{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%use plotly"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# API"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "enum class Severity(val penalty: Double){\n",
    "    MINOR(1.0),\n",
    "    MAJOR(2.0),\n",
    "    CRITICAL(3.0)\n",
    "}\n",
    "\n",
    "enum class State{\n",
    "    OPEN,\n",
    "    ASSIGNED,\n",
    "    RESOLVED\n",
    "}\n",
    "\n",
    "data class Issue(val id: String, val dayCreated: Int, val severity: Severity, val complexity: Int, \n",
    "                 var state: State = State.OPEN, var dayAssigned: Int? = null, var dayResolved: Int? = null){\n",
    "    fun activate(day: Int){ \n",
    "        state = State.ASSIGNED\n",
    "        dayAssigned = day\n",
    "    }\n",
    "    \n",
    "    fun resolve(day: Int){\n",
    "        state = State.RESOLVED\n",
    "        dayResolved = day\n",
    "    }\n",
    "    \n",
    "    internal fun tryResolve(day: Int){\n",
    "        if(state == State.ASSIGNED && day >= (dayAssigned ?: 0) + complexity ){\n",
    "            resolve(day)\n",
    "        }\n",
    "    }\n",
    "}\n",
    "\n",
    "class Worker(val name: String){\n",
    "    var currentIssue: Issue? = null\n",
    "       private set\n",
    "    \n",
    "    fun isBusy(): Boolean = currentIssue != null\n",
    "    \n",
    "    fun update(day: Int){\n",
    "        currentIssue?.tryResolve(day)\n",
    "        if(currentIssue?.state == State.RESOLVED){\n",
    "            currentIssue = null\n",
    "        }\n",
    "    }\n",
    "    \n",
    "    fun assign(day: Int, issue: Issue){\n",
    "        if(currentIssue != null) error(\"Can't assign work to a worker which is busy\")\n",
    "        issue.activate(day)\n",
    "        currentIssue = issue\n",
    "    }\n",
    "}\n",
    "\n",
    "interface IssueGenerator{\n",
    "    fun generate(day: Int): List<Issue>\n",
    "}\n",
    "\n",
    "interface Strategy{\n",
    "    fun selectIssue(day: Int, issues: List<Issue>): Issue?\n",
    "}\n",
    "\n",
    "class WorkResult(val issues: List<Issue>, val workers: Int, val days: Int)\n",
    "\n",
    "@OptIn(kotlin.ExperimentalStdlibApi::class)\n",
    "fun simulate(generator: IssueGenerator, strategy: Strategy, numWorkers: Int = 10, days: Int = 100): WorkResult{\n",
    "    val workers = (0 until numWorkers).map{Worker(\"worker $it\")}\n",
    "    val issues =  buildList<Issue>{\n",
    "        for(day in 0 until days){\n",
    "            //update all workers\n",
    "            workers.forEach { it.update(day) }\n",
    "            //generate new issues\n",
    "            val newIssues = generator.generate(day)\n",
    "            addAll(newIssues)\n",
    "            //Select all free workers\n",
    "            workers.filter { !it.isBusy() }.forEach { worker->\n",
    "                val unasigned = filter { it.state == State.OPEN }\n",
    "                val anIssue = strategy.selectIssue(day, unasigned) //select an issue to assign from all unassigned issues\n",
    "                if(anIssue != null){\n",
    "                    worker.assign(day, anIssue)\n",
    "                }\n",
    "            }\n",
    "        }\n",
    "    }\n",
    "    return WorkResult(issues, numWorkers, days)\n",
    "}\n",
    "\n",
    "fun WorkResult.computeLoss(): Double = issues.sumByDouble { ((it.dayResolved ?: days) - it.dayCreated)*it.severity.penalty } / days / workers / issues.size"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Implementations"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import kotlin.random.Random\n",
    "import kotlin.math.pow\n",
    "\n",
    "/**\n",
    "* Generate one random issue per day\n",
    "*/\n",
    "class RandomIssueGenerator(seed: Long, val issuesPerDay: Int = 4 ) : IssueGenerator{\n",
    "    private val random = Random(seed)\n",
    "    override fun generate(day: Int): List<Issue>{\n",
    "        return List(issuesPerDay){\n",
    "            val severity = Severity.values()[random.nextInt(3)]\n",
    "            val complexity = random.nextInt(15)\n",
    "            Issue(\"${day}_${it}\", day, severity, complexity)\n",
    "        }\n",
    "    }\n",
    "}\n",
    "\n",
    "object TakeOldest: Strategy{\n",
    "    override fun selectIssue(day: Int, issues: List<Issue>): Issue?{\n",
    "        return issues.minByOrNull { it.dayCreated }\n",
    "    }\n",
    "}\n",
    "\n",
    "class TakeRandom(seed: Long): Strategy{\n",
    "    private val random = Random(seed)\n",
    "    override fun selectIssue(day: Int, issues: List<Issue>): Issue?{\n",
    "        if(issues.isEmpty()) return null\n",
    "        return issues.random(random)\n",
    "    }\n",
    "}\n",
    "\n",
    "object TakeCritical: Strategy{\n",
    "    override fun selectIssue(day: Int, issues: List<Issue>): Issue?{\n",
    "        return  issues.maxByOrNull { it.severity.penalty*(day - it.dayCreated) }\n",
    "    }\n",
    "}\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Simulate lossseverity"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "val seed = 89L\n",
    "val days = 100\n",
    "val workers = 10"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Take oldest"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "val result = simulate(RandomIssueGenerator(seed, workers),TakeOldest, days = days)\n",
    "//result.issues.forEach { println(it)}\n",
    "result.computeLoss()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Take random"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "simulate(RandomIssueGenerator(seed, workers),TakeRandom(seed), days = days).computeLoss()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Take critical"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "simulate(RandomIssueGenerator(seed, workers), TakeCritical, days = days).computeLoss()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "val seeds = List(1000){Random.nextLong()}\n",
    "\n",
    "Plotly.plot{\n",
    "    trace{\n",
    "        x.numbers = seeds.map{ seed -> simulate(RandomIssueGenerator(seed, workers), TakeOldest, days = days).computeLoss()}\n",
    "        name = \"oldest\"\n",
    "        type = TraceType.histogram\n",
    "    }\n",
    "    trace{\n",
    "        x.numbers = seeds.map{ seed -> simulate(RandomIssueGenerator(seed, workers), TakeRandom(seed), days = days).computeLoss()}\n",
    "        name = \"random\"\n",
    "        type = TraceType.histogram\n",
    "    }\n",
    "    trace{\n",
    "        x.numbers = seeds.map{ seed -> simulate(RandomIssueGenerator(seed, workers), TakeCritical, days = days).computeLoss()}\n",
    "        name = \"critical\"\n",
    "        type = TraceType.histogram\n",
    "    }\n",
    "    layout{\n",
    "        title = \"Loss distribtution\"\n",
    "        xaxis {\n",
    "            title = \"Loss\"\n",
    "        }\n",
    "    }\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
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   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
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   "source": []
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