{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Use case: formula one pitstop\n",
    "\n",
    "This example is based on the DailyMail blog entry https://www.dailymail.co.uk/sport/formulaone/article-4401632/Formula-One-pit-stop-does-crew-work.html where a nice image shows 21 people changing the 4 tires of a Formula 1 Ferrari. In this example, only 16 out 21 people are represented. This notebook can be tested online at mybinder.org\n",
    "[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/tpaviot/ProcessScheduler/HEAD?filepath=doc/use-case-formula-one-change-tires.ipynb)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from IPython.display import YouTubeVideo\n",
    "\n",
    "YouTubeVideo(\"aHSUp7msCIE\", width=800, height=300)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Imports"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import processscheduler as ps\n",
    "\n",
    "%config InlineBackend.figure_formats = ['svg']"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Create the scheduling problem\n",
    "The total horizon is not knwown, leave it empty and only set the problem name."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "change_tires_problem = ps.SchedulingProblem(\"ChangeTires\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Create the 16 available resources\n",
    "Each people in and around the car is represented as a worker."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "nb_lifters = 2\n",
    "nb_gunners = 4\n",
    "nb_tyre_handlers = 8\n",
    "nb_stabilizers = 2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Lift tasks\n",
    "lifters = [ps.Worker(\"JackOperator%i\" % (i + 1)) for i in range(nb_lifters)]\n",
    "gunners = [ps.Worker(\"Gunner%i\" % (i + 1)) for i in range(nb_gunners)]\n",
    "tyre_handlers = [ps.Worker(\"Handler%i\" % (i + 1)) for i in range(nb_tyre_handlers)]\n",
    "stabilizers = [ps.Worker(\"Stabilizer%i\" % (i + 1)) for i in range(nb_stabilizers)]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Create tasks and assign resources\n",
    "One period is mapped to one second. For example, if lifting the rear take 2sec then the duration will be set to 2."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# lift tasks and lifters\n",
    "# both lift tasks can be processed by any one of the lifters\n",
    "lift_rear_up = ps.FixedDurationTask(\"LiftRearUp\", duration=2)\n",
    "lift_front_up = ps.FixedDurationTask(\"LiftFrontUp\", duration=2)\n",
    "lift_rear_up.add_required_resource(lifters[0])\n",
    "lift_front_up.add_required_resource(lifters[1])\n",
    "\n",
    "lift_rear_down = ps.FixedDurationTask(\"LiftRearDown\", duration=2)\n",
    "lift_front_down = ps.FixedDurationTask(\"LiftFrontDown\", duration=2)\n",
    "lift_rear_down.add_required_resource(lifters[0])\n",
    "lift_front_down.add_required_resource(lifters[1])\n",
    "\n",
    "# unscrew tasks\n",
    "unscrew_front_left_tyre = ps.FixedDurationTask(\"UnScrewFrontLeftTyre\", duration=2)\n",
    "unscrew_front_right_tyre = ps.FixedDurationTask(\"UnScrewFrontRightTyre\", duration=2)\n",
    "unscrew_rear_left_tyre = ps.FixedDurationTask(\"UnScrewRearLeftTyre\", duration=2)\n",
    "unscrew_rear_right_tyre = ps.FixedDurationTask(\"UnScrewRearRightTyre\", duration=2)\n",
    "\n",
    "gunner_unscrew_front_left_tyre = ps.SelectWorkers(gunners, 1)\n",
    "unscrew_front_left_tyre.add_required_resource(gunner_unscrew_front_left_tyre)\n",
    "\n",
    "gunner_unscrew_front_right_tyre = ps.SelectWorkers(gunners, 1)\n",
    "unscrew_front_right_tyre.add_required_resource(gunner_unscrew_front_right_tyre)\n",
    "\n",
    "gunner_unscrew_rear_left_tyre = ps.SelectWorkers(gunners, 1)\n",
    "unscrew_rear_left_tyre.add_required_resource(gunner_unscrew_rear_left_tyre)\n",
    "\n",
    "gunner_unscrew_rear_right_tyre = ps.SelectWorkers(gunners, 1)\n",
