Add get-a-repository-README endpoint (#2535)

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

@@ -908,10 +908,6 @@ trait RepositoryViewerControllerBase extends ControllerBase {
     lazy val isValid: Boolean = fileIds.nonEmpty
   }
 
-  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/controller/api/ApiRepositoryContentsControllerBase.scala

@@ -1,6 +1,7 @@
 package gitbucket.core.controller.api
 import gitbucket.core.api.{ApiContents, ApiError, CreateAFile, JsonFormat}
 import gitbucket.core.controller.ControllerBase
+import gitbucket.core.plugin.PluginRegistry
 import gitbucket.core.service.{RepositoryCommitFileService, RepositoryService}
 import gitbucket.core.util.Directory.getRepositoryDir
 import gitbucket.core.util.JGitUtil.{FileInfo, getContentFromId, getFileList}
@@ -8,15 +9,27 @@ import gitbucket.core.util._
 import gitbucket.core.view.helpers.{isRenderable, renderMarkup}
 import gitbucket.core.util.Implicits._
 import org.eclipse.jgit.api.Git
+
 import scala.util.Using
 
 trait ApiRepositoryContentsControllerBase extends ControllerBase {
   self: ReferrerAuthenticator with WritableUsersAuthenticator with RepositoryCommitFileService =>
 
-  /*
-   * i. Get the README
-   * https://developer.github.com/v3/repos/contents/#get-the-readme
+  /**
+   * i. Get a repository README
+   * https://docs.github.com/en/rest/reference/repos#get-a-repository-readme
    */
+  get("/api/v3/repos/:owner/:repository/readme")(referrersOnly { repository =>
+    Using.resource(Git.open(getRepositoryDir(params("owner"), params("repository")))) {
+      git =>
+        val refStr = params.getOrElse("ref", repository.repository.defaultBranch)
+        val fileList = getFileList(git, refStr, ".", maxFiles = context.settings.repositoryViewer.maxFiles)
+        fileList.map(f => f.name).find(p => readmeFiles.map(_.toLowerCase).contains(p.toLowerCase)) match {
+          case Some(x) => getContents(repository = repository, path = x, refStr = refStr, ignoreCase = true)
+          case _       => NotFound()
+        }
+    }
+  })
 
   /**
    * ii. Get contents
@@ -34,22 +47,32 @@ trait ApiRepositoryContentsControllerBase extends ControllerBase {
     getContents(repository, multiParams("splat").head, params.getOrElse("ref", repository.repository.defaultBranch))
   })
 
-  private def getContents(repository: RepositoryService.RepositoryInfo, path: String, refStr: String) = {
-    def getFileInfo(git: Git, revision: String, pathStr: String): Option[FileInfo] = {
+  private def getContents(
+    repository: RepositoryService.RepositoryInfo,
+    path: String,
+    refStr: String,
+    ignoreCase: Boolean = false
+  ) = {
+    def getFileInfo(git: Git, revision: String, pathStr: String, ignoreCase: Boolean): Option[FileInfo] = {
       val (dirName, fileName) = pathStr.lastIndexOf('/') match {
         case -1 =>
           (".", pathStr)
         case n =>
           (pathStr.take(n), pathStr.drop(n + 1))
       }
-      getFileList(git, revision, dirName, maxFiles = context.settings.repositoryViewer.maxFiles)
-        .find(_.name.equals(fileName))
+      if (ignoreCase) {
+        getFileList(git, revision, dirName, maxFiles = context.settings.repositoryViewer.maxFiles)
+          .find(_.name.toLowerCase.equals(fileName.toLowerCase))
+      } else {
+        getFileList(git, revision, dirName, maxFiles = context.settings.repositoryViewer.maxFiles)
+          .find(_.name.equals(fileName))
+      }
     }
 
     Using.resource(Git.open(getRepositoryDir(params("owner"), params("repository")))) { git =>
       val fileList = getFileList(git, refStr, path, maxFiles = context.settings.repositoryViewer.maxFiles)
       if (fileList.isEmpty) { // file or NotFound
-        getFileInfo(git, refStr, path)
+        getFileInfo(git, refStr, path, ignoreCase)
           .flatMap { f =>
             val largeFile = params.get("large_file").exists(s => s.equals("true"))
             val content = getContentFromId(git, f.id, largeFile)

src/main/scala/gitbucket/core/service/RepositoryCommitFileService.scala

@@ -116,6 +116,11 @@ trait RepositoryCommitFileService {
     }
   }
 
+  def readmeFiles: Seq[String] =
+    PluginRegistry().renderableExtensions.map { extension =>
+      s"readme.${extension}"
+    } ++ Seq("readme.txt", "readme")
+
   private def _commitFile(
     repository: RepositoryService.RepositoryInfo,
     branch: String,