From 318c5e49a6d9439147175fe7fcadf400ce8a0d2f Mon Sep 17 00:00:00 2001
From: Adam Shannon <adamkshannon@gmail.com>
Date: Mon, 18 Dec 2023 15:17:56 -0600
Subject: [PATCH] feat: add camt.029 Case Assignment ID

---
 pkg/rtp/case_assignment.go      | 25 +++++++++++++++++++++++++
 pkg/rtp/case_assignment_test.go | 23 +++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 pkg/rtp/case_assignment.go
 create mode 100644 pkg/rtp/case_assignment_test.go

diff --git a/pkg/rtp/case_assignment.go b/pkg/rtp/case_assignment.go
new file mode 100644
index 0000000..5bfef42
--- /dev/null
+++ b/pkg/rtp/case_assignment.go
@@ -0,0 +1,25 @@
+package rtp
+
+import (
+	"fmt"
+	"time"
+)
+
+// CaseAssignmentID generates an Assignment Identifier for a Case.
+// This is used in camt.029 responses.
+//
+// Format: MYYYYMMDDbbbbbbbbbbbBAAAnnnnnnnnnnn
+// Pos. 01-01 – Prefix ‘M’
+// Pos. 02-09 - File creation date in format YYYYMMDD
+// Pos. 10-20 - Participant ID (11 characters)
+// Pos. 21-21 - Message generation source ("B" if generated by a Participant)
+// Pos. 22-24 - Discretionary bank field (3 digit alpha numeric that can be used to serialize, identify specific systems, etc.)
+// Pos. 25-35 - Message serial number (11 numeric characters)
+func CaseAssignmentID(ts time.Time, participantID, bankField string) string {
+	timestamp := ts.Format("20060102")
+	partID := fmt.Sprintf("%011.11s", participantID)
+	bank := fmt.Sprintf("%03.3s", bankField)
+	serial := NumericSerialNumber(11)
+
+	return fmt.Sprintf("M%s%sB%s%011.11s", timestamp, partID, bank, serial)
+}
diff --git a/pkg/rtp/case_assignment_test.go b/pkg/rtp/case_assignment_test.go
new file mode 100644
index 0000000..e744d32
--- /dev/null
+++ b/pkg/rtp/case_assignment_test.go
@@ -0,0 +1,23 @@
+package rtp_test
+
+import (
+	"regexp"
+	"testing"
+	"time"
+
+	"github.com/moov-io/rtp20022/pkg/rtp"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCaseAssignment(t *testing.T) {
+	eastern, _ := time.LoadLocation("America/New_York")
+	when := time.Date(2015, time.November, 15, 0, 30, 0, 0, eastern)
+	participantID := "11021200201"
+
+	caseAssignmentID := rtp.CaseAssignmentID(when, participantID, "FFF")
+	require.Contains(t, caseAssignmentID, "M2015111511021200201BFFF")
+
+	rr := regexp.MustCompile(`^M[0-9]{4}(((01|03|05|07|08|10|12)((0[1-9])|([1-2][0-9])|(3[0-1])))|((04|06|09|11)((0[1-9])|([1-2][0-9])|30))|((02)((0[1-9])|([1-2][0-9]))))[A-Z0-9]{11}.*$`)
+	require.True(t, rr.MatchString(caseAssignmentID))
+}