Text classification experiment

ATTRIBUTION.md

@@ -29,3 +29,4 @@ FairEmail uses:
 * [Over-Scroll Support For Android's RecyclerView, ListView, GridView, ScrollView ...](https://github.com/EverythingMe/overscroll-decor). Copyright (c) 2015, DoAT Media Ltd. [BSD-2-Clause License](https://github.com/EverythingMe/overscroll-decor/blob/master/LICENSE)
 * [Compact Encoding Detection](https://github.com/google/compact_enc_det). Copyright 2016 Google Inc. [Apache License 2.0](https://github.com/google/compact_enc_det/blob/master/LICENSE).
 * [POI-HMEF](https://poi.apache.org/components/hmef/index.html). Copyright © 2001-2020 The Apache Software Foundation. [Apache Software License v2](https://poi.apache.org/devel/guidelines.html#The+Licensing).
+* [Java Naive Bayes Classifier](https://github.com/ptnplanet/Java-Naive-Bayes-Classifier). Copyright (c) 2012-2017 Philipp Nolte. [MIT License](https://github.com/ptnplanet/Java-Naive-Bayes-Classifier#the-mit-license-mit).

app/build.gradle

@@ -278,6 +278,7 @@ dependencies {
     def appauth_version = "0.7.1"
     def jcharset_version = "2.1"
     def apache_poi = "3.17"
+    def bayes_version = "1.0.7"
 
     // https://developer.android.com/jetpack/androidx/releases/
 
@@ -442,4 +443,7 @@ dependencies {
     // https://poi.apache.org/components/hmef/index.html
     // https://mvnrepository.com/artifact/org.apache.poi/poi-scratchpad
     implementation "org.apache.poi:poi-scratchpad:$apache_poi"
+
+    // https://github.com/ptnplanet/Java-Naive-Bayes-Classifier
+    implementation "com.github.ptnplanet:Java-Naive-Bayes-Classifier:$bayes_version"
 }

app/src/main/assets/ATTRIBUTION.md

@@ -29,3 +29,4 @@ FairEmail uses:
 * [Over-Scroll Support For Android's RecyclerView, ListView, GridView, ScrollView ...](https://github.com/EverythingMe/overscroll-decor). Copyright (c) 2015, DoAT Media Ltd. [BSD-2-Clause License](https://github.com/EverythingMe/overscroll-decor/blob/master/LICENSE)
 * [Compact Encoding Detection](https://github.com/google/compact_enc_det). Copyright 2016 Google Inc. [Apache License 2.0](https://github.com/google/compact_enc_det/blob/master/LICENSE).
 * [POI-HMEF](https://poi.apache.org/components/hmef/index.html). Copyright © 2001-2020 The Apache Software Foundation. [Apache Software License v2](https://poi.apache.org/devel/guidelines.html#The+Licensing).
+* [Java Naive Bayes Classifier](https://github.com/ptnplanet/Java-Naive-Bayes-Classifier). Copyright (c) 2012-2017 Philipp Nolte. [MIT License](https://github.com/ptnplanet/Java-Naive-Bayes-Classifier#the-mit-license-mit).

app/src/main/java/eu/faircode/email/WorkerFts.java

@@ -22,6 +22,7 @@
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.database.Cursor;
+import android.text.TextUtils;
 
 import androidx.annotation.NonNull;
 import androidx.preference.PreferenceManager;
@@ -34,17 +35,22 @@
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
+import de.daslaboratorium.machinelearning.classifier.Classification;
+import de.daslaboratorium.machinelearning.classifier.bayes.BayesClassifier;
 import io.requery.android.database.sqlite.SQLiteDatabase;
 
 import static android.os.Process.THREAD_PRIORITY_BACKGROUND;
 
 public class WorkerFts extends Worker {
-    private static final int INDEX_DELAY = 30; // seconds
+    private static final int INDEX_DELAY = BuildConfig.DEBUG ? 3 : 30; // seconds
     private static final int INDEX_BATCH_SIZE = 100;
 
+    private static BayesClassifier<String, String> classifier = new BayesClassifier<>();
+
     public WorkerFts(@NonNull Context context, @NonNull WorkerParameters workerParams) {
         super(context, workerParams);
         Log.i("Instance " + getName());
@@ -78,6 +84,30 @@ public Result doWork() {
                             File file = message.getFile(getApplicationContext());
                             String text = HtmlHelper.getFullText(file);
 
+                            if (BuildConfig.DEBUG) {
+                                EntityFolder folder = db.folder().getFolder(message.folder);
+                                if (folder != null) {
+                                    // \\P{L}+
+                                    List<String> features = new ArrayList<>();
+                                    for (String word : text.trim().toLowerCase().split("\\W+")) {
+                                        if (word.matches(".*\\d.*"))
+                                            continue;
+                                        if (word.endsWith("."))
+                                            word = word.substring(0, word.length() - 1);
+                                        features.add(word);
+                                    }
+
+                                    Collection<Classification<String, String>> classifications = classifier.classifyDetailed(features);
+                                    for (Classification<String, String> classification : classifications)
+                                        Log.i("MMM folder=" + folder.name +
+                                                " classified=" + classification.getCategory() +
+                                                " probability=" + classification.getProbability() +
+                                                " features=" + TextUtils.join(", ", features.subList(0, Math.min(features.size(), 20))));
+
+                                    classifier.learn(EntityFolder.JUNK.equals(folder.type) ? "spam" : "ham", features);
+                                }
+                            }
+
                             try {
                                 sdb.beginTransaction();
                                 FtsDbHelper.insert(sdb, message, text);