src/com/android/browser/provider/SnapshotProvider.java

/*
 * Copyright (C) 2011 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.browser.provider;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.os.FileUtils;
import android.provider.BrowserContract;
import android.text.TextUtils;

import java.io.File;

public class SnapshotProvider extends ContentProvider {

    public static interface Snapshots {

        public static final Uri CONTENT_URI = Uri.withAppendedPath(
                SnapshotProvider.AUTHORITY_URI, "snapshots");
        public static final String _ID = "_id";
        @Deprecated
        public static final String VIEWSTATE = "view_state";
        public static final String BACKGROUND = "background";
        public static final String TITLE = "title";
        public static final String URL = "url";
        public static final String FAVICON = "favicon";
        public static final String THUMBNAIL = "thumbnail";
        public static final String DATE_CREATED = "date_created";
        public static final String VIEWSTATE_PATH = "viewstate_path";
        public static final String VIEWSTATE_SIZE = "viewstate_size";
    }

    public static final String AUTHORITY = "com.android.browser.snapshots";
    public static final Uri AUTHORITY_URI = Uri.parse("content://" + AUTHORITY);

    static final String TABLE_SNAPSHOTS = "snapshots";
    static final int SNAPSHOTS = 10;
    static final int SNAPSHOTS_ID = 11;
    static final UriMatcher URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
    // Workaround that we can't remove the "NOT NULL" constraint on VIEWSTATE
    static final byte[] NULL_BLOB_HACK = new byte[0];

    SnapshotDatabaseHelper mOpenHelper;

    static {
        URI_MATCHER.addURI(AUTHORITY, "snapshots", SNAPSHOTS);
        URI_MATCHER.addURI(AUTHORITY, "snapshots/#", SNAPSHOTS_ID);
    }

    final static class SnapshotDatabaseHelper extends SQLiteOpenHelper {

        static final String DATABASE_NAME = "snapshots.db";
        static final int DATABASE_VERSION = 3;

        public SnapshotDatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE " + TABLE_SNAPSHOTS + "(" +
                    Snapshots._ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
                    Snapshots.TITLE + " TEXT," +
                    Snapshots.URL + " TEXT NOT NULL," +
                    Snapshots.DATE_CREATED + " INTEGER," +
                    Snapshots.FAVICON + " BLOB," +
                    Snapshots.THUMBNAIL + " BLOB," +
                    Snapshots.BACKGROUND + " INTEGER," +
                    Snapshots.VIEWSTATE + " BLOB NOT NULL," +
                    Snapshots.VIEWSTATE_PATH + " TEXT," +
                    Snapshots.VIEWSTATE_SIZE + " INTEGER" +
                    ");");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            if (oldVersion < 2) {
                db.execSQL("DROP TABLE " + TABLE_SNAPSHOTS);
                onCreate(db);
            }
            if (oldVersion < 3) {
                db.execSQL("ALTER TABLE " + TABLE_SNAPSHOTS + " ADD COLUMN "
                        + Snapshots.VIEWSTATE_PATH + " TEXT");
                db.execSQL("ALTER TABLE " + TABLE_SNAPSHOTS + " ADD COLUMN "
                        + Snapshots.VIEWSTATE_SIZE + " INTEGER");
                db.execSQL("UPDATE " + TABLE_SNAPSHOTS + " SET "
                        + Snapshots.VIEWSTATE_SIZE + " = length("
                        + Snapshots.VIEWSTATE + ")");
            }
        }

    }

    static File getOldDatabasePath(Context context) {
        File dir = context.getExternalFilesDir(null);
        return new File(dir, SnapshotDatabaseHelper.DATABASE_NAME);
    }

    private void migrateToDataFolder() {
        File dbPath = getContext().getDatabasePath(SnapshotDatabaseHelper.DATABASE_NAME);
        if (dbPath.exists()) return;
        File oldPath = getOldDatabasePath(getContext());
        if (oldPath.exists()) {
            // Try to move
            if (!oldPath.renameTo(dbPath)) {
                // Failed, do a copy
                FileUtils.copyFile(oldPath, dbPath);
            }
            // Cleanup
            oldPath.delete();
        }
    }

