Fix the problem of not being able to request SinglePage with slug name containing special characters (#2479)

#### What type of PR is this?

/kind bug
/kind api-change
/area core
/milestone 2.0

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

Support setting special characters on slug name of SinglePage.

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

Partial Fixes https://github.com/halo-dev/halo/issues/2473

#### Special notes for your reviewer:

Steps to test:

1. Create single pags with slug name `中文`, `/a/b/c/d` or `a / b`
2. Request it with permalink generated by Halo

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

```release-note
None
```

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

@@ -1,5 +1,8 @@
 package run.halo.app.core.extension.reconciler;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.springframework.web.util.UriUtils.encodePath;
+
 import java.time.Instant;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
@@ -150,8 +153,10 @@ public class SinglePageReconciler implements Reconciler<Reconciler.Request> {
             final SinglePage oldPage = JsonUtils.deepCopy(singlePage);
             permalinkOnDelete(oldPage);
 
+            var permalink = encodePath(singlePage.getSpec().getSlug(), UTF_8);
+            permalink = StringUtils.prependIfMissing(permalink, "/");
             singlePage.getStatusOrDefault()
-                .setPermalink(PathUtils.combinePath(singlePage.getSpec().getSlug()));
+                .setPermalink(permalink);
             if (isPublished(singlePage)) {
                 permalinkOnAdd(singlePage);
             }

src/main/java/run/halo/app/theme/engine/SpringWebFluxTemplateEngine.java

@@ -200,7 +200,6 @@ public class SpringWebFluxTemplateEngine extends SpringTemplateEngine
                     try {
 
                         process(templateName, markupSelectors, context, writer);
-                        Mono.empty().block();
 
                     } catch (final Throwable t) {
                         logger.error(

src/main/java/run/halo/app/theme/router/PermalinkIndexer.java

@@ -157,6 +157,24 @@ public class PermalinkIndexer {
         }
     }
 
+    /**
+     * Get extension name by permalink.
+     *
+     * @param gvk is GroupVersionKind of extension
+     * @param permalink is encoded permalink
+     * @return extension name or null
+     */
+    @Nullable
+    public String getNameByPermalink(GroupVersionKind gvk, String permalink) {
+        readWriteLock.readLock().lock();
+        try {
+            var locator = permalinkLocatorLookup.get(permalink);
+            return locator == null ? null : locator.name();
+        } finally {
+            readWriteLock.readLock().unlock();
+        }
+    }
+
     /**
      * Only for test.
      *

src/main/java/run/halo/app/theme/router/strategy/PermalinkPredicates.java

@@ -0,0 +1,17 @@
+package run.halo.app.theme.router.strategy;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.springframework.web.reactive.function.server.RequestPredicates.method;
+import static org.springframework.web.reactive.function.server.RequestPredicates.path;
+
+import org.springframework.http.HttpMethod;
+import org.springframework.web.reactive.function.server.RequestPredicate;
+import org.springframework.web.util.UriUtils;
+
+public enum PermalinkPredicates {
+    ;
+
+    public static RequestPredicate get(String permalink) {
+        return method(HttpMethod.GET).and(path(UriUtils.decode(permalink, UTF_8)));
+    }
+}

src/main/java/run/halo/app/theme/router/strategy/SinglePageRouteStrategy.java

@@ -1,14 +1,13 @@
 package run.halo.app.theme.router.strategy;
 
 import static org.springframework.web.reactive.function.server.RequestPredicates.accept;
+import static run.halo.app.theme.router.strategy.PermalinkPredicates.get;
 
 import java.util.List;
 import java.util.Map;
-import org.apache.commons.lang3.StringUtils;
 import org.springframework.http.MediaType;
 import org.springframework.stereotype.Component;
 import org.springframework.web.reactive.function.server.RequestPredicate;
-import org.springframework.web.reactive.function.server.RequestPredicates;
 import org.springframework.web.reactive.function.server.RouterFunction;
 import org.springframework.web.reactive.function.server.RouterFunctions;
 import org.springframework.web.reactive.function.server.ServerResponse;
@@ -49,13 +48,12 @@ public class SinglePageRouteStrategy implements TemplateRouterStrategy {
 
         List<String> permalinks = permalinkIndexer.getPermalinks(gvk);
         for (String permalink : permalinks) {
-            requestPredicate = requestPredicate.or(RequestPredicates.GET(permalink));
+            requestPredicate = requestPredicate.or(get(permalink));
         }
 
         return RouterFunctions
             .route(requestPredicate.and(accept(MediaType.TEXT_HTML)), request -> {
-                String slug = StringUtils.removeStart(request.path(), "/");
-                String name = permalinkIndexer.getNameBySlug(gvk, slug);
+                var name = permalinkIndexer.getNameByPermalink(gvk, request.path());
                 if (name == null) {
                     return ServerResponse.notFound().build();
                 }

src/test/java/run/halo/app/theme/router/PermalinkIndexerTest.java

@@ -2,6 +2,8 @@ package run.halo.app.theme.router;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 import java.util.List;
 import java.util.NoSuchElementException;
@@ -106,4 +108,16 @@ class PermalinkIndexerTest {
             permalinkIndexer.getNameBySlug(gvk, "nothing");
         }).isInstanceOf(NoSuchElementException.class);
     }
+
+    @Test
+    void getNameByPermalink() {
+        ExtensionLocator locator = new ExtensionLocator(gvk, "test-name", "test-slug");
+        permalinkIndexer.register(locator, "/test-permalink");
+
+        var name = permalinkIndexer.getNameByPermalink(gvk, "/test-permalink");
+        assertEquals("test-name", name);
+
+        name = permalinkIndexer.getNameByPermalink(gvk, "/invalid-permalink");
+        assertNull(name);
+    }
 }

src/test/java/run/halo/app/theme/router/strategy/SinglePageRouteStrategyTest.java

