Add thumbnail routing with dynamic width handling and URI generation

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

@@ -3,6 +3,7 @@ package run.halo.app.core.extension.attachment.endpoint;
 import java.net.URI;
 import java.time.Duration;
 import java.util.Map;
+import java.util.Optional;
 import org.pf4j.ExtensionPoint;
 import org.springframework.http.codec.multipart.FilePart;
 import reactor.core.publisher.Mono;
@@ -69,6 +70,17 @@ public interface AttachmentHandler extends ExtensionPoint {
         return Mono.empty();
     }
 
+    /**
+     * Build the thumbnail links from the given permalink.
+     *
+     * @param permalink the permalink
+     * @return an optional map of thumbnail sizes to their respective URIs
+     */
+    default Optional<Map<ThumbnailSize, URI>> buildThumbnailLinks(URI permalink) {
+        // resolve the thumbnail link
+        return Optional.empty();
+    }
+
     interface UploadContext {
 
         FilePart file();

application/src/main/java/run/halo/app/core/attachment/ThumbnailImgTagPostProcessor.java

@@ -100,7 +100,10 @@ class ThumbnailImgTagPostProcessor implements ElementTagPostProcessor {
         var modelFactory = context.getModelFactory();
         if (!tag.hasAttribute("sizes")) {
             tag = modelFactory.setAttribute(tag, "sizes", """
-                (min-width: 800px) 800px, 100vw\
+                (max-width: 640px) 94vw, \
+                (max-width: 768px) 92vw, \
+                (max-width: 1024px) 88vw, \
+                min(800px, 85vw)\
                 """);
         }
         var srcset = thumbnails.keySet().stream()

application/src/main/java/run/halo/app/core/attachment/ThumbnailUtils.java

@@ -51,12 +51,11 @@ public enum ThumbnailUtils {
             return Map.of();
         }
         return Arrays.stream(ThumbnailSize.values())
-            .collect(Collectors.toMap(t -> t, t -> {
-                var prefix = "/thumbnails/w" + t.getWidth();
-                return UriComponentsBuilder.fromUri(permalink)
-                    .replacePath(prefix + permalink.getPath())
+            .collect(Collectors.toMap(t -> t, t ->
+                UriComponentsBuilder.fromUri(permalink)
+                    .queryParam("width", t.getWidth())
                     .build()
-                    .toUri();
-            }));
+                    .toUri()
+            ));
     }
 }

application/src/main/java/run/halo/app/core/attachment/endpoint/ThumbnailRouters.java

@@ -1,6 +1,8 @@
 package run.halo.app.core.attachment.endpoint;
 
 import static java.nio.file.StandardOpenOption.READ;
+import static org.springframework.web.reactive.function.server.RequestPredicates.accept;
+import static org.springframework.web.reactive.function.server.RequestPredicates.queryParam;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -13,6 +15,7 @@ import org.apache.commons.io.FilenameUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.springframework.context.annotation.Bean;
 import org.springframework.core.io.FileSystemResource;
+import org.springframework.http.MediaType;
 import org.springframework.stereotype.Component;
 import org.springframework.web.reactive.function.server.RouterFunction;
 import org.springframework.web.reactive.function.server.RouterFunctions;
@@ -29,6 +32,8 @@ import run.halo.app.core.attachment.ThumbnailUtils;
 @Component
 class ThumbnailRouters {
 