    @Override
    public boolean onCreate() {
        migrateToDataFolder();
        mOpenHelper = new SnapshotDatabaseHelper(getContext());
        return true;
    }

    SQLiteDatabase getWritableDatabase() {
        return mOpenHelper.getWritableDatabase();
    }

    SQLiteDatabase getReadableDatabase() {
        return mOpenHelper.getReadableDatabase();
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        SQLiteDatabase db = getReadableDatabase();
        if (db == null) {
            return null;
        }
        final int match = URI_MATCHER.match(uri);
        SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
        String limit = uri.getQueryParameter(BrowserContract.PARAM_LIMIT);
        switch (match) {
        case SNAPSHOTS_ID:
            selection = DatabaseUtils.concatenateWhere(selection, "_id=?");
            selectionArgs = DatabaseUtils.appendSelectionArgs(selectionArgs,
                    new String[] { Long.toString(ContentUris.parseId(uri)) });
            // fall through
        case SNAPSHOTS:
            qb.setTables(TABLE_SNAPSHOTS);
            break;

        default:
            throw new UnsupportedOperationException("Unknown URL " + uri.toString());
        }
        Cursor cursor = qb.query(db, projection, selection, selectionArgs,
                null, null, sortOrder, limit);
        cursor.setNotificationUri(getContext().getContentResolver(),
                AUTHORITY_URI);
        return cursor;
    }

    @Override
    public String getType(Uri uri) {
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = getWritableDatabase();
        if (db == null) {
            return null;
        }
        int match = URI_MATCHER.match(uri);
        long id = -1;
        switch (match) {
        case SNAPSHOTS:
            if (!values.containsKey(Snapshots.VIEWSTATE)) {
                values.put(Snapshots.VIEWSTATE, NULL_BLOB_HACK);
            }
            id = db.insert(TABLE_SNAPSHOTS, Snapshots.TITLE, values);
            break;
        default:
            throw new UnsupportedOperationException("Unknown insert URI " + uri);
        }
        if (id < 0) {
            return null;
        }
        Uri inserted = ContentUris.withAppendedId(uri, id);
        getContext().getContentResolver().notifyChange(inserted, null, false);
        return inserted;
    }

    static final String[] DELETE_PROJECTION = new String[] {
        Snapshots.VIEWSTATE_PATH,
    };
    private void deleteDataFiles(SQLiteDatabase db, String selection,
            String[] selectionArgs) {
        Cursor c = db.query(TABLE_SNAPSHOTS, DELETE_PROJECTION, selection,
                selectionArgs, null, null, null);
        final Context context = getContext();
        while (c.moveToNext()) {
            String filename = c.getString(0);
            if (TextUtils.isEmpty(filename)) {
                continue;
            }
            File f = context.getFileStreamPath(filename);
            if (f.exists()) {
                if (!f.delete()) {
                    f.deleteOnExit();
                }
            }
        }
        c.close();
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        SQLiteDatabase db = getWritableDatabase();
        if (db == null) {
            return 0;
        }
        int match = URI_MATCHER.match(uri);
        int deleted = 0;
        switch (match) {
        case SNAPSHOTS_ID: {
            selection = DatabaseUtils.concatenateWhere(selection, TABLE_SNAPSHOTS + "._id=?");
            selectionArgs = DatabaseUtils.appendSelectionArgs(selectionArgs,
                    new String[] { Long.toString(ContentUris.parseId(uri)) });
            // fall through
        }
        case SNAPSHOTS:
            deleteDataFiles(db, selection, selectionArgs);
            deleted = db.delete(TABLE_SNAPSHOTS, selection, selectionArgs);
            break;
        default:
            throw new UnsupportedOperationException("Unknown delete URI " + uri);
        }
        if (deleted > 0) {
            getContext().getContentResolver().notifyChange(uri, null, false);
        }
        return deleted;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection,
            String[] selectionArgs) {
        throw new UnsupportedOperationException("not implemented");
    }

}