mihon/app/src/main/java/eu/kanade/mangafeed/util/DiskUtils.java

package eu.kanade.mangafeed.util;

import android.content.Context;
import android.os.Build;
import android.os.Environment;
import android.text.TextUtils;

import java.io.File;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Pattern;

import okio.BufferedSink;
import okio.BufferedSource;
import okio.Okio;

public final class DiskUtils {
    private static final Pattern DIR_SEPARATOR = Pattern.compile("/");

    private DiskUtils() {
        throw new AssertionError();
    }

    // http://stackoverflow.com/questions/13976982/removable-storage-external-sdcard-path-by-manufacturers
    // http://stackoverflow.com/questions/11281010/how-can-i-get-external-sd-card-path-for-android-4-0
    public static String[] getStorageDirectories(Context context) {
        final Set<String> storageDirectories = new HashSet<String>();

        storageDirectories.add(context.getFilesDir().getAbsolutePath());

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            File[] directories = context.getExternalFilesDirs(null);
            if (directories != null) {
                for (File storage : directories) {
                    if (storage != null) {
                        storageDirectories.add(storage.getAbsolutePath());
                    }
                }
            }
        } else {
            final String rawExternalStorage = System.getenv("EXTERNAL_STORAGE");
            final String rawSecondaryStoragesStr = System.getenv("SECONDARY_STORAGE");
            final String rawEmulatedStorageTarget = System.getenv("EMULATED_STORAGE_TARGET");

            if (TextUtils.isEmpty(rawEmulatedStorageTarget)) {
                if (TextUtils.isEmpty(rawExternalStorage)) {
                    storageDirectories.add("/storage/sdcard0" + File.separator + context.getPackageName());
                } else {
                    storageDirectories.add(rawExternalStorage + File.separator + context.getPackageName());
                }
            } else {
                final String rawUserId;

                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
                    rawUserId = "";
                } else {
                    final String path = Environment.getExternalStorageDirectory().getAbsolutePath();
                    final String[] folders = DIR_SEPARATOR.split(path);
                    final String lastFolder = folders[folders.length - 1];
                    boolean isDigit = false;

                    try {
                        Integer.valueOf(lastFolder);
                        isDigit = true;
                    } catch (NumberFormatException e) {
                        // Do Nothing.
                    }

                    rawUