#1254 Create command to see recently logged in players

- Create datasource method to fetch most recent players by last login date
- Add command to view last logged in players

src/main/java/fr/xephi/authme/command/executable/authme/RecentPlayersCommand.java

@@ -0,0 +1,50 @@
+package fr.xephi.authme.command.executable.authme;
+
+import com.google.common.annotations.VisibleForTesting;
+import fr.xephi.authme.command.ExecutableCommand;
+import fr.xephi.authme.data.auth.PlayerAuth;
+import fr.xephi.authme.datasource.DataSource;
+import org.bukkit.ChatColor;
+import org.bukkit.command.CommandSender;
+
+import javax.inject.Inject;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+
+import static java.time.Instant.ofEpochMilli;
+
+/**
+ * Command showing the most recent logged in players.
+ */
+public class RecentPlayersCommand implements ExecutableCommand {
+
+    /** DateTime formatter, producing Strings such as "10:42 AM, 11 Jul". */
+    private static final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ofPattern("hh:mm a, dd MMM");
+
+    @Inject
+    private DataSource dataSource;
+
+    @Override
+    public void executeCommand(CommandSender sender, List<String> arguments) {
+        List<PlayerAuth> recentPlayers = dataSource.getRecentlyLoggedInPlayers();
+
+        sender.sendMessage(ChatColor.BLUE + "[AuthMe] Recently logged in players");
+        for (PlayerAuth auth : recentPlayers) {
+            sender.sendMessage(formatPlayerMessage(auth));
+        }
+    }
+
+    @VisibleForTesting
+    ZoneId getZoneId() {
+        return ZoneId.systemDefault();
+    }
+
+    private String formatPlayerMessage(PlayerAuth auth) {
+        LocalDateTime lastLogin = LocalDateTime.ofInstant(ofEpochMilli(auth.getLastLogin()), getZoneId());
+        String lastLoginText = DATE_FORMAT.format(lastLogin);
+
+        return "- " + auth.getRealName() + " (" + lastLoginText + " with IP " + auth.getLastIp() + ")";
+    }
+}