Adding backend for an App

### What's done:
- new backend project
- script for deployment
- small changes to frontend

backend/build.gradle.kts

@@ -0,0 +1,34 @@
+plugins {
+    kotlin("multiplatform")
+    kotlin("plugin.spring") version "1.9.25"
+    id("org.springframework.boot") version "3.3.3"
+    id("io.spring.dependency-management") version "1.1.6"
+    kotlin("plugin.jpa") version "1.9.25"
+}
+
+kotlin {
+    jvm()
+    sourceSets {
+        jvmMain.dependencies {
+            implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+            implementation("org.springframework.boot:spring-boot-starter-oauth2-client")
+            // implementation("org.springframework.boot:spring-boot-starter-security")
+            implementation("org.springframework.boot:spring-boot-starter-validation")
+            implementation("org.springframework.boot:spring-boot-starter-web")
+            implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+            implementation("org.jetbrains.kotlin:kotlin-reflect")
+            implementation("io.jsonwebtoken:jjwt-api:0.11.5")
+            implementation("com.h2database:h2:2.3.232")
+            runtimeOnly("io.jsonwebtoken:jjwt-impl:0.11.5")
+            runtimeOnly("io.jsonwebtoken:jjwt-jackson:0.11.5")
+        }
+
+        jvmToolchain {
+            languageVersion.set(JavaLanguageVersion.of(21))
+        }
+    }
+
+    tasks.withType<Test> {
+        useJUnitPlatform()
+    }
+}

backend/src/jvmMain/kotlin/ru/posidata/backend/BackendApplication.kt

@@ -0,0 +1,13 @@
+package ru.posidata.backend
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+import org.springframework.context.annotation.ComponentScan
+
+@SpringBootApplication
+@ComponentScan(basePackages = ["ru.posidata"])
+class BackendApplication
+
+fun main(args: Array<String>) {
+	runApplication<BackendApplication>(*args)
+}

backend/src/jvmMain/kotlin/ru/posidata/backend/controller/TelegramAuthController.kt

@@ -0,0 +1,36 @@
+package ru.posidata.backend.controller
+
+import org.springframework.http.HttpStatus
+import org.springframework.http.ResponseEntity
+import org.springframework.security.core.Authentication
+import org.springframework.web.bind.annotation.*
+import ru.posidata.backend.service.TelegramAuthService
+
+
+@RestController
+@RequestMapping(path = ["/api/v1/"])
+class TelegramAuthController(private val telegramAuthService: TelegramAuthService) {
+    @GetMapping("/user-info")
+    fun getSelfUserInfo(authentication: Authentication?): String {
+        return authentication?.principal.toString()
+    }
+
+    @PostMapping("/test")
+    fun test(@RequestBody request: Map<String, Any>): String {
+        return "$request"
+    }
+
+    @PostMapping("auth/telegram")
+    fun telegramAuth(@RequestBody request: Map<String, Any>): ResponseEntity<Any> {
+        return try {
+            val authResult = telegramAuthService.authenticate(request)
+            if (authResult.isAuthenticated) {
+                ResponseEntity.ok(authResult.token)
+            } else {
+                ResponseEntity.status(HttpStatus.FORBIDDEN).body("Login info hash mismatch")
+            }
+        } catch (e: Exception) {
+            ResponseEntity.status(HttpStatus.FORBIDDEN).body("Server error while authenticating")
+        }
+    }
+}

backend/src/jvmMain/kotlin/ru/posidata/backend/entity/User.kt

@@ -0,0 +1,15 @@
+package ru.posidata.backend.entity
+
+import jakarta.persistence.*
+
+@Entity
+@Table(name = "users")
+data class User(
+    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
+    val id: Long = 0,
+    @Column(unique = true)
+    val telegramId: Long,
+    val firstName: String,
+    val lastName: String?,
+    val username: String?
+)

backend/src/jvmMain/kotlin/ru/posidata/backend/repository/UserRepository.kt

@@ -0,0 +1,10 @@
+package ru.posidata.backend.repository
+
+import org.springframework.data.jpa.repository.JpaRepository
+import org.springframework.stereotype.Repository
+import ru.posidata.backend.entity.User
+
+@Repository
+interface UserRepository : JpaRepository<User, Long> {
+    fun findByTelegramId(telegramId: Long): User?
+}

backend/src/jvmMain/kotlin/ru/posidata/backend/service/TelegramAuthService.kt

@@ -0,0 +1,43 @@
+package ru.posidata.backend.service
+
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.stereotype.Service
+import java.security.MessageDigest
+import java.util.*
+import javax.crypto.Mac
+import javax.crypto.spec.SecretKeySpec
+
+@Service
+class TelegramAuthService(
+    @Value("\${telegram.bot.token}") private val telegramToken: String,
+    private val userService: UserService
+) {
+    fun authenticate(request: Map<String, Any>): AuthResult {
+        val hash = request["hash"] as String
+        val sortedRequest = request.toMutableMap().apply { remove("hash") }
+
+        val dataCheckString = sortedRequest.entries
+            .sortedBy { it.key.lowercase(Locale.getDefault()) }
+            .joinToString("\n") { "${it.key}=${it.value}" }
+
+        val secretKey = SecretKeySpec(
+            MessageDigest.getInstance("SHA-256").digest(telegramToken.toByteArray(Charsets.UTF_8)),
+            "HmacSHA256"
+        )
+        val mac = Mac.getInstance("HmacSHA256")
+        mac.init(secretKey)
+
+        val result = mac.doFinal(dataCheckString.toByteArray(Charsets.UTF_8))
+        val calculatedHash = result.joinToString("") { "%02x".format(it) }
+
+        return if (hash.equals(calculatedHash, ignoreCase = true)) {
+            val user = userService.findOrCreateUser(request)
+            println(user)
+            AuthResult(true, "token")
+        } else {
+            AuthResult(false, null)
+        }
+    }
+}
+
+data class AuthResult(val isAuthenticated: Boolean, val token: String?)

