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# Comprehensive timetable operations engine.
# Handles ALL types of changes — not just rescheduling.
from typing import List, Dict, Any, Tuple, Optional
from collections import defaultdict
from ortools.sat.python import cp_model
from copy import deepcopy
from models import Task, Faculty, Section, Room, SubjectType
import constants as const
DAY_INDEX = {'MON':0,'TUE':1,'WED':2,'THU':3,'FRI':4,'SAT':5}
DAY_NAME = {v: k for k, v in DAY_INDEX.items()}
def _slot(day, period): return day * const.NUM_TEACHING_SLOTS_PER_DAY + period
def _day(slot): return slot // const.NUM_TEACHING_SLOTS_PER_DAY
def _period(slot): return slot % const.NUM_TEACHING_SLOTS_PER_DAY
MORNING_PERIODS = list(range(0, const.NUM_TEACHING_SLOTS_PER_DAY // 2))
AFTERNOON_PERIODS = list(range(const.NUM_TEACHING_SLOTS_PER_DAY // 2,
const.NUM_TEACHING_SLOTS_PER_DAY))
class PartialOptimizer:
"""
Handles every possible timetable operation via natural language → JSON constraint.
Supported operations:
┌─────────────────────────────────────────────────────────────────┐
│ SCHEDULING │
│ FACULTY_UNAVAILABLE — block faculty on day/slot │
│ FACULTY_FREE_DAY — give faculty a free day │
│ FACULTY_MAX_DAILY_HOURS — limit daily hours │
│ SECTION_FREE_SLOT — block a slot for a section │
│ WORKING_DAYS — restrict to certain days │
│ SUBJECT_PREFERRED_TIME — move subject to morning/afternoon │
│ HEAVY_SUBJECT_MORNING — heavy subjects in morning │
│ LAB_MUST_CONSECUTIVE — labs in consecutive slots │
│ │
│ DIRECT CHANGES (no re-solve needed) │
│ FACULTY_SUBSTITUTION — replace faculty for a day/subject │
│ MOVE_CLASS — move specific class to new slot │
│ SWAP_CLASSES — swap two classes with each other │
│ CANCEL_CLASS — remove a class from timetable │
│ CHANGE_ROOM — assign different room to a class │
│ ADD_EXTRA_CLASS — add a makeup/extra class │
│ MARK_HOLIDAY — clear all classes on a day │
│ RESCHEDULE_LAB — move lab to a new day │
│ CHANGE_FACULTY — permanently change who teaches │
│ FREEZE_SLOT — lock a slot so it never changes │
└─────────────────────────────────────────────────────────────────┘
"""
def __init__(self, tasks, faculties, sections, rooms, current_solution):
self.tasks = tasks
self.faculties = faculties
self.sections = sections
self.rooms = rooms
self.current_solution = current_solution
self.tasks_by_id = {t.task_id: t for t in tasks}
self.fac_by_id = {f.id: f for f in faculties}
self.room_by_id = {r.room_id: r for r in rooms}
self.tasks_by_faculty = defaultdict(list)
self.tasks_by_section = defaultdict(list)
self.tasks_by_subject = defaultdict(list)
for t in tasks:
self.tasks_by_faculty[t.faculty.id].append(t)
self.tasks_by_section[t.section.section_id].append(t)
self.tasks_by_subject[t.subject.subject_code].append(t)
# ═════════════════════════════════════════════════════════════════
# PUBLIC ENTRY POINT
# ═════════════════════════════════════════════════════════════════
def apply_constraint_and_reoptimize(
self,
slm_constraint: Dict[str, Any],
time_limit: int = 30
) -> Tuple[str, Dict[str, Any], List[str], str]:
"""
Route to the correct handler based on constraint type.
Returns: (status, new_solution, affected_task_ids, summary)
"""
ctype = slm_constraint.get('type', '').upper()
# Direct mutation handlers (no CP-SAT needed)
direct_handlers = {
'FACULTY_SUBSTITUTION': self._op_faculty_substitution,
'MOVE_CLASS': self._op_move_class,
'SWAP_CLASSES': self._op_swap_classes,
'CANCEL_CLASS': self._op_cancel_class,
'CHANGE_ROOM': self._op_change_room,
'ADD_EXTRA_CLASS': self._op_add_extra_class,
'MARK_HOLIDAY': self._op_mark_holiday,
'RESCHEDULE_LAB': self._op_reschedule_lab,
'CHANGE_FACULTY': self._op_change_faculty,
'FREEZE_SLOT': self._op_freeze_slot,
}
# Re-optimization handlers (CP-SAT partial solve)
reopt_handlers = {
'FACULTY_UNAVAILABLE': True,
'FACULTY_FREE_DAY': True,
'FACULTY_MAX_DAILY_HOURS': True,
'FACULTY_NO_CONSECUTIVE': True,
'SECTION_FREE_SLOT': True,
'WORKING_DAYS': True,
'SUBJECT_PREFERRED_TIME': True,
'HEAVY_SUBJECT_MORNING': True,
'LAB_MUST_CONSECUTIVE': True,
'NO_BACK_TO_BACK_SUBJECTS': True,
'DISTRIBUTE_SUBJECTS_EVENLY': True,
'SUBJECT_SPACING': True,
'NO_FREE_PERIOD': True,
}
# ── Type aliases — map SLM variants to canonical types ──────────
aliases = {
'SUBJECT_FREE_DAY': 'CANCEL_CLASS',
'FACULTY_LEAVE': 'FACULTY_SUBSTITUTION',
'BLOCK_SLOT': 'SECTION_FREE_SLOT',
'REMOVE_CLASS': 'CANCEL_CLASS',
'DELETE_CLASS': 'CANCEL_CLASS',
'CLASS_CANCELLED': 'CANCEL_CLASS',
'SHIFT_CLASS': 'MOVE_CLASS',
'RELOCATE_CLASS': 'MOVE_CLASS',
'TEACHER_SUBSTITUTION': 'FACULTY_SUBSTITUTION',
'REPLACE_FACULTY': 'FACULTY_SUBSTITUTION',
'SWAP_FACULTY': 'FACULTY_SUBSTITUTION',
'SUBJECT_UNAVAILABLE': 'CANCEL_CLASS',
'NO_CLASS': 'CANCEL_CLASS',
