"""Claim/proof receipts for ANNEX-2.3 R2 governed claim audit read-back.

A receipt is a minimal, tamper-evident record generated alongside a governed
claim.  Its digest is sha256(canonical_json(payload)) so the payload can be
re-verified on read-back, consistent with the evidence and event chain.
"""

from __future__ import annotations

import time
import uuid
from dataclasses import dataclass
from typing import Any

from .models import compute_sha256_hex


def receipt_digest(payload: dict[str, Any]) -> str:
    return compute_sha256_hex(payload)


@dataclass
class ClaimReceipt:
    receipt_id: str
    kind: str
    task_id: str
    worker_id: str
    claim_id: str | None
    proof_id: str | None
    digest: str
    payload: dict[str, Any]
    created_at: float

    def to_dict(self) -> dict[str, Any]:
        return {
            "receipt_id": self.receipt_id,
            "kind": self.kind,
            "task_id": self.task_id,
            "worker_id": self.worker_id,
            "claim_id": self.claim_id,
            "proof_id": self.proof_id,
            "digest": self.digest,
            "payload": self.payload,
            "created_at": self.created_at,
        }


def build_receipt(
    *,
    kind: str,
    task_id: str,
    worker_id: str,
    claim_id: str | None = None,
    proof_id: str | None = None,
    extra: dict[str, Any] | None = None,
    created_at: float | None = None,
) -> ClaimReceipt:
    """Build a ClaimReceipt whose digest covers the full digestable payload."""
    extra = extra or {}
    payload = {
        "kind": kind,
        "task_id": task_id,
        "worker_id": worker_id,
        "claim_id": claim_id,
        "proof_id": proof_id,
        **extra,
    }
    return ClaimReceipt(
        receipt_id=f"rct-{uuid.uuid4()}",
        kind=kind,
        task_id=task_id,
        worker_id=worker_id,
        claim_id=claim_id,
        proof_id=proof_id,
        digest=receipt_digest(payload),
        payload=payload,
        created_at=created_at if created_at is not None else time.time(),
    )