backend/src/jvmMain/kotlin/ru/posidata/backend/service/UserService.kt

@@ -0,0 +1,23 @@
+package ru.posidata.backend.service
+
+import org.springframework.stereotype.Service
+import ru.posidata.backend.entity.User
+import ru.posidata.backend.repository.UserRepository
+
+@Service
+class UserService(private val userRepository: UserRepository) {
+    fun findOrCreateUser(telegramData: Map<String, Any>): User {
+        val telegramId = telegramData["id"] as Long
+        return userRepository.findByTelegramId(telegramId) ?: createUser(telegramData)
+    }
+
+    private fun createUser(telegramData: Map<String, Any>): User {
+        val user = User(
+            telegramId = telegramData["id"] as Long,
+            firstName = telegramData["first_name"] as String,
+            lastName = telegramData["last_name"] as? String,
+            username = telegramData["username"] as? String
+        )
+        return userRepository.save(user)
+    }
+}

backend/src/jvmMain/resources/application.yml

@@ -0,0 +1,8 @@
+spring:
+  application:
+    name:
+      backend
+
+telegram:
+  bot:
+    token:

backend/src/test/kotlin/ru/posidata/backend/BackendApplicationTests.kt

@@ -0,0 +1,13 @@
+package ru.posidata.backend
+
+import org.junit.jupiter.api.Test
+import org.springframework.boot.test.context.SpringBootTest
+
+@SpringBootTest
+class BackendApplicationTests {
+
+	@Test
+	fun contextLoads() {
+	}
+
+}

build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    java
+    kotlin("multiplatform") version("2.0.0") apply(false)
 }
 
 group = "ru.posidata"

common/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    kotlin("multiplatform") version("2.0.0")
+    kotlin("multiplatform")
 }
 
 kotlin {

frontend/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    kotlin("multiplatform") version ("2.0.0")
+    kotlin("multiplatform")
 }
 
 kotlin {
@@ -59,7 +59,6 @@ kotlin {
             implementation(npm("react-dom", "^18.0.0"))
             implementation(npm("react-modal", "^3.0.0"))
             implementation(npm("@popperjs/core", "2.11.8"))
-            implementation(npm("animate.css", "^4.1.1"))
             // ====== font awesome ======
             implementation(npm("@fortawesome/fontawesome-svg-core", "6.5.2"))
             implementation(npm("@fortawesome/free-solid-svg-icons", "6.5.2"))
@@ -68,7 +67,7 @@ kotlin {
             implementation(npm("@fortawesome/fontawesome-free", "6.5.2"))
             implementation(npm("@fortawesome/react-fontawesome", "0.2.2"))
             // ====== cookies ======
-            implementation(npm("js-cookie", "^3.0.5"))
+            // implementation(npm("js-cookie", "^3.0.5"))
             // ====== animation =========
             implementation(npm("animate.css", "^4.1.1"))
             implementation(npm("react-tsparticles", "1.42.1"))

frontend/src/jsMain/kotlin/ru/posidata/views/components/LogoButtons.kt

@@ -9,7 +9,9 @@ import react.dom.html.ReactHTML.button
 import react.dom.html.ReactHTML.span
 import web.cssom.*
 
-
+/**
+ * Wrapper for css style for a glowing neon text, see .glow.scss
+ */
 fun ChildrenBuilder.neonLightingText(input: String) {
     button {
         className = ClassName("glowing-btn")
@@ -19,4 +21,3 @@ fun ChildrenBuilder.neonLightingText(input: String) {
         }
     }
 }
-

frontend/src/jsMain/kotlin/ru/posidata/views/main/MainView.kt

@@ -3,6 +3,8 @@ package ru.posidata.views.main
 import js.objects.jso
 import react.FC
 import react.dom.html.ReactHTML.div
+import react.dom.html.ReactHTML.h1
+import react.dom.html.ReactHTML.script
 import react.react
 import react.useState
 import ru.posidata.views.utils.internals.Answer.NONE
@@ -26,12 +28,15 @@ val mainView = FC {
     val (uniqueRandom, setUniqueRandom) = useState<List<Int>>(listOf())
 
     div {
+
         className = ClassName("full-width-container")
         div {
             className = ClassName("row justify-content-center align-items-center")
             style = jso {
                 minHeight = "100vh".unsafeCast<MinHeight>()
             }
+
+
             div {
                 id = "back"
                 className = ClassName("card col-xl-4 col-lg-5 col-md-7 col-sm-8 col-12")
@@ -56,6 +61,7 @@ val mainView = FC {
                                 this.setSelection = setSelection
                             }
                         }
+
                         QUESTION -> questionCard {
                             this.counter = counter
                             this.setCounter = setCounter