Fallback geocode when postal code has zero results

src/main/kotlin/com/android/trisolarisserver/component/GoogleGeocodingClient.kt

@@ -28,16 +28,39 @@ class GoogleGeocodingClient(
                 .queryParam("region", "IN")
                 .queryParam("key", apiKey)
                 .toUriString()
-            val response = restTemplate.getForEntity(url, String::class.java)
-            val body = response.body ?: return GeocodeResult(null, null, "EMPTY_BODY")
-            val parsed = parseCityState(body)
-            GeocodeResult(parsed, body, "OK")
+            val primary = fetch(url)
+            if (primary.status == "OK") {
+                return primary
+            }
+            if (primary.status == "ZERO_RESULTS") {
+                val fallbackUrl = UriComponentsBuilder.fromUriString(baseUrl)
+                    .queryParam("address", "$pinCode India")
+                    .queryParam("region", "IN")
+                    .queryParam("key", apiKey)
+                    .toUriString()
+                val fallback = fetch(fallbackUrl)
+                if (fallback.resolvedCityState != null) return fallback
+                return primary
+            }
+            primary
         } catch (ex: Exception) {
             logger.warn("Geocoding failed: {}", ex.message)
             GeocodeResult(null, null, "ERROR")
         }
     }
 
+    private fun fetch(url: String): GeocodeResult {
+        val response = restTemplate.getForEntity(url, String::class.java)
+        val body = response.body ?: return GeocodeResult(null, null, "EMPTY_BODY")
+        val status = parseStatus(body)
+        val parsed = if (status == "OK") parseCityState(body) else null
+        return GeocodeResult(parsed, body, status ?: "UNKNOWN_STATUS")
+    }
+
+    private fun parseStatus(body: String): String? {
+        return objectMapper.readTree(body).path("status").asText(null)
+    }
+
     private fun parseCityState(body: String): String? {
         val root = objectMapper.readTree(body)
         val results = root.path("results")