import json
from typing import Any, Dict, Optional, Tuple

from flask import Request


def parse_json_request(req: Request, allow_gzip: bool = False) -> Tuple[Optional[Dict[str, Any]], Optional[str]]:
    """Парсинг JSON-тела запроса с опциональной поддержкой gzip."""
    if allow_gzip and req.headers.get("Content-Encoding", "") == "gzip":
        import gzip

        try:
            payload = gzip.decompress(req.data)
            data = json.loads(payload.decode("utf-8"))
        except (gzip.BadGzipFile, json.JSONDecodeError, UnicodeDecodeError):
            return None, "Ошибка распаковки сжатых данных"
        if not isinstance(data, dict):
            return None, "Тело запроса должно быть JSON-объектом"
        return data, None

    if not req.is_json:
        return None, "Content-Type должен быть application/json"

    data = req.get_json() or {}
    if not isinstance(data, dict):
        return None, "Тело запроса должно быть JSON-объектом"
    return data, None


def parse_pull_payload(
    data: Dict[str, Any],
) -> Tuple[Optional[str], Optional[int], Optional[str], Optional[str]]:
    """(client_id, limit, client_name, error). client_name — опционально для реестра на сервере."""
    client_id = data.get("client_id")
    if not client_id:
        return None, None, None, "client_id обязателен"

    limit = data.get("limit")
    lim: Optional[int] = None
    if limit is not None:
        try:
            lim = int(limit)
        except (TypeError, ValueError):
            return None, None, None, "limit должен быть числом"

    cn_raw = data.get("client_name")
    client_name: Optional[str] = None
    if cn_raw is not None:
        s = str(cn_raw).strip()
        if s:
            client_name = s[:100]

    return str(client_id).strip(), lim, client_name, None


def parse_confirm_payload(data: Dict[str, Any]) -> Tuple[Optional[str], Optional[list], Optional[str]]:
    client_id = data.get("client_id")
    task_ids = data.get("task_ids") or []
    if not client_id:
        return None, None, "client_id обязателен"
    if not isinstance(task_ids, list) or not task_ids:
        return None, None, "task_ids обязателен и должен быть списком"
    return client_id, task_ids, None


def parse_push_payload(data: Dict[str, Any]) -> Tuple[Optional[str], Any, Optional[str]]:
    client_id = data.get("client_id")
    if not client_id:
        return None, None, "client_id обязателен"
    changes = data.get("changes", [])
    return client_id, changes, None