Fixed detecting and correcting annual jump from booking date to value date

fints4k/src/main/kotlin/net/dankito/banking/fints/transactions/mt940/Mt940Parser.kt

@@ -232,7 +232,7 @@ open class Mt940Parser : IMt940Parser {
 
         val bookingDateString = if (creditMarkMatcher.start() > 6) fieldValue.substring(6, 10) else null
         val bookingDate = bookingDateString?.let { // bookingDateString has format MMdd -> add year from valueDateString
-            parseMt940Date(valueDateString.substring(0, 2) + bookingDateString)
+            parseMt940BookingDate(bookingDateString, valueDateString, valueDate)
         }
 
         val amountMatcher = AmountPattern.matcher(fieldValue)
@@ -418,6 +418,20 @@ open class Mt940Parser : IMt940Parser {
         return DateFormat.parse(dateString) // fallback to not thread-safe SimpleDateFormat. Works in most cases but not all
     }
 
+    /**
+     * Booking date string consists only of MMDD -> we need to take the year from value date string.
+     */
+    protected open fun parseMt940BookingDate(bookingDateString: String, valueDateString: String, valueDate: Date): Date {
+        val bookingDate = parseMt940Date(valueDateString.substring(0, 2) + bookingDateString)
+
+        // there are rare cases that booking date is e.g. on 31.12.2019 and value date on 01.01.2020 -> booking date would be on 31.12.2020 (and therefore in the future)
+        if (bookingDate.month != valueDate.month && bookingDate.month == 11) {
+            return parseMt940Date("" + (valueDate.year - 1 - 100) + bookingDateString)
+        }
+
+        return bookingDate
+    }
+
     protected open fun parseAmount(amountString: String): BigDecimal {
         return amountString.replace(',', '.').toBigDecimal()
     }

fints4k/src/test/kotlin/net/dankito/banking/fints/transactions/Mt940ParserTest.kt

@@ -127,6 +127,37 @@ class Mt940ParserTest : FinTsTestBase() {
             AccountStatement1Transaction2OtherPartyBankCode, AccountStatement1Transaction2OtherPartyAccountId)
     }
 
+    @Test
+    fun `Fix annual jump from booking date to value date`() {
+
+        val transactionsString = ":20:STARTUMSE\n" +
+                ":25:72051210/0560165557\n" +
+                ":28C:00000/001\n" +
+                ":60F:C191227EUR104501,86\n" +
+                ":61:2001011230DR3,99N024NONREF\n" +
+                ":86:809?00ENTGELTABSCHLUSS?106666?20Entgeltabrechnung?21siehe Anl\n" +
+                "age?3072051210\n" +
+                ":61:2001011230CR0,00N066NONREF\n" +
+                ":86:805?00ABSCHLUSS?106666?20Abrechnung 30.12.2019?21siehe Anlage\n" +
+                "?3072051210\n" +
+                ":62F:C191230EUR104490,88\n" +
+                "-"
+
+
+        // when
+        val result = underTest.parseMt940String(transactionsString)
+
+
+        // then
+        assertThat(result).hasSize(1)
+        assertThat(result.first().transactions).hasSize(2)
+
+        assertThat(result.first().transactions[0].turnover.bookingDate).isEqualTo(Date(119, 11, 30))
+        assertThat(result.first().transactions[0].turnover.valueDate).isEqualTo(Date(120, 0, 1))
+        assertThat(result.first().transactions[1].turnover.bookingDate).isEqualTo(Date(119, 11, 30))
+        assertThat(result.first().transactions[1].turnover.valueDate).isEqualTo(Date(120, 0, 1))
+    }
+
     @Test
     fun parseTransactions() {