"""Детерминированный content_hash для сущностей с полем content_hash (sync pull/push)."""

from __future__ import annotations

import hashlib
import json
from typing import Any

# Не входят в хеш: версия/метаданные синка и аудит (иначе хеш «прыгает» без смены данных).
_EXCLUDED_FROM_HASH = frozenset(
    {
        "version",
        "content_hash",
        "sync_timestamp",
        "sync_status",
        "created_at",
        "updated_at",
        "created_by",
        "updated_by",
        "client_id",
        "server_synced",
        "is_deleted",
        "deleted_at",
        "deleted_by",
        "deleted_reason",
        "restored_at",
        "restored_by",
        "restored_reason",
        "delete_restore_count",
    }
)


def stable_payload_for_hash(data: dict[str, Any]) -> dict[str, Any]:
    return {k: v for k, v in data.items() if k not in _EXCLUDED_FROM_HASH}


def compute_content_hash_hex(payload: dict[str, Any]) -> str:
    raw = json.dumps(payload, sort_keys=True, ensure_ascii=False, default=str).encode("utf-8")
    return hashlib.sha256(raw).hexdigest()


def compute_content_hash_for_object(obj: Any) -> str:
    from app.services.sync_record_data import get_object_data

    data = get_object_data(obj)
    if not isinstance(data, dict):
        return ""
    stable = stable_payload_for_hash(data)
    return compute_content_hash_hex(stable)


def refresh_content_hash_if_applicable(obj: Any) -> None:
    if not hasattr(obj, "content_hash"):
        return
    new_hash = compute_content_hash_for_object(obj)
    if new_hash and getattr(obj, "content_hash", None) != new_hash:
        obj.content_hash = new_hash


def refresh_content_hashes_for_session(session) -> None:
    """Вызывать из before_flush: новые и изменённые строки с content_hash."""
    seen: set[int] = set()
    for obj in list(session.new) + list(session.dirty):
        oid = id(obj)
        if oid in seen:
            continue
        seen.add(oid)
        if not hasattr(obj, "content_hash"):
            continue
        refresh_content_hash_if_applicable(obj)