'HOLIDAY': 'MARK_HOLIDAY',
'MOVE_LAB': 'RESCHEDULE_LAB',
'SHIFT_LAB': 'RESCHEDULE_LAB',
'LOCK_SLOT': 'FREEZE_SLOT',
'PIN_SLOT': 'FREEZE_SLOT',
}
if ctype in aliases:
slm_constraint = dict(slm_constraint)
slm_constraint['type'] = aliases[ctype]
ctype = aliases[ctype]
if ctype in direct_handlers:
return direct_handlers[ctype](slm_constraint)
elif ctype in reopt_handlers:
return self._reoptimize(slm_constraint, time_limit)
else:
return ('NO_CHANGE', self.current_solution, [],
f'⚠️ Unknown constraint type: {ctype}')
# ═════════════════════════════════════════════════════════════════
# DIRECT MUTATION OPERATIONS
# ═════════════════════════════════════════════════════════════════
def _op_faculty_substitution(self, c):
"""
Replace from_faculty with to_faculty.
Optionally filter by days and/or subjects.
Prompt examples:
"Replace Prof. Anu's classes on Friday with Prof. Syed"
"Prof. Kavitha is on leave Monday, Praveen will cover"
"Syed will take all of Anu's NLP classes"
"""
from_id = c.get('from_faculty_id') or c.get('from_faculty')
to_id = c.get('to_faculty_id') or c.get('to_faculty')
days = [DAY_INDEX[d] for d in (c.get('days') or []) if d in DAY_INDEX]
scodes = set(c.get('subject_codes') or [])
sections = set(c.get('section_ids') or [])
if not from_id or not to_id:
return self._fail('FACULTY_SUBSTITUTION needs from_faculty_id and to_faculty_id')
to_fac = self.fac_by_id.get(to_id)
if not to_fac:
return self._fail(f'Faculty not found: {to_id}')
new_sol, changes = dict(self.current_solution), []
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task or task.faculty.id != from_id: continue
if days and info['day_index'] not in days: continue
if scodes and task.subject.subject_code not in scodes: continue
if sections and not any(self._sec_matches(task.section.section_id, s) for s in sections): continue
updated = dict(info)
updated['faculty_name'] = to_fac.name
new_sol[task_id] = updated
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}) "
f"{const.DAYS[info['day_index']]} P{info['period_index']+1}: "
f"{task.faculty.name} → {to_fac.name}"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [],
f'No matching classes found for substitution.')
return ('FEASIBLE', new_sol, [],
f"✅ {len(changes)} class(es) reassigned:\n" + "\n".join(changes))
def _op_move_class(self, c):
"""
Move a specific class to a new day/period.
Prompt examples:
"Move Monday's NLP class of 6A to Wednesday period 3"
"Shift Anu's Tuesday class to Thursday"
"Move section 5A's TOC from Monday to Friday"
"""
from_day = DAY_INDEX.get((c.get('from_day') or '').upper())
to_day = DAY_INDEX.get((c.get('to_day') or '').upper())
from_period = c.get('from_period') # 1-based
to_period = c.get('to_period') # 1-based
scode = c.get('subject_code')
sid = c.get('section_id')
fid = c.get('faculty_id')
if from_day is None or to_day is None:
return self._fail('MOVE_CLASS needs from_day and to_day')
new_sol, changes = dict(self.current_solution), []
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task: continue
if info['day_index'] != from_day: continue
if scode and task.subject.subject_code != scode: continue
if sid and not self._sec_matches(task.section.section_id, sid): continue
if fid and task.faculty.id != fid: continue
if from_period and info['period_index'] != from_period - 1: continue
# Build candidate periods to try: specified first, then all others
preferred = (to_period - 1) if to_period else info['period_index']
candidates = [preferred] + [
p for p in range(const.NUM_TEACHING_SLOTS_PER_DAY)
if p != preferred
]
placed = False
fac_id = task.faculty.id if task else None
sec_id = task.section.section_id if task else None
for try_period in candidates:
if try_period + task.duration > const.NUM_TEACHING_SLOTS_PER_DAY:
continue
# Check faculty conflict
fac_conflict = self._check_conflict(
task_id, to_day, try_period, task.duration, fid=fac_id)
# Check section conflict
sec_conflict = self._check_conflict(
task_id, to_day, try_period, task.duration, sid=sec_id)
if fac_conflict or sec_conflict:
continue
updated = dict(info)
updated['day_index'] = to_day
updated['day_name'] = const.DAYS[to_day]
updated['period_index'] = try_period
updated['start_slot'] = _slot(to_day, try_period)
new_sol[task_id] = updated
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}): "
f"{const.DAYS[from_day]} P{info['period_index']+1} → "
f"{const.DAYS[to_day]} P{try_period+1}"
+ (f" (requested P{to_period}, auto-placed)" if to_period and try_period != to_period-1 else "")
)
placed = True
break
if not placed:
changes.append(
f"⚠️ No free slot on {const.DAYS[to_day]} for "
f"{info['subject_code'].upper()} ({info['section_id']}) "
f"— all periods occupied"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [], 'No matching class found to move.')
