feat: Add /firm timer command

src/main/kotlin/commands/Duration.kt

@@ -0,0 +1,75 @@
+package moe.nea.firmament.commands
+
+import com.mojang.brigadier.StringReader
+import com.mojang.brigadier.arguments.ArgumentType
+import com.mojang.brigadier.context.CommandContext
+import com.mojang.brigadier.exceptions.DynamicCommandExceptionType
+import com.mojang.brigadier.suggestion.Suggestions
+import com.mojang.brigadier.suggestion.SuggestionsBuilder
+import java.util.concurrent.CompletableFuture
+import java.util.function.Function
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.DurationUnit
+import kotlin.time.toDuration
+import moe.nea.firmament.util.tr
+
+object DurationArgumentType : ArgumentType<Duration> {
+	val unknownTimeCode = DynamicCommandExceptionType { timeCode ->
+		tr("firmament.command-argument.duration.error",
+		   "Unknown time code '$timeCode'")
+	}
+
+	override fun parse(reader: StringReader): Duration {
+		val start = reader.cursor
+		val string = reader.readUnquotedString()
+		val matcher = regex.matcher(string)
+		var s = 0
+		var time = 0.seconds
+		fun createError(till: Int) {
+			throw unknownTimeCode.createWithContext(
+				reader.also { it.cursor = start + s },
+				string.substring(s, till))
+		}
+
+		while (matcher.find()) {
+			if (matcher.start() != s) {
+				createError(matcher.start())
+			}
+			s = matcher.end()
+			val amount = matcher.group("count").toDouble()
+			val what = timeSuffixes[matcher.group("what").single()]!!
+			time += amount.toDuration(what)
+		}
+		if (string.length != s) {
+			createError(string.length)
+		}
+		return time
+	}
+
+
+	override fun <S : Any?> listSuggestions(
+		context: CommandContext<S>,
+		builder: SuggestionsBuilder
+	): CompletableFuture<Suggestions> {
+		val remaining = builder.remainingLowerCase.substringBefore(' ')
+		if (remaining.isEmpty()) return super.listSuggestions(context, builder)
+		if (remaining.last().isDigit()) {
+			for (timeSuffix in timeSuffixes.keys) {
+				builder.suggest(remaining + timeSuffix)
+			}
+		}
+		return builder.buildFuture()
+	}
+
+	val timeSuffixes = mapOf(
+		'm' to DurationUnit.MINUTES,
+		's' to DurationUnit.SECONDS,
+		'h' to DurationUnit.HOURS,
+	)
+	val regex = "(?<count>[0-9]+)(?<what>[${timeSuffixes.keys.joinToString("")}])".toPattern()
+
+	override fun getExamples(): Collection<String> {
+		return listOf("3m", "20s", "1h45m")
+	}
+}