Implement a command system

src/main/java/codes/som/hibiscus/mixins/MixinClientPlayerEntity.java

@@ -2,6 +2,7 @@ package codes.som.hibiscus.mixins;
 
 import codes.som.hibiscus.HibiscusMod;
 import codes.som.hibiscus.events.PlayerTickEvent;
+import codes.som.hibiscus.events.SendChatEvent;
 import net.minecraft.client.network.ClientPlayerEntity;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
@@ -14,4 +15,12 @@ public abstract class MixinClientPlayerEntity {
     private void onPostTick(CallbackInfo ci) {
         HibiscusMod.bus().fire(PlayerTickEvent.INSTANCE);
     }
+
+    @Inject(method = "sendChatMessage", at = @At("HEAD"), cancellable = true)
+    private void onChatMessage(String message, CallbackInfo ci) {
+        var event = new SendChatEvent(message);
+        HibiscusMod.bus().fire(event);
+        if (event.isCancelled())
+            ci.cancel();
+    }
 }

src/main/kotlin/codes/som/hibiscus/HibiscusLog.kt

@@ -0,0 +1,20 @@
+package codes.som.hibiscus
+
+import net.minecraft.text.LiteralText
+import net.minecraft.util.Formatting
+
+object HibiscusLog {
+    private val hibiscusMessagePrefix
+        get() = LiteralText("[H] ").styled { it.withColor(0xFFC1F8L.toInt()) }
+
+    fun info(message: String) {
+        val messageText = LiteralText(message).styled { it.withColor(Formatting.WHITE) }
+        player.sendMessage(hibiscusMessagePrefix.append(messageText), false)
+    }
+
+    fun error(message: String) {
+        val errorText = LiteralText("Error: ").styled { it.withColor(Formatting.RED) }
+        val messageText = LiteralText(message).styled { it.withColor(Formatting.WHITE) }
+        player.sendMessage(hibiscusMessagePrefix.append(errorText).append(messageText), false)
+    }
+}

src/main/kotlin/codes/som/hibiscus/HibiscusMod.kt

@@ -1,9 +1,12 @@
 package codes.som.hibiscus
 
+import codes.som.hibiscus.api.command.CommandManager
 import codes.som.hibiscus.api.event.EventBus
+import codes.som.hibiscus.api.event.EventPhase
 import codes.som.hibiscus.events.KeyEvent
 import codes.som.hibiscus.features.FeaturesRegistry
 import codes.som.hibiscus.gui.ImGuiScreen
+import codes.som.hibiscus.util.command.ChatCommandListener
 import codes.som.hibiscus.util.netmoving.NetworkMovingDispatcher
 import net.fabricmc.api.ModInitializer
 import org.lwjgl.glfw.GLFW
@@ -18,9 +21,13 @@ object HibiscusMod : ModInitializer {
     val bus = EventBus()
 
     val features = FeaturesRegistry()
+    val commands = CommandManager()
 
     override fun onInitialize() {
-        bus.register(NetworkMovingDispatcher())
+        for (feature in features.getAllFeatures()) {
+            commands.register(feature.createFeatureCommand())
+        }
+
         bus.register { event: KeyEvent ->
             if (event.key != GLFW_KEY_RIGHT_SHIFT || event.action != GLFW.GLFW_PRESS)
                 return@register
@@ -30,5 +37,8 @@ object HibiscusMod : ModInitializer {
 
             mc.setScreen(ImGuiScreen)
         }
+
+        bus.register(NetworkMovingDispatcher(), EventPhase.AFTER)
+        bus.register(ChatCommandListener())
     }
 }