return ('FEASIBLE', new_sol, [],
f"✅ Move operation:\n" + "\n".join(changes))
def _op_swap_classes(self, c):
"""
Swap two classes with each other.
Prompt examples:
"Swap Monday P1 NLP with Wednesday P3 ML for section 6A"
"Swap Anu's Monday class with Syed's Wednesday class"
"""
task1_id = c.get('task1_id')
task2_id = c.get('task2_id')
day1 = DAY_INDEX.get((c.get('day1') or '').upper())
day2 = DAY_INDEX.get((c.get('day2') or '').upper())
period1 = c.get('period1')
period2 = c.get('period2')
sid = c.get('section_id')
# Extract subject codes for subject-based lookup
scode1 = c.get('subject_code1') or c.get('subject_code')
scode2 = c.get('subject_code2')
scodes = c.get('subject_codes') or []
if scodes and len(scodes) >= 2:
scode1, scode2 = scodes[0], scodes[1]
elif scodes and len(scodes) == 1 and not scode1:
scode1 = scodes[0]
fid1 = c.get('faculty_id1')
fid2 = c.get('faculty_id2')
# Find tasks: try period → subject → faculty (in priority order)
if not task1_id and day1 is not None:
if period1 is not None:
task1_id = self._find_task_at(day1, period1-1, sid)
if not task1_id and scode1:
task1_id = self._find_task_by_subject(day1, scode1, sid)
if not task1_id and fid1:
task1_id = self._find_task_by_faculty(day1, fid1, sid)
if not task2_id and day2 is not None:
if period2 is not None:
task2_id = self._find_task_at(day2, period2-1, sid)
if not task2_id and scode2:
task2_id = self._find_task_by_subject(day2, scode2, sid)
if not task2_id and fid2:
task2_id = self._find_task_by_faculty(day2, fid2, sid)
if not task1_id or not task2_id:
d1 = const.DAYS[day1] if day1 is not None else '?'
d2 = const.DAYS[day2] if day2 is not None else '?'
return self._fail(
f'SWAP_CLASSES: could not find both classes. '
f'Looking for {scode1 or "?"} on {d1} and {scode2 or "?"} on {d2} '
f'for section {sid or "all"}')
info1 = dict(self.current_solution.get(task1_id, {}))
info2 = dict(self.current_solution.get(task2_id, {}))
if not info1 or not info2:
return self._fail('One or both tasks not found in current schedule.')
new_sol = dict(self.current_solution)
# Swap day + period + start_slot
for key in ('day_index','day_name','period_index','start_slot'):
info1[key], info2[key] = info2[key], info1[key]
new_sol[task1_id] = info1
new_sol[task2_id] = info2
t1 = self.tasks_by_id.get(task1_id)
t2 = self.tasks_by_id.get(task2_id)
summary = (
f"✅ Swapped:\n"
f"• {t1.subject.subject_code.upper() if t1 else task1_id} ↔ "
f"{t2.subject.subject_code.upper() if t2 else task2_id}"
)
return ('FEASIBLE', new_sol, [task1_id, task2_id], summary)
def _op_cancel_class(self, c):
"""
Remove a class from the timetable (e.g. cancelled due to event).
Prompt examples:
"Cancel NLP class on Friday for section 6A"
"No class for 5A on Monday period 2"
"Cancel all classes on Thursday for Anu"
"""
day = DAY_INDEX.get((c.get('day') or '').upper())
period = c.get('period')
scode = c.get('subject_code')
sid = c.get('section_id')
fid = c.get('faculty_id')
new_sol, changes = dict(self.current_solution), []
# sid may be a full section id ("6a-E1") or a parent prefix ("6A")
sid_is_prefix = sid and '-' not in sid
for task_id, info in list(self.current_solution.items()):
task = self.tasks_by_id.get(task_id)
if not task: continue
if day is not None and info['day_index'] != day: continue
if period is not None and info['period_index'] != period - 1: continue
if scode and task.subject.subject_code != scode: continue
if fid and task.faculty.id != fid: continue
# Section filter: exact match OR parent prefix match
if sid:
sec = task.section.section_id
if sid_is_prefix:
# "6A" matches "6a-E1", "6a-E2" but NOT "6b-E1"
if not sec.lower().startswith(sid.lower()):
continue
else:
if sec != sid:
continue
del new_sol[task_id]
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}) "
f"{const.DAYS[info['day_index']]} P{info['period_index']+1} — CANCELLED"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [], 'No matching class found to cancel.')
return ('FEASIBLE', new_sol, [],
f"✅ {len(changes)} class(es) cancelled:\n" + "\n".join(changes))
def _op_change_room(self, c):
"""
Assign a different room to a class.