    "unscrew_rear_right_tyre.add_required_resource(gunner_unscrew_rear_right_tyre)\n",
    "\n",
    "# screw tasks and gunners\n",
    "screw_front_left_tyre = ps.FixedDurationTask(\"ScrewFrontLeftTyre\", duration=2)\n",
    "screw_front_right_tyre = ps.FixedDurationTask(\"ScrewFrontRightTyre\", duration=2)\n",
    "screw_rear_left_tyre = ps.FixedDurationTask(\"ScrewRearLeftTyre\", duration=2)\n",
    "screw_rear_right_tyre = ps.FixedDurationTask(\"ScrewRearRightTyre\", duration=2)\n",
    "\n",
    "gunner_screw_front_left_tyre = ps.SelectWorkers(gunners)\n",
    "screw_front_left_tyre.add_required_resource(gunner_screw_front_left_tyre)\n",
    "\n",
    "gunner_screw_front_right_tyre = ps.SelectWorkers(gunners)\n",
    "screw_front_right_tyre.add_required_resource(gunner_screw_front_right_tyre)\n",
    "\n",
    "gunner_screw_rear_left_tyre = ps.SelectWorkers(gunners)\n",
    "screw_rear_left_tyre.add_required_resource(gunner_screw_rear_left_tyre)\n",
    "\n",
    "gunner_screw_rear_right_tyre = ps.SelectWorkers(gunners)\n",
    "screw_rear_right_tyre.add_required_resource(gunner_screw_rear_right_tyre)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# tires OFF and handlers\n",
    "front_left_tyre_off = ps.FixedDurationTask(\"FrontLeftTyreOff\", duration=2)\n",
    "front_right_tyre_off = ps.FixedDurationTask(\"FrontRightTyreOff\", duration=2)\n",
    "rear_left_tyre_off = ps.FixedDurationTask(\"RearLeftTyreOff\", duration=2)\n",
    "rear_right_tyre_off = ps.FixedDurationTask(\"RearRightTyreOff\", duration=2)\n",
    "\n",
    "for tyre_off_task in [\n",
    "    front_left_tyre_off,\n",
    "    front_right_tyre_off,\n",
    "    rear_left_tyre_off,\n",
    "    rear_right_tyre_off,\n",
    "]:\n",
    "    tyre_off_task.add_required_resource(ps.SelectWorkers(tyre_handlers))\n",
    "\n",
    "# tires ON and handlers, same as above\n",
    "front_left_tyre_on = ps.FixedDurationTask(\"FrontLeftTyreOn\", duration=2)\n",
    "front_right_tyre_on = ps.FixedDurationTask(\"FrontRightTyreOn\", duration=2)\n",
    "rear_left_tyre_on = ps.FixedDurationTask(\"RearLeftTyreOn\", duration=2)\n",
    "rear_right_tyre_on = ps.FixedDurationTask(\"RearRightTyreOn\", duration=2)\n",
    "\n",
    "for tyre_on_task in [\n",
    "    front_left_tyre_on,\n",
    "    front_right_tyre_on,\n",
    "    rear_left_tyre_on,\n",
    "    rear_right_tyre_on,\n",
    "]:\n",
    "    tyre_on_task.add_required_resource(ps.SelectWorkers(tyre_handlers))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Stabilizers** start their job as soon as the car is stopped until the end of the whole activity."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "stabilize_left = ps.VariableDurationTask(\"StabilizeLeft\")\n",
    "stabilize_right = ps.VariableDurationTask(\"StabilizeRight\")\n",
    "\n",
    "stabilize_left.add_required_resource(stabilizers[0])\n",
    "stabilize_right.add_required_resource(stabilizers[1])\n",
    "\n",
    "ps.TaskStartAt(stabilize_left, 0)\n",
    "ps.TaskStartAt(stabilize_right, 0)\n",
    "\n",
    "ps.TaskEndAt(stabilize_left, change_tires_problem.horizon)\n",
    "ps.TaskEndAt(stabilize_right, change_tires_problem.horizon)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Task precedences"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# front left tyre operations\n",
    "fr_left = [\n",
    "    unscrew_front_left_tyre,\n",
    "    front_left_tyre_off,\n",
    "    front_left_tyre_on,\n",
    "    screw_front_left_tyre,\n",
    "]\n",
    "for i in range(len(fr_left) - 1):\n",
    "    ps.TaskPrecedence(fr_left[i], fr_left[i + 1])\n",
    "# front right tyre operations\n",
    "fr_right = [\n",
    "    unscrew_front_right_tyre,\n",
    "    front_right_tyre_off,\n",
    "    front_right_tyre_on,\n",
    "    screw_front_right_tyre,\n",
    "]\n",
