Add an implementation of the example using Ktor (#6)

Author: GuillaumeTaffin

examples/README.md

@@ -29,3 +29,11 @@ This example uses the plain Java `HttpServer` to serve the front end. ([code](ja
 ```shell
 cd ./java-httpserver ; jbang server.kt ; cd ..
 ```
+
+### Ktor
+
+This example uses the `Ktor` to serve the front end. ([code](ktor/server.kt))
+
+```shell
+cd ./ktor ; jbang server.kt ; cd ..
+```

examples/java-httpserver/server.kt

@@ -48,6 +48,9 @@ fun server(
                 this@sseContext.patchElements(
                     """<span id="counter">${event}</span>"""
                 )
+                if (event == 3) {
+                    this@sseContext.executeScript("""alert('Thanks for trying Datastar!')""")
+                }
             }
         }
     }

examples/ktor/server.kt

@@ -0,0 +1,97 @@
+import dev.datastar.kotlin.sdk.Response
+import dev.datastar.kotlin.sdk.ServerSentEventGenerator
+import io.ktor.http.ContentType
+import io.ktor.http.HttpStatusCode.Companion.NoContent
+import io.ktor.http.HttpStatusCode.Companion.OK
+import io.ktor.server.engine.embeddedServer
+import io.ktor.server.netty.Netty
+import io.ktor.server.response.respondBytes
+import io.ktor.server.response.respondTextWriter
+import io.ktor.server.routing.get
+import io.ktor.server.routing.post
+import io.ktor.server.routing.routing
+import kotlinx.coroutines.flow.MutableStateFlow
+import java.io.File
+import java.io.Writer
+
+///usr/bin/env jbang "$0" "$@" ; exit $?
+//JAVA 21
+//KOTLIN 2.2.0
+//DEPS dev.cloudgt.datastar:kotlin-sdk:0.1.0
+//DEPS io.ktor:ktor-server-core-jvm:3.2.3
+//DEPS io.ktor:ktor-server-netty-jvm:3.2.3
+
+
+fun main() {
+    server().run {
+        println("Let's go counting star... http://localhost:8080")
+        start(wait = true)
+    }
+}
+
+fun server(
+    counter: MutableStateFlow<Int> = MutableStateFlow(0),
+) = embeddedServer(Netty, port = 8080) {
+
+    val counterPage = File(
+        "../front/counter.html"
+    ).readBytes()
+
+    routing {
+
+        get("/") {
+            call.response.headers.append("Content-Type", "text/html")
+            call.response.status(OK)
+            call.respondBytes(counterPage)
+        }
+
+        get("/counter") {
+            call.respondTextWriter(
+                status = OK,
+                contentType = ContentType.Text.EventStream,
+            ) {
+
+                val response = adaptResponse(this)
+                val generator = ServerSentEventGenerator(response)
+
+                counter.collect { event ->
+                    generator.patchElements("""<span id="counter">${event}</span>""")
+
+                    if (event == 3) {
+                        generator.executeScript("""alert('Thanks for trying Datastar!')""")
+                    }
+                }
+
+            }
+        }
+
+        post("/increment") {
+            counter.value++
+            call.response.status(NoContent)
+        }
+
+        post("/decrement") {
+            counter.value--
+            call.response.status(NoContent)
+        }
+
+    }
+}
+
+private fun adaptResponse(writer: Writer): Response =
+    object : Response {
+        override fun sendConnectionHeaders(
+            status: Int,
+            headers: Map<String, List<String>>,
+        ) {
+            // connection is already set up when used
+        }
+
+        override fun write(text: String) {
+            writer.write(text)
+        }
+
+        override fun flush() {
+            writer.flush()
+        }
+    }