fix: plugin disappeared after plugin with same name reinstalled (#3198)

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

#### What this PR does / why we need it:
修复重复安装插件时 JAR 文件被删除的问题

需要注意的场景：
prod 模式下，假如安装一个 sitemap 插件，版本为 1.0.0 ，而此时 plugins 目录已经存在同名文件 sitemap-1.0.0.jar 文件但 sitemap 的 plugin.yaml 没有被持久化过，则能正常安装，旧的 JAR 文件被覆盖。

see #3159 for more details
#### Which issue(s) this PR fixes:

Fixes #3159

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

```release-note
修复重复安装插件时 JAR 文件被删除的问题
```

src/main/java/run/halo/app/core/extension/endpoint/PluginEndpoint.java

@@ -22,6 +22,7 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.nio.file.StandardCopyOption;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Comparator;
@@ -61,6 +62,7 @@ import run.halo.app.extension.ConfigMap;
 import run.halo.app.extension.ReactiveExtensionClient;
 import run.halo.app.extension.router.IListRequest.QueryListRequest;
 import run.halo.app.infra.SystemVersionSupplier;
+import run.halo.app.infra.exception.PluginInstallationException;
 import run.halo.app.infra.exception.UnsatisfiedAttributeValueException;
 import run.halo.app.infra.utils.FileUtils;
 import run.halo.app.infra.utils.VersionUtils;
@@ -455,25 +457,25 @@ public class PluginEndpoint implements CustomEndpoint {
                 // Disable auto enable during installation
                 plugin.getSpec().setEnabled(false);
                 return client.fetch(Plugin.class, plugin.getMetadata().getName())
-                    .switchIfEmpty(Mono.defer(() -> client.create(plugin)))
+                    .doOnNext(oldPlugin -> {
+                        String pluginName = oldPlugin.getMetadata().getName();
+                        throw new PluginInstallationException(
+                            "Plugin [" + pluginName + "] already installed",
+                            "problemDetail.plugin.install.alreadyInstalled",
+                            new Object[] {pluginName});
+                    })
+                    .then(client.create(plugin))
                     .publishOn(Schedulers.boundedElastic())
-                    .map(created -> {
+                    .doOnNext(created -> {
                         String fileName = created.generateFileName();
                         var pluginRoot = Paths.get(pluginProperties.getPluginsRoot());
                         createDirectoriesIfNotExists(pluginRoot);
                         Path pluginFilePath = pluginRoot.resolve(fileName);
-                        if (Files.exists(pluginFilePath)) {
-                            throw new IllegalArgumentException(
-                                "Plugin already installed : " + pluginFilePath);
-                        }
-                        FileUtils.copy(tempJarFilePath, pluginFilePath);
-                        return created;
+                        // move the plugin jar file to the plugin root
+                        // replace the old plugin jar file if exists
+                        FileUtils.copy(tempJarFilePath, pluginFilePath,
+                            StandardCopyOption.REPLACE_EXISTING);
                     })
-                    .onErrorResume(
-                        error -> client.fetch(Plugin.class, plugin.getMetadata().getName())
-                            .flatMap(client::delete)
-                            .then(Mono.error(error))
-                    )
                     .doFinally(signalType -> {
                         try {
                             Files.deleteIfExists(tempJarFilePath);

src/main/java/run/halo/app/infra/exception/PluginInstallationException.java

@@ -0,0 +1,19 @@
+package run.halo.app.infra.exception;
+
+import jakarta.validation.constraints.Null;
+import org.springframework.lang.Nullable;
+import org.springframework.web.server.ServerWebInputException;
+
+/**
+ * {@link ServerWebInputException} subclass that indicates plugin installation failure.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+public class PluginInstallationException extends ServerWebInputException {
+
+    public PluginInstallationException(String reason, @Nullable String messageDetailCode,
+        @Null Object[] messageDetailArguments) {
+        super(reason, null, null, messageDetailCode, messageDetailArguments);
+    }
+}

src/main/resources/config/i18n/messages.properties

@@ -14,6 +14,7 @@ problemDetail.title.run.halo.app.infra.exception.AccessDeniedException=Access De
 problemDetail.title.reactor.core.Exceptions.RetryExhaustedException=Retry Exhausted
 problemDetail.title.run.halo.app.infra.exception.ThemeInstallationException=Theme Install Error
 problemDetail.title.run.halo.app.infra.exception.ThemeUpgradeException=Theme Upgrade Error
+problemDetail.title.run.halo.app.infra.exception.PluginInstallationException=Plugin Install Error
 
 # Detail definitions
 problemDetail.org.springframework.web.server.UnsupportedMediaTypeStatusException=Content type {0} is not supported. Supported media types: {1}.
@@ -38,3 +39,4 @@ problemDetail.theme.version.unsatisfied.requires=The theme requires a minimum sy
 problemDetail.directoryTraversal=Directory traversal detected. Base path is {0}, but real path is {1}.
 
 problemDetail.plugin.version.unsatisfied.requires=Plugin requires a minimum system version of {0}, but the current version is {1}.
+problemDetail.plugin.install.alreadyInstalled=Plugin {0} already installed.

src/main/resources/config/i18n/messages_zh.properties

@@ -1,9 +1,11 @@
 problemDetail.title.org.springframework.web.server.ServerWebInputException=请求参数有误
 problemDetail.title.run.halo.app.infra.exception.UnsatisfiedAttributeValueException=请求参数属性值不满足要求
+problemDetail.title.run.halo.app.infra.exception.PluginInstallationException=插件安装失败
 problemDetail.title.run.halo.app.infra.exception.AttachmentAlreadyExistsException=附件已存在
 
 problemDetail.run.halo.app.infra.exception.AttachmentAlreadyExistsException=文件 {0} 已存在，建议更名后重试。
 
 problemDetail.plugin.version.unsatisfied.requires=插件要求一个最小的系统版本为 {0}, 但当前版本为 {1}。
+problemDetail.plugin.install.alreadyInstalled=插件 {0} 已经被安装。
 
 problemDetail.theme.version.unsatisfied.requires=主题要求一个最小的系统版本为 {0}, 但当前版本为 {1}。