Prompt examples:
"Move NLP class on Monday to Lab 2"
"Change room for 6A's ML on Tuesday to R3"
"Shift all of section 5A's labs to L2"
"""
new_room_id = c.get('room_id') or c.get('new_room_id')
scode = c.get('subject_code')
sid = c.get('section_id')
day = DAY_INDEX.get((c.get('day') or '').upper())
period = c.get('period')
if not new_room_id:
return self._fail('CHANGE_ROOM needs room_id')
new_room = self.room_by_id.get(new_room_id)
if not new_room:
return self._fail(f'Room not found: {new_room_id}')
new_sol, changes = dict(self.current_solution), []
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task: continue
if scode and task.subject.subject_code != scode: continue
if sid and not self._sec_matches(task.section.section_id, sid): continue
if day is not None and info['day_index'] != day: continue
if period is not None and info['period_index'] != period-1: continue
updated = dict(info)
updated['room_id'] = new_room.room_id
updated['room_name'] = f"{new_room.room_id} ({new_room.building})"
new_sol[task_id] = updated
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}) "
f"{const.DAYS[info['day_index']]} P{info['period_index']+1}: "
f"Room → {new_room.room_id}"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [], 'No matching class found.')
return ('FEASIBLE', new_sol, [],
f"✅ {len(changes)} room change(s):\n" + "\n".join(changes))
def _op_add_extra_class(self, c):
"""
Add a makeup/extra class to the timetable.
Prompt examples:
"Add a makeup NLP class on Saturday period 1 for 6A by Anu"
"Schedule extra ML session for 5B on Friday afternoon"
"""
scode = c.get('subject_code')
sid = c.get('section_id')
fid = c.get('faculty_id')
day_raw = (c.get('day') or '').upper()
# day may be a string key like "SAT" or already an int index
if isinstance(day_raw, int):
day = day_raw
else:
day = DAY_INDEX.get(day_raw)
period = c.get('period')
room_id = c.get('room_id')
if day is None or not scode or not sid or not fid:
return self._fail(
'ADD_EXTRA_CLASS needs subject_code, section_id, faculty_id, and day')
fac = self.fac_by_id.get(fid)
room = self.room_by_id.get(room_id) if room_id else next(
(r for r in self.rooms if not r.is_lab), self.rooms[0])
if not fac:
return self._fail(f'Faculty not found: {fid}')
day_name = const.DAYS[day] if day < len(const.DAYS) else day_raw
# Auto-find free period if not specified
if not period:
for try_p in range(const.NUM_TEACHING_SLOTS_PER_DAY):
fc = self._check_conflict(None, day, try_p, 1, fid=fid)
sc = self._check_conflict(None, day, try_p, 1, sid=sid)
if not fc and not sc:
period = try_p + 1 # 1-indexed
break
if not period:
return self._fail(
f'No free slot on {day_name} for {scode.upper()} ({sid})')
# Check conflict at chosen period
conflict = (self._check_conflict(None, day, period-1, 1, fid=fid) or
self._check_conflict(None, day, period-1, 1, sid=sid))
if conflict:
return self._fail(f'Slot conflict at P{period}: {conflict}')
task_id = f"EXTRA-{scode}-{sid}-{day_name}-P{period}"
new_sol = dict(self.current_solution)
new_sol[task_id] = {
'start_slot': _slot(day, period-1),
'day_index': day,
'day_name': day_name,
'period_index': period - 1,
'room_id': room.room_id,
'room_name': f"{room.room_id} ({room.building})",
'faculty_name': fac.name,
'subject_code': scode,
'section_id': sid,
'duration': 1,
'is_extra': True,
}
return ('FEASIBLE', new_sol, [task_id],
f"✅ Extra class added: {scode.upper()} ({sid}) "
f"{day_name} P{period} by {fac.name}")
def _op_mark_holiday(self, c):
"""
Clear all classes on a specific day (holiday/event).
Prompt examples:
"Mark Friday as holiday"
"No classes on Monday for all sections"
"Cancel all Thursday classes for section 6A"
"""
days = [DAY_INDEX[d] for d in (c.get('days') or []) if d in DAY_INDEX]
sid = c.get('section_id')
if not days:
return self._fail('MARK_HOLIDAY needs at least one day')
new_sol, changes = dict(self.current_solution), []
for task_id, info in list(self.current_solution.items()):
if info['day_index'] not in days: continue
if sid and info['section_id'] != sid: continue
del new_sol[task_id]
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}) "
f"P{info['period_index']+1}"
)
day_names = [const.DAYS[d] for d in days]
return ('FEASIBLE', new_sol, [],
f"✅ Holiday on {', '.join(day_names)}: "
f"{len(changes)} class(es) cleared")
def _op_reschedule_lab(self, c):
"""
Move a lab session to a different day (keeps it as 2-hour block).
