Ktor Autoreload Snippet

KtorAutoReload.kt

// implementation("io.methvin:directory-watcher:0.15.0")

import io.ktor.server.application.*
import io.ktor.server.response.*
import io.ktor.server.routing.*
import io.methvin.watcher.*
import java.io.*

var resourceVersion = 0L

// @TODO: Use websockets instead for instant refresh
fun getAutoreloadScript(): String {
    return """
        <script>
            const resourceVersion = $resourceVersion;
            setInterval(async () => {
                const newResourceVersion = Number(await (await fetch("/__resourceVersion__")).text())
                if (resourceVersion != newResourceVersion) {
                    document.location.reload();
                }
            }, 1000);
        </script>
    """.trimIndent()
}

suspend fun Application.configureAutoreload(folder: File) {
    routing {
        get("/__resourceVersion__") {
            call.respondText("$resourceVersion")
        }
    }

    println("WATCHING...")
    resourceVersion = System.currentTimeMillis()

    DirectoryWatcher.builder()
        .path(folder.toPath())
        .listener {
            //println(it.eventType())
            resourceVersion = System.currentTimeMillis()
        }
        .build()
        .watchAsync()
    println("...configured")
}