Add linux schedule management functions

src/main/java/name/nathanmcrae/numbersstation/LinuxScheduler.java

@@ -60,6 +60,10 @@ public class LinuxScheduler {
                     matcher.appendReplacement(sb, "");
                 }
 
+                if (foundMultiple) {
+                    logger.log(Level.WARNING, "Found multiple instances of '" + taskName + "' prior to replacement");
+                }
+
                 matcher.appendTail(sb);
             } else {
                 sb.append(currentCrontab);
@@ -95,6 +99,105 @@ public class LinuxScheduler {
         return Results.success(true);
     }
 
+    public static Result<Boolean, String> scheduleExists(StationSettings settings) {
+        try {
+            String taskName = "numbers-station-main_" + settings.getName();
+
+            Process listProcess = new ProcessBuilder("crontab", "-l").start();
+            if (!listProcess.waitFor(5, TimeUnit.SECONDS)) {
+                String message = "Failed to query " + taskName + " task: process timed out";
+                logger.log(Level.SEVERE, message);
+                return Results.failure(message);
+            }
+
+            Pair<String, String> output = WindowsScheduler.captureProcessOutput(listProcess);
+            if(listProcess.exitValue() != 0) {
+                String message = "Failed to get user id. Exit code: " + listProcess.exitValue() + ". stdout: " + output.getKey() + "\n\tstderr: " + output.getValue();
+                logger.log(Level.SEVERE, message);
+                return Results.failure(message);
+            }
+
+            String currentCrontab = output.getKey();
+
+            String cronEntry = "# " + taskName + "\n" + cronExpression(settings) + "\n\n";
+
+            Pattern pattern = Pattern.compile("# " + taskName + "\\n[^\\n]+\\n\\n");
+
+            Matcher matcher = pattern.matcher(currentCrontab);
+
+            if (matcher.find()) {
+                return Results.success(true);
+            } else {
+                return Results.success(true);
+            }
+        } catch (CronExpressionException | IOException | InterruptedException e) {
+            String message = "Exception while checking for schedule";
+            logger.log(Level.SEVERE, message, e);
+            return Results.failure(message);
+        }
+    }
+
+    public static Result<Boolean, String> removeSchedule(StationSettings settings) {
+        try {
+            String taskName = "numbers-station-main_" + settings.getName();
+
+            Process listProcess = new ProcessBuilder("crontab", "-l").start();
+            if (!listProcess.waitFor(5, TimeUnit.SECONDS)) {
+                String message = "Failed to query " + taskName + " task: process timed out";
+                logger.log(Level.SEVERE, message);
+                return Results.failure(message);
+            }
+
+            Pair<String, String> output = WindowsScheduler.captureProcessOutput(listProcess);
+            if(listProcess.exitValue() != 0) {
+                String message = "Failed to get user id. Exit code: " + listProcess.exitValue() + ". stdout: " + output.getKey() + "\n\tstderr: " + output.getValue();
+                logger.log(Level.SEVERE, message);
+                return Results.failure(message);
+            }
+
+            String currentCrontab = output.getKey();
+
+            String cronEntry = "# " + taskName + "\n" + cronExpression(settings) + "\n\n";
+
+            Pattern pattern = Pattern.compile("# " + taskName + "\\n[^\\n]+\\n\\n");
+
+            Matcher matcher = pattern.matcher(currentCrontab);
+
+            StringBuilder sb = new StringBuilder();
+
+            while (matcher.find()) {
+                matcher.appendReplacement(sb, "");
+            }
+
+            String newCrontab = sb.toString();
+
+            Process addProcess = new ProcessBuilder("crontab", "-").start();
+            Writer w = new OutputStreamWriter(addProcess.getOutputStream(), "UTF-8");
+            System.out.println(newCrontab);
+            w.write(newCrontab);
+            w.flush();
+            w.close();
+            if (!addProcess.waitFor(5, TimeUnit.SECONDS)) {
+                String message = "Failed to register " + taskName + " task: process timed out";
+                logger.log(Level.SEVERE, message);
+                return Results.failure(message);
+            }
+
+            if(addProcess.exitValue() != 0) {
+                Pair<String, String> addOutput = WindowsScheduler.captureProcessOutput(addProcess);
+                String message = "Failed to get user id. Exit code: " + addProcess.exitValue() + ". stdout: " + addOutput.getKey() + ". stderr: " + addOutput.getValue();
+                logger.log(Level.SEVERE, message);
+                return Results.failure(message);
+            }
+        } catch (CronExpressionException | IOException | InterruptedException e) {
+            String message = "Exception while removing schedule";
+            logger.log(Level.SEVERE, message, e);
+            return Results.failure(message);
+        }
+
+        return Results.success(true);
+    }
+
     /**
      *  * * * * * {command to execute}
      *  | | | | |

src/main/java/name/nathanmcrae/numbersstation/StationSettings.java

@@ -81,8 +81,7 @@ public class StationSettings {
         if (osName.contains("win")) {
             WindowsScheduler.removeSchedule(temp);
         } else if (osName.contains("nix") || osName.contains("nux") || osName.contains("aix")) {
-            // TODO: linux
+            LinuxScheduler.removeSchedule(temp);
-            logger.log(Level.SEVERE, "Unsupported OS " + osName);
         } else {
             logger.log(Level.SEVERE, "Unsupported OS " + osName);
         }
@@ -101,8 +100,10 @@ public class StationSettings {
                 return true;
             }
         } else if (osName.contains("nix") || osName.contains("nux") || osName.contains("aix")) {
-            // TODO: linux
+            Result<Boolean, String> result = LinuxScheduler.scheduleExists(temp);
-            logger.log(Level.SEVERE, "Unsupported OS " + osName);
+            if (result.hasSuccess() && result.getSuccess().get()) {
+                return true;
+            }
         } else {
             logger.log(Level.SEVERE, "Unsupported OS " + osName);
         }