Prompt examples:
"Move NLP Lab from Wednesday to Thursday"
"Reschedule ML Lab for section 6A to Friday"
"""
scode = c.get('subject_code')
sid = c.get('section_id')
from_day = DAY_INDEX.get((c.get('from_day') or '').upper())
to_day = DAY_INDEX.get((c.get('to_day') or '').upper())
to_period = c.get('to_period', 1)
if to_day is None:
return self._fail('RESCHEDULE_LAB needs to_day')
new_sol, changes = dict(self.current_solution), []
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task or task.duration < 2: continue
# Match by subject code OR by partial name match (nlp matches nlplab)
code_match = (scode and (
task.subject.subject_code == scode or
task.subject.subject_code.startswith(scode) or
scode.startswith(task.subject.subject_code)
))
if not code_match: continue
if sid and not self._sec_matches(task.section.section_id, sid): continue
# If from_day specified, only move labs on that day
if from_day is not None and info['day_index'] != from_day: continue
# Auto-find a free lab slot on to_day if specified period conflicts
# Try: specified period first, then all ALLOWED_LAB_START_INDICES
candidates = []
if to_period:
candidates.append(to_period - 1)
for p in const.ALLOWED_LAB_START_INDICES:
if p not in candidates:
candidates.append(p)
placed = False
fac_id2 = task.faculty.id if task else None
sec_id2 = task.section.section_id if task else None
for try_period in candidates:
# Make sure the 2-hour block doesn't cross day boundary
if try_period + task.duration > const.NUM_TEACHING_SLOTS_PER_DAY:
continue
fac_conflict = self._check_conflict(
task_id, to_day, try_period, task.duration, fid=fac_id2)
sec_conflict = self._check_conflict(
task_id, to_day, try_period, task.duration, sid=sec_id2)
if fac_conflict or sec_conflict:
continue
# Free slot found — place it
updated = dict(info)
updated['day_index'] = to_day
updated['day_name'] = const.DAYS[to_day]
updated['period_index'] = try_period
updated['start_slot'] = _slot(to_day, try_period)
new_sol[task_id] = updated
changes.append(
f"• {scode.upper()} Lab ({info['section_id']}): "
f"{const.DAYS[info['day_index']]} P{info['period_index']+1} → "
f"{const.DAYS[to_day]} P{try_period+1}"
)
placed = True
break
if not placed:
changes.append(
f"⚠️ No free lab slot found on {const.DAYS[to_day]} "
f"for {scode.upper()} ({info['section_id']}) — "
f"all slots are occupied"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [], f'Lab {scode} not found.')
return ('FEASIBLE', new_sol, [],
f"✅ Lab rescheduled:\n" + "\n".join(changes))
def _op_change_faculty(self, c):
"""
Permanently change faculty for a subject/section (all occurrences).
Prompt examples:
"Assign all NLP classes of 6A to Prof. Syed instead of Anu"
"Transfer Anu's 5B classes to Kavitha permanently"
"""
from_id = c.get('from_faculty_id') or c.get('from_faculty')
to_id = c.get('to_faculty_id') or c.get('to_faculty')
scode = c.get('subject_code')
sid = c.get('section_id')
if not to_id:
return self._fail('CHANGE_FACULTY needs to_faculty_id')
to_fac = self.fac_by_id.get(to_id)
if not to_fac:
return self._fail(f'Faculty not found: {to_id}')
new_sol, changes = dict(self.current_solution), []
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task: continue
if from_id and task.faculty.id != from_id: continue
if scode and task.subject.subject_code != scode: continue
if sid and not self._sec_matches(task.section.section_id, sid): continue
updated = dict(info)
updated['faculty_name'] = to_fac.name
new_sol[task_id] = updated
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}) "
f"ALL slots: faculty → {to_fac.name}"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [], 'No matching classes found.')
# Deduplicate summary
unique = list(dict.fromkeys(changes))
return ('FEASIBLE', new_sol, [],
f"✅ Faculty changed for {len(changes)} slot(s):\n" + "\n".join(unique[:10]))
def _op_freeze_slot(self, c):
"""
Mark a slot as frozen (metadata only — solver will skip it in future updates).
Prompt examples:
"Lock Monday P1 NLP for section 6A"
"Freeze Anu's Wednesday slots"
"""
# Freeze is stored as metadata in the info dict
day = DAY_INDEX.get((c.get('day') or '').upper())
period = c.get('period')
sid = c.get('section_id')
scode = c.get('subject_code')
new_sol, changes = dict(self.current_solution), []
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task: continue
if day is not None and info['day_index'] != day: continue
if period is not None and info['period_index'] != period-1: continue
if sid and not self._sec_matches(task.section.section_id, sid): continue
if scode and task.subject.subject_code != scode: continue
updated = dict(info)
updated['frozen'] = True
new_sol[task_id] = updated
changes.append(
f"• {info['subject_code'].upper()} ({info['section_id']}) "
f"{const.DAYS[info['day_index']]} P{info['period_index']+1} — FROZEN"
)
if not changes:
return ('NO_CHANGE', self.current_solution, [], 'No matching slot to freeze.')
return ('FEASIBLE', new_sol, [],
f"✅ {len(changes)} slot(s) frozen:\n" + "\n".join(changes))
# ═════════════════════════════════════════════════════════════════
# CP-SAT RE-OPTIMIZATION (for scheduling constraint types)
# ═════════════════════════════════════════════════════════════════
def _reoptimize(self, slm_constraint, time_limit):
ctype = slm_constraint.get('type', '').upper()
affected_ids = self._find_affected_tasks(slm_constraint)
if not affected_ids:
return ('NO_CHANGE', self.current_solution, [],
f'No tasks affected by: {ctype}')
status, partial = self._solve_partial(affected_ids, [slm_constraint], time_limit)
if status not in ('OPTIMAL', 'FEASIBLE'):
return (status, self.current_solution, affected_ids,
f'❌ Could not reschedule {len(affected_ids)} task(s). '
f'Constraint may be too restrictive.')
