fix(fanavaran): select latest active policy by end date

Why:
- Fanavaran policy inquiry response order is inconsistent, so selecting the last item can choose an old or expired policy.

Changes:
- Select the policy with the latest Jalali EndDate.
- Reject empty policy responses, expired latest policies, and latest policies without a valid PolicyId.
- Stop Fanavaran submission when PolicyId cannot be resolved.

Impact:
- Fanavaran submit now fails clearly instead of continuing with PolicyId: null.

src/claim-request-management/fanavaran-policy-selection.ts

@@ -0,0 +1,95 @@
+import { BadRequestException } from "@nestjs/common";
+import { jalaliToGregorianDate } from "src/helpers/date-jalali";
+import { gregorianDateInIran } from "src/helpers/iran-datetime";
+
+export type FanavaranPolicyInquiryRow = {
+  PolicyId?: unknown;
+  EndDate?: unknown;
+};
+
+export type SelectedFanavaranPolicy = {
+  policy: FanavaranPolicyInquiryRow;
+  policyId: number;
+  endDate: string;
+  endDateGregorian: string;
+};
+
+type DatedFanavaranPolicy = {
+  policy: FanavaranPolicyInquiryRow;
+  endDate: string;
+  endDateGregorian: string;
+};
+
+const NO_POLICY_MESSAGE =
+  "No Fanavaran policies were found for the insurer national code. PolicyId is required; contact the administrator.";
+
+const EXPIRED_POLICY_MESSAGE =
+  "The latest insurance policy is expired and cannot be sent to Fanavaran. Contact the administrator.";
+
+const INVALID_POLICY_MESSAGE =
+  "Fanavaran policy inquiry returned policies without a valid PolicyId or EndDate. PolicyId is required; contact the administrator.";
+
+function parsePolicyId(value: unknown): number | null {
+  if (value === null || value === undefined) return null;
+  if (typeof value === "string" && value.trim() === "") return null;
+  const id = Number(value);
+  return Number.isFinite(id) && id > 0 ? id : null;
+}
+
+function normalizeEndDate(value: unknown): {
+  endDate: string;
+  endDateGregorian: string;
+} | null {
+  if (value === null || value === undefined) return null;
+  const endDate = String(value).trim();
+  if (!endDate) return null;
+
+  const endDateGregorian = jalaliToGregorianDate(endDate);
+  if (!endDateGregorian) return null;
+
+  return { endDate, endDateGregorian };
+}
+
+export function selectLatestActiveFanavaranPolicy(
+  policies: unknown,
+  todayGregorian: string = gregorianDateInIran(new Date()),
+): SelectedFanavaranPolicy {
+  if (!Array.isArray(policies) || policies.length === 0) {
+    throw new BadRequestException(NO_POLICY_MESSAGE);
+  }
+
+  const candidates = policies
+    .map((policy) => {
+      if (!policy || typeof policy !== "object") return null;
+      const row = policy as FanavaranPolicyInquiryRow;
+      const endDate = normalizeEndDate(row.EndDate);
+      if (!endDate) return null;
+      return {
+        policy: row,
+        endDate: endDate.endDate,
+        endDateGregorian: endDate.endDateGregorian,
+      };
+    })
+    .filter((policy): policy is DatedFanavaranPolicy => policy !== null);
+
+  if (candidates.length === 0) {
+    throw new BadRequestException(INVALID_POLICY_MESSAGE);
+  }
+
+  const latest = candidates.reduce((currentLatest, candidate) =>
+    candidate.endDateGregorian > currentLatest.endDateGregorian
+      ? candidate
+      : currentLatest,
+  );
+
+  if (latest.endDateGregorian < todayGregorian) {
+    throw new BadRequestException(EXPIRED_POLICY_MESSAGE);
+  }
+
+  const policyId = parsePolicyId(latest.policy.PolicyId);
+  if (policyId === null) {
+    throw new BadRequestException(INVALID_POLICY_MESSAGE);
+  }
+
+  return { ...latest, policyId };
+}