/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.launcher3.model;
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import android.content.Context;
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import android.database.sqlite.SQLiteDatabase;
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import android.database.sqlite.SQLiteException;
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import android.util.Log;
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import android.util.SparseArray;
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import com.android.launcher3.R;
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import com.android.launcher3.provider.LauncherDbUtils.SQLiteTransaction;
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import com.android.launcher3.util.IOUtils;
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import org.json.JSONArray;
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import org.json.JSONException;
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import org.json.JSONObject;
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import java.io.File;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.ArrayList;
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import java.util.Collections;
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/**
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* Utility class to handle DB downgrade
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*/
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public class DbDowngradeHelper {
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private static final String TAG = "DbDowngradeHelper";
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private static final String KEY_VERSION = "version";
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private static final String KEY_DOWNGRADE_TO = "downgrade_to_";
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private final SparseArray<String[]> mStatements = new SparseArray<>();
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public final int version;
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private DbDowngradeHelper(int version) {
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this.version = version;
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}
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public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
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ArrayList<String> allCommands = new ArrayList<>();
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for (int i = oldVersion - 1; i >= newVersion; i--) {
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String[] commands = mStatements.get(i);
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if (commands == null) {
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throw new SQLiteException("Downgrade path not supported to version " + i);
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}
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Collections.addAll(allCommands, commands);
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}
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try (SQLiteTransaction t = new SQLiteTransaction(db)) {
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for (String sql : allCommands) {
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db.execSQL(sql);
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}
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t.commit();
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}
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}
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public static DbDowngradeHelper parse(File file) throws JSONException, IOException {
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JSONObject obj = new JSONObject(new String(IOUtils.toByteArray(file)));
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DbDowngradeHelper helper = new DbDowngradeHelper(obj.getInt(KEY_VERSION));
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for (int version = helper.version - 1; version > 0; version--) {
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if (obj.has(KEY_DOWNGRADE_TO + version)) {
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JSONArray statements = obj.getJSONArray(KEY_DOWNGRADE_TO + version);
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String[] parsed = new String[statements.length()];
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for (int i = 0; i < parsed.length; i++) {
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parsed[i] = statements.getString(i);
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}
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helper.mStatements.put(version, parsed);
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}
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}
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return helper;
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}
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public static void updateSchemaFile(File schemaFile, int expectedVersion, Context context) {
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try {
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if (DbDowngradeHelper.parse(schemaFile).version >= expectedVersion) {
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return;
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}
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} catch (Exception e) {
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// Schema error
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}
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// Write the updated schema
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try (FileOutputStream fos = new FileOutputStream(schemaFile);
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InputStream in = context.getResources().openRawResource(R.raw.downgrade_schema)) {
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IOUtils.copy(in, fos);
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} catch (IOException e) {
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Log.e(TAG, "Error writing schema file", e);
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}
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}
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}
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