Auto rename attachment if it exists (#3305)

#### What type of PR is this?

/kind improvement
/area core
/milestone 2.3.x

#### What this PR does / why we need it:

Before this PR, halo will throw an FileAlreadyExists exception if users upload file which already exists.

But now, we will rename the attachment automatically on filename conflict. e.g.:

```bash
halo.run -> halo-xyz.run
.run -> xyz.run
halo -> halo-xyz
```

#### Which issue(s) this PR fixes:

Fixes https://github.com/halo-dev/halo/issues/3218

#### Special notes for your reviewer:

![image](https://user-images.githubusercontent.com/16865714/218670068-87389289-1248-48e8-82a4-1bcf939e64e3.png)

#### Does this PR introduce a user-facing change?

```release-note
附件已存在时自动重命名
```

src/main/java/run/halo/app/core/extension/attachment/endpoint/LocalAttachmentUploadHandler.java

@@ -1,6 +1,7 @@
 package run.halo.app.core.extension.attachment.endpoint;
 
 import static java.nio.file.StandardOpenOption.CREATE_NEW;
+import static run.halo.app.infra.utils.FileNameUtils.randomFileName;
 import static run.halo.app.infra.utils.FileUtils.checkDirectoryTraversal;
 
 import java.io.IOException;
@@ -12,16 +13,20 @@ import java.util.ArrayList;
 import java.util.Map;
 import java.util.Optional;
 import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
 import lombok.Data;
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.http.MediaType;
 import org.springframework.stereotype.Component;
 import org.springframework.util.StringUtils;
 import org.springframework.web.util.UriComponentsBuilder;
 import reactor.core.Exceptions;
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
+import reactor.util.retry.Retry;
 import run.halo.app.core.extension.attachment.Attachment;
 import run.halo.app.core.extension.attachment.Attachment.AttachmentSpec;
 import run.halo.app.core.extension.attachment.Constant;
@@ -76,18 +81,17 @@ class LocalAttachmentUploadHandler implements AttachmentHandler {
                             }
                         })
                     .subscribeOn(Schedulers.boundedElastic())
-                    // save the attachment
+                    .then(writeContent(file.content(), attachmentPath, true))
-                    .then(DataBufferUtils.write(file.content(), attachmentPath, CREATE_NEW))
+                    .map(path -> {
-                    .then(Mono.fromCallable(() -> {
+                        log.info("Wrote attachment {} into {}", file.filename(), path);
-                        log.info("Wrote attachment {} into {}", file.filename(), attachmentPath);
                         // TODO check the file extension
                         var metadata = new Metadata();
                         metadata.setName(UUID.randomUUID().toString());
-                        var relativePath = attachmentsRoot.relativize(attachmentPath).toString();
+                        var relativePath = attachmentsRoot.relativize(path).toString();
 
                         var pathSegments = new ArrayList<String>();
                         pathSegments.add("upload");
-                        for (Path p : uploadRoot.relativize(attachmentPath)) {
+                        for (Path p : uploadRoot.relativize(path)) {
                             pathSegments.add(p.toString());
                         }
 
@@ -100,17 +104,16 @@ class LocalAttachmentUploadHandler implements AttachmentHandler {
                             Constant.LOCAL_REL_PATH_ANNO_KEY, relativePath,
                             Constant.URI_ANNO_KEY, uri));
                         var spec = new AttachmentSpec();
-                        spec.setSize(attachmentPath.toFile().length());
+                        spec.setSize(path.toFile().length());
-                        file.headers().getContentType();
                         spec.setMediaType(Optional.ofNullable(file.headers().getContentType())
                             .map(MediaType::toString)
                             .orElse(null));
-                        spec.setDisplayName(file.filename());
+                        spec.setDisplayName(path.getFileName().toString());
                         var attachment = new Attachment();
                         attachment.setMetadata(metadata);
                         attachment.setSpec(spec);
                         return attachment;
-                    }))
+                    })
                     .onErrorMap(FileAlreadyExistsException.class,
                         e -> new AttachmentAlreadyExistsException(e.getFile()));
             });
@@ -165,4 +168,37 @@ class LocalAttachmentUploadHandler implements AttachmentHandler {
         private String location;
 
     }
+
+    /**
+     * Write content into file. We will detect duplicate filename and auto-rename it with 3 times
+     * retry.
+     *
+     * @param content is file content
+     * @param targetPath is target path
+     * @return file path
+     */
+    private Mono<Path> writeContent(Flux<DataBuffer> content,
+        Path targetPath,
+        boolean renameIfExists) {
+        return Mono.defer(() -> {
+            final var pathRef = new AtomicReference<>(targetPath);
+            return Mono.defer(
+                    // we have to use defer method to obtain a fresh path
+                    () -> DataBufferUtils.write(content, pathRef.get(), CREATE_NEW))
+                .retryWhen(Retry.max(3)
+                    .filter(t -> {
+                        if (renameIfExists) {
+                            return t instanceof FileAlreadyExistsException;
+                        }
+                        return false;
+                    })
+                    .doAfterRetry(signal -> {
+                        // rename the path
+                        var oldPath = pathRef.get();
+                        var fileName = randomFileName(oldPath.toString(), 4);
+                        pathRef.set(oldPath.resolveSibling(fileName));
+                    }))
+                .then(Mono.fromSupplier(pathRef::get));
+        });
+    }
 }

src/main/java/run/halo/app/infra/utils/FileNameUtils.java

@@ -1,5 +1,9 @@
 package run.halo.app.infra.utils;
 
