(refs #775)Add new extension point to add markup render

src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala

@@ -1,6 +1,7 @@
 package gitbucket.core.controller
 
 import gitbucket.core.api._
+import gitbucket.core.plugin.PluginRegistry
 import gitbucket.core.repo.html
 import gitbucket.core.helper
 import gitbucket.core.service._
@@ -546,7 +547,9 @@ trait RepositoryViewerControllerBase extends ControllerBase {
   }
 
 
-  private val readmeFiles = view.helpers.renderableSuffixes.map(suffix => s"readme${suffix}") ++ Seq("readme.txt", "readme")
+  private val readmeFiles = PluginRegistry().renderableExtensions.map { extension =>
+    s"readme.${extension}"
+  } ++ Seq("readme.txt", "readme")
 
   /**
    * Provides HTML of the file list.

src/main/scala/gitbucket/core/plugin/Plugin.scala

@@ -32,6 +32,11 @@ trait Plugin {
    */
   val javaScripts: Seq[(String, String)] = Nil
 
+  /**
+   * Override to declare this plug-in provides renderers.
+   */
+  val renderers: Seq[(String, Renderer)] = Nil
+
   /**
    * This method is invoked in initialization of plugin system.
    * Register plugin functionality to PluginRegistry.
@@ -46,6 +51,9 @@ trait Plugin {
     javaScripts.foreach { case (path, script) =>
       registry.addJavaScript(path, script)
     }
+    renderers.foreach { case (extension, renderer) =>
+      registry.addRenderer(extension, renderer)
+    }
   }
 
   /**

src/main/scala/gitbucket/core/plugin/PluginRegistory.scala

@@ -24,6 +24,10 @@ class PluginRegistry {
   private val javaScripts = new ListBuffer[(String, String)]
   private val controllers = new ListBuffer[(ControllerBase, String)]
   private val images = mutable.Map[String, String]()
+  private val renderers = mutable.Map[String, Renderer]()
+  renderers ++= Seq(
+    "md" -> MarkdownRenderer, "markdown" -> MarkdownRenderer
+  )
 
   def addPlugin(pluginInfo: PluginInfo): Unit = {
     plugins += pluginInfo
@@ -60,15 +64,23 @@ class PluginRegistry {
   def getControllers(): List[(ControllerBase, String)] = controllers.toList
 
   def addJavaScript(path: String, script: String): Unit = {
-    javaScripts += Tuple2(path, script)
+    javaScripts += ((path, script))
   }
 
-  //def getJavaScripts(): List[(String, String)] = javaScripts.toList
-
   def getJavaScript(currentPath: String): List[String] = {
     javaScripts.filter(x => currentPath.matches(x._1)).toList.map(_._2)
   }
 
+  def addRenderer(extension: String, renderer: Renderer): Unit = {
+    renderers += ((extension, renderer))
+  }
+
+  def getRenderer(extension: String): Renderer = {
+    renderers.get(extension).getOrElse(DefaultRenderer)
+  }
+
+  def renderableExtensions: Seq[String] = renderers.keys.toSeq
+
   private case class GlobalAction(
     method: String,
     path: String,
@@ -97,6 +109,10 @@ object PluginRegistry {
    */
   def apply(): PluginRegistry = instance
 
+  def isRenderable(fileName: String): Boolean = {
+    instance.renderableExtensions.exists(extension => fileName.toLowerCase.endsWith("." + extension))
+  }
+
   /**
    * Initializes all installed plugins.
    */

src/main/scala/gitbucket/core/plugin/Renderer.scala

@@ -0,0 +1,44 @@
+package gitbucket.core.plugin
+
+import gitbucket.core.controller.Context
+import gitbucket.core.service.RepositoryService
+import gitbucket.core.view.Markdown
+import play.twirl.api.Html
+
+/**
+ * A render engine to render content to HTML.
+ */
+trait Renderer {
+
+  /**
+   * Render the given request to HTML.
+   */
+  def render(request: RenderRequest): Html
+
+}
+
+object MarkdownRenderer extends Renderer {
+  override def render(request: RenderRequest): Html = {
+    import request._
+    Html(Markdown.toHtml(fileContent, repository, enableWikiLink, enableRefsLink)(context))
+  }
+}
+
+object DefaultRenderer extends Renderer {
+  override def render(request: RenderRequest): Html = {
+    import request._
+    Html(
+      s"<tt>${
+        fileContent.split("(\\r\\n)|\\n").map(xml.Utility.escape(_)).mkString("<br/>")
+      }</tt>"
+    )
+  }
+}
+
+case class RenderRequest(filePath: List[String],
+   fileContent: String,
+   branch: String,
+   repository: RepositoryService.RepositoryInfo,
+   enableWikiLink: Boolean,
+   enableRefsLink: Boolean,
+   context: Context)

