introduction plugin

introduction/build.gradle

@@ -0,0 +1,30 @@
+buildscript {
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath libs.kotlin.gradle.plugin
+        classpath libs.kotlin.serialization.plugin
+    }
+}
+
+plugins {
+    alias libs.plugins.kotlin.jvm
+    alias libs.plugins.kotlin.serialization
+}
+
+repositories {
+    mavenCentral()
+    mavenLocal()
+}
+
+dependencies {
+    implementation libs.kotlin
+    api libs.plagubot.plugin
+    api libs.kslog
+}
+
+application {
+    mainClassName = 'dev.inmo.plagubot.AppKt'
+}

introduction/src/main/kotlin/IntroductionPlugin.kt

@@ -0,0 +1,44 @@
+import dev.inmo.kslog.common.logger
+import dev.inmo.kslog.common.w
+import dev.inmo.plagubot.Plugin
+import dev.inmo.tgbotapi.extensions.api.send.reply
+import dev.inmo.tgbotapi.extensions.api.send.sendMessage
+import dev.inmo.tgbotapi.extensions.behaviour_builder.BehaviourContext
+import dev.inmo.tgbotapi.extensions.behaviour_builder.triggers_handling.onCommand
+import dev.inmo.tgbotapi.extensions.behaviour_builder.triggers_handling.onMyChatMemberUpdated
+import dev.inmo.tgbotapi.types.chat.PrivateChat
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.*
+import org.jetbrains.exposed.sql.Database
+import org.koin.core.Koin
+import org.koin.core.module.Module
+
+@Serializable
+class IntroductionPlugin : Plugin {
+    private val log = logger
+
+    @Serializable
+    private class Config(
+        val onStartCommandMessage: String
+    )
+
+    override fun Module.setupDI(database: Database, params: JsonObject) {
+        single { get<Json>().decodeFromJsonElement(Config.serializer(), params["introduction"] ?: return@single null) }
+    }
+
+    override suspend fun BehaviourContext.setupBotPlugin(koin: Koin) {
+        val config = koin.getOrNull<Config>()
+
+        if (config == null) {
+            log.w("Plugin has been disabled due to absence of \"introduction\" field in config or some error during configuration loading")
+            return
+        }
+
+        onCommand("start", initialFilter = { it.chat is PrivateChat }) {
+            sendMessage(
+                it.chat,
+                config.onStartCommandMessage
+            )
+        }
+    }
+}