"""ERP (procurement/inventory) read-only connector.

Auth: Casdoor password grant with a dedicated service account (no changes to
the ERP codebase). The token is cached until expiry. ERP stays the source of
truth for physical stock; PM only READS it (reservations/purchase requests are
PM-owned operational overlays).
"""
import asyncio
import logging
import time
from typing import Any

import httpx

from app.config import settings
from app.errors import UpstreamError

logger = logging.getLogger("pm.erp")


class ERPClient:
    def __init__(self):
        self._token: str | None = None
        self._token_exp: float = 0
        self._lock = asyncio.Lock()

    async def _ensure_token(self) -> str:
        async with self._lock:
            if self._token and time.time() < self._token_exp - 30:
                return self._token
            usernames = [
                settings.ERP_SERVICE_USERNAME,
                f"{settings.ERP_CASDOOR_ORGANIZATION}/{settings.ERP_SERVICE_USERNAME}",
            ]
            last_error: Exception | None = None
            async with httpx.AsyncClient(timeout=12) as client:
                for username in usernames:
                    try:
                        resp = await client.post(
                            f"{settings.ERP_CASDOOR_ENDPOINT}/api/login/oauth/access_token",
                            data={
                                "grant_type": "password",
                                "client_id": settings.ERP_CASDOOR_CLIENT_ID,
                                "client_secret": settings.ERP_CASDOOR_CLIENT_SECRET,
                                "username": username,
                                "password": settings.ERP_SERVICE_PASSWORD,
                            },
                        )
                        resp.raise_for_status()
                        data = resp.json()
                        token = data.get("access_token")
                        if token:
                            self._token = token
                            self._token_exp = time.time() + int(data.get("expires_in") or 3600)
                            return token
                    except Exception as exc:  # noqa: BLE001
                        last_error = exc
                        logger.warning("ERP token grant failed for %s: %s", username, exc)
            raise UpstreamError(f"احراز هویت سرویس با ERP/Casdoor ناموفق بود: {last_error}")

    async def get(self, path: str, params: dict | None = None) -> Any:
        token = await self._ensure_token()
        try:
            async with httpx.AsyncClient(timeout=15) as client:
                resp = await client.get(
                    f"{settings.ERP_BASE_URL}{path}",
                    params=params,
                    headers={"Authorization": f"Bearer {token}"},
                )
        except httpx.HTTPError as exc:
            raise UpstreamError(f"ERP در دسترس نیست: {exc.__class__.__name__}") from exc
        if resp.status_code == 401:
            self._token = None
            raise UpstreamError("توکن سرویس ERP نامعتبر شد")
        if resp.status_code >= 400:
            logger.warning("ERP GET %s → %s %s", path, resp.status_code, resp.text[:200])
            raise UpstreamError(f"خطای ERP ({resp.status_code})")
        if not resp.content:
            return {}
        return resp.json()

    # --- domain reads (normalize to PM-friendly dicts) -----------------------

    async def materials(self) -> list[dict]:
        """Global material catalog: [{id, name, unit_id, unit_name}]"""
        materials: list[dict] = []
        page = 1
        while True:
            data = await self.get(f"/api/v1/materials?page_size=100&page={page}")
            elements = data.get("data", []) if isinstance(data, dict) else []
            materials.extend(elements)
            meta = data.get("meta", {}) if isinstance(data, dict) else {}
            if not elements or page * 100 >= int(meta.get("total") or len(materials)):
                break
            page += 1

        unit_names: dict[int, str] = {}
        try:
            units = await self.get("/api/v1/units?page_size=100")
            for u in units.get("data", []):
                unit_names[u.get("id")] = u.get("name_fa") or u.get("name") or u.get("code") or ""
        except Exception:  # noqa: BLE001 — unit names are cosmetic
            pass

        return [
            {
                "id": m.get("id"),
                "name": m.get("name") or "",
                "unit_id": m.get("canonical_unit_id"),
                "unit_name": unit_names.get(m.get("canonical_unit_id"), ""),
            }
            for m in materials
            if m.get("id") and (m.get("status") or "active") == "active"
        ]

    async def projects(self) -> list[dict]:
        """ERP projects for the mapping picker: [{id, name}]"""
        data = await self.get("/api/v1/projects?page_size=100")
        elements = data.get("data", []) if isinstance(data, dict) else []
        return [{"id": p.get("id"), "name": p.get("name") or ""} for p in elements if p.get("id")]

    async def warehouses(self, erp_project_id: str) -> list[dict]:
        data = await self.get("/api/v1/inventory/warehouses")
        elements = data.get("data", data) if isinstance(data, dict) else data
        if isinstance(elements, dict):
            elements = elements.get("data", [])
        return [w for w in (elements or []) if w.get("project_id") == erp_project_id]

    async def inventory_rows(self) -> list[dict]:
        """Normalized stock rows: [{warehouse_id, material_id, quantity}].

        ERP returns nested objects (warehouse: {...}, material: {...}) plus a
        numeric `quantity_number` — flatten to the three fields PM needs.
        """
        rows: list[dict] = []
        page = 1
        while True:
            data = await self.get(f"/api/v1/inventory?page_size=100&page={page}")
            elements = data.get("data", []) if isinstance(data, dict) else []
            for r in elements:
                warehouse = r.get("warehouse") or {}
                material = r.get("material") or {}
                qty = r.get("quantity_number")
                if qty is None:
                    qty = r.get("quantity")
                rows.append(
                    {
                        "warehouse_id": warehouse.get("id"),
                        "material_id": material.get("id"),
                        "quantity": float(qty or 0),
                    }
                )
            meta = data.get("meta", {}) if isinstance(data, dict) else {}
            if not elements or page * 100 >= int(meta.get("total") or len(rows)):
                break
            page += 1
        return rows


erp_client = ERPClient()