initial project

controller/conflict_checker/student_conflict_checker.py

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+"""
+Verifies that no batch (and therefore no student in that batch) is booked
+into two courses — lecture or lab — at the same day+slot.
+
+This is an independent verification pass over the scheduler's output: it
+does not trust the scheduler's own busy-maps, it re-derives every batch's
+occupied (day, slot_index) cells directly from the session list and flags
+any cell used by more than one session.
+"""
+
+from collections import defaultdict
+
+
+def check_student_conflicts(sessions):
+    """
+    Returns a list of conflict dicts, one per (batch, day, slot) where two
+    or more sessions overlap for that batch:
+        {
+            "batch_code": str,
+            "day": str,
+            "slot_index": int,
+            "sessions": [session, session, ...],
+        }
+    Sessions that span multiple slot_indices (labs) occupy every one of
+    their slot_indices, so a lab overlapping a lecture in either of its two
+    slots is caught too.
+    """
+    # (batch_code, day, slot_index) -> list of sessions occupying that cell
+    occupied = defaultdict(list)
+
+    for session in sessions:
+        day = session["day"]
+        for slot_index in session["slot_indices"]:
+            for batch_code in session["batch_codes"]:
+                occupied[(batch_code, day, slot_index)].append(session)
+
+    conflicts = []
+    for (batch_code, day, slot_index), cell_sessions in occupied.items():
+        if len(cell_sessions) > 1:
+            conflicts.append({
+                "batch_code": batch_code,
+                "day": day,
+                "slot_index": slot_index,
+                "sessions": cell_sessions,
+            })
+
+    conflicts.sort(key=lambda c: (c["batch_code"], c["day"], c["slot_index"]))
+    return conflicts
+
+
+def format_student_conflicts(conflicts):
+    """Human-readable lines describing each student/batch conflict."""
+    lines = []
+    for c in conflicts:
+        course_list = ", ".join(
+            f'{s["course_id"]} ({s["course_type"]}) with {s["instructor_name"]} in {s["room_id"]}'
+            for s in c["sessions"]
+        )
+        lines.append(
+            f'Batch {c["batch_code"]} has {len(c["sessions"])} overlapping courses on '
+            f'{c["day"]} slot {c["slot_index"]}: {course_list}'
+        )
+    return lines