src/main/kotlin/codes/som/hibiscus/api/command/Command.kt

@@ -0,0 +1,72 @@
+package codes.som.hibiscus.api.command
+
+import codes.som.hibiscus.api.command.ExecutableCommand.CommandBranch
+import codes.som.hibiscus.api.command.parser.ArgumentParser
+import java.lang.reflect.ParameterizedType
+
+open class Command(val name: String) {
+    private val branches = mutableListOf<BranchDeclaration>()
+    private val aliases = mutableListOf<String>()
+
+    fun alias(aliasName: String) {
+        aliases += aliasName
+    }
+
+    fun branch(branchName: String? = null, handler: Function<*>): BranchDeclaration {
+        val params = handler.javaClass.genericInterfaces
+        for (param in params) {
+            if (param is ParameterizedType) {
+                val parameterTypes = mutableListOf<Class<*>>()
+
+                param.actualTypeArguments
+                    .filterIndexed { index, _ -> index != param.actualTypeArguments.lastIndex }
+                    .filterIsInstance<Class<*>>()
+                    .forEach { parameterTypes += it }
+
+                val branchDecl = BranchDeclaration(branchName, handler, parameterTypes.toTypedArray())
+                branches += branchDecl
+
+                return branchDecl
+            }
+        }
+
+        throw IllegalStateException("Handler function had no generic parameters!")
+    }
+
+    fun buildCommand(): ExecutableCommand {
+        val command = ExecutableCommand(name, aliases.toTypedArray())
+        command.branches.addAll(
+            branches.asSequence()
+                .map {
+                    CommandBranch(
+                        it.branchName,
+                        it.aliases.toTypedArray(),
+                        it.parameterTypes,
+                        it.handler,
+                        it.typeHints
+                    )
+                }
+        )
+
+        return command
+    }
+
+    inner class BranchDeclaration internal constructor(
+        val branchName: String?,
+        val handler: Function<*>,
+        val parameterTypes: Array<Class<*>>
+    ) {
+        internal val aliases = mutableListOf<String>()
+        internal val typeHints = mutableMapOf<Int, ArgumentParser<*>>()
+
+        fun alias(aliasName: String): BranchDeclaration {
+            aliases += aliasName
+            return this
+        }
+
+        fun typeHint(index: Int, parser: ArgumentParser<*>): BranchDeclaration {
+            typeHints.put(index, parser)
+            return this
+        }
+    }
+}

src/main/kotlin/codes/som/hibiscus/api/command/CommandContext.kt

@@ -0,0 +1,7 @@
+package codes.som.hibiscus.api.command
+
+enum class CommandContext {
+    MANUAL,
+    KEYBIND,
+    OTHER,
+}

