data class MySession(val name: String)

val accounts = HashMap<String, String>()

fun main(args: Array<String>) {
    val server = embeddedServer(Netty, 8080) {
        install(FreeMarker) {
            templateLoader = ClassTemplateLoader(this::class.java.classLoader, "templates")
        }
        install(Sessions) {
            cookie<MySession>("SESSION")
        }
        routing {
            route("/register") {
                get {
                    if (call.sessions.get<MySession>() != null) {
                        call.respondRedirect("/")
                    }
                    call.respond(FreeMarkerContent("register.ftl", null))
                }
                post {
                    if (call.sessions.get<MySession>() != null) {
                        call.respondRedirect("/")
                    }
                    val post = context.receiveParameters()
                    if (post["login"].isNullOrEmpty() || post["password"].isNullOrEmpty()) {
                        call.respond(FreeMarkerContent("register.ftl", mapOf("error" to "Login or password cannot be empty!")))
                    }
                    val login = post["login"].toString()
                    val password = post["password"].toString()
                    if (accounts[login] != null) {
                        call.respond(FreeMarkerContent("register.ftl", mapOf("error" to "User with that name already exists!")))
                    }
                    accounts[login] = password
                    call.sessions.set("SESSION", MySession(login))
                    call.respondRedirect("/")
                }
            }
            route("/login") {
                get {
                    if (call.sessions.get<MySession>() != null) {
                        call.respondRedirect("/")
                    }
                    call.respond(FreeMarkerContent("login.ftl", null))
                }
                post {
                    if (call.sessions.get<MySession>() != null) {
                        call.respondRedirect("/")
                    }
                    val post = context.receiveParameters()
                    if (post["login"].isNullOrEmpty() || post["password"].isNullOrEmpty()) {
                        call.respond(FreeMarkerContent("login.ftl", mapOf("error" to "Login or password cannot be empty!")))
                    }
                    val login = post["login"].toString()
                    val password = post["password"].toString()
                    if (accounts[login] == null) {
                        call.respond(FreeMarkerContent("login.ftl", mapOf("error" to "User with that name does not exist!")))
                    }
                    if (accounts[login] != password) {
                        call.respond(FreeMarkerContent("login.ftl", mapOf("error" to "Wrong password!")))
                    }
                    call.sessions.set("SESSION", MySession(login))
                    call.respondRedirect("/")
                }
            }
            get("/logout") {
                val session = call.sessions.get<MySession>()
                if (session != null) {
                    call.sessions.set("SESSION", null)
                }
                call.respondRedirect("/login")
            }
            get("/") {
                val session = call.sessions.get<MySession>()
                if (session == null) {
                    call.respondRedirect("/login")
                }
                call.respond(FreeMarkerContent("index.ftl", mapOf("user" to session!!.name)))
            }
        }
    }.start(true)
}