1.3.0: add `/blame stat` for showing statistics.

3 files changed, 140 insertions, 2 deletions

diff --git a/src/main/java/com/keuin/blame/Blame.java b/src/main/java/com/keuin/blame/Blame.java
index 2bf93ca..a4c806d 100644
--- a/src/main/java/com/keuin/blame/Blame.java
+++ b/src/main/java/com/keuin/blame/Blame.java
@@ -5,6 +5,7 @@ import com.keuin.blame.adapter.*;
 import com.keuin.blame.adapter.handler.PlaceBlockHandler;
 import com.keuin.blame.command.BlameBlockCommand;
 import com.keuin.blame.command.BlameLimitCommand;
+import com.keuin.blame.command.BlameStatCommand;
 import com.keuin.blame.config.BlameConfig;
 import com.keuin.blame.lookup.LookupManager;
 import com.keuin.blame.util.DatabaseUtil;
@@ -124,11 +125,17 @@ public class Blame implements ModInitializer {
                                         .then(CommandManager.argument("y", IntegerArgumentType.integer())
                                                 .then(CommandManager.argument("z", IntegerArgumentType.integer())
                                                         .then(CommandManager.argument("world", StringArgumentType.greedyString())
-                                                                .executes(BlameBlockCommand::blameGivenBlockPos)))))));
+                                                                .executes(BlameBlockCommand::blameGivenBlockPos))))))
+                );
                 commandDispatcher.register(
                         CommandManager.literal("blame").then(CommandManager.literal("limit")
                                 .then(CommandManager.argument("limit", IntegerArgumentType.integer(1, 255))
-                                        .executes(BlameLimitCommand::setLimit))));
+                                        .executes(BlameLimitCommand::setLimit)))
+                );
+                commandDispatcher.register(
+                        CommandManager.literal("blame").then(CommandManager.literal("stat")
+                        .executes(BlameStatCommand::showStat))
+                );
             }
         });
     }
diff --git a/src/main/java/com/keuin/blame/command/BlameStatCommand.java b/src/main/java/com/keuin/blame/command/BlameStatCommand.java
new file mode 100644
index 0000000..677ea88
--- /dev/null
+++ b/src/main/java/com/keuin/blame/command/BlameStatCommand.java
@@ -0,0 +1,109 @@
+package com.keuin.blame.command;
+
+import com.keuin.blame.data.entry.LogEntry;
+import com.keuin.blame.data.helper.VersionedLogEntryHelper;
+import com.keuin.blame.util.DatabaseUtil;
+import com.keuin.blame.util.PrintUtil;
+import com.mojang.brigadier.context.CommandContext;
+import com.mongodb.MongoClientException;
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+import net.minecraft.server.command.ServerCommandSource;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.*;
+import java.util.logging.Logger;
+
+public class BlameStatCommand {
+
+    private static final Logger logger = Logger.getLogger(BlameStatCommand.class.getName());
+
+    public static int showStat(CommandContext<ServerCommandSource> context) {
+        showStat(new ShowStatCallback() {
+            @Override
+            public void showStat(@Nullable BlameStat stat) {
+                StringBuilder sb = new StringBuilder();
+                if (stat != null) {
+                    sb.append("Data statistics\n");
+                    sb.append("===============\n");
+                    sb.append("\n");
+                    sb.append("# Count by subjects\n");
+                    stat.getCountMap().forEach((subjectId, count) -> {
+                        sb.append(subjectId).append(": ").append(count).append("\n");
+                    });
+                    sb.append("\n");
+                    sb.append("=== END ===\n");
+                } else {
+                    sb.append("Failed to get statistics. Please refer to server log for more information.\n");
+                }
+                PrintUtil.msgInfo(context, sb.toString());
+            }
+        });
+        return Commands.SUCCESS;
+    }
+
+    public static void showStat(ShowStatCallback callback) {
+        Objects.requireNonNull(callback);
+        new Thread(new Runnable() {
+            @Override
+            public void run() {
+                logger.info("Collecting statistics...");
+                try (final MongoClient mongoClient = MongoClients.create(DatabaseUtil.CLIENT_SETTINGS)) {
+                    final MongoDatabase db = mongoClient.getDatabase(
+                            DatabaseUtil.MONGO_CONFIG.getDatabaseName()
+                    );
+                    final MongoCollection<LogEntry> collection = db.getCollection(
+                            DatabaseUtil.MONGO_CONFIG.getLogCollectionName(), LogEntry.class
+                    );
+                    Collection<String> ids = VersionedLogEntryHelper.getLoggedSubjectsId(collection);
+
+                    // count by distinct subjects
+                    Map<String, Long> countMap = new HashMap<>();
+                    for (String subjectId : ids) {
+                        long count = VersionedLogEntryHelper.countBySubjectId(collection, subjectId);
+                        countMap.put(subjectId, count);
+                    }
+
+                    // invoke callback
+                    callback.showStat(new BlameStat(countMap));
+                } catch (MongoClientException exception) {
+                    logger.severe("Failed when querying the database: " + exception +
+                            ". Failed to get statistics.");
+                    callback.showStat(null);
+                }
+            }
+        }).start();
+    }
+
+    public static class BlameStat {
+        private final Map<String, Long> countMap;
+
+        public BlameStat(Map<String, Long> countMap) {
+            this.countMap = countMap;
+        }
+
+        public Map<String, Long> getCountMap() {
+            return Collections.unmodifiableMap(countMap);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            BlameStat blameStat = (BlameStat) o;
+            return Objects.equals(countMap, blameStat.countMap);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(countMap);
+        }
+    }
+
+    public interface ShowStatCallback {
+        void showStat(@Nullable BlameStat stat);
+    }
+
+}
diff --git a/src/main/java/com/keuin/blame/data/helper/VersionedLogEntryHelper.java b/src/main/java/com/keuin/blame/data/helper/VersionedLogEntryHelper.java
new file mode 100644
index 0000000..064ae87
--- /dev/null
+++ b/src/main/java/com/keuin/blame/data/helper/VersionedLogEntryHelper.java
@@ -0,0 +1,22 @@
+package com.keuin.blame.data.helper;
+
+import com.keuin.blame.data.entry.LogEntry;
+import com.keuin.blame.data.entry.LogEntryNames;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.model.Filters;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+public class VersionedLogEntryHelper {
+    public static Collection<String> getLoggedSubjectsId(MongoCollection<LogEntry> collection) {
+        List<String> list = new ArrayList<>();
+        for (String s : collection.distinct(LogEntryNames.SUBJECT_ID, String.class))
+            list.add(s);
+        return list;
+    }
+    public static long countBySubjectId(MongoCollection<LogEntry> collection, String subjectId) {
+        return collection.countDocuments(Filters.eq(LogEntryNames.SUBJECT_ID, subjectId));
+    }
+}