updated start date validation to be dependant on value of dateofapplication

components/elements/index.js

@@ -651,40 +651,50 @@ const RenderDatePicker = ({
     const router = useRouter();
 
     let { t } = useTranslation();
-    var startDateArr =
-        custom.dateStart != "0" ? custom.dateStart.split("") : custom.dateStart;
-    var endDateArr =
-        custom.dateEnd != "0" ? custom.dateEnd.split("") : custom.dateEnd;
 
-    var minDate =
-        startDateArr == 0
-            ? new Date()
-            : startDateArr[0] == "-"
-            ? startDateArr[2] == "y"
-                ? subYears(new Date(), startDateArr[1])
-                : startDateArr[2] == "m"
-                ? subMonths(new Date(), startDateArr[1])
-                : subDays(new Date(), startDateArr[1])
-            : startDateArr[2] == "y"
-            ? addYears(new Date(), startDateArr[1])
-            : startDateArr[2] == "m"
-            ? addMonths(new Date(), startDateArr[1])
-            : addDays(new Date(), startDateArr[1]);
+    function dateFromOffset(offsetStr) {
+        const today = new Date();
 
-    var maxDate =
-        endDateArr == 0
-            ? new Date()
-            : startDateArr[0] == "-"
-            ? startDateArr[2] == "y"
-                ? subYears(new Date(), startDateArr[1])
-                : startDateArr[2] == "m"
-                ? subMonths(new Date(), startDateArr[1])
-                : subDays(new Date(), startDateArr[1])
-            : startDateArr[2] == "y"
-            ? addYears(new Date(), startDateArr[1])
-            : startDateArr[2] == "m"
-            ? addMonths(new Date(), startDateArr[1])
-            : addDays(new Date(), startDateArr[1]);
+        // "0" means today
+        if (!offsetStr || offsetStr === "0") {
+            return today;
+        }
+
+        // Expect formats like: -5d, +18m, -10y
+        const match = offsetStr.match(/^([+-])(\d+)([dmy])$/i);
+
+        if (!match) {
+            console.warn("Invalid offset format:", offsetStr);
+            return today; // fallback
+        }
+
+        const [, sign, numberStr, unitRaw] = match;
+        const amount = parseInt(numberStr, 10);
+        const unit = unitRaw.toLowerCase();
+        const isNegative = sign === "-";
+
+        switch (unit) {
+            case "y":
+                return isNegative
+                    ? subYears(today, amount)
+                    : addYears(today, amount);
+
+            case "m":
+                return isNegative
+                    ? subMonths(today, amount)
+                    : addMonths(today, amount);
+
+            case "d":
+                return isNegative
+                    ? subDays(today, amount)
+                    : addDays(today, amount);
+
+            default:
+                return today;
+        }
+    }
+    const minDate = dateFromOffset(custom.dateStart);
+    const maxDate = dateFromOffset(custom.dateEnd);
 
     return (
         <>
@@ -783,12 +793,11 @@ export function DateFieldPicker(props) {
         formProps,
         parentFieldShowOnValue,
         validation,
-        dateStart,
-        dateEnd,
     } = props;
+    let dateStart = props.dateStart;
+    let dateEnd = props.dateEnd;
     let { t } = useTranslation();
     const required = (value) => (value ? undefined : "Required");
-
     var showIfHasParentShowValue =
         (parentField != false &&
             !_.isEmpty(formProps[form]) &&
@@ -798,6 +807,28 @@ export function DateFieldPicker(props) {
     const requiredMessage = t("newappeal:is-required-label");
     const emojiNotAllowedMessage = t("newappeal:emojis-not-allowed-label");
     const invalidPostcodeMessage = t("newappeal:invalid-postcode-label");
+
+    // a and b are javascript Date objects
+    function dateDiffInDays(a, b) {
+        const _MS_PER_DAY = 1000 * 60 * 60 * 24;
+        // Discard the time and time-zone information.
+        const utc1 = Date.UTC(a.getFullYear(), a.getMonth(), a.getDate());
+        const utc2 = Date.UTC(b.getFullYear(), b.getMonth(), b.getDate());
+
+        return Math.floor((utc2 - utc1) / _MS_PER_DAY);
+    }
+
+    dateStart =
+        showIfHasParentShowValue && name == "pinswg_dateoflpadecision"
+            ? "-" +
+              (dateDiffInDays(
+                  new Date(formProps[form].values["pinswg_dateofapplication"]),
+                  new Date()
+              ) -
+                  1) +
+              "d"
+            : dateStart;
+
     return (
         <div className="govuk-form-group">
             {parentField != false ? (