open-api: Allow to specify a custom openapi file fix #3571

Author: jknack

jooby/src/main/java/io/jooby/OpenAPIModule.java

@@ -8,11 +8,7 @@
 import java.io.ByteArrayInputStream;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
-import java.util.EnumSet;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
+import java.util.*;
 
 import edu.umd.cs.findbugs.annotations.NonNull;
 import edu.umd.cs.findbugs.annotations.Nullable;
@@ -109,13 +105,23 @@ public enum Format {
     JSON,
 
     /** YAML. */
-    YAML
+    YAML;
+
+    public static Format from(@NonNull String filePath) {
+      for (Format value : values()) {
+        if (filePath.endsWith("." + value.name().toLowerCase())) {
+          return value;
+        }
+      }
+      throw new IllegalArgumentException("Unsupported format: " + filePath);
+    }
   }
 
   private final String openAPIPath;
   private String swaggerUIPath = "/swagger";
   private String redocPath = "/redoc";
   private EnumSet<Format> format = EnumSet.of(Format.JSON, Format.YAML);
+  private final Set<String> customFiles = new LinkedHashSet<>();
 
   /**
    * Creates an OpenAPI module. The path is used to route the open API files. For example:
@@ -141,6 +147,17 @@ public OpenAPIModule() {
     this("/");
   }
 
+  /**
+   * Set custom openapi file to use. Could be a file system or classpath resource.
+   *
+   * @param path Path.
+   * @return This module.
+   */
+  public @NonNull OpenAPIModule file(String path) {
+    customFiles.add(path);
+    return this;
+  }
+
   /**
    * Customize the swagger-ui path. Defaults is <code>/swagger</code>.
    *
@@ -178,22 +195,42 @@ public OpenAPIModule() {
 
   @Override
   public void install(@NonNull Jooby application) throws Exception {
-    String dir = Optional.ofNullable(application.getBasePackage()).orElse("/").replace(".", "/");
-
-    String appName = application.getClass().getSimpleName()
-        .replace("Jooby", "openapi")
-        .replace("Kooby", "openapi");
-    for (Format ext : format) {
-      String filename = String.format("/%s.%s", appName, ext.name().toLowerCase());
-      String openAPIFileLocation = Router.normalizePath(dir) + filename;
-      application.assets(
-          fullPath(openAPIPath, "/openapi." + ext.name().toLowerCase()), openAPIFileLocation);
-    }
+    var filePaths = computeOpenAPIFiles(application);
+
+    /*
+     Add /openapi.json and/or /openapi.yaml paths
+    */
+    filePaths.forEach((path, source) -> application.assets(fullPath(openAPIPath, path), source));
 
     /** Configure UI: */
     configureUI(application);
   }
 
+  private Map<String, String> computeOpenAPIFiles(Jooby application) {
+    final Map<String, String> filePaths = new LinkedHashMap<>();
+    if (customFiles.isEmpty()) {
+      // Generated by open api
+      String dir = Optional.ofNullable(application.getBasePackage()).orElse("/").replace(".", "/");
+      String appName =
+          application
+              .getClass()
+              .getSimpleName()
+              .replace("Jooby", "openapi")
+              .replace("Kooby", "openapi");
+      for (Format ext : format) {
+        String filename = String.format("/%s.%s", appName, ext.name().toLowerCase());
+        String openAPIFileLocation = Router.normalizePath(dir) + filename;
+        filePaths.put("/openapi." + ext.name().toLowerCase(), openAPIFileLocation);
+      }
+    } else {
+      // Custom files
+      for (String file : customFiles) {
+        filePaths.put("/openapi." + Format.from(file).name().toLowerCase(), file);
+      }
+    }
+    return filePaths;
+  }
+
   private void configureUI(Jooby application) {
     Map<String, Consumer2<Jooby, AssetSource>> ui = new HashMap<>();
     ui.put("swagger-ui", this::swaggerUI);