Add search loader for installed apps.

- The loader filters out system apps.
- Loader performs case-insensitive match with app names.
- SearchResultAdapter combines results from multiple loaders into a
  single list.

Fixes: 33347966
Test: make RunSettingsRoboTests
Change-Id: I228ca6fb82f0ac5151b2346c079c2de41104a4df

src/com/android/settings/search2/InstalledAppResultLoader.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.search2;
+
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.UserInfo;
+import android.net.Uri;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.provider.Settings;
+import android.text.TextUtils;
+
+import com.android.settings.applications.PackageManagerWrapper;
+import com.android.settings.utils.AsyncLoader;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Search loader for installed apps.
+ */
+public class InstalledAppResultLoader extends AsyncLoader<List<SearchResult>> {
+
+    private static final int NAME_NO_MATCH = -1;
+    private static final int NAME_EXACT_MATCH = 0;
+
+    private final String mQuery;
+    private final UserManager mUserManager;
+    private final PackageManagerWrapper mPackageManager;
+
+    public InstalledAppResultLoader(Context context, PackageManagerWrapper pmWrapper,
+            String query) {
+        super(context);
+        mUserManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+        mPackageManager = pmWrapper;
+        mQuery = query;
+    }
+
+    @Override
+    public List<SearchResult> loadInBackground() {
+        final List<SearchResult> results = new ArrayList<>();
+        final PackageManager pm = mPackageManager.getPackageManager();
+
+        for (UserInfo user : getUsersToCount()) {
+            final List<ApplicationInfo> apps =
+                    mPackageManager.getInstalledApplicationsAsUser(
+                            PackageManager.MATCH_DISABLED_COMPONENTS
+                                    | PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS
+                                    | (user.isAdmin() ? PackageManager.MATCH_ANY_USER : 0),
+                            user.id);
+            for (ApplicationInfo info : apps) {
+                if (info.isSystemApp()) {
+                    continue;
+                }
+                final CharSequence label = info.loadLabel(pm);
+                final int wordDiff = getWordDifference(label.toString(), mQuery);
+                if (wordDiff == NAME_NO_MATCH) {
+                    continue;
+                }
+                final Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS)
+                        .setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS)
+                        .setData(Uri.fromParts("package", info.packageName, null));
+
+                final SearchResult.Builder builder = new SearchResult.Builder();
+                builder.addIcon(info.loadIcon(pm))
+                        .addTitle(info.loadLabel(pm))
+                        .addRank(wordDiff)
+                        .addPayload(new IntentPayload(intent));
+                results.add(builder.build());
+            }
+        }
+        Collections.sort(results);
+        return results;
+    }
+
+    @Override
+    protected void onDiscardResult(List<SearchResult> result) {
+
+    }
+
+    private List<UserInfo> getUsersToCount() {
+        return mUserManager.getProfiles(UserHandle.myUserId());
+    }
+
+    /**
+     * Returns "difference" between appName and query string. appName must contain all
+     * characters from query, in the same order. If not, returns NAME_NO_MATCH. If they do match,
+     * returns an int value representing how different they are, NAME_EXACT_MATCH means they match
+     * perfectly, and larger values means they are less similar.
+     * <p/>
+     * Example:
+     * appName: Abcde, query: Abcde, Returns NAME_EXACT_MATCH
+     * appName: Abcde, query: ade, Returns 2
+     * appName: Abcde, query: ae, Returns 3
+     * appName: Abcde, query: ea, Returns NAME_NO_MATCH
+     * appName: Abcde, query: xyz, Returns NAME_NO_MATCH
+     */
+    private int getWordDifference(String appName, String query) {
+        if (TextUtils.isEmpty(appName) || TextUtils.isEmpty(query)) {
+            return NAME_NO_MATCH;
+        }
+        final char[] queryTokens = query.toString().toLowerCase().toCharArray();
+        final char[] valueText = appName.toLowerCase().toCharArray();
+        if (queryTokens.length > valueText.length) {
+            return NAME_NO_MATCH;
+        }
+        int i = 0;
+        int j = 0;
+        while (i < valueText.length && j < queryTokens.length) {
+            if (valueText[i++] == queryTokens[j]) {
+                j++;
+            }
+        }
+        if (j != queryTokens.length) {
+            return NAME_NO_MATCH;
+        }
+        // Use the diff in length as a proxy of how close the 2 words match. Value range from 0
+        // to infinity.
+        return valueText.length - queryTokens.length;
+    }
+}