src/main/kotlin/codes/som/hibiscus/api/command/CommandManager.kt

@@ -0,0 +1,231 @@
+package codes.som.hibiscus.api.command
+
+import codes.som.hibiscus.api.command.ExecutableCommand.CommandBranch
+import codes.som.hibiscus.api.command.context.CommandExecutionContext
+import codes.som.hibiscus.api.command.exceptions.*
+import codes.som.hibiscus.api.command.parser.ArgumentParser
+import codes.som.hibiscus.api.command.utils.PeekableIterator
+import codes.som.hibiscus.api.command.utils.splitExceptingQuotes
+
+class CommandManager(private val registerDefaultParsers: Boolean = true) {
+    private val parserRegistry = mutableMapOf<Class<*>, ArgumentParser<*>>()
+    val commands = mutableListOf<ExecutableCommand>()
+
+    var context: CommandContext = CommandContext.OTHER
+
+    init {
+        registerDefaultParsersIfApplicable()
+    }
+
+    private fun registerDefaultParsersIfApplicable() {
+        if (registerDefaultParsers) {
+            addDefaultParsers(parserRegistry)
+        }
+    }
+
+    fun <T> registerParser(type: Class<T>, parser: ArgumentParser<T>) {
+        parserRegistry.put(type, parser)
+    }
+
+    private fun verifyCommand(command: ExecutableCommand) {
+        // TODO: Prevent name collisions for commands / aliases
+
+        command.branches.forEach {
+            it.parameterTypes
+                .filter { it !in parserRegistry }
+                .forEach { throw MissingParserException(it) }
+        }
+    }
+
+    @Throws(CommandRegistrationException::class)
+    fun register(declaration: Command) {
+        try {
+            val command = declaration.buildCommand()
+
+            verifyCommand(command)
+            commands += command
+        } catch (e: Exception) {
+            throw CommandRegistrationException(e)
+        }
+    }
+
+    @Throws(CommandExecutionException::class)
+    fun executeCommand(fullCommand: String) {
+        try {
+            val args = splitExceptingQuotes(fullCommand, true).toList()
+            if (args.isEmpty())
+                throw CommandNotFoundException("")
+
+            val commandName = args[0]
+
+            val matchingCommands = commands.filter { commandMatches(commandName, it) }
+            when {
+                matchingCommands.isEmpty() -> throw CommandNotFoundException(commandName)
+                matchingCommands.size > 1 -> throw CommandIsAmbiguousException(commandName)
+            }
+
+            val command = matchingCommands.first()
+
+            fun isBranchViable(branch: CommandBranch, args: List<String>): Boolean {
+                try {
+                    val argObjects = parseArgumentsForBranch(branch, args)
+                    if (argObjects.size == branch.parameterTypes.size) {
+                        return true
+                    }
+                } catch (e: Exception) {
+                    return false
+                }
+
+                return false
+            }
+
+            val viableBranches = command.branches.filter { branchMatches(args, it) }.filter { isBranchViable(it, args) }
+
+            val viableNamedBranches = viableBranches.filter { it.name != null }
+            if (viableNamedBranches.size > 1)
+                throw BranchesAreAmbiguousException(commandName, args[1])
+
+            // Loop through named branches first, as branch names have priority over arguments.
+            for (branch in viableNamedBranches) {
+                executeBranch(branch, args)
+                return
+            }
+
+            for (branch in viableBranches.filter { it.name == null }) {
+                executeBranch(branch, args)
+                return
+            }
+
+            throw NoMatchingBranchesException()
+        } catch (e: Exception) {
+            throw CommandExecutionException(e)
+        }
+    }
+
+    fun completeCommand(fullCommand: String): Array<String> {
+        return completeCommandDuplicatesSpaces(fullCommand)
+            .map {
+                if (it.toCharArray().any { it.isWhitespace() }) "\"$it\"" else it
+            } // Wrap suggestions containing spaces in quotes
+            .toSet() // Remove duplicates
+            .toTypedArray()
+    }
+
+    private fun completeCommandDuplicatesSpaces(fullCommand: String): List<String> {
+        val args = splitExceptingQuotes(fullCommand, true).toList()
+
+        if (args.isEmpty())
+            return commands.map { it.name }
+
+        if (args.size == 1) {
+            val namesAndAliasesOfCommands = mutableListOf<String>().apply {
+                addAll(commands.map { it.name })
+                commands.forEach { addAll(it.aliases) }
+            }
+
+            return namesAndAliasesOfCommands.filter { it.toLowerCase().startsWith(fullCommand.toLowerCase()) }
+        }
+
+        val commandName = args[0]
+        val matchingCommands = commands.filter { commandMatches(commandName, it) }
+        when {
+            matchingCommands.isEmpty() -> return emptyList()
+            matchingCommands.size > 1 -> throw CommandIsAmbiguousException(commandName)
+        }
+
+        val command = matchingCommands.first()
+
+        if (args[1].isBlank())
+            return command.branches.mapNotNull { it.name }
+
+        val matchingBranches = mutableListOf<String>().apply {
+            addAll(command.branches.mapNotNull { it.name })
+            command.branches.forEach { addAll(it.aliases) }
+        }.filter { it.startsWith(args[1]) }
+
+        if (args.size == 2)
+            return matchingBranches
+
+        // TODO: Tab completion for parameters
+        // - Solve ambiguity issues
+        // ????
+
+        return emptyList()
+    }
+
+    private fun parseArgumentsForBranch(branch: CommandBranch, args: List<String>): Array<Any> {
+        val parsers = mutableListOf<ArgumentParser<*>>()
+        for ((index, parameterType) in branch.parameterTypes.withIndex()) {
+            if (index in branch.typeHints) {
+                parsers.add(branch.typeHints[index]!!)
+            } else {
+                if (parameterType !in parserRegistry)
+                    throw MissingParserException(parameterType)
+
+                parsers.add(parserRegistry[parameterType]!!)
+            }
+        }
+
+        val startIndex = if (branch.name == null) 1 else 2
+
+        if (parsers.isEmpty() && args.size > startIndex) {
+            throw ParsingException(
+                InvalidArgumentCount(
+                    branch.name
+                        ?: "<blank>"
+                )
+            )
+        }
+
+        val argsIterator = PeekableIterator(args.listIterator(startIndex))
+
+        val context = CommandExecutionContext(argsIterator, branch.parameterTypes, 0)
+
+        val argumentObjects = mutableListOf<Any>()
+
+        val minArgs = parsers.map { it.minimumAcceptedArguments() }.sum()
+
+        if (args.size - startIndex >= minArgs && args.size - startIndex >= parsers.size) {
+            for ((index, parser) in parsers.withIndex()) {
+                context.currentParameter = index
+
+                try {
+                    argumentObjects += parser.parse(context)!!
+                } catch (e: Exception) {
+                    throw ParsingException(e)
+                }
+            }
+        } else {
+            throw ParsingException(
+                InvalidArgumentCount(
+                    branch.name
+                        ?: "<blank>"
+                )
+            )
+        }
+
+        return argumentObjects.toTypedArray()
+    }
+
+    private fun executeBranch(branch: CommandBranch, args: List<String>) {
+        val argumentObjects = parseArgumentsForBranch(branch, args)
+        branch.execute(*argumentObjects)
+    }
+
+    private fun commandMatches(commandName: String, command: ExecutableCommand): Boolean {
+        return command.name.equals(commandName, ignoreCase = true) ||
+            command.aliases.any { it.equals(commandName, ignoreCase = true) }
+    }
+
+    private fun branchMatches(args: List<String>, branch: CommandBranch): Boolean {
+        return branch.name == null ||
+            (args.size > 1 && (branch.name.equals(args[1], ignoreCase = true) ||
+                branch.aliases.any { it.equals(args[1], ignoreCase = true) }))
+    }
+
+    fun reset() {
+        commands.clear()
+        parserRegistry.clear()
+        registerDefaultParsersIfApplicable()
+    }
+}

