Add a constraint of renewable ressource - or-tools

Question

I am new to these optimisation problems, I just found the or-tools library and saw that cp_model can fix problems that are close to mine.
I have printers and some tasks, that I want to schedule in order to finish the production the earliest. The tasks uses time on machine and raw material, that I must refill at the end of coil. For the moment, I don't consider changing a plastic coil before using all the material.
Here is some information about my situation:
1- The printers are all same, they can do every task, with the same efficiency.
2- A printer can only print one task at a time.
3- A printer cannot start without human around, so tasks can start only at certain hours (in the code below, from 0AM to 10 AM).
4- A task can finish at any time.
5- If a printer has no more material, it needs to be change, this can happen only on opening hours.
6- If a printer has no more material, the task is paused until new material is put.
7- I consider having unlimited quantity of material coil.
Thanks to examples and some search in the documentation, I have been able to fix all the issues that are not related to material. I have been able to set a maximum quantity per machine, but it is not my issue.
I don't understand how I can pause/resume my intervals (for the moment I set the duration to a fixed one).
from ortools.sat.python import cp_model
from ortools.util.python import sorted_interval_list
import random
Domain = sorted_interval_list.Domain
def main():
random.seed(0)
nb_jobs = 10
nb_machine = 2
horizon = 30000000
job_list = [] #Job : (id,time,quantity)
listOfEnds = []
quantityPerMachine = []
maxQuantity = 5
#create the jobs
for i in range(nb_jobs):
time = random.randrange(1,24)
quantity = random.randrange(1,4)
job_list.append([i,time,quantity])
print([job[1] for job in job_list])
print("total time to print = ",horizon)
print("quantity")
print([job[2] for job in job_list])
print("total quantity = ",sum([job[2] for job in job_list]))
model = cp_model.CpModel()
makespan = model.NewIntVar(0, horizon, 'makespan')
machineForJob = {}
#boolean variable for each combination of machine and job. if True then machine works on this job
for machine in range(nb_machine):
for job in job_list:
j = job[0]
machineForJob[(machine,j)]=(model.NewBoolVar(f'x[{machine},{j}]'))
#for each job, apply sum()==1 to ensure one machine works on each job only
for j in range(nb_jobs):
model.Add(sum([machineForJob[(machine,j)] for machine in range(nb_machine)])==1)
#set the affectation of the jobs
time_intervals={}
starts = {}
ends = {}
#Time domain represents working hours when someone can start the taks
timeDomain = []#[[0],[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[24],[25],[26]]
for i in range(20):
for j in range(10):
t= [j +i*24]
timeDomain.append(t)
for machine in range(nb_machine):
time_intervals[machine] = []
for job in job_list:
j = job[0]
duration = job[1]
starts[(machine,j)] = model.NewIntVarFromDomain(Domain.FromIntervals(timeDomain),f'start {machine},{j}')
ends[(machine,j)] = (model.NewIntVar(0, horizon, f'end {machine},{j}'))
time_intervals[machine].append(model.NewOptionalIntervalVar(starts[(machine,j)], duration, ends[(machine,j)],
machineForJob[(machine,j)],f'interval {machine},{j} '))
#time should not overlap, quantity of raw material is limited,
for machine in range(nb_machine):
#model.Add(quantityPerMachine[machine] <= maxQuantity) Not working as expected as the raw material cannot be refilled
model.AddNoOverlap(time_intervals[machine])
#calculate time per machine
time_per_machine = []
for machine in range(nb_machine):
q = 0
s = 0
for job in job_list:
s+= job[1]*machineForJob[(machine,job[0])]
listOfEnds.append(ends[(machine,job[0])])
q+= job[2]*machineForJob[(machine,job[0])]
time_per_machine.append(s)
quantityPerMachine.append(q)
#Goal is to finish all taks earliest
model.AddMaxEquality(makespan,listOfEnds)
model.Minimize(makespan)
solver = cp_model.CpSolver()
# Sets a time limit of 10 seconds.
solver.parameters.max_time_in_seconds = 600.0
#Solve and prints
status = solver.Solve(model)
if status == cp_model.OPTIMAL or status == cp_model.FEASIBLE:
print("optimal =",status == cp_model.OPTIMAL )
print(f'Total cost = {solver.ObjectiveValue()}')
for i in range(nb_machine):
for j in range(nb_jobs):
if solver.BooleanValue(machineForJob[(i,j)]):
print(
f'Machine {i} assigned to Job {j} Time = {job_list[j][1]},Quantity = {job_list[j][2]}')
print(f"[{solver.Value(starts[(i,j)])} ,{solver.Value(ends[(i,j)])}]")
else:
print('No solution found.')
# Statistics.
print('\nStatistics')
print(' - conflicts: %i' % solver.NumConflicts())
print(' - branches : %i' % solver.NumBranches())
print(' - wall time: %f s' % solver.WallTime())