feat: implement wot client

Author: AndreaGiulianelli

src/env/infrastructure/wot/WotClient.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2023. Smart Operating Block
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+
+package infrastructure.wot;
+
+import city.sane.wot.DefaultWot;
+import city.sane.wot.Wot;
+import city.sane.wot.WotException;
+import city.sane.wot.thing.ConsumedThing;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.ExecutionException;
+import java.util.logging.Logger;
+
+/**
+ * Web of things client.
+ */
+public class WotClient {
+    private static final String THING_DIRECTORY_VARIABLE = "THING_DESCRIPTION_DIRECTORY_BASE_URL";
+    private ConsumedThing thing;
+
+    static {
+        // Checks on existence of environmental variable
+        Objects.requireNonNull(
+                System.getenv(THING_DIRECTORY_VARIABLE),
+                "Thing Description Directory service base url is required"
+        );
+    }
+
+    /**
+     * Default constructor.
+     * @param thingId the thing id to use.
+     */
+    public WotClient(final String thingId) {
+        try {
+            final String thingUrl = System.getenv(THING_DIRECTORY_VARIABLE) + thingId;
+            final Wot wotClient = DefaultWot.clientOnly();
+            final String thingDescription = this.obtainThingDescription(thingUrl);
+            this.thing = wotClient.consume(thingDescription);
+        } catch (final WotException e) {
+            Logger.getLogger(WotClient.class.toString()).info("Wot TDD configuration error");
+        } catch (IOException e) {
+            Logger.getLogger(WotClient.class.toString()).info(thingId + " does not have a Thing Description associated");
+        }
+    }
+
+    /**
+     * Invoke an action on the thing.
+     * @param action the name of the action.
+     * @param inputs the inputs of the action.
+     */
+    public void invoke(final String action, final Map<String, Object> inputs) {
+        try {
+            this.thing.getActions().get(action).invoke(inputs).get();
+        } catch (final InterruptedException | ExecutionException e) {
+            Logger.getLogger(WotClient.class.toString()).info("Error in invoking '" + action + "' on " + thing.getId());
+        }
+    }
+
+    private String obtainThingDescription(final String thingUrl) throws IOException {
+        // We need that because sane-city wot doesn't support application/td+json schema.
+        final OkHttpClient httpClient = new OkHttpClient();
+        final Request request = new Request.Builder().url(thingUrl).get().build();
+        try (Response response = httpClient.newCall(request).execute()) {
+            return Optional.ofNullable(response.body()).map(responseBody -> {
+                try {
+                    return responseBody.string();
+                } catch (IOException e) {
+                    return "";
+                }
+            }).orElse("");
+        }
+    }
+}