src/main/kotlin/codes/som/hibiscus/api/command/DefaultParsers.kt

@@ -0,0 +1,23 @@
+package codes.som.hibiscus.api.command
+
+import codes.som.hibiscus.api.command.parser.*
+
+fun addDefaultParsers(parserRegistry: MutableMap<Class<*>, ArgumentParser<*>>) {
+    parserRegistry[String::class.java] = StringParser()
+
+    parserRegistry[Int::class.java] = IntParser()
+    parserRegistry[Float::class.java] = FloatParser()
+    parserRegistry[Double::class.java] = DoubleParser()
+    parserRegistry[Short::class.java] = ShortParser()
+    parserRegistry[Long::class.java] = LongParser()
+    parserRegistry[Char::class.java] = CharParser()
+
+
+    // Java interop
+    parserRegistry[java.lang.Integer::class.java] = parserRegistry[Int::class.java]!!
+    parserRegistry[java.lang.Float::class.java] = parserRegistry[Float::class.java]!!
+    parserRegistry[java.lang.Double::class.java] = parserRegistry[Double::class.java]!!
+    parserRegistry[java.lang.Short::class.java] = parserRegistry[Short::class.java]!!
+    parserRegistry[java.lang.Long::class.java] = parserRegistry[Long::class.java]!!
+    parserRegistry[java.lang.Character::class.java] = parserRegistry[Char::class.java]!!
+}

src/main/kotlin/codes/som/hibiscus/api/command/ExecutableCommand.kt

@@ -0,0 +1,29 @@
+package codes.som.hibiscus.api.command
+
+import codes.som.hibiscus.api.command.parser.ArgumentParser
+
+class ExecutableCommand(val name: String, val aliases: Array<String>) {
+    companion object {
+        fun declare(name: String, init: Command.() -> Unit): Command {
+            val declaration = Command(name)
+            init(declaration)
+
+            return declaration
+        }
+    }
+
+    val branches = mutableListOf<CommandBranch>()
+
+    class CommandBranch(
+        val name: String?,
+        val aliases: Array<String>,
+        val parameterTypes: Array<Class<*>>,
+        private val handler: Function<*>,
+        val typeHints: Map<Int, ArgumentParser<*>>
+    ) {
+        fun execute(vararg args: Any) {
+            handler.javaClass.declaredMethods.first { it.name == "invoke" }.apply { this.isAccessible = true }
+                .invoke(handler, *args)
+        }
+    }
+}

src/main/kotlin/codes/som/hibiscus/api/command/context/CommandExecutionContext.kt