src/main/scala/gitbucket/core/view/helpers.scala

@@ -5,8 +5,9 @@ import java.util.{Date, Locale, TimeZone}
 
 import gitbucket.core.controller.Context
 import gitbucket.core.model.CommitState
+import gitbucket.core.plugin.{RenderRequest, PluginRegistry, Renderer}
 import gitbucket.core.service.{RepositoryService, RequestCache}
-import gitbucket.core.util.{JGitUtil, StringUtil}
+import gitbucket.core.util.{FileUtil, JGitUtil, StringUtil}
 
 import play.twirl.api.Html
 
@@ -83,14 +84,6 @@ object helpers extends AvatarImageProvider with LinkConverter with RequestCache
   def plural(count: Int, singular: String, plural: String = ""): String =
     if(count == 1) singular else if(plural.isEmpty) singular + "s" else plural
 
-  private[this] val renderersBySuffix: Seq[(String, (List[String], String, String, RepositoryService.RepositoryInfo, Boolean, Boolean, Context) => Html)] =
-    Seq(
-      ".md"       -> ((filePath, fileContent, branch, repository, enableWikiLink, enableRefsLink, context) => markdown(fileContent, repository, enableWikiLink, enableRefsLink)(context)),
-      ".markdown" -> ((filePath, fileContent, branch, repository, enableWikiLink, enableRefsLink, context) => markdown(fileContent, repository, enableWikiLink, enableRefsLink)(context))
-    )
-
-  def renderableSuffixes: Seq[String] = renderersBySuffix.map(_._1)
-
   /**
    * Converts Markdown of Wiki pages to HTML.
    */
@@ -107,15 +100,10 @@ object helpers extends AvatarImageProvider with LinkConverter with RequestCache
                    repository: RepositoryService.RepositoryInfo,
                    enableWikiLink: Boolean, enableRefsLink: Boolean)(implicit context: Context): Html = {
 
-    val fileNameLower = filePath.reverse.head.toLowerCase
-    renderersBySuffix.find { case (suffix, _) => fileNameLower.endsWith(suffix) } match {
-      case Some((_, handler)) => handler(filePath, fileContent, branch, repository, enableWikiLink, enableRefsLink, context)
-      case None => Html(
-        s"<tt>${
-          fileContent.split("(\\r\\n)|\\n").map(xml.Utility.escape(_)).mkString("<br/>")
-        }</tt>"
-      )
-    }
+    val fileName  = filePath.reverse.head.toLowerCase
+    val extension = FileUtil.getExtension(fileName)
+    val renderer  = PluginRegistry().getRenderer(extension)
+    renderer.render(RenderRequest(filePath, fileContent, branch, repository, enableWikiLink, enableRefsLink, context))
   }
 
   /**

src/main/twirl/gitbucket/core/repo/blob.scala.html

@@ -7,6 +7,7 @@
   isBlame: Boolean)(implicit context: gitbucket.core.controller.Context)
 @import context._
 @import gitbucket.core.view.helpers._
+@import gitbucket.core.plugin.PluginRegistry
 @html.main(s"${repository.owner}/${repository.name}", Some(repository)) {
   @html.menu("code", repository){
     <div class="head">
@@ -75,7 +76,7 @@
       <tr>
         <td>
           @if(content.viewType == "text"){
-            @defining(renderableSuffixes.find(suffix => pathList.reverse.head.toLowerCase.endsWith(suffix))) { isRrenderable =>
+            @defining(PluginRegistry.isRenderable(pathList.reverse.head)){ isRrenderable =>
               @if(!isBlame && isRrenderable) {
                 <div class="box-content markdown-body" style="border: none; padding-left: 16px; padding-right: 16px;">
                   @renderMarkup(pathList, content.content.get, branch, repository, false, false)

src/main/twirl/gitbucket/core/repo/editor.scala.html

@@ -5,6 +5,7 @@
   content: gitbucket.core.util.JGitUtil.ContentInfo)(implicit context: gitbucket.core.controller.Context)
 @import context._
 @import gitbucket.core.view.helpers._
+@import gitbucket.core.plugin.PluginRegistry
 @html.main(if(fileName.isEmpty) "New File" else s"Editing ${fileName.get} at ${branch} - ${repository.owner}/${repository.name}", Some(repository)) {
   @html.menu("code", repository){
     <form method="POST" action="@url(repository)/@if(fileName.isEmpty){create}else{update}" validate="true">
@@ -120,7 +121,7 @@ $(function(){
     $('#editor').hide();
     $('#preview').show()
 
-    @if(renderableSuffixes.find(suffix => fileName.map(_.toLowerCase.endsWith(suffix)).getOrElse(false))) {
+    @if(fileName.map(PluginRegistry.isRenderable _).getOrElse(false)) {
       // update preview
       $('#preview').html('<img src="@assets/common/images/indicator.gif"> Previewing...');
       $.post('@url(repository)/_preview', {