refactor: initialize default config value by settings after plugin installation (#3161)

#### What type of PR is this?
/kind improvement
/area core
/milestone 2.2.x

#### What this PR does / why we need it:
插件安装后根据配置的 settingName 读取默认值创建 ConfigMap
如果配置了 settingName 而没有配置 configMapName 则会自动填充为 uuid 并创建一个 ConfigMap
#### Which issue(s) this PR fixes:

Fixes #3160

#### Special notes for your reviewer:
/cc @halo-dev/sig-halo 
#### Does this PR introduce a user-facing change?

```release-note
插件安装后自动初始化 Setting 的默认值
```

src/main/java/run/halo/app/core/extension/reconciler/PluginReconciler.java

@@ -18,9 +18,14 @@ import org.pf4j.PluginRuntimeException;
 import org.pf4j.PluginState;
 import org.pf4j.PluginWrapper;
 import org.pf4j.RuntimeMode;
+import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.stereotype.Component;
+import org.springframework.util.Assert;
 import run.halo.app.core.extension.Plugin;
 import run.halo.app.core.extension.ReverseProxy;
+import run.halo.app.core.extension.Setting;
+import run.halo.app.core.extension.theme.SettingUtils;
+import run.halo.app.extension.ConfigMap;
 import run.halo.app.extension.ExtensionClient;
 import run.halo.app.extension.Metadata;
 import run.halo.app.extension.controller.Controller;
@@ -32,6 +37,7 @@ import run.halo.app.infra.utils.PathUtils;
 import run.halo.app.plugin.HaloPluginManager;
 import run.halo.app.plugin.PluginConst;
 import run.halo.app.plugin.PluginStartingError;
+import run.halo.app.plugin.event.PluginCreatedEvent;
 import run.halo.app.plugin.resources.BundleResourceUtils;
 
 /**
@@ -47,6 +53,7 @@ public class PluginReconciler implements Reconciler<Request> {
     private static final String FINALIZER_NAME = "plugin-protection";
     private final ExtensionClient client;
     private final HaloPluginManager haloPluginManager;
+    private final ApplicationEventPublisher eventPublisher;
 
     @Override
     public Result reconcile(Request request) {
@@ -146,6 +153,8 @@ public class PluginReconciler implements Reconciler<Request> {
                 plugin.statusNonNull().setLastStartTime(Instant.now());
             }
 
+            settingDefaultConfig(plugin);
+
             Plugin.PluginStatus status = plugin.statusNonNull();
             String jsBundlePath =
                 BundleResourceUtils.getJsBundlePath(haloPluginManager, pluginName);
@@ -257,6 +266,9 @@ public class PluginReconciler implements Reconciler<Request> {
                 }
                 newFinalizers.add(FINALIZER_NAME);
                 client.update(plugin);
+
+                eventPublisher.publishEvent(
+                    new PluginCreatedEvent(this, plugin.getMetadata().getName()));
             });
     }
 
@@ -321,6 +333,35 @@ public class PluginReconciler implements Reconciler<Request> {
             }, () -> client.create(reverseProxy));
     }
 
+    private void settingDefaultConfig(Plugin plugin) {
+        Assert.notNull(plugin, "The plugin must not be null.");
+        if (StringUtils.isBlank(plugin.getSpec().getSettingName())) {
+            return;
+        }
+
+        final String configMapNameToUse = plugin.getSpec().getConfigMapName();
+        if (StringUtils.isBlank(configMapNameToUse)) {
+            return;
+        }
+
+        boolean existConfigMap = client.fetch(ConfigMap.class, configMapNameToUse)
+            .isPresent();
+        if (existConfigMap) {
+            return;
+        }
+
+        client.fetch(Setting.class, plugin.getSpec().getSettingName())
+            .ifPresent(setting -> {
+                var data = SettingUtils.settingDefinedDefaultValueMap(setting);
+                // Create with or without default value
+                ConfigMap configMap = new ConfigMap();
+                configMap.setMetadata(new Metadata());
+                configMap.getMetadata().setName(configMapNameToUse);
+                configMap.setData(data);
+                client.create(configMap);
+            });
+    }
+
     static String initialReverseProxyName(String pluginName) {
         return pluginName + "-system-generated-reverse-proxy";
     }