new_sol = dict(self.current_solution)
new_sol.update(partial)
changes = []
for tid in affected_ids:
old = self.current_solution.get(tid, {})
new = new_sol.get(tid, {})
if old and new:
old_slot = f"{const.DAYS[old['day_index']]} P{old['period_index']+1}"
new_slot = f"{const.DAYS[new['day_index']]} P{new['period_index']+1}"
if old_slot != new_slot:
changes.append(
f"• {new.get('subject_code','?').upper()} "
f"({new.get('section_id','?')}): "
f"{old_slot} → {new_slot}"
)
summary = (f"✅ {len(changes)} slot(s) moved:\n" + "\n".join(changes)
if changes else "✅ Constraint applied — no slot changes needed.")
return (status, new_sol, affected_ids, summary)
def _find_affected_tasks(self, c):
ctype = c.get('type', '').upper()
affected = set()
if ctype == 'FACULTY_UNAVAILABLE':
fid = c.get('faculty_id')
days = [DAY_INDEX[d] for d in (c.get('days') or []) if d in DAY_INDEX]
slots = c.get('slots') or []
for task in self.tasks_by_faculty.get(fid, []):
info = self.current_solution.get(task.task_id, {})
if not info: continue
if not days or info['day_index'] in days:
if not slots or info['period_index'] in slots:
affected.add(task.task_id)
elif ctype == 'FACULTY_FREE_DAY':
fid = c.get('faculty_id')
pday = c.get('preferred_day')
if pday and pday in DAY_INDEX:
for task in self.tasks_by_faculty.get(fid, []):
info = self.current_solution.get(task.task_id, {})
if info and info['day_index'] == DAY_INDEX[pday]:
affected.add(task.task_id)
elif ctype == 'FACULTY_MAX_DAILY_HOURS':
fid = c.get('faculty_id')
max_hrs = c.get('max_hours') or 999
by_day = defaultdict(list)
for task in self.tasks_by_faculty.get(fid, []):
info = self.current_solution.get(task.task_id, {})
if info: by_day[info['day_index']].append(task.task_id)
for day, tids in by_day.items():
total = sum(self.tasks_by_id[t].duration for t in tids)
if total > max_hrs: affected.update(tids)
elif ctype in ('SUBJECT_PREFERRED_TIME', 'HEAVY_SUBJECT_MORNING'):
scode = c.get('subject_code')
sid = c.get('section_id')
period = str(c.get('period', '')).upper()
target = MORNING_PERIODS if 'MORNING' in period else AFTERNOON_PERIODS
src = self.tasks_by_subject.get(scode, []) if scode else self.tasks
for task in src:
if sid and task.section.section_id != sid: continue
info = self.current_solution.get(task.task_id, {})
if info and target and info['period_index'] not in target:
affected.add(task.task_id)
elif ctype == 'SECTION_FREE_SLOT':
sid = c.get('section_id')
slot = c.get('slot')
days = [DAY_INDEX[d] for d in (c.get('days') or []) if d in DAY_INDEX]
for task in self.tasks_by_section.get(sid, []):
info = self.current_solution.get(task.task_id, {})
if not info: continue
if slot is not None and info['period_index'] == slot - 1:
if not days or info['day_index'] in days:
affected.add(task.task_id)
elif ctype == 'LAB_MUST_CONSECUTIVE':
scode = c.get('subject_code')
for task in self.tasks_by_subject.get(scode, []):
affected.add(task.task_id)
elif ctype == 'WORKING_DAYS':
allowed = {DAY_INDEX[d] for d in (c.get('days') or []) if d in DAY_INDEX}
if allowed:
for task in self.tasks:
info = self.current_solution.get(task.task_id, {})
if info and info['day_index'] not in allowed:
affected.add(task.task_id)
elif ctype in ('NO_BACK_TO_BACK_SUBJECTS', 'DISTRIBUTE_SUBJECTS_EVENLY',
'SUBJECT_SPACING'):
scode = c.get('subject_code')
codes = c.get('subject_codes') or ([scode] if scode else [])
sid = c.get('section_id')
for code in codes:
for task in self.tasks_by_subject.get(code, []):
if sid and task.section.section_id != sid: continue
affected.add(task.task_id)
elif ctype == 'NO_FREE_PERIOD':
# Find tasks that are NOT in the required period on any day
# so we can move them there, OR find tasks blocking required period
# Strategy: collect all tasks that need to shift to fill the required period
raw_periods = c.get('periods') or []
# Resolve -1 to last teaching period
required_periods = [
const.NUM_TEACHING_SLOTS_PER_DAY - 1 if p == -1 else p
for p in raw_periods
] # e.g. [0] for P1, [7] for last
sids = [s.section_id for s in self.sections]
# Find sections that have a free slot in required period on any day
# We need to reschedule tasks to fill those gaps
# Collect all tasks — let solver figure out placement
for task in self.tasks:
info = self.current_solution.get(task.task_id, {})
if info and required_periods:
# Add tasks not currently in the required period
if info.get('period_index') not in required_periods:
affected.add(task.task_id)
# If no periods specified, affect nothing
if not required_periods:
affected = set()
else:
affected.update(t.task_id for t in self.tasks)
# Never move frozen slots
frozen = {tid for tid, info in self.current_solution.items()
if info.get('frozen')}
return list(affected - frozen)
def _solve_partial(self, affected_ids, constraints, time_limit):
model = cp_model.CpModel()
solver = cp_model.CpSolver()
affected_tasks = [self.tasks_by_id[tid] for tid in affected_ids