@@ -0,0 +1,9 @@
+package codes.som.hibiscus.api.command.context
+
+import codes.som.hibiscus.api.command.utils.PeekableIterator
+
+class CommandExecutionContext(
+    val arguments: PeekableIterator<String>,
+    val parameters: Array<Class<*>>,
+    var currentParameter: Int
+)

src/main/kotlin/codes/som/hibiscus/api/command/exceptions/CommandExceptions.kt

@@ -0,0 +1,11 @@
+package codes.som.hibiscus.api.command.exceptions
+
+class CommandExecutionException(cause: Exception) : RuntimeException("Exception while executing command", cause)
+class CommandRegistrationException(cause: Exception) : RuntimeException("Exception while registering command", cause)
+
+class CommandNotFoundException(name: String) : RuntimeException("The command '$name' was not found.")
+class CommandIsAmbiguousException(name: String) : RuntimeException("The command '$name' is ambiguous.")
+
+class NoMatchingBranchesException : RuntimeException("No branches matching were found")
+class BranchesAreAmbiguousException(command: String, branchName: String?) :
+    RuntimeException("Branch '$branchName' is ambiguous for command '$command'.")

src/main/kotlin/codes/som/hibiscus/api/command/exceptions/ParserExceptions.kt

@@ -0,0 +1,8 @@
+package codes.som.hibiscus.api.command.exceptions
+
+class MissingParserException(classToParse: Class<*>) :
+    RuntimeException("No parser found for type: ${classToParse.name}")
+
+class ParsingException(cause: Exception) : RuntimeException("Exception while parsing", cause)
+
+class InvalidArgumentCount(branchName: String) : RuntimeException("Invalid amount of arguments for branch: $branchName")

src/main/kotlin/codes/som/hibiscus/api/command/parser/ArgumentParser.kt

@@ -0,0 +1,10 @@
+package codes.som.hibiscus.api.command.parser
+
+import codes.som.hibiscus.api.command.context.CommandExecutionContext
+
+interface ArgumentParser<out T> {
+    fun parse(context: CommandExecutionContext): T?
+    fun provideSuggestions(context: CommandExecutionContext): List<String> = emptyList()
+
+    fun minimumAcceptedArguments(): Int = 1
+}

src/main/kotlin/codes/som/hibiscus/api/command/parser/PrimitiveParsers.kt

@@ -0,0 +1,60 @@
+package codes.som.hibiscus.api.command.parser
+
+import codes.som.hibiscus.api.command.context.CommandExecutionContext
+
+class StringParser : ArgumentParser<String> {
+    override fun parse(context: CommandExecutionContext): String {
+        return if (context.currentParameter == context.parameters.lastIndex) {
+            buildString {
+                for (arg in context.arguments) {
+                    append(arg)
+
+                    if (context.arguments.hasNext())
+                        append(" ")
+                }
+            }
+        } else {
+            context.arguments.next()
+        }
+    }
+}
+
+
+class IntParser : ArgumentParser<Int> {
+    override fun parse(context: CommandExecutionContext): Int {
+        return context.arguments.next().toInt()
+    }
+}
+
+class FloatParser : ArgumentParser<Float> {
+    override fun parse(context: CommandExecutionContext): Float {
+        return context.arguments.next().toFloat()
+    }
+}
+
+class DoubleParser : ArgumentParser<Double> {
+    override fun parse(context: CommandExecutionContext): Double {
+        return context.arguments.next().toDouble()
+    }
+}
+
+class ShortParser : ArgumentParser<Short> {
+    override fun parse(context: CommandExecutionContext): Short {
+        return context.arguments.next().toShort()
+    }
+}
+
+class LongParser : ArgumentParser<Long> {
+    override fun parse(context: CommandExecutionContext): Long {
+        return context.arguments.next().toLong()
+    }
+}
+
+class CharParser : ArgumentParser<Char> {
+    override fun parse(context: CommandExecutionContext): Char {
+        val chars = context.arguments.next().toCharArray()
+        assert(chars.size == 1)
+
+        return chars.first()
+    }
+}

