GH-458 Generate and link frontend with a dedicated resource handler

reposilite-backend/src/main/kotlin/org/panda_lang/reposilite/frontend/infrastructure/FrontendHandler.kt

@@ -19,29 +19,47 @@ import com.dzikoysk.openapi.annotations.HttpMethod
 import com.dzikoysk.openapi.annotations.OpenApi
 import com.dzikoysk.openapi.annotations.OpenApiResponse
 import io.javalin.http.Context
+import org.eclipse.jetty.http.HttpStatus
+import org.eclipse.jetty.http.MimeTypes
 import org.panda_lang.reposilite.frontend.FrontendFacade
 import org.panda_lang.reposilite.web.api.RouteHandler
 import org.panda_lang.reposilite.web.api.RouteMethod.GET
+import org.panda_lang.reposilite.web.encoding
+
+private const val ROUTE = "/*"
 
 internal class FrontendHandler(private val frontendFacade: FrontendFacade) : RouteHandler {
 
-    override val route = "/js/app.js"
+    override val route = ROUTE
     override val methods = listOf(GET)
 
     @OpenApi(
-        path = "/js/app.js",
+        path = ROUTE,
         method = HttpMethod.GET,
-        operationId = "getApp",
+        operationId = "frontend",
         summary = "Get frontend application",
         description = "Returns Vue.js application wrapped into one app.js file",
         tags = [ "Resource" ],
         responses = [ OpenApiResponse(status = "200", description = "Default response") ]
     )
     override fun handle(context: Context) {
-        with(context.result(frontendFacade.getApp())) {
-            header("Content-Type", "application/javascript")
-            res.characterEncoding = "UTF-8"
+        var qualifier = context.splat(0) ?: ""
+
+        if (qualifier.isEmpty()) {
+            qualifier = "index.html"
+        }
+
+        val resource = FrontendFacade::class.java.getResourceAsStream("/static/$qualifier")
+
+        if (resource == null) {
+            context.status(HttpStatus.NOT_FOUND_404)
+            return
         }
+
+        context
+            .result(resource)
+            .contentType(MimeTypes.getDefaultMimeByExtension(qualifier))
+            .encoding("UTF-8")
     }
 
 }