src/main/java/run/halo/app/plugin/PluginCreatedEventReconciler.java

@@ -0,0 +1,107 @@
+package run.halo.app.plugin;
+
+import io.micrometer.common.util.StringUtils;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.UUID;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.context.SmartLifecycle;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+import reactor.core.Exceptions;
+import reactor.core.publisher.Mono;
+import run.halo.app.core.extension.Plugin;
+import run.halo.app.extension.ReactiveExtensionClient;
+import run.halo.app.extension.controller.Controller;
+import run.halo.app.extension.controller.ControllerBuilder;
+import run.halo.app.extension.controller.DefaultController;
+import run.halo.app.extension.controller.DefaultDelayQueue;
+import run.halo.app.extension.controller.Reconciler;
+import run.halo.app.extension.controller.RequestQueue;
+import run.halo.app.plugin.event.PluginCreatedEvent;
+
+/**
+ * Plugin event reconciler.
+ * If other plugin events need to be reconciled, consider sharing this reconciler.
+ *
+ * @author guqing
+ * @since 2.2.0
+ */
+@Slf4j
+@Component
+public class PluginCreatedEventReconciler
+    implements Reconciler<PluginCreatedEvent>, SmartLifecycle {
+
+    private final RequestQueue<PluginCreatedEvent> pluginEventQueue;
+
+    private final ReactiveExtensionClient client;
+
+    private final Controller pluginEventController;
+
+    private boolean running = false;
+
+    public PluginCreatedEventReconciler(ReactiveExtensionClient client) {
+        this.client = client;
+        pluginEventQueue = new DefaultDelayQueue<>(Instant::now);
+        pluginEventController = this.setupWith(null);
+    }
+
+    @Override
+    public Result reconcile(PluginCreatedEvent pluginCreatedEvent) {
+        String pluginName = pluginCreatedEvent.getPluginName();
+        try {
+            ensureConfigMapNameNotEmptyIfSettingIsNotBlank(pluginName);
+        } catch (InterruptedException e) {
+            throw Exceptions.propagate(e);
+        }
+        return null;
+    }
+
+    @Override
+    public Controller setupWith(ControllerBuilder builder) {
+        return new DefaultController<>(
+            this.getClass().getName(),
+            this,
+            pluginEventQueue,
+            null,
+            Duration.ofMillis(100),
+            Duration.ofSeconds(1000)
+        );
+    }
+
+    @EventListener(PluginCreatedEvent.class)
+    public void handlePluginCreated(PluginCreatedEvent pluginCreatedEvent) {
+        pluginEventQueue.addImmediately(pluginCreatedEvent);
+    }
+
+    void ensureConfigMapNameNotEmptyIfSettingIsNotBlank(String pluginName)
+        throws InterruptedException {
+        client.fetch(Plugin.class, pluginName)
+            .switchIfEmpty(Mono.error(new IllegalStateException("Plugin not found: " + pluginName)))
+            .filter(plugin -> StringUtils.isNotBlank(plugin.getSpec().getSettingName()))
+            .filter(plugin -> StringUtils.isBlank(plugin.getSpec().getConfigMapName()))
+            .doOnNext(plugin -> {
+                // has settingName value but configMapName not configured
+                plugin.getSpec().setConfigMapName(UUID.randomUUID().toString());
+            })
+            .flatMap(client::update)
+            .block();
+    }
+
+    @Override
+    public void start() {
+        pluginEventController.start();
+        running = true;
+    }
+
+    @Override
+    public void stop() {
+        running = false;
+        pluginEventController.dispose();
+    }
+
+    @Override
+    public boolean isRunning() {
+        return running;
+    }
+}

src/main/java/run/halo/app/plugin/event/PluginCreatedEvent.java

@@ -0,0 +1,21 @@
+package run.halo.app.plugin.event;
+
+import lombok.Getter;
+import org.springframework.context.ApplicationEvent;
+import run.halo.app.core.extension.Plugin;
+
+/**
+ * The {@link Plugin} created event.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Getter
+public class PluginCreatedEvent extends ApplicationEvent {
+    private final String pluginName;
+
+    public PluginCreatedEvent(Object source, String pluginName) {
+        super(source);
+        this.pluginName = pluginName;
+    }
+}

src/test/java/run/halo/app/core/extension/reconciler/PluginReconcilerTest.java

@@ -28,6 +28,7 @@ import org.pf4j.PluginState;
 import org.pf4j.PluginWrapper;
 import org.pf4j.RuntimeMode;
 import org.skyscreamer.jsonassert.JSONAssert;
+import org.springframework.context.ApplicationEventPublisher;
 import run.halo.app.core.extension.Plugin;
 import run.halo.app.core.extension.ReverseProxy;
 import run.halo.app.extension.ExtensionClient;
@@ -55,11 +56,14 @@ class PluginReconcilerTest {
     @Mock
     PluginWrapper pluginWrapper;
 
+    @Mock
+    ApplicationEventPublisher eventPublisher;
+
     PluginReconciler pluginReconciler;
 
     @BeforeEach
     void setUp() {
-        pluginReconciler = new PluginReconciler(extensionClient, haloPluginManager);
+        pluginReconciler = new PluginReconciler(extensionClient, haloPluginManager, eventPublisher);
         lenient().when(haloPluginManager.validatePluginVersion(any())).thenReturn(true);
         lenient().when(haloPluginManager.getSystemVersion()).thenReturn("0.0.0");
         lenient().when(haloPluginManager.getPlugin(any())).thenReturn(pluginWrapper);