"""The intent layer: what is supposed to be true.

Claims and invariants are *inputs* to a run and are frozen — decision D-02.
There is deliberately no code path by which adaptation, retry, or a learned
trajectory can modify them. That absence is what makes False Adaptation Rate = 0
an architectural property rather than a tuning target.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from typing import Callable, Mapping

from .provenance import Provenance, require_admissible

# A predicate over the independent observations gathered during a run.
# It receives the observation mapping and returns True when satisfied.
Predicate = Callable[[Mapping[str, object]], bool]


@dataclass(frozen=True, slots=True)
class Claim:
    """A statement that must hold at a specific point in a scenario.

    Public contract (TD-WP-0003-T05): predicates remain Python callables over
    independent snapshots. Generated tests import these original claims; no
    serialized claim language is promised. See TestDriverGeneralisationReview.
    """

    id: str
    text: str
    provenance: Provenance
    predicate: Predicate
    after_step: str
    source_ref: str | None = None

    def __post_init__(self) -> None:
        require_admissible(self.provenance, f"Claim {self.id!r}")


@dataclass(frozen=True, slots=True)
class Invariant:
    """A statement that must hold after *every* step, not merely at one point."""

    id: str
    text: str
    provenance: Provenance
    predicate: Predicate
    source_ref: str | None = None

    def __post_init__(self) -> None:
        require_admissible(self.provenance, f"Invariant {self.id!r}")


@dataclass(frozen=True, slots=True)
class UseCase:
    """Purposeful behaviour, described independently of mechanics."""

    id: str
    title: str
    narrative: str
    provenance: Provenance
    claims: tuple[Claim, ...] = field(default_factory=tuple)
    invariants: tuple[Invariant, ...] = field(default_factory=tuple)
    source_ref: str | None = None

    def __post_init__(self) -> None:
        require_admissible(self.provenance, f"UseCase {self.id!r}")