[#321] Needs test

src/main/java/frc/robot/Alert.java

@@ -0,0 +1,117 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package frc.robot;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import edu.wpi.first.util.sendable.Sendable;
+import edu.wpi.first.util.sendable.SendableBuilder;
+import frc.robot.Constants.AlertsConstants.AlertType;
+import edu.wpi.first.wpilibj.DriverStation;
+import edu.wpi.first.wpilibj.Timer;
+import edu.wpi.first.wpilibj.smartdashboard.SmartDashboard;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.function.Predicate;
+
+/** Class for managing persistent alerts to be sent over NetworkTables. */
+public class Alert {
+	private static Map<String, SendableAlerts> groups = new HashMap<String, SendableAlerts>();
+
+	private final AlertType type;
+	private boolean active = false;
+	private double activeStartTime = 0.0;
+	private String text;
+
+	/**
+	 * Creates a new Alert. If this is the first to be instantiated in its group, the appropriate
+	 * entries will be added to NetworkTables.
+	 *
+	 * @param group Group identifier, also used as NetworkTables title
+	 * @param text Text to be displayed when the alert is active.
+	 * @param type Alert level specifying urgency.
+	 */
+	public Alert(String group, String text, AlertType type) {
+		if (!groups.containsKey(group)) {
+			groups.put(group, new SendableAlerts());
+			SmartDashboard.putData(group, groups.get(group));
+		}
+
+		this.text = text;
+		this.type = type;
+		groups.get(group).alerts.add(this);
+	}
+
+	/**
+	 * Creates a new Alert in the default group - "Alerts". If this is the first to be instantiated, the
+	 * appropriate entries will be added to NetworkTables.
+	 *
+	 * @param text Text to be displayed when the alert is active.
+	 * @param type Alert level specifying urgency.
+	 */
+	public Alert(String text, AlertType type) {
+		this("Alerts", text, type);
+	}
+
+	/**
+	 * Sets whether the alert should currently be displayed. When activated, the alert text will also be
+	 * sent to the console.
+	 */
+	public void set(boolean active) {
+		if (active && !this.active) {
+			activeStartTime = Timer.getFPGATimestamp();
+			switch (type) {
+				case ERROR:
+					DriverStation.reportError(text, false);
+					break;
+				case WARNING:
+					DriverStation.reportWarning(text, false);
+					break;
+				case INFO:
+					System.out.println(text);
+					break;
+			}
+		}
+		this.active = active;
+	}
+
+	/** Updates current alert text. */
+	public void setText(String text) {
+		if (active && !text.equals(this.text)) {
+			switch (type) {
+				case ERROR:
+					DriverStation.reportError(text, false);
+					break;
+				case WARNING:
+					DriverStation.reportWarning(text, false);
+					break;
+				case INFO:
+					System.out.println(text);
+					break;
+			}
+		}
+		this.text = text;
+	}
+
+	private static class SendableAlerts implements Sendable {
+		public final List<Alert> alerts = new ArrayList<>();
+
+		public String[] getStrings(AlertType type) {
+			Predicate<Alert> activeFilter = (Alert x) -> x.type == type && x.active;
+			Comparator<Alert> timeSorter = (Alert a1, Alert a2) -> (int) (a2.activeStartTime - a1.activeStartTime);
+			return alerts.stream().filter(activeFilter).sorted(timeSorter).map((Alert a) -> a.text).toArray(String[]::new);
+		}
+
+		@Override
+		public void initSendable(SendableBuilder builder) {
+			builder.setSmartDashboardType("Alerts");
+			builder.addStringArrayProperty("errors", () -> getStrings(AlertType.ERROR), null);
+			builder.addStringArrayProperty("warnings", () -> getStrings(AlertType.WARNING), null);
+			builder.addStringArrayProperty("infos", () -> getStrings(AlertType.INFO), null);
+		}
+	}
+}

src/main/java/frc/robot/Constants.java

@@ -566,4 +566,13 @@ public static enum ScoreingState {
             setLift, moveToScore, score, moveToStow, stow
         }
     }
+
+    public static final class AlertsConstants {
+        public static final double LOG_PERIOD = 0.5;
+        public static enum AlertType {
+            ERROR, // High priority alert  RED X
+            WARNING, // Medium priority alert YELLOW !
+            INFO // Low priority alert GREEN i
+        }
+    }
 }