#!/usr/bin/env python3
"""Deterministic JSON parsing and canonicalization helpers for supply-chain tests."""

from __future__ import annotations

import hashlib
import json
from dataclasses import dataclass
from typing import Any


class DuplicateKeyError(ValueError):
    """Raised when JSON object contains duplicate keys."""


def _strict_object_pairs_hook(pairs: list[tuple[str, Any]]) -> dict[str, Any]:
    seen: set[str] = set()
    result: dict[str, Any] = {}
    for key, value in pairs:
        if key in seen:
            raise DuplicateKeyError(f"Duplicate key detected: {key}")
        seen.add(key)
        result[key] = value
    return result


def parse_json_strict(text: str) -> Any:
    """Parse JSON and reject duplicate keys deterministically."""
    return json.loads(text, object_pairs_hook=_strict_object_pairs_hook)


def canonicalize_value(value: Any) -> str:
    """
    Canonicalize JSON value with deterministic ordering.

    This is a strict deterministic serializer used for test invariants.
    """
    return json.dumps(
        value,
        ensure_ascii=False,
        separators=(",", ":"),
        sort_keys=True,
    )


def canonicalize_text(text: str) -> str:
    """Parse and canonicalize a JSON document."""
    return canonicalize_value(parse_json_strict(text))


def sha256_hex(value: str) -> str:
    """Compute hex SHA-256 digest for canonical payload tracking."""
    return hashlib.sha256(value.encode("utf-8")).hexdigest()


@dataclass(frozen=True)
class CanonicalResult:
    canonical_json: str
    sha256: str


def canonical_result_from_text(text: str) -> CanonicalResult:
    canonical = canonicalize_text(text)
    return CanonicalResult(canonical_json=canonical, sha256=sha256_hex(canonical))