@@ -4,7 +4,9 @@ import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.lenient;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
+import static run.halo.app.theme.DefaultTemplateEnum.SINGLE_PAGE;
 
 import java.util.List;
 import org.junit.jupiter.api.BeforeEach;
@@ -13,15 +15,11 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
-import org.springframework.http.HttpStatus;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.reactive.function.server.HandlerStrategies;
-import org.springframework.web.reactive.function.server.RouterFunction;
-import org.springframework.web.reactive.function.server.ServerResponse;
 import org.springframework.web.reactive.result.view.ViewResolver;
 import reactor.core.publisher.Mono;
 import run.halo.app.extension.ListResult;
-import run.halo.app.theme.DefaultTemplateEnum;
 import run.halo.app.theme.finders.SinglePageFinder;
 import run.halo.app.theme.router.PermalinkIndexer;
 
@@ -50,37 +48,66 @@ class SinglePageRouteStrategyTest {
     void setUp() {
         lenient().when(singlePageFinder.list(anyInt(), anyInt()))
             .thenReturn(new ListResult<>(1, 10, 0, List.of()));
-        when(permalinkIndexer.getPermalinks(any()))
-            .thenReturn(List.of("/fake-slug"));
-        when(permalinkIndexer.getNameBySlug(any(), eq("fake-slug")))
-            .thenReturn("fake-name");
+        lenient().when(viewResolver.resolveViewName(eq(SINGLE_PAGE.getValue()), any()))
+            .thenReturn(Mono.just(new EmptyView()));
     }
 
     @Test
-    void getRouteFunction() {
-        RouterFunction<ServerResponse> routeFunction =
-            strategy.getRouteFunction(DefaultTemplateEnum.SINGLE_PAGE.getValue(),
-                null);
+    void shouldResponse404IfNoPermalinkFound() {
+        createClient().get()
+            .uri("/nothing")
+            .exchange()
+            .expectStatus().isNotFound();
+    }
 
-        WebTestClient client = WebTestClient.bindToRouterFunction(routeFunction)
-            .handlerStrategies(HandlerStrategies.builder()
-                .viewResolver(viewResolver)
-                .build())
-            .build();
-
-        when(viewResolver.resolveViewName(eq(DefaultTemplateEnum.SINGLE_PAGE.getValue()), any()))
-            .thenReturn(Mono.just(new EmptyView()));
-
-        client.get()
+    @Test
+    void shouldResponse200IfPermalinkFound() {
+        when(permalinkIndexer.getPermalinks(any()))
+            .thenReturn(List.of("/fake-slug"));
+        when(permalinkIndexer.getNameByPermalink(any(), eq("/fake-slug")))
+            .thenReturn("fake-name");
+        createClient().get()
             .uri("/fake-slug")
             .exchange()
             .expectStatus()
             .isOk();
 
-        client.get()
-            .uri("/nothing")
-            .exchange()
-            .expectStatus()
-            .isEqualTo(HttpStatus.NOT_FOUND);
+        verify(permalinkIndexer).getNameByPermalink(any(), eq("/fake-slug"));
     }
-}
+
+    @Test
+    void shouldResponse200IfSlugNameContainsSpecialChars() {
+        when(permalinkIndexer.getPermalinks(any()))
+            .thenReturn(List.of("/fake%20/%20slug"));
+        when(permalinkIndexer.getNameByPermalink(any(), eq("/fake%20/%20slug")))
+            .thenReturn("fake-name");
+        createClient().get()
+            .uri("/fake / slug")
+            .exchange()
+            .expectStatus().isOk();
+        verify(permalinkIndexer).getNameByPermalink(any(), eq("/fake%20/%20slug"));
+    }
+
+    @Test
+    void shouldResponse200IfSlugNameContainsChineseChars() {
+        when(permalinkIndexer.getPermalinks(any()))
+            .thenReturn(List.of("/%E4%B8%AD%E6%96%87"));
+        when(permalinkIndexer.getNameByPermalink(any(), eq("/%E4%B8%AD%E6%96%87")))
+            .thenReturn("fake-name");
+        createClient().get()
+            .uri("/中文")
+            .exchange()
+            .expectStatus().isOk();
+        verify(permalinkIndexer).getNameByPermalink(any(), eq("/%E4%B8%AD%E6%96%87"));
+    }
+
+    WebTestClient createClient() {
+        var routeFunction = strategy.getRouteFunction(SINGLE_PAGE.getValue(), null);
+
+        return WebTestClient.bindToRouterFunction(routeFunction)
+            .handlerStrategies(HandlerStrategies.builder()
+                .viewResolver(viewResolver)
+                .build())
+            .build();
+    }
+}