add methods to access crontablist and get next/previous executions

Next executions plugin currently uses reflection to get the next
executions. By adding a java api the plugin can make use of that api.
Also add a method to get the next ParameterizedCronTab so one has access
to the parameters.

Author: mawinter69

pom.xml

@@ -66,6 +66,12 @@
 			<groupId>org.jenkins-ci.plugins.workflow</groupId>
 			<artifactId>workflow-job</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.kohsuke</groupId>
+			<artifactId>access-modifier-suppressions</artifactId>
+			<version>1.35</version>
+			<scope>provided</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.jenkins-ci.plugins.workflow</groupId>
 			<artifactId>workflow-cps</artifactId>

src/main/java/org/jenkinsci/plugins/parameterizedscheduler/ParameterizedCronTab.java

@@ -8,6 +8,7 @@
 import hudson.scheduler.CronTab;
 import hudson.scheduler.CronTabList;
 import hudson.scheduler.Hash;
+import org.kohsuke.accmod.restrictions.suppressions.SuppressRestrictedWarnings;
 
 /**
  * this is a copy of {@link CronTab} with added parameters map support
@@ -18,6 +19,7 @@ public class ParameterizedCronTab {
 
 	private final Map<String, String> parameterValues;
 	private final CronTabList cronTabList;
+	private final CronTab cronTab;
 
 	/**
 	 * @param cronTab the crontab to use as a template
@@ -26,6 +28,7 @@ public class ParameterizedCronTab {
 	public ParameterizedCronTab(CronTab cronTab, Map<String, String> parameters) {
 		cronTabList = new CronTabList(Collections.singleton(cronTab));
 		parameterValues = parameters;
+		this.cronTab = cronTab;
 	}
 
 	/**
@@ -60,4 +63,22 @@ public boolean check(Calendar calendar) {
 	public String checkSanity() {
 		return cronTabList.checkSanity();
 	}
+
+	@SuppressRestrictedWarnings(CronTabList.class)
+	public Calendar previous() {
+		return cronTabList.previous();
+	}
+
+	@SuppressRestrictedWarnings(CronTabList.class)
+	public Calendar next() {
+		return cronTabList.next();
+	}
+
+	public Calendar ceil(long timeInMillis) {
+		return cronTab.ceil(timeInMillis);
+	}
+
+	public Calendar floor(long timeInMillis) {
+		return cronTab.floor(timeInMillis);
+	}
 }

src/main/java/org/jenkinsci/plugins/parameterizedscheduler/ParameterizedCronTabList.java

@@ -1,5 +1,6 @@
 package org.jenkinsci.plugins.parameterizedscheduler;
 
+import edu.umd.cs.findbugs.annotations.CheckForNull;
 import hudson.scheduler.CronTabList;
 import hudson.scheduler.Hash;
 
@@ -63,4 +64,63 @@ public String checkSanity() {
 		}
 		return null;
 	}
+
+	public @CheckForNull Calendar previous() {
+		Calendar nearest = null;
+		for (ParameterizedCronTab tab : cronTabs) {
+			Calendar next = tab.next();
+			if (next == null || next.before(nearest)) {
+				nearest = next;
+			}
+		}
+		return nearest;
+	}
+
+	public @CheckForNull Calendar next() {
+		Calendar nearest = null;
+		for (ParameterizedCronTab tab : cronTabs) {
+			Calendar previous = tab.previous();
+			if (nearest == null || nearest.after(previous)) {
+				nearest = previous;
+			}
+		}
+		return nearest;
+	}
+
+	public @CheckForNull ParameterizedCronTab nextParameterizedCronTab() {
+		Calendar nearest = null;
+		ParameterizedCronTab next = null;
+		for (ParameterizedCronTab tab : cronTabs) {
+			Calendar previous = tab.previous();
+			if (nearest == null || nearest.after(previous)) {
+				nearest = previous;
+				next = tab;
+			}
+		}
+		return next;
+	}
+
+	@CheckForNull
+	public Calendar ceil(long timestamp) {
+		Calendar ceil = null;
+		for (ParameterizedCronTab wrapper: cronTabs) {
+			Calendar scheduled = wrapper.ceil(timestamp);
+			if (ceil == null || (scheduled != null && ceil.after(scheduled))) {
+				ceil = scheduled;
+			}
+		}
+		return ceil;
+	}
+
+	@CheckForNull
+	public Calendar floor(long timestamp) {
+		Calendar floor = null;
+		for (ParameterizedCronTab wrapper: cronTabs) {
+			Calendar scheduled = wrapper.floor(timestamp);
+			if (floor == null || (scheduled != null && floor.before(scheduled))) {
+				floor = scheduled;
+			}
+		}
+		return floor;
+	}
 }

src/main/java/org/jenkinsci/plugins/parameterizedscheduler/ParameterizedTimerTrigger.java

@@ -38,6 +38,10 @@ public ParameterizedTimerTrigger(String parameterizedSpecification) {
 		this.cronTabList = ParameterizedCronTabList.create(parameterizedSpecification);
 	}
 
+	public ParameterizedCronTabList getCronTabList() {
+		return cronTabList;
+	}
+
 	@Override
 	public void run() {
 		LOGGER.fine("tried to run from base Trigger, nothing will happen");