Add coordinate cache to avoid redundant API calls

- Cache stored in ~/.cache/cpc_stations_coords.json
- Cache key based on station name + city + district + address
- Shows cache hit/miss statistics on stderr
- Subsequent runs are instant for cached stations

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cpc_direct_stations.py

@@ -19,6 +19,7 @@ from __future__ import annotations
 import argparse
 import csv
 import json
+import os
 import re
 import sys
 import time
@@ -26,10 +27,12 @@ import urllib.parse
 import urllib.request
 from html import unescape
 from html.parser import HTMLParser
+from pathlib import Path
 from typing import Dict, List, Optional
 
 BASE_URL = "https://vipmbr.cpc.com.tw/mbwebs/service_search.aspx"
 USER_AGENT = "Mozilla/5.0 (OpenClaw; cpc-direct-stations)"
+CACHE_FILE = Path.home() / ".cache" / "cpc_stations_coords.json"
 CITY_MAP = {
     "台北市": "A ",
     "新北市": "B ",
@@ -135,6 +138,29 @@ def extract_hidden_fields(html: str) -> Dict[str, str]:
     return fields
 
 
+def load_coords_cache() -> Dict[str, Dict[str, float]]:
+    """載入座標快取。"""
+    if CACHE_FILE.exists():
+        try:
+            with open(CACHE_FILE, "r", encoding="utf-8") as f:
+                return json.load(f)
+        except Exception:
+            pass
+    return {}
+
+
+def save_coords_cache(cache: Dict[str, Dict[str, float]]) -> None:
+    """儲存座標快取。"""
+    CACHE_FILE.parent.mkdir(parents=True, exist_ok=True)
+    with open(CACHE_FILE, "w", encoding="utf-8") as f:
+        json.dump(cache, f, ensure_ascii=False, indent=2)
+
+
+def make_cache_key(station: Dict[str, str]) -> str:
+    """產生快取鍵值：使用站名+縣市+完整地址。"""
+    return f"{station['站名']}|{station['縣市']}|{station['鄉鎮區']}|{station['地址']}"
+
+
 def geocode(address: str, station_name: str, city: str, district: str) -> Optional[Dict[str, float]]:
     """使用 Nominatim (OpenStreetMap) API 將地址轉換為座標。
 
@@ -173,22 +199,44 @@ def geocode(address: str, station_name: str, city: str, district: str) -> Option
 
 
 def add_coordinates(stations: List[Dict[str, str]], delay: float = 1.0) -> List[Dict[str, str]]:
-    """為站點資料加上座標資訊。"""
+    """為站點資料加上座標資訊（使用快取）。"""
+    cache = load_coords_cache()
+    cache_updated = False
+    missing_coords = []
+
+    # 先從快取讀取
     for station in stations:
-        full_address = f"{station['縣市']}{station['鄉鎮區']}{station['地址']}"
-        coords = geocode(
-            address=full_address,
-            station_name=station["站名"],
-            city=station["縣市"],
-            district=station["鄉鎮區"],
-        )
-        if coords:
-            station["緯度"] = str(coords["lat"])
-            station["經度"] = str(coords["lon"])
+        key = make_cache_key(station)
+        if key in cache:
+            station["緯度"] = str(cache[key]["lat"])
+            station["經度"] = str(cache[key]["lon"])
         else:
             station["緯度"] = ""
             station["經度"] = ""
-        time.sleep(delay)  # 避免 Nominatim 請求過快
+            missing_coords.append(station)
+
+    # 查詢缺少的座標
+    if missing_coords:
+        print(f"快取命中: {len(stations) - len(missing_coords)}/{len(stations)}，需查詢: {len(missing_coords)}", file=sys.stderr)
+        for station in missing_coords:
+            full_address = f"{station['縣市']}{station['鄉鎮區']}{station['地址']}"
+            coords = geocode(
+                address=full_address,
+                station_name=station["站名"],
+                city=station["縣市"],
+                district=station["鄉鎮區"],
+            )
+            if coords:
+                station["緯度"] = str(coords["lat"])
+                station["經度"] = str(coords["lon"])
+                key = make_cache_key(station)
+                cache[key] = coords
+                cache_updated = True
+            time.sleep(delay)  # 避免 Nominatim 請求過快
+
+        if cache_updated:
+            save_coords_cache(cache)
+
     return stations