src/main/kotlin/codes/som/hibiscus/api/command/utils/PeekableIterator.kt

@@ -0,0 +1,20 @@
+package codes.som.hibiscus.api.command.utils
+
+class PeekableIterator<T>(internal val wrapped: ListIterator<T>) : Iterator<T> {
+    override fun hasNext(): Boolean {
+        return wrapped.hasNext()
+    }
+
+    override fun next(): T {
+        return wrapped.next()
+    }
+
+    fun peek(): T {
+        val next = wrapped.next()
+        wrapped.previous()
+
+        return next
+    }
+
+    internal fun previous(): T = wrapped.previous()
+}

src/main/kotlin/codes/som/hibiscus/api/command/utils/StringUtilities.kt

@@ -0,0 +1,25 @@
+package codes.som.hibiscus.api.command.utils
+
+import java.util.regex.Pattern
+
+fun join(strings: Array<String>, delimiter: String): String {
+    val str = StringBuilder()
+    for (string in strings) {
+        str.append(string)
+        str.append(delimiter)
+    }
+
+    return str.substring(0, str.length - delimiter.length)
+}
+
+fun splitExceptingQuotes(string: String, stripQuotes: Boolean): Array<String> {
+    val list = arrayListOf<String>()
+    val m = Pattern.compile("([^\"]\\S*|\".+?\")\\s*").matcher(string)
+    while (m.find())
+        list.add(if (stripQuotes) m.group(1).replace("\"", "") else m.group(1))
+
+    if (string.endsWith(" "))
+        list.add("")
+
+    return list.toTypedArray()
+}

src/main/kotlin/codes/som/hibiscus/api/event/EventBus.kt

@@ -3,25 +3,36 @@ package codes.som.hibiscus.api.event
 import java.util.concurrent.CopyOnWriteArrayList
 
 class EventBus {
-    private val listenerMap = mutableMapOf<Class<out Event>, MutableList<Listener<*>>>()
+    private val allListeners = mutableMapOf<EventPhase, MutableMap<Class<*>, MutableList<Listener<*>>>>()
+
+    inline fun <reified T : Event> register(listener: Listener<T>, phase: EventPhase) {
+        this.register(T::class.java, listener, phase)
+    }
 
     inline fun <reified T : Event> register(listener: Listener<T>) {
         this.register(T::class.java, listener)
     }
 
-    fun <T : Event> register(type: Class<T>, listener: Listener<T>) {
+    fun <T : Event> register(type: Class<T>, listener: Listener<T>, phase: EventPhase = EventPhase.NORMAL) {
+        val listenerMap = allListeners.getOrPut(phase, ::mutableMapOf)
         listenerMap.getOrPut(type, ::CopyOnWriteArrayList).add(listener)
     }
 
-    inline fun <reified T : Event> unregister(listener: Listener<T>) =
-        unregister(T::class.java, listener)
+    inline fun <reified T : Event> unregister(listener: Listener<T>, phase: EventPhase = EventPhase.NORMAL) =
+        unregister(T::class.java, listener, phase)
 
-    fun <T : Event> unregister(type: Class<T>, listener: Listener<T>) =
+    fun <T : Event> unregister(type: Class<T>, listener: Listener<T>, phase: EventPhase = EventPhase.NORMAL) {
+        val listenerMap = allListeners[phase] ?: return
         listenerMap[type]?.remove(listener)
+    }
 
     fun <T : Event> fire(event: T) {
-        @Suppress("UNCHECKED_CAST")
-        val listeners = (listenerMap[event.javaClass] ?: return) as List<Listener<T>>
-        listeners.forEach { it.on(event) }
+        for (phase in EventPhase.values()) {
+            val listenerMap = allListeners[phase] ?: continue
+
+            @Suppress("UNCHECKED_CAST")
+            val listeners = (listenerMap[event.javaClass] ?: continue) as List<Listener<T>>
+            listeners.forEach { it.on(event) }
+        }
     }
 }

src/main/kotlin/codes/som/hibiscus/api/event/EventPhase.kt

@@ -0,0 +1,7 @@
+package codes.som.hibiscus.api.event
+
+enum class EventPhase {
+    BEFORE,
+    NORMAL,
+    AFTER
+}

src/main/kotlin/codes/som/hibiscus/api/feature/Feature.kt

@@ -1,6 +1,7 @@
 package codes.som.hibiscus.api.feature
 
 import codes.som.hibiscus.HibiscusMod
+import codes.som.hibiscus.api.command.Command
 import codes.som.hibiscus.api.event.*
 import codes.som.hibiscus.api.feature.values.ValueRegistry
 
