port ac power detection to new method

Signed-off-by: Sujal Singh <email.sujalsingh@gmail.com>

psutil/_pslinux.py

@@ -1472,11 +1472,7 @@ def multi_bcat(*paths):
                     return ret.strip()
         return None
 
-    def detect_battery():
-        expected_files = (
-            "energy_now", "charge_now", "power_now", "current_now",
-            "energy_full", "charge_full", "capacity"
-        )
+    def detect_battery(*expected_files):
         results = defaultdict(list)
 
         for path in os.listdir(POWER_SUPPLY_PATH):
@@ -1492,7 +1488,10 @@ def detect_battery():
         else:
             return None
 
-    root = detect_battery()
+    root = detect_battery(
+        "energy_now", "charge_now", "power_now", "current_now",
+        "energy_full", "charge_full", "capacity"
+    )
     if root is None:
         return None
 
@@ -1524,11 +1523,10 @@ def detect_battery():
     # Note: AC0 is not always available and sometimes (e.g. CentOS7)
     # it's called "AC".
     power_plugged = None
-    online = multi_bcat(
-        os.path.join(POWER_SUPPLY_PATH, "AC0/online"),
-        os.path.join(POWER_SUPPLY_PATH, "AC/online"))
-    if online is not None:
-        power_plugged = online == 1
+    online = detect_battery("online")
+    if online:
+        path = os.path.join(POWER_SUPPLY_PATH, online)
+        power_plugged = multi_bcat(path) == 1
     else:
         status = cat(root + "/status", fallback="").strip().lower()
         if status == "discharging":