"""Thin client for the Feishu Open Platform Helpdesk API.

The Helpdesk API needs TWO auth headers on every call:

  * ``Authorization: Bearer <tenant_access_token>`` — the standard app
    token, obtained from the app's ``app_id`` / ``app_secret`` (reuses
    :class:`FeishuApprovalClient`'s cached token machinery).
  * ``X-Lark-Helpdesk-Authorization: base64(helpdesk_id:helpdesk_token)``
    — the per-服务台 credential, generated by a helpdesk admin in
    服务台后台 → 开发者选项.

The app must also hold the ``helpdesk:all:readonly`` scope (granted +
published on the Feishu open platform). Without it the API returns
``99991672`` (verified against prod 2026-06-22).

Query-filter timestamps (``update_time_start`` / ``update_time_end`` /
``create_time_*``) are **epoch milliseconds** — same unit as the
response timestamps (verified against prod: a seconds-valued window
returns 0 rows). Pagination is 1-based ``page`` + ``page_size``; the
response carries no ``has_more`` flag, so callers paginate until a page
returns fewer than ``page_size`` rows.
"""
from __future__ import annotations

import base64
import logging
from typing import Any

import httpx

from app.approval.feishu_client import FeishuApprovalClient
from app.core.exceptions import AppException

logger = logging.getLogger(__name__)

_BASE_URL = "https://open.feishu.cn/open-apis"
# Feishu helpdesk tickets list caps page_size at 50.
_PAGE_SIZE = 50
# Hard ceiling on pages per sync window so a misconfigured giant window
# can't run unbounded. 50 × 400 = 20k tickets per window — far above any
# 12-hour delta.
_MAX_PAGES = 400


class FeishuHelpdeskClient:
    """One instance per integration row (driver/sync is per-invocation)."""

    def __init__(
        self,
        *,
        app_id: str,
        app_secret: str,
        helpdesk_id: str,
        helpdesk_token: str,
    ) -> None:
        if not helpdesk_id or not helpdesk_token:
            raise AppException(
                code="FEISHU_HELPDESK_NOT_CONFIGURED",
                message=(
                    "飞书服务台 helpdesk_id / helpdesk_token 未配置。请到 "
                    "管理后台 > 连接器 编辑该服务台连接器并填写。"
                ),
                status_code=503,
            )
        # FeishuApprovalClient validates app_id/app_secret + caches the token.
        self._token_client = FeishuApprovalClient(
            app_id=app_id, app_secret=app_secret,
        )
        self.helpdesk_id = helpdesk_id
        self._helpdesk_auth = base64.b64encode(
            f"{helpdesk_id}:{helpdesk_token}".encode(),
        ).decode()

    async def _headers(self) -> dict[str, str]:
        token = await self._token_client.get_tenant_access_token()
        return {
            "Authorization": f"Bearer {token}",
            "X-Lark-Helpdesk-Authorization": self._helpdesk_auth,
        }

    async def _get(
        self, path: str, *, params: dict[str, Any],
    ) -> dict[str, Any]:
        headers = await self._headers()
        async with httpx.AsyncClient(
            timeout=30, trust_env=False, follow_redirects=False,
        ) as client:
            resp = await client.get(
                f"{_BASE_URL}{path}", params=params, headers=headers,
            )
            payload = resp.json()
        if payload.get("code") != 0:
            logger.warning(
                "feishu helpdesk: GET %s returned non-zero: %s", path, payload,
            )
            raise AppException(
                code="FEISHU_HELPDESK_API_ERROR",
                message=(
                    f"Feishu API error {payload.get('code')}: "
                    f"{payload.get('msg', 'helpdesk request failed')}"
                ),
                status_code=502,
            )
        return payload.get("data") or {}

    async def get_helpdesk_name(self) -> str | None:
        """Best-effort helpdesk display name (from the first ticket page).

        The list endpoint echoes ``helpdesk_name`` per ticket; there is no
        cheaper "describe helpdesk" read that this app's scope covers.
        Returns ``None`` when the helpdesk has no tickets yet.
        """
        data = await self._get(
            "/helpdesk/v1/tickets", params={"page": 1, "page_size": 1},
        )
        tickets = data.get("tickets") or []
        if tickets:
            name = tickets[0].get("helpdesk_name")
            if isinstance(name, str) and name.strip():
                return name.strip()
        return None

    async def iter_tickets(
        self,
        *,
        update_time_start_ms: int | None = None,
        update_time_end_ms: int | None = None,
    ) -> list[dict[str, Any]]:
        """Return every ticket whose ``updated_at`` falls in the window.

        Both bounds are epoch-ms and optional (omit for a full pull). The
        list is accumulated across all pages.
        """
        out: list[dict[str, Any]] = []
        for page in range(1, _MAX_PAGES + 1):
            params: dict[str, Any] = {"page": page, "page_size": _PAGE_SIZE}
            if update_time_start_ms is not None:
                params["update_time_start"] = update_time_start_ms
            if update_time_end_ms is not None:
                params["update_time_end"] = update_time_end_ms
            data = await self._get("/helpdesk/v1/tickets", params=params)
            tickets = data.get("tickets") or []
            out.extend(t for t in tickets if isinstance(t, dict))
            if len(tickets) < _PAGE_SIZE:
                break
        else:
            logger.warning(
                "feishu helpdesk: hit _MAX_PAGES=%d for helpdesk_id=%s — "
                "window may be too wide; some tickets not fetched this run",
                _MAX_PAGES, self.helpdesk_id,
            )
        return out

    async def test_connection_total(self) -> int:
        """Cheap health probe: one-row read returns the helpdesk total."""
        data = await self._get(
            "/helpdesk/v1/tickets", params={"page": 1, "page_size": 1},
        )
        total = data.get("total")
        return int(total) if isinstance(total, int) else 0