Coverage Summary for Class: UntypedModule (day20p2)

 package day20p2
 
 import day20p2.Pulse.High
 
 fun String.numberOfButtonPressesForFirstLowPulseToRx(): Long {
   val modules = toModules()
   return modules.numberOfButtonPressesForFirstLowPulseToRx()
 }
 
 fun String.pressButtonAndCountNumberOfPulses(): Long {
   val modules = toModules()
   return modules.pressButtonAndCountNumberOfPulses(1_000)
 }
 
 fun String.toModules(): Modules {
   val builders = mutableMapOf(buttonModuleName to ModuleBuilder(buttonModuleName))
   lineSequence().forEach { line ->
     val (typedName, outputs) = line.split(" -> ").let { (name, outputs) -> name to outputs.split(", ").map { it.md } }
     val (name, builder) = if (typedName.startsWith("%")) {
       val n = typedName.substring(1).md
       n to builders.moduleBuilder(n).asFlipFlop()
     } else if (typedName.startsWith("&")) {
       val n = typedName.substring(1).md
       n to builders.moduleBuilder(n).asConjunction()
     } else {
       val n = typedName.md
       n to builders.moduleBuilder(n)
     }
     builder.addOutputs(outputs)
     outputs.forEach { output -> builders.moduleBuilder(output).addInput(name) }
   }
   return Modules(builders.mapValues { it.value.build() })
 }
 
 private fun MutableMap<ModuleName, ModuleBuilder>.moduleBuilder(name: ModuleName): ModuleBuilder =
   computeIfAbsent(name) { ModuleBuilder(name) }
 
 data class ModuleBuilder(val name: ModuleName) {
   private val inputs = mutableSetOf<ModuleName>()
   private val outputs = mutableListOf<ModuleName>()
   private var builderFn: (ModuleBuilder.() -> Module) = when (name) {
     buttonModuleName -> {
       {
         require(inputs.isEmpty())
         require(outputs.isEmpty())
         ButtonModule
       }
     }
 
     broadcasterModuleName -> {
       {
         require(inputs.isEmpty())
         require(outputs.isNotEmpty())
         Broadcaster(outputs)
       }
     }
 
     else -> {
       {
         require(inputs.isNotEmpty())
         require(outputs.isEmpty())
         UntypedModule(name, inputs)
       }
     }
   }
 
   fun asFlipFlop(): ModuleBuilder {
     builderFn = {
       require(inputs.isNotEmpty())
       require(outputs.isNotEmpty())
       FlipFlop(name, inputs, outputs)
     }
     return this
   }
 
   fun asConjunction(): ModuleBuilder {
     builderFn = {
       require(inputs.isNotEmpty())
       require(outputs.isNotEmpty())
       Conjunction(name, inputs, outputs)
     }
     return this
   }
 
   fun addInput(name: ModuleName): ModuleBuilder {
     inputs.add(name)
     return this
   }
 
   fun addOutputs(outputs: List<ModuleName>): ModuleBuilder {
     this.outputs.addAll(outputs)
     return this
   }
 
   fun build(): Module = builderFn()
 }
 
 data class Modules(val modules: Map<ModuleName, Module>) {
   private val buttonModule = modules.getValue(buttonModuleName) as ButtonModule
 
   fun pressButton(times: Int = 1): Pair<List<PulseMessage>, Modules> {
     var current = this
     var eventLog = emptyList<PulseMessage>()
     repeat(times) {
       val updatedModules = current.deepCopy()
       eventLog = updatedModules.doPressButton()
       current = updatedModules
     }
     return eventLog to current
   }
 
   fun pressButtonAndCountNumberOfPulses(times: Int): Long {
     var current = this
     var countHigh = 0L
     var countLow = 0L
     repeat(times) {
       val (eventLog, updatedModules) = current.pressButton()
       current = updatedModules
       eventLog.forEach {
         if (it.value == High) countHigh++ else countLow++
       }
     }
     return countHigh * countLow
   }
 
   fun numberOfButtonPressesForFirstLowPulseToRx(): Long {
     val rx = modules.getValue("rx".md)
     require(rx is MultipleInputModule)
     require(rx.inputs.size == 1)
     val rxInputName = rx.inputs.single()
     val rxInput = modules.getValue(rxInputName)
     require(rxInput is Conjunction)
 
     val inputsToTrack = rxInput.inputs.toMutableSet()
     val numOfButtonPresses = mutableSetOf<Long>()
     var countPresses = 0L
     while (inputsToTrack.isNotEmpty()) {
       countPresses++
       doPressButton { message ->
         if (message.value == High && message.to == rxInputName) {
           inputsToTrack.remove(message.from)
           numOfButtonPresses.add(countPresses)
         }
       }
     }
 
