Add function to get offender info in batches

src/main/kotlin/uk/gov/justice/digital/hmpps/approvedpremisesapi/service/OffenderService.kt

@@ -1,5 +1,6 @@
 package uk.gov.justice.digital.hmpps.approvedpremisesapi.service
 
+import org.apache.commons.collections4.ListUtils
 import org.slf4j.LoggerFactory
 import org.springframework.http.HttpStatus
 import org.springframework.stereotype.Service
@@ -47,6 +48,7 @@ import uk.gov.justice.digital.hmpps.approvedpremisesapi.transformer.PersonTransf
 import uk.gov.justice.digital.hmpps.approvedpremisesapi.util.asCaseSummary
 import java.io.OutputStream
 import java.time.LocalDate
+import java.util.stream.Collectors
 
 @Service
 class OffenderService(
@@ -109,6 +111,32 @@ class OffenderService(
     data class ReturnRestrictedIfLimitedAccess(val deliusUsername: String) : LimitedAccessStrategy
   }
 
+  /**
+   * The [getPersonSummaryInfoResults] function is limited to providing information for up to 500 CRNs
+   *
+   * If information is required about more than 500 CRNs, this function should be used instead
+   *
+   * Note - this should be used with care and only used for infrequently ran operations, e.g. monthly
+   * reports, seed jobs as this should not be a typical operation
+   */
+  fun getPersonSummaryInfoResultsInBatches(
+    crns: Set<String>,
+    limitedAccessStrategy: LimitedAccessStrategy,
+    batchSize: Int = 500,
+  ): List<PersonSummaryInfoResult> {
+    if (batchSize > MAX_OFFENDER_REQUEST_COUNT) {
+      throw InternalServerErrorProblem("Cannot request more than $MAX_OFFENDER_REQUEST_COUNT CRNs. A batch size of $batchSize has been requested.")
+    }
+
+    return ListUtils.partition(crns.toList(), batchSize)
+      .stream()
+      .map { crnSubset ->
+        getPersonSummaryInfoResults(crnSubset.toSet(), limitedAccessStrategy)
+      }
+      .flatMap { it.stream() }
+      .collect(Collectors.toList())
+  }
+
   fun getPersonSummaryInfoResults(
     crns: Set<String>,
     limitedAccessStrategy: LimitedAccessStrategy,
@@ -117,6 +145,10 @@ class OffenderService(
       return emptyList()
     }
 
+    if (crns.size > MAX_OFFENDER_REQUEST_COUNT) {
+      throw InternalServerErrorProblem("Cannot request more than $MAX_OFFENDER_REQUEST_COUNT CRNs. ${crns.size} have been provided.")
+    }
+
     val crnsList = crns.toList()
 
     val caseSummariesByCrn = when (val result = apDeliusContextApiClient.getSummariesForCrns(crnsList)) {

src/test/kotlin/uk/gov/justice/digital/hmpps/approvedpremisesapi/unit/service/OffenderServiceTest.kt

@@ -2098,6 +2098,58 @@ class OffenderServiceTest {
     }
   }
 
+  @Nested
+  inner class GetPersonSummaryInfoResultsInBatches {
+
+    @Test
+    fun `error if batch size greater than 500`() {
+      assertThatThrownBy {
+        offenderService.getPersonSummaryInfoResultsInBatches(
+          crns = emptySet(),
+          batchSize = 501,
+          limitedAccessStrategy = LimitedAccessStrategy.IgnoreLimitedAccess,
+        )
+      }.isInstanceOf(InternalServerErrorProblem::class.java)
+        .hasMessage("Internal Server Error: Cannot request more than 500 CRNs. A batch size of 501 has been requested.")
+    }
+
+    @Test
+    fun `request offender info in batches of 400`() {
+      val crns = (1..750).map { "CRN$it" }
+      val offenderSummaries = crns.map { CaseSummaryFactory().withCrn(it).produce() }
+      val caseAccesses = crns.map { CaseAccessFactory().withCrn(it).produce() }
+
+      every {
+        mockApDeliusContextApiClient.getSummariesForCrns((1..400).map { "CRN$it" })
+      } returns ClientResult.Success(HttpStatus.OK, CaseSummaries(offenderSummaries.subList(0, 400)))
+
+      every {
+        mockApDeliusContextApiClient.getSummariesForCrns((401..750).map { "CRN$it" })
+      } returns ClientResult.Success(HttpStatus.OK, CaseSummaries(offenderSummaries.subList(400, 750)))
+
+      every {
+        mockApDeliusContextApiClient.getUserAccessForCrns(USERNAME, (1..400).map { "CRN$it" })
+      } returns ClientResult.Success(HttpStatus.OK, UserAccess(caseAccesses.subList(0, 400)))
+
+      every {
+        mockApDeliusContextApiClient.getUserAccessForCrns(USERNAME, (401..750).map { "CRN$it" })
+      } returns ClientResult.Success(HttpStatus.OK, UserAccess(caseAccesses.subList(401, 750)))
+
+      val results = offenderService.getPersonSummaryInfoResultsInBatches(
+        crns = crns.toSet(),
+        limitedAccessStrategy = ReturnRestrictedIfLimitedAccess(USERNAME),
+        batchSize = 400,
+      )
+
+      assertThat(results).hasSize(750)
+      (0..749).forEach {
+        val result = results[it]
+        assertThat(result).isInstanceOf(PersonSummaryInfoResult.Success.Full::class.java)
+        assertThat((result as PersonSummaryInfoResult.Success.Full).summary).isEqualTo(offenderSummaries[it])
+      }
+    }
+  }
+
   private fun clientResultSuccess(
     userRestricted: Boolean,
     userExcluded: Boolean,