+    private static final MediaType IMAGE_MEDIA_TYPE = MediaType.parseMediaType("image/*");
+
     private final Path uploadRoot;
 
     private final Path thumbnailRoot;
@@ -49,46 +54,50 @@ class ThumbnailRouters {
     @Bean
     RouterFunction<ServerResponse> thumbnailRouter() {
         return RouterFunctions.route()
-            .GET("/thumbnails/w{width}/upload/{*filename}", serverRequest -> {
-                var width = serverRequest.pathVariable("width");
-                String originalFilename = serverRequest.pathVariable("filename");
-                var filename = StringUtils.removeStart(originalFilename, "/");
-                if (StringUtils.isBlank(filename)) {
-                    log.trace("Filename is blank");
-                    return Mono.error(new NoResourceFoundException(filename));
-                }
-                var size = ThumbnailSize.fromWidth(width);
-                // try to resolve the thumbnail
-                // build thumbnail path
-                var thumbnailPath = thumbnailRoot.resolve("w" + size.getWidth())
-                    .resolve(filename);
-                var thumbnailResource = new FileSystemResource(thumbnailPath);
-                if (thumbnailResource.isReadable()) {
-                    return ServerResponse.ok().bodyValue(thumbnailResource);
-                }
-
-                var uploadPath = uploadRoot.resolve(filename);
-                var fileSuffix = FilenameUtils.getExtension(filename);
-                if (!ThumbnailUtils.isSupportedImage(fileSuffix)) {
-                    log.warn("File suffix {} is not supported for thumbnail generation, return "
-                        + "original file", fileSuffix);
-                    // return the original file
-                    thumbnailResource = new FileSystemResource(uploadPath);
-                    if (!thumbnailResource.isReadable()) {
+            .GET(
+                "/upload/{*filename}",
+                queryParam("width", StringUtils::isNotBlank).and(accept(IMAGE_MEDIA_TYPE)),
+                serverRequest -> {
+                    var size = serverRequest.queryParam("width")
+                        .map(ThumbnailSize::fromWidth)
+                        .orElse(ThumbnailSize.M);
+                    String originalFilename = serverRequest.pathVariable("filename");
+                    var filename = StringUtils.removeStart(originalFilename, "/");
+                    if (StringUtils.isBlank(filename)) {
+                        log.trace("Filename is blank");
                         return Mono.error(new NoResourceFoundException(filename));
                     }
-                    return ServerResponse.ok().bodyValue(thumbnailResource);
-                }
+                    // try to resolve the thumbnail
+                    // build thumbnail path
+                    var thumbnailPath = thumbnailRoot.resolve("w" + size.getWidth())
+                        .resolve(filename);
+                    var thumbnailResource = new FileSystemResource(thumbnailPath);
+                    if (thumbnailResource.isReadable()) {
+                        return ServerResponse.ok().bodyValue(thumbnailResource);
+                    }
 
-                // generate for the attachment
-                return Mono.fromCallable(
-                        () -> generateThumbnail(uploadPath, thumbnailPath, size)
-                    )
-                    .subscribeOn(this.thumbnailGeneratingScheduler)
-                    .switchIfEmpty(Mono.error(() -> new NoResourceFoundException(filename)))
-                    .map(FileSystemResource::new)
-                    .flatMap(resource -> ServerResponse.ok().bodyValue(resource));
-            })
+                    var uploadPath = uploadRoot.resolve(filename);
+                    var fileSuffix = FilenameUtils.getExtension(filename);
+                    if (!ThumbnailUtils.isSupportedImage(fileSuffix)) {
+                        log.warn("File suffix {} is not supported for thumbnail generation, return "
+                            + "original file", fileSuffix);
+                        // return the original file
+                        thumbnailResource = new FileSystemResource(uploadPath);
+                        if (!thumbnailResource.isReadable()) {
+                            return Mono.error(new NoResourceFoundException(filename));
+                        }
+                        return ServerResponse.ok().bodyValue(thumbnailResource);
+                    }
+
+                    // generate for the attachment
+                    return Mono.fromCallable(
+                            () -> generateThumbnail(uploadPath, thumbnailPath, size)
+                        )
+                        .subscribeOn(this.thumbnailGeneratingScheduler)
+                        .switchIfEmpty(Mono.error(() -> new NoResourceFoundException(filename)))
+                        .map(FileSystemResource::new)
+                        .flatMap(resource -> ServerResponse.ok().bodyValue(resource));
+                })
             .build();
     }