feat: support post custom template.

src/main/java/run/halo/app/controller/admin/api/ThemeController.java

@@ -80,9 +80,14 @@ public class ThemeController {
         themeService.saveTemplateContent(themeId, param.getPath(), param.getContent());
     }
 
-    @GetMapping("files/custom")
+    @GetMapping("activation/template/custom/sheet")
-    public Set<String> customTemplate() {
+    public Set<String> customSheetTemplate() {
-        return themeService.listCustomTemplates(themeService.getActivatedThemeId());
+        return themeService.listCustomTemplates(themeService.getActivatedThemeId(), ThemeService.CUSTOM_SHEET_PREFIX);
+    }
+
+    @GetMapping("activation/template/custom/post")
+    public Set<String> customPostTemplate() {
+        return themeService.listCustomTemplates(themeService.getActivatedThemeId(), ThemeService.CUSTOM_POST_PREFIX);
     }
 
     @PostMapping("{themeId}/activation")

src/main/java/run/halo/app/controller/content/ContentArchiveController.java

@@ -21,6 +21,7 @@ import run.halo.app.model.entity.Post;
 import run.halo.app.model.entity.PostMeta;
 import run.halo.app.model.entity.Tag;
 import run.halo.app.model.enums.PostStatus;
+import run.halo.app.model.support.HaloConst;
 import run.halo.app.model.vo.BaseCommentVO;
 import run.halo.app.model.vo.PostListVO;
 import run.halo.app.service.*;
@@ -160,6 +161,10 @@ public class ContentArchiveController {
         model.addAttribute("metas", postMetaService.convertToMap(metas));
         model.addAttribute("comments", comments);
 
+        if (themeService.templateExists(ThemeService.CUSTOM_POST_PREFIX + post.getTemplate() + HaloConst.SUFFIX_FTL)) {
+            return themeService.render(ThemeService.CUSTOM_POST_PREFIX + post.getTemplate());
+        }
+
         return themeService.render("post");
     }
 

src/main/java/run/halo/app/service/ThemeService.java

@@ -70,10 +70,15 @@ public interface ThemeService {
     String THEMES_CACHE_KEY = "themes";
 
     /**
-     * Custom sheet prefix.
+     * Custom sheet template prefix.
      */
     String CUSTOM_SHEET_PREFIX = "sheet_";
 
+    /**
+     * Custom post template prefix.
+     */
+    String CUSTOM_POST_PREFIX = "post_";
+
     /**
      * Theme provider remote name.
      */
@@ -132,8 +137,18 @@ public interface ThemeService {
      * @param themeId theme id must not be blank
      * @return a set of templates
      */
+    @Deprecated
     Set<String> listCustomTemplates(@NonNull String themeId);
 
+    /**
+     * Lists a set of custom template, such as sheet_xxx.ftl/post_xxx.ftl, and xxx will be template name
+     *
+     * @param themeId theme id must not be blank
+     * @param prefix  post_ or sheet_
+     * @return a set of templates
+     */
+    Set<String> listCustomTemplates(@NonNull String themeId, @NonNull String prefix);
+
     /**
      * Judging whether template exists under the specified theme
      *

src/main/java/run/halo/app/service/impl/ThemeServiceImpl.java

@@ -187,6 +187,25 @@ public class ThemeServiceImpl implements ThemeService {
         }
     }
 
+    @Override
+    public Set<String> listCustomTemplates(String themeId, String prefix) {
+        // Get the theme path
+        Path themePath = Paths.get(getThemeOfNonNullBy(themeId).getThemePath());
+
+        try (Stream<Path> pathStream = Files.list(themePath)) {
+            return pathStream.filter(path -> StringUtils.startsWithIgnoreCase(path.getFileName().toString(), prefix))
+                    .map(path -> {
+                        // Remove prefix
+                        String customTemplate = StringUtils.removeStartIgnoreCase(path.getFileName().toString(), prefix);
+                        // Remove suffix
+                        return StringUtils.removeEndIgnoreCase(customTemplate, HaloConst.SUFFIX_FTL);
+                    })
+                    .collect(Collectors.toSet());
+        } catch (IOException e) {
+            throw new ServiceException("Failed to list files of path " + themePath.toString(), e);
+        }
+    }
+
     @Override
     public boolean templateExists(String template) {
         if (StringUtils.isBlank(template)) {