Use 1 pased pagination and translate to and from alerts API (#756)

Author: tomwatkins1994

src/main/kotlin/uk/gov/justice/digital/hmpps/hmppsintegrationapi/gateways/PrisonerAlertsGateway.kt

@@ -26,6 +26,10 @@ class PrisonerAlertsGateway(
     )
   }
 
+  /**
+   * @param page page number (1 based)
+   * @param size records per page
+   */
   fun getPrisonerAlerts(
     prisonerNumber: String,
     page: Int,
@@ -34,7 +38,7 @@ class PrisonerAlertsGateway(
     val result =
       webClient.request<PAPaginatedAlerts>(
         HttpMethod.GET,
-        "/prisoners/$prisonerNumber/alerts?page=$page&size=$size",
+        "/prisoners/$prisonerNumber/alerts?page=${page - 1}&size=$size",
         authenticationHeader(),
         UpstreamApi.PRISONER_ALERTS,
         badRequestAsError = true,

src/main/kotlin/uk/gov/justice/digital/hmpps/hmppsintegrationapi/models/prisonerAlerts/PAPaginatedAlerts.kt

@@ -22,7 +22,7 @@ data class PAPaginatedAlerts(
       totalCount = this.totalElements,
       isLastPage = this.last,
       count = this.numberOfElements,
-      page = this.number,
+      page = this.number + 1, // Alerts API pagination is 0 based
       perPage = this.size,
     )
 }

src/test/kotlin/uk/gov/justice/digital/hmpps/hmppsintegrationapi/gateways/prisonerAlerts/GetAlertsForPrisonerTest.kt

@@ -35,7 +35,7 @@ class GetAlertsForPrisonerTest(
       val prisonerNumber = "zyx987"
       val page = 1
       val size = 10
-      val path = "/prisoners/$prisonerNumber/alerts?page=$page&size=$size"
+      val path = "/prisoners/$prisonerNumber/alerts?page=${page - 1}&size=$size"
 
       beforeEach {
         apiMockServer.start()