introduce docsify; refactor the daemon

src/main/java/de/kosit/validationtool/daemon/GuiHandler.java

@@ -0,0 +1,52 @@
+package de.kosit.validationtool.daemon;
+
+import com.sun.net.httpserver.HttpExchange;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.apache.commons.io.IOUtils;
+
+import java.io.IOException;
+import java.net.URL;
+import java.nio.charset.Charset;
+import java.util.Arrays;
+
+public class GuiHandler extends BaseHandler {
+
+    private static final URL INDEX_HTML = GuiHandler.class.getClassLoader().getResource("gui/index.html");
+
+    public GuiHandler() {
+        if (INDEX_HTML == null) {
+            throw new IllegalStateException("No html found");
+        }
+    }
+
+    @Override
+    public void handle(HttpExchange exchange) throws IOException {
+        assert INDEX_HTML != null;
+        final String path = exchange.getRequestURI().toASCIIString();
+        if (path.equals("/")) {
+            write(exchange, IOUtils.toString(INDEX_HTML, Charset.defaultCharset()).getBytes(), "text/html");
+        } else{
+            final URL resource = GuiHandler.class.getClassLoader().getResource("gui" + path);
+            if (resource != null) {
+                write(exchange,IOUtils.toString(resource, Charset.defaultCharset()).getBytes(), Mediatype.resolveBySuffix(resource.getPath()).getMimeType());;
+            }else {
+                error(exchange,404,"not found");
+            }
+        }
+    }
+
+
+    @RequiredArgsConstructor
+    @Getter
+    protected enum Mediatype {
+        JS("application/javascript"),
+        MD("text/markdown"),
+        CSS("text/css");
+        private final String mimeType;
+
+        static Mediatype resolveBySuffix(String path){
+            return Arrays.stream(values()).filter(e->path.toUpperCase().endsWith("."+e.name())).findFirst().orElse(Mediatype.MD);
+        }
+    }
+}