From f52fe001cc4b8077ffb8bb16affa3ed0d960482c Mon Sep 17 00:00:00 2001
From: Jun-te Kim <juntekim@googlemail.com>
Date: Tue, 12 May 2026 10:14:16 +0000
Subject: [PATCH] renamed file

---
 backend/epc_client/epc_client_service.py | 99 ++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 backend/epc_client/epc_client_service.py

diff --git a/backend/epc_client/epc_client_service.py b/backend/epc_client/epc_client_service.py
new file mode 100644
index 00000000..d00a164f
--- /dev/null
+++ b/backend/epc_client/epc_client_service.py
@@ -0,0 +1,99 @@
+# Spec: https://raw.githubusercontent.com/communitiesuk/epb-data-warehouse/main/api/api.yml
+from __future__ import annotations
+
+from typing import Any, Optional
+
+import httpx
+
+from backend.epc_client.exceptions import (
+    EpcApiError,
+    EpcNotFoundError,
+    EpcRateLimitError,
+)
+from backend.epc_client._retry import call_with_retry
+from datatypes.epc.domain.epc_property_data import EpcPropertyData
+from datatypes.epc.domain.mapper import EpcPropertyDataMapper
+from datatypes.epc.search import EpcSearchResult
+
+
+class EpcClientService:
+    BASE_URL = "https://api.get-energy-performance-data.communities.gov.uk"
+
+    def __init__(self, auth_token: str) -> None:
+        self._headers = {
+            "Authorization": f"Bearer {auth_token}",
+            "Accept": "application/json",
+        }
+
+    def get_by_certificate_number(self, cert_num: str) -> EpcPropertyData:
+        raw = call_with_retry(lambda: self._fetch_certificate(cert_num))
+        return EpcPropertyDataMapper.from_api_response(raw)
+
+    def get_by_uprn(self, uprn: int) -> Optional[EpcPropertyData]:
+        results = call_with_retry(lambda: self._search(uprn=uprn))
+        if not results:
+            return None
+        latest = max(results, key=lambda r: r.registration_date)
+        return self.get_by_certificate_number(latest.certificate_number)
+
+    def search_by_postcode(self, postcode: str) -> list[EpcSearchResult]:
+        return call_with_retry(lambda: self._search(postcode=postcode))
+
+    # ------------------------------------------------------------------
+    # Private helpers
+    # ------------------------------------------------------------------
+
+    def _fetch_certificate(self, cert_num: str) -> dict[str, Any]:
+        resp = httpx.get(
+            f"{self.BASE_URL}/api/certificate",
+            params={"certificate_number": cert_num},
+            headers=self._headers,
+        )
+        if resp.status_code == 404:
+            raise EpcNotFoundError(cert_num)
+        if resp.status_code == 429:
+            raise EpcRateLimitError("Rate limited by EPC API")
+        if not resp.is_success:
+            raise EpcApiError(f"EPC API error {resp.status_code}: {resp.text}")
+        return resp.json()["data"]
+
+    def _search(
+        self,
+        postcode: Optional[str] = None,
+        uprn: Optional[int] = None,
+    ) -> list[EpcSearchResult]:
+        params: dict[str, str | int] = {}
+        if postcode:
+            params["postcode"] = postcode
+        if uprn is not None:
+            params["uprn"] = uprn
+
+        resp = httpx.get(
+            f"{self.BASE_URL}/api/domestic/search",
+            params=params,
+            headers=self._headers,
+        )
+        if resp.status_code == 404:
+            return []
+        if resp.status_code == 429:
+            raise EpcRateLimitError("Rate limited by EPC API")
+        if not resp.is_success:
+            raise EpcApiError(f"EPC API error {resp.status_code}: {resp.text}")
+
+        rows = resp.json().get("data", [])
+        return [self._parse_search_result(r) for r in rows]
+
+    @staticmethod
+    def _parse_search_result(row: dict[str, Any]) -> EpcSearchResult:
+        return EpcSearchResult(
+            certificate_number=row["certificateNumber"],
+            address_line_1=row["addressLine1"],
+            address_line_2=row.get("addressLine2"),
+            address_line_3=row.get("addressLine3"),
+            address_line_4=row.get("addressLine4"),
+            postcode=row["postcode"],
+            post_town=row["postTown"],
+            uprn=row.get("uprn"),
+            current_energy_efficiency_band=row["currentEnergyEfficiencyBand"],
+            registration_date=row["registrationDate"],
+        )