if tid in self.tasks_by_id]
locked_fac = defaultdict(set)
locked_sec = defaultdict(set)
locked_room = defaultdict(set)
for task_id, info in self.current_solution.items():
if task_id in affected_ids: continue
task = self.tasks_by_id.get(task_id)
if not task: continue
for offset in range(task.duration):
s = _slot(info['day_index'], info['period_index']) + offset
locked_fac[task.faculty.id].add(s)
locked_sec[task.section.section_id].add(s)
task_vars = {}
for task in affected_tasks:
allowed = self._compute_allowed(task, constraints, locked_fac, locked_sec)
if not allowed: allowed = self._all_starts(task)
sv = model.NewIntVarFromDomain(
cp_model.Domain.FromValues(sorted(allowed)), f'{task.task_id}_s')
ev = model.NewIntVar(0, const.TOTAL_TEACHING_SLOTS_PER_WEEK, f'{task.task_id}_e')
iv = model.NewIntervalVar(sv, task.duration, ev, f'{task.task_id}_i')
ri = model.NewIntVarFromDomain(
cp_model.Domain.FromValues(self._allowed_rooms(task)), f'{task.task_id}_r')
task_vars[task.task_id] = (sv, ev, iv, ri)
# No-overlap faculty
ivs_fac = defaultdict(list)
for t in affected_tasks:
ivs_fac[t.faculty.id].append(task_vars[t.task_id][2])
for ivs in ivs_fac.values():
if len(ivs) > 1: model.AddNoOverlap(ivs)
# No-overlap section
ivs_sec = defaultdict(list)
for t in affected_tasks:
ivs_sec[t.section.section_id].append(task_vars[t.task_id][2])
for ivs in ivs_sec.values():
if len(ivs) > 1: model.AddNoOverlap(ivs)
content_solution_ref = self.current_solution # used in NO_FREE_PERIOD
# ── NO_FREE_PERIOD enforcement ─────────────────────────────────────
# For each section and each working day, ensure at least one task
# is assigned to the required period(s).
for c in constraints:
if c.get('type','').upper() != 'NO_FREE_PERIOD':
continue
required_periods = c.get('periods') or []
filter_sid = c.get('section_id') # None = all sections
filter_days = c.get('days') or list(range(const.NUM_WORKING_DAYS))
for day in filter_days:
# Group affected tasks by section
tasks_by_sec = defaultdict(list)
for task in affected_tasks:
if filter_sid and task.section.section_id != filter_sid:
continue
tasks_by_sec[task.section.section_id].append(task)
for sec_id, sec_tasks in tasks_by_sec.items():
for req_period in required_periods:
target_slot = _slot(day, req_period)
# Create boolean: is_in_slot[task] = 1 if task covers target_slot
in_slot_vars = []
for task in sec_tasks:
if task.task_id not in task_vars:
continue
sv = task_vars[task.task_id][0]
b = model.NewBoolVar(
f'{task.task_id}_covers_d{day}_p{req_period}')
# task covers target_slot if sv <= target_slot < sv + duration
model.Add(sv <= target_slot).OnlyEnforceIf(b)
model.Add(sv + task.duration > target_slot).OnlyEnforceIf(b)
model.Add(sv > target_slot).OnlyEnforceIf(b.Not())
in_slot_vars.append(b)
# Also check non-affected (locked) tasks for this section+day+period
locked_covers = False
for tid, info in content_solution_ref.items():
if tid in affected_ids: continue
t = self.tasks_by_id.get(tid)
if not t or t.section.section_id != sec_id: continue
if info['day_index'] != day: continue
t_start = _slot(info['day_index'], info['period_index'])
if t_start <= target_slot < t_start + t.duration:
locked_covers = True
break
# Only add constraint if locked tasks don't already cover it
if not locked_covers and in_slot_vars:
model.AddAtLeastOne(in_slot_vars)
# Minimize changes from original
penalties = []
for task in affected_tasks:
orig = self.current_solution.get(task.task_id, {})
if orig:
orig_slot = _slot(orig['day_index'], orig['period_index'])
sv = task_vars[task.task_id][0]
changed = model.NewBoolVar(f'{task.task_id}_chg')
model.Add(sv != orig_slot).OnlyEnforceIf(changed)
model.Add(sv == orig_slot).OnlyEnforceIf(changed.Not())
penalties.append(changed)
if penalties: model.Minimize(sum(penalties))
solver.parameters.max_time_in_seconds = time_limit
solver.parameters.log_search_progress = False
sv_val = solver.Solve(model)
if sv_val not in (cp_model.OPTIMAL, cp_model.FEASIBLE):
return ('INFEASIBLE', {})
result = {}
for task in affected_tasks:
sv, _, _, rv = task_vars[task.task_id]
start = solver.Value(sv)
room = self.rooms[solver.Value(rv)]
result[task.task_id] = {
'start_slot': start,
'day_index': _day(start),
'day_name': const.DAYS[_day(start)],
'period_index': _period(start),
'room_id': room.room_id,
'room_name': f'{room.room_id} ({room.building})',
'faculty_name': task.faculty.name,
'subject_code': task.subject.subject_code,
'section_id': task.section.section_id,
'duration': task.duration,
}
status = 'OPTIMAL' if sv_val == cp_model.OPTIMAL else 'FEASIBLE'
return (status, result)
# ═════════════════════════════════════════════════════════════════
# HELPERS
# ═════════════════════════════════════════════════════════════════
def _sec_matches(self, task_section_id: str, sid_filter: str) -> bool:
"""
Returns True if task_section_id matches sid_filter.
