"""Stratified evidence — decision D-01.

    S1 Surface      how an action was performed (selectors, routes, payloads)
    S2 Realization  whether it happened, and through which surface
    S3 Judgment     whether that was correct

Each stratum has a different authority. Models may write S1. Nothing but an
independent Observer writes S2 or S3.

See docs/TestDriverClassificationDesign.md, Part A.
"""

from __future__ import annotations

import json
from dataclasses import dataclass, field, asdict
from datetime import datetime, timezone
from enum import Enum
from typing import Any


class Stratum(str, Enum):
    SURFACE = "S1"
    REALIZATION = "S2"
    JUDGMENT = "S3"


def _now() -> str:
    return datetime.now(timezone.utc).isoformat()


@dataclass(frozen=True, slots=True)
class Observation:
    """One recorded fact, attributed to a stratum and a collector.

    `collector` is never an actor for S2/S3 observations. The runner enforces
    this; see runner._assert_collector_independence.
    """

    id: str
    stratum: Stratum
    collector: str
    step_id: str | None
    kind: str
    data: dict[str, Any]
    at: str = field(default_factory=_now)


@dataclass(slots=True)
class EvidencePack:
    """Everything retained from one run.

    The pack must be sufficient to replay the run and to diagnose a finding
    without the original process. An assertion that cannot be supported from the
    pack is an EVIDENCE_FAILURE, not a defect in the system under test.
    """

    run_id: str
    scenario_id: str
    use_case_id: str
    sut_version: str
    started_at: str = field(default_factory=_now)
    finished_at: str | None = None
    observations: list[Observation] = field(default_factory=list)
    verdicts: list[dict[str, Any]] = field(default_factory=list)
    energy_events: list[dict[str, Any]] = field(default_factory=list)
    provenance_index: dict[str, str] = field(default_factory=dict)

    def record(self, observation: Observation) -> None:
        self.observations.append(observation)

    def of_stratum(self, stratum: Stratum) -> list[Observation]:
        return [o for o in self.observations if o.stratum is stratum]

    def to_json(self) -> str:
        payload = asdict(self)
        payload["observations"] = [
            {**asdict(o), "stratum": o.stratum.value} for o in self.observations
        ]
        return json.dumps(payload, indent=2, sort_keys=True, default=str)