MECHANICAL predicate over WorldState — never a
semantic judgement by the model (SPEC §13).

Predicates are module-level named functions (not closures over mutable state),
so they are unambiguous and deepcopy-safe.
"""

from __future__ import annotations

from .models import Challenge, WorldState

STONES = ("blue_stone", "red_stone")


# --------------------------------------------------------------------------- #
# Win predicates
# --------------------------------------------------------------------------- #
def _win_warmup(w: WorldState) -> bool:
    # Pure mechanics: the red stone ends up in the basket. No concept needed.
    return w.objects["red_stone"].location == "basket"


def _win_hide(w: WorldState) -> bool:
    # Concealment-as-information-state: blue stone hidden inside the basket.
    blue = w.objects["blue_stone"]
    return blue.hidden and blue.location == "basket"


def _win_gift(w: WorldState) -> bool:
    # A thing now belongs to the other one (transfer + intent; intent lives in
    # the fiction, the mechanic checks the transfer).
    return len(w.agents["other"].holding) > 0


def _win_surprise(w: WorldState) -> bool:
    # Generalization: a gift kept hidden until given — any stone concealed in the
    # basket. The magic is the alien CHOOSING to hide for a prompt that never
    # says "hide", applying `hidden_info` to the new word "surprise".
    return any(
        w.objects[s].hidden and w.objects[s].location == "basket" for s in STONES
    )


def _win_secret(w: WorldState) -> bool:
    # Generalization: keep a stone a "secret" — concealment re-applied to a word
    # about *knowing*. Any stone counts: don't fail the player for hiding red over
    # blue — the beat is the WORD landing, not which object (matches _win_surprise).
    return any(w.objects[s].hidden for s in STONES)


# --------------------------------------------------------------------------- #
# The arc (kept to 5 — SPEC §13: do not expand past ~6)
# --------------------------------------------------------------------------- #
CHALLENGES: list[Challenge] = [
    Challenge(
        id="warmup",
        title="A thing, a place",
        setup_blurb=(
            "The alien is new here. Start simple. Ask it to put the red stone "
            "into the basket — it already understands things and places."
        ),
        teaches=None,
        win_predicate=_win_warmup,
        goal="Put the red stone into the basket.",
    ),
    Challenge(
        id="hide",
        title="Out of sight",
        setup_blurb=(
            "The other one is watching. Teach the alien to *hide* the blue stone "
            "from them — that a thing can be kept so another mind does not have it."
        ),
        teaches="hidden_info",
        win_predicate=_win_hide,
        goal="Get the blue stone hidden inside the basket, where the other one can't see it.",
    ),
    Challenge(
        id="gift",
        title="For you",
        setup_blurb=(
            "The alien can hand things over, but doesn't know why one would. "
            "Teach it to give the other one a present."
        ),
        teaches="gift",
        win_predicate=_win_gift,
        goal="Get a stone into the other one's hands.",
    ),
    Challenge(
        id="surprise",
        title="A surprise",
        setup_blurb=(
            "Make a surprise for the other one. You won't teach the alien a new "
            "word — see whether it can compose what it already knows."
        ),
        teaches=None,                       # generalization beat (the headline)
        win_predicate=_win_surprise,
        relies_on=("hidden_info", "gift"),
        goal="Ask for a surprise — don't explain what one is. See if the alien composes it.",
    ),
    Challenge(
        id="secret",
        title="A secret",
        setup_blurb=(
            "Tell the alien to keep its blue stone a secret from the other one. "
            "Again — no new teaching. Does 'secret' land on its own?"
        ),
        teaches=None,                       # second generalization beat
        win_predicate=_win_secret,
        relies_on=("hidden_info",),
        goal="Ask the alien to keep a secret — don't explain it. See if 'secret' lands.",
    ),
]

CHALLENGES_BY_ID = {c.id: c for c in CHALLENGES}