@@ -33,5 +34,9 @@ abstract class Feature(val name: String, val category: FeatureCategory) {
     open fun onEnable() {}
     open fun onDisable() {}
 
+    open fun createFeatureCommand(): Command {
+        return FeatureCommand(this)
+    }
+
     // TODO: Module commands
 }

src/main/kotlin/codes/som/hibiscus/api/feature/FeatureCommand.kt

@@ -0,0 +1,38 @@
+package codes.som.hibiscus.api.feature
+
+import codes.som.hibiscus.HibiscusLog
+import codes.som.hibiscus.HibiscusMod
+import codes.som.hibiscus.api.command.Command
+import codes.som.hibiscus.api.command.CommandContext
+
+class FeatureCommand(feature: Feature) : Command(feature.name.replace(" ", "").lowercase()) {
+    init {
+        branch {
+            feature.enabled = !feature.enabled
+
+            if (HibiscusMod.commands.context == CommandContext.MANUAL) {
+                val state = if (feature.enabled) "enabled" else "disabled"
+                HibiscusLog.info("${feature.name} is now $state.")
+            }
+        }
+
+        if (feature.values.exist()) {
+            for (value in feature.values) {
+                val simplifiedValueName = value.name.toLowerCase().replace(" ", "")
+
+                branch(simplifiedValueName) {
+                    HibiscusLog.info("Value of '${value.name}': " + value.getValueAsString())
+                }
+
+                branch(simplifiedValueName) { newValue: String ->
+                    try {
+                        value.setValueFromString(newValue)
+                        HibiscusLog.info("Value of '${value.name}': " + value.getValueAsString())
+                    } catch (e: Exception) {
+                        HibiscusLog.info("Could not set the value of '${value.name}' to '$newValue'")
+                    }
+                }
+            }
+        }
+    }
+}

src/main/kotlin/codes/som/hibiscus/events/PlayerEvents.kt

@@ -1,5 +1,7 @@
 package codes.som.hibiscus.events
 
+import codes.som.hibiscus.api.event.Cancellable
 import codes.som.hibiscus.api.event.Event
 
 object PlayerTickEvent : Event
+class SendChatEvent(val message: String) : Cancellable(), Event

src/main/kotlin/codes/som/hibiscus/features/FeaturesRegistry.kt

@@ -2,6 +2,5 @@ package codes.som.hibiscus.features
 
 class FeaturesRegistry {
     private val features = ALL_FEATURES.map { it() }
-
     fun getAllFeatures() = features.asSequence()
 }

src/main/kotlin/codes/som/hibiscus/features/player/NoFallDamage.kt

@@ -16,4 +16,9 @@ class NoFallDamage : Feature("No Fall Damage", FeatureCategory.PLAYER) {
             }
         }
     }
+
+    override fun createFeatureCommand() =
+        super.createFeatureCommand().apply {
+            alias("nofall")
+        }
 }

src/main/kotlin/codes/som/hibiscus/util/command/ChatCommandListener.kt

@@ -0,0 +1,24 @@
+package codes.som.hibiscus.util.command
+
+import codes.som.hibiscus.HibiscusLog
+import codes.som.hibiscus.HibiscusMod
+import codes.som.hibiscus.api.command.CommandContext
+import codes.som.hibiscus.api.command.exceptions.CommandExecutionException
+import codes.som.hibiscus.api.event.TypedListener
+import codes.som.hibiscus.events.SendChatEvent
+
+class ChatCommandListener : TypedListener<SendChatEvent>(SendChatEvent::class.java) {
+    override fun on(event: SendChatEvent) {
+        if (event.message.startsWith(".")) {
+            try {
+                HibiscusMod.commands.context = CommandContext.MANUAL
+                HibiscusMod.commands.executeCommand(event.message.substring(1))
+            } catch (e: CommandExecutionException) {
+                // e.printStackTrace()
+                e.cause?.message?.let { HibiscusLog.error(it) }
+            }
+
+            event.cancel()
+        }
+    }
+}