     return numOfButtonPresses.reduce { a, b -> a * b }
   }
 
   private fun doPressButton(onEvent: (PulseMessage) -> Unit = {}): List<PulseMessage> {
     val messages = mutableListOf<PulseMessage>()
     val eventLog = mutableListOf<PulseMessage>()
 
     buttonModule.press(messages)
     while (messages.isNotEmpty()) {
       val message = messages.removeFirst()
       eventLog += message
       val toModule = modules.getValue(message.to)
       require(toModule is ModuleWithInput)
       toModule.send(message, messages)
       onEvent(message)
     }
     return eventLog
   }
 
   private fun deepCopy(): Modules = Modules(modules.mapValues { it.value.deepCopy() })
 }
 
 data class PulseMessage(val from: ModuleName, val to: ModuleName, val value: Pulse) {
   override fun toString(): String = "$from -${value.toString().lowercase()}-> $to"
 }
 
 data class ModuleName(val name: String) {
   override fun toString(): String = name
 }
 
 sealed interface Module {
   val name: ModuleName
 
   fun toNamedPair(): Pair<ModuleName, Module> = name to this
   fun deepCopy(): Module = this
 }
 
 sealed interface ModuleWithInput : Module {
   fun send(message: PulseMessage, messageBus: MutableList<PulseMessage>)
 }
 
 sealed interface SingleInputModule : ModuleWithInput {
   val input: ModuleName
 }
 
 sealed interface MultipleInputModule : ModuleWithInput {
   val inputs: Set<ModuleName>
 }
 
 
 sealed interface SingleOutputModule : Module {
   val output: ModuleName
 }
 
 sealed interface MultipleOutputModule : Module {
   val outputs: List<ModuleName>
 }
 
 val String.md: ModuleName
   get() = ModuleName(this)
 
 fun moduleNames(vararg names: String) = names.map { it.md }
 
 val outputModuleName = ModuleName("output")
 val buttonModuleName = ModuleName("button")
 val broadcasterModuleName = ModuleName("broadcaster")
 
 data class UntypedModule(override val name: ModuleName, override val inputs: Set<ModuleName>) : MultipleInputModule {
   override fun send(message: PulseMessage, messageBus: MutableList<PulseMessage>) {
     // ignored
   }
 }
 
 data object ButtonModule : SingleOutputModule {
   fun press(messages: MutableList<PulseMessage>) {
     messages += PulseMessage(buttonModuleName, broadcasterModuleName, Pulse.Low)
   }
 
   override val name = buttonModuleName
   override val output = broadcasterModuleName
 }
 
 data class Broadcaster(override val outputs: List<ModuleName>) : SingleInputModule, MultipleOutputModule {
   override val name = broadcasterModuleName
   override val input = buttonModuleName
 
   override fun send(message: PulseMessage, messageBus: MutableList<PulseMessage>) {
     outputs.forEach { output -> messageBus += PulseMessage(broadcasterModuleName, output, message.value) }
   }
 }
 
 data class FlipFlop(
   override val name: ModuleName,
   override val inputs: Set<ModuleName>,
   override val outputs: List<ModuleName>,
   var on: Boolean = false
 ) : MultipleInputModule, MultipleOutputModule {
   override fun deepCopy(): FlipFlop = copy()
 
   override fun send(message: PulseMessage, messageBus: MutableList<PulseMessage>) {
     if (message.value == High) return
 
     if (!on) {
       on = true
       outputs.forEach { output -> messageBus += PulseMessage(name, output, High) }
     } else {
       on = false
       outputs.forEach { output -> messageBus += PulseMessage(name, output, Pulse.Low) }
     }
   }
 }
 
 data class Conjunction(
   override val name: ModuleName,
   override val inputs: Set<ModuleName>,
   override val outputs: List<ModuleName>,
   val lastPulses: MutableMap<ModuleName, Pulse> = inputs.associateWith { Pulse.Low }.toMutableMap()
 ) : MultipleInputModule, MultipleOutputModule {
   override fun deepCopy(): Conjunction = copy(lastPulses = lastPulses.toMutableMap())
 
   override fun send(message: PulseMessage, messageBus: MutableList<PulseMessage>) {
     lastPulses[message.from] = message.value
     val pulseToSend = if (lastPulses.values.all { it == High }) Pulse.Low else High
     outputs.forEach { output -> messageBus += PulseMessage(name, output, pulseToSend) }
   }
 }
 
 enum class Pulse {
   Low, High
 }