+import com.google.common.io.Files;
+import org.apache.commons.lang3.RandomStringUtils;
+import org.apache.commons.lang3.StringUtils;
+
 public final class FileNameUtils {
 
     private FileNameUtils() {
@@ -12,4 +16,29 @@ public final class FileNameUtils {
         var extPattern = "(?<!^)[.]" + (removeAllExtensions ? ".*" : "[^.]*$");
         return filename.replaceAll(extPattern, "");
     }
+
+    /**
+     * Append random string after file name.
+     * <pre>
+     * Case 1: halo.run -> halo-xyz.run
+     * Case 2: .run -> xyz.run
+     * Case 3: halo -> halo-xyz
+     * </pre>
+     *
+     * @param filename is name of file.
+     * @param length is for generating random string with specific length.
+     * @return File name with random string.
+     */
+    public static String randomFileName(String filename, int length) {
+        var nameWithoutExt = Files.getNameWithoutExtension(filename);
+        var ext = Files.getFileExtension(filename);
+        var random = RandomStringUtils.randomAlphabetic(length).toLowerCase();
+        if (StringUtils.isBlank(nameWithoutExt)) {
+            return random + "." + ext;
+        }
+        if (StringUtils.isBlank(ext)) {
+            return nameWithoutExt + "-" + random;
+        }
+        return nameWithoutExt + "-" + random + "." + ext;
+    }
 }

src/test/java/run/halo/app/infra/utils/FileNameUtilsTest.java

@@ -2,50 +2,77 @@ package run.halo.app.infra.utils;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static run.halo.app.infra.utils.FileNameUtils.randomFileName;
+import static run.halo.app.infra.utils.FileNameUtils.removeFileExtension;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 class FileNameUtilsTest {
 
+    @Nested
+    class RemoveFileExtensionTest {
+
         @Test
         public void shouldNotRemoveExtIfNoExt() {
-        assertEquals("halo", FileNameUtils.removeFileExtension("halo", true));
+            assertEquals("halo", removeFileExtension("halo", true));
-        assertEquals("halo", FileNameUtils.removeFileExtension("halo", false));
+            assertEquals("halo", removeFileExtension("halo", false));
         }
 
         @Test
         public void shouldRemoveExtIfHasOnlyOneExt() {
-        assertEquals("halo", FileNameUtils.removeFileExtension("halo.run", true));
+            assertEquals("halo", removeFileExtension("halo.run", true));
-        assertEquals("halo", FileNameUtils.removeFileExtension("halo.run", false));
+            assertEquals("halo", removeFileExtension("halo.run", false));
         }
 
         @Test
         public void shouldNotRemoveExtIfDotfile() {
-        assertEquals(".halo", FileNameUtils.removeFileExtension(".halo", true));
+            assertEquals(".halo", removeFileExtension(".halo", true));
-        assertEquals(".halo", FileNameUtils.removeFileExtension(".halo", false));
+            assertEquals(".halo", removeFileExtension(".halo", false));
         }
 
         @Test
         public void shouldRemoveExtIfDotfileHasOneExt() {
-        assertEquals(".halo", FileNameUtils.removeFileExtension(".halo.run", true));
+            assertEquals(".halo", removeFileExtension(".halo.run", true));
-        assertEquals(".halo", FileNameUtils.removeFileExtension(".halo.run", false));
+            assertEquals(".halo", removeFileExtension(".halo.run", false));
         }
 
         @Test
         public void shouldRemoveExtIfHasTwoExt() {
-        assertEquals("halo", FileNameUtils.removeFileExtension("halo.tar.gz", true));
+            assertEquals("halo", removeFileExtension("halo.tar.gz", true));
-        assertEquals("halo.tar", FileNameUtils.removeFileExtension("halo.tar.gz", false));
+            assertEquals("halo.tar", removeFileExtension("halo.tar.gz", false));
         }
 
         @Test
         public void shouldRemoveExtIfDotfileHasTwoExt() {
-        assertEquals(".halo", FileNameUtils.removeFileExtension(".halo.tar.gz", true));
+            assertEquals(".halo", removeFileExtension(".halo.tar.gz", true));
-        assertEquals(".halo.tar", FileNameUtils.removeFileExtension(".halo.tar.gz", false));
+            assertEquals(".halo.tar", removeFileExtension(".halo.tar.gz", false));
         }
 
         @Test
         void shouldReturnNullIfFilenameIsNull() {
-        assertNull(FileNameUtils.removeFileExtension(null, true));
+            assertNull(removeFileExtension(null, true));
-        assertNull(FileNameUtils.removeFileExtension(null, false));
+            assertNull(removeFileExtension(null, false));
+        }
+    }
+
+    @Nested
+    class AppendRandomFileNameTest {
+        @Test
+        void normalFileName() {
+            String randomFileName = randomFileName("halo.run", 3);
+            assertEquals(12, randomFileName.length());
+            assertTrue(randomFileName.startsWith("halo-"));
+            assertTrue(randomFileName.endsWith(".run"));
+
+            randomFileName = randomFileName(".run", 3);
+            assertEquals(7, randomFileName.length());
+            assertTrue(randomFileName.endsWith(".run"));
+
+            randomFileName = randomFileName("halo", 3);
+            assertEquals(8, randomFileName.length());
+            assertTrue(randomFileName.startsWith("halo-"));
+        }
     }
 }