    "for i in range(len(fr_right) - 1):\n",
    "    ps.TaskPrecedence(fr_right[i], fr_right[i + 1])\n",
    "# rear left tyre operations\n",
    "re_left = [\n",
    "    unscrew_rear_left_tyre,\n",
    "    rear_left_tyre_off,\n",
    "    rear_left_tyre_on,\n",
    "    screw_rear_left_tyre,\n",
    "]\n",
    "for i in range(len(re_left) - 1):\n",
    "    ps.TaskPrecedence(re_left[i], re_left[i + 1])\n",
    "# front left tyre operations\n",
    "re_right = [\n",
    "    unscrew_rear_right_tyre,\n",
    "    rear_right_tyre_off,\n",
    "    rear_right_tyre_on,\n",
    "    screw_rear_right_tyre,\n",
    "]\n",
    "for i in range(len(re_right) - 1):\n",
    "    ps.TaskPrecedence(re_right[i], re_right[i + 1])\n",
    "\n",
    "# all un screw operations must start after the car is lift by both front and rear jacks\n",
    "for unscrew_tasks in [\n",
    "    unscrew_front_left_tyre,\n",
    "    unscrew_front_right_tyre,\n",
    "    unscrew_rear_left_tyre,\n",
    "    unscrew_rear_right_tyre,\n",
    "]:\n",
    "    ps.TaskPrecedence(lift_rear_up, unscrew_tasks)\n",
    "    ps.TaskPrecedence(lift_front_up, unscrew_tasks)\n",
    "\n",
    "# lift down operations must occur after each screw task is completed\n",
    "for screw_task in [\n",
    "    screw_front_left_tyre,\n",
    "    screw_front_right_tyre,\n",
    "    screw_rear_left_tyre,\n",
    "    screw_rear_right_tyre,\n",
    "]:\n",
    "    ps.TaskPrecedence(screw_task, lift_rear_down)\n",
    "    ps.TaskPrecedence(screw_task, lift_front_down)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### First solution, plot the schedule"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "solver = ps.SchedulingSolver(change_tires_problem)\n",
    "solution_1 = solver.solve()\n",
    "solution_1.render_gantt_matplotlib(fig_size=(10, 5), render_mode=\"Resource\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Second solution: add a makespan objective\n",
    "Obviously, the former solution is not the *best* solution, not sure Ferrari will win this race ! The whole \"change tires\" activity must be as short as possible, so let's add a *makespan* objective, i.e. a constraint that minimizes the schedule horizon."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# add makespan objective\n",
    "change_tires_problem.add_objective_makespan()\n",
    "\n",
    "solver_2 = ps.SchedulingSolver(change_tires_problem)\n",
    "solution_2 = solver_2.solve()\n",
    "solution_2.render_gantt_matplotlib(fig_size=(9, 5), render_mode=\"Task\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Third solution: constraint workers\n",
    "This is not the best possible solution. Indeed, we can notice that the Gunner2 unscrews the RearRightTyre and screw the RearLeft tyre. We cannot imagine that a solution where gunners turn around the car is acceptable. There are two solutions to fix the schedule:\n",
    "-   let the gunner be able to turn around the car, and add a \"Move\" task with a duration that represent the time necessary to move from one tyre to the other,\n",
    "-   constraint the worker to screw the same tyre he unscrewed. Let's go this way"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "ps.SameWorkers(gunner_unscrew_front_left_tyre, gunner_screw_front_left_tyre)\n",
    "ps.SameWorkers(gunner_unscrew_front_right_tyre, gunner_screw_front_right_tyre)\n",
    "ps.SameWorkers(gunner_unscrew_rear_left_tyre, gunner_screw_rear_left_tyre)\n",
    "ps.SameWorkers(gunner_unscrew_rear_right_tyre, gunner_screw_rear_right_tyre)\n",
    "\n",
    "solver_3 = ps.SchedulingSolver(change_tires_problem)\n",
    "solution_3 = solver_3.solve()\n",
    "solution_3.render_gantt_matplotlib(fig_size=(9, 5), render_mode=\"Task\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This is much better !"
   ]
  }
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