/*
 * Copyright (C) 2014 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.camera.session;

import android.content.Context;

import com.android.camera.debug.Log;
import com.android.camera.util.FileUtil;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;

/**
 * Default implementation of {@link SessionStorageManager}.
 */
public class SessionStorageManagerImpl implements SessionStorageManager {
    private static final Log.Tag TAG = new Log.Tag("SesnStorageMgrImpl");

    /** Delete temporary session directory remnants after ONE day. */
    private static final int MAX_SESSION_AGE_MILLIS = 24 * 60 * 60 * 1000;

    /** The base directory for all temporary data. */
    private final File mBaseDirectory;

    /**
     * This is where we used to store temp session data, but it was the wrong
     * place. But we want to make sure it's cleaned up for users that upgraded.
     */
    private final File mDeprecatedBaseDirectory;

    /**
     * Creates a new {@link SessionStorageManager} instance.
     *
     * @param context A valid Android context to be used for determining the
     *            base directory.
     * @return A session storage manager.
     */
    public static SessionStorageManager create(Context context) {
        return new SessionStorageManagerImpl(context.getExternalCacheDir(),
                context.getExternalFilesDir(null));
    }

    SessionStorageManagerImpl(File baseDirectory, File deprecatedBaseDirectory) {
        mBaseDirectory = baseDirectory;
        mDeprecatedBaseDirectory = deprecatedBaseDirectory;
    }

    @Override
    public File getSessionDirectory(String subDirectory) throws IOException {
        File sessionDirectory = new File(mBaseDirectory, subDirectory);
        if (!sessionDirectory.exists() && !sessionDirectory.mkdirs()) {
            throw new IOException("Could not create session directory: " + sessionDirectory);
        }

        if (!sessionDirectory.isDirectory()) {
            throw new IOException("Session directory is not a directory: " + sessionDirectory);
        }

        // Make sure there are no expired sessions in this directory.
        cleanUpExpiredSessions(sessionDirectory);

        // For upgraded users, make sure we also clean up the old location.
        File deprecatedSessionDirectory = new File(mDeprecatedBaseDirectory, subDirectory);
        cleanUpExpiredSessions(deprecatedSessionDirectory);

        return sessionDirectory;
    }

    @Override
    public File createTemporaryOutputPath(String subDirectory, String title) throws IOException {
        File tempDirectory = null;
        try {
            tempDirectory = new File(
                    getSessionDirectory(subDirectory), title);
        } catch (IOException e) {
            Log.e(TAG, "Could not get temp session directory", e);
            throw new IOException("Could not get temp session directory", e);
        }
        if (!tempDirectory.mkdirs()) {
            throw new IOException("Could not create output data directory.");
        }
        File tempFile = new File(tempDirectory, title + ".jpg");
        try {
            if (!tempFile.exists()) {
                if (!tempFile.createNewFile()) {
                    throw new IOException("Could not create output data file.");
                }
            }
        } catch (IOException e) {
            Log.e(TAG, "Could not create temp session file", e);
            throw new IOException("Could not create temp session file", e);
        }

        if (!tempFile.canWrite()) {
            throw new IOException("Temporary output file is not writeable.");
        }
        return tempFile;
    }

    /**
     * Goes through all temporary sessions and deletes the ones that are older
     * than a certain age.
     */
    private void cleanUpExpiredSessions(File baseDirectory) {
        File[] sessionDirs = baseDirectory.listFiles(new FileFilter() {
            @Override
            public boolean accept(File file) {
                return file.isDirectory();
            }
        });
        if (sessionDirs == null) {
            return;
        }

        final long nowInMillis = System.currentTimeMillis();
        for (File sessionDir : sessionDirs) {
            Log.v(TAG, "Check for potential clean-up: " + sessionDir.getAbsolutePath());
            if (sessionDir.lastModified() < (nowInMillis - MAX_SESSION_AGE_MILLIS)) {
                if (!FileUtil.deleteDirectoryRecursively(sessionDir)) {
                    Log.w(TAG, "Could not clean up " + sessionDir.getAbsolutePath());
                }
            }
        }
    }
}