sid_filter can be:
- exact id: "6a-E1" -> only matches "6a-E1"
- parent prefix: "6A" -> matches "6a-E1", "6a-E2" but not "6b-E1"
- None: matches everything
"""
if not sid_filter:
return True
if '-' not in sid_filter:
# prefix match
return task_section_id.lower().startswith(sid_filter.lower())
return task_section_id == sid_filter
def _check_conflict(self, skip_task_id, day, period, duration,
fid=None, sid=None):
"""Returns conflict description if slot is taken, else None."""
target_slots = set(range(_slot(day, period),
_slot(day, period) + duration))
for task_id, info in self.current_solution.items():
if task_id == skip_task_id: continue
task = self.tasks_by_id.get(task_id)
if not task: continue
task_slots = set(range(
_slot(info['day_index'], info['period_index']),
_slot(info['day_index'], info['period_index']) + info['duration']
))
if not target_slots.isdisjoint(task_slots):
if fid and task.faculty.id == fid:
return f"{task.faculty.name} busy"
if sid and task.section.section_id == sid:
return f"Section {info['section_id']} busy"
if not fid and not sid:
return f"{info['subject_code']} at that slot"
return None
def _find_task_at(self, day, period, sid=None):
for task_id, info in self.current_solution.items():
if info['day_index'] != day: continue
if info['period_index'] != period: continue
if sid and not self._sec_matches(info['section_id'], sid): continue
return task_id
return None
def _find_task_by_subject(self, day, scode, sid=None):
"""Find first task matching subject code on a given day."""
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task: continue
if info['day_index'] != day: continue
tc = task.subject.subject_code.lower()
sc = scode.lower()
if tc != sc and not tc.startswith(sc) and not sc.startswith(tc):
continue
if sid and not self._sec_matches(info['section_id'], sid): continue
return task_id
return None
def _find_task_by_faculty(self, day, fid, sid=None):
"""Find first task by faculty on a given day."""
for task_id, info in self.current_solution.items():
task = self.tasks_by_id.get(task_id)
if not task: continue
if info['day_index'] != day: continue
if task.faculty.id != fid: continue
if sid and not self._sec_matches(info['section_id'], sid): continue
return task_id
return None
def _all_starts(self, task):
if task.duration > 1:
result = []
for day in range(const.NUM_WORKING_DAYS):
for pos in const.ALLOWED_LAB_START_INDICES:
result.append(day * const.NUM_TEACHING_SLOTS_PER_DAY + pos)
return result
return list(range(const.TOTAL_TEACHING_SLOTS_PER_WEEK))
def _compute_allowed(self, task, constraints, locked_fac, locked_sec):
base = set(self._all_starts(task))
for offset in range(task.duration):
for s in locked_fac.get(task.faculty.id, set()):
base.discard(s - offset)
for s in locked_sec.get(task.section.section_id, set()):
base.discard(s - offset)
for c in constraints:
ctype = c.get('type', '').upper()
if ctype == 'FACULTY_UNAVAILABLE' and c.get('faculty_id') == task.faculty.id:
days = [DAY_INDEX[d] for d in (c.get('days') or []) if d in DAY_INDEX]
for day in days:
off = day * const.NUM_TEACHING_SLOTS_PER_DAY
for p in range(const.NUM_TEACHING_SLOTS_PER_DAY):
for o in range(task.duration): base.discard(off + p - o)
elif ctype == 'SUBJECT_PREFERRED_TIME':
if c.get('subject_code') == task.subject.subject_code:
period = str(c.get('period','')).upper()
target = MORNING_PERIODS if 'MORNING' in period else AFTERNOON_PERIODS
if target:
base = {s for s in base if _period(s) in target}
elif ctype == 'NO_FREE_PERIOD':
required_periods = c.get('periods') or []
sid = c.get('section_id')
# Only enforce for this task's section if section filter set
if required_periods and (not sid or task.section.section_id == sid):
# Prefer slots in required period — don't fully restrict
# (hard enforcement done via AddAtLeastOne in solver)
pass
elif ctype == 'WORKING_DAYS':
allowed_days = {DAY_INDEX[d] for d in (c.get('days') or [])
if d in DAY_INDEX}
if allowed_days:
base = {s for s in base if _day(s) in allowed_days}
return list(base)
def _allowed_rooms(self, task):
allowed = [i for i, r in enumerate(self.rooms)
if ((task.subject.subject_type == SubjectType.LAB) == r.is_lab
and r.capacity >= task.section.student_strength)]
return allowed if allowed else [0]
def _fail(self, msg):
return ('NO_CHANGE', self.current_solution, [], f'❌ {msg}') |