feat: locking days, if they are submitted and accepted

fixed #76

Backend/models/user.go

@@ -292,10 +292,42 @@ func (u *User) GetNextWeek() WorkWeek {
 func (u *User) GetLastWorkWeekSubmission() time.Time {
 	var lastSub time.Time
 	qStr, err := DB.Prepare(`
-	SELECT COALESCE(
-	    (SELECT woche_start + INTERVAL '1 week' FROM wochen_report WHERE personal_nummer = $1 ORDER BY woche_start DESC LIMIT 1),
-	    (SELECT timestamp FROM anwesenheit WHERE card_uid = $2 ORDER BY timestamp LIMIT 1)
-    ) AS letzte_buchung;
+		SELECT new_week
+FROM (
+    -- Highest priority
+    SELECT
+        woche_start AS new_week,
+        1 AS priority
+    FROM wochen_report
+    WHERE personal_nummer = $1
+      AND bestaetigt IS NULL
+
+    UNION ALL
+
+    -- Fallback if #1 returns nothing
+    SELECT
+        woche_start + INTERVAL '1 week' AS new_week,
+        2 AS priority
+    FROM wochen_report wo
+    WHERE personal_nummer = $1
+      AND NOT EXISTS (
+          SELECT 1
+          FROM wochen_report wi
+          WHERE wi.woche_start = wo.woche_start + INTERVAL '1 week'
+            AND wi.personal_nummer = wo.personal_nummer
+      )
+
+    UNION ALL
+
+    -- Final fallback
+    SELECT
+        timestamp AS new_week,
+        3 AS priority
+    FROM anwesenheit
+    WHERE card_uid = $2
+) t
+ORDER BY priority, new_week
+LIMIT 1;
 `)
 	if err != nil {
 		slog.Debug("Error preparing query statement.", "error", err)