O3-310: allow Put operations on an application-writable config.json file

There should be a `config.json` file that the application is allowed to manage, which lives in the application data directory.

omod-1.9/src/main/java/org/openmrs/module/webservices/rest/web/v1_0/controller/openmrs1_9/FrontendJsonConfigController1_9.java

@@ -0,0 +1,136 @@
+/**
+ * This Source Code Form is subject to the terms of the Mozilla Public License,
+ * v. 2.0. If a copy of the MPL was not distributed with this file, You can
+ * obtain one at http://mozilla.org/MPL/2.0/. OpenMRS is also distributed under
+ * the terms of the Healthcare Disclaimer located at http://openmrs.org/license.
+ *
+ * Copyright (C) OpenMRS Inc. OpenMRS is a registered trademark and the OpenMRS
+ * graphic logo is a trademark of OpenMRS Inc.
+ */
+package org.openmrs.module.webservices.rest.web.v1_0.controller.openmrs1_9;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.charset.StandardCharsets;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.openmrs.User;
+import org.openmrs.api.AdministrationService;
+import org.openmrs.api.context.Context;
+import org.openmrs.module.webservices.rest.web.RestConstants;
+import org.openmrs.module.webservices.rest.web.v1_0.controller.BaseRestController;
+import org.openmrs.util.OpenmrsUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.codehaus.jackson.JsonProcessingException;
+import org.codehaus.jackson.map.ObjectMapper;
+
+@Controller
+@RequestMapping(value = "/rest/" + RestConstants.VERSION_1 + "/frontend/config.json")
+public class FrontendJsonConfigController1_9 extends BaseRestController {
+
+    private static final String DEFAULT_FRONTEND_DIRECTORY = "frontend";
+    private static final String GP_LOCAL_DIRECTORY = "spa.local.directory";
+    private static final String JSON_CONFIG_FILE_NAME = "config.json";
+
+    private static final Logger log = LoggerFactory.getLogger(FrontendJsonConfigController1_9.class);
+
+    @RequestMapping(method = RequestMethod.GET)
+	public void getFrontendConfigFile(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        File jsonConfigFile = getJsonConfigFile();
+        if (!jsonConfigFile.exists()) {
+            log.debug("Configuration file does not exist");
+            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Configuration file does not exist");
+        }
+        try {
+            InputStream inputStream = new FileInputStream(jsonConfigFile);
+            OutputStream outStream = response.getOutputStream();
+            OpenmrsUtil.copyFile(inputStream, outStream);
+
+            response.setContentType("application/json");
+            response.setHeader("Content-Disposition", "attachment; filename=" + jsonConfigFile.getName());
+            response.setStatus(HttpServletResponse.SC_OK);
+        } catch (IOException e) {
+            log.error("Error reading Configuration file: " + jsonConfigFile.getAbsolutePath(), e);
+            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Error reading Configuration file: " + jsonConfigFile.getPath());
+        }
+	}
+
+    @RequestMapping(method = RequestMethod.POST)
+    @ResponseStatus(HttpStatus.OK)
+    public void saveFrontendConfigFile(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        User user = Context.getAuthenticatedUser();
+        if (user == null || !user.isSuperUser()) {
+            log.error("Authorization error while creating a config.json file");
+            response.sendError(HttpServletResponse.SC_FORBIDDEN, "Authorization error while creating a config.json file");
+            return;
+        }
+        saveJsonConfigFile(request, response);
+    }
+
+    private void saveJsonConfigFile(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        File jsonConfigFile = getJsonConfigFile();
+        try {
+            BufferedReader reader = request.getReader();
+            StringBuilder stringBuilder = new StringBuilder();
+            String line;
+            while ((line = reader.readLine()) != null) {
+                stringBuilder.append(line);
+            }
+            String requestBody = stringBuilder.toString();
+
+            // verify that is in a valid JSON format
+            new ObjectMapper().readTree(requestBody);
+
+            InputStream inputStream = new ByteArrayInputStream(requestBody.getBytes(StandardCharsets.UTF_8));
+            OutputStream outStream = Files.newOutputStream(jsonConfigFile.toPath());
+            OpenmrsUtil.copyFile(inputStream, outStream);
+
+            if (jsonConfigFile.exists()) {
+                log.debug("file: '{}' written successfully", jsonConfigFile.getAbsolutePath());
+                response.setStatus(HttpServletResponse.SC_OK);
+            }
+        } catch (JsonProcessingException e) {
+            log.error("Invalid JSON format", e);
+            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Invalid JSON format");
+        }
+    }
+
+    private File getJsonConfigFile() throws IOException {
+        File folder = getSpaStaticFilesDir();
+        if (!folder.isDirectory()) {
+            log.debug("Unable to find the OpenMRS SPA module frontend directory hence creating it at: " + folder.getAbsolutePath());
+            if (!folder.mkdirs()) {
+                throw new IOException("Failed to create the OpenMRS SPA module frontend directory at: " + folder.getPath());
+            }
+        }
+        return new File(folder.getAbsolutePath(), JSON_CONFIG_FILE_NAME);
+    }
+
+    private File getSpaStaticFilesDir() {
+        AdministrationService as = Context.getAdministrationService();
+        String folderName = as.getGlobalProperty(GP_LOCAL_DIRECTORY, DEFAULT_FRONTEND_DIRECTORY);
+
+        // try to load the repository folder straight away.
+        File folder = new File(folderName);
+
+        // if the property wasn't a full path already, assume it was intended to be a
+        // folder in the application directory
+        if (!folder.exists()) {
+            folder = new File(OpenmrsUtil.getApplicationDataDirectory(), folderName);
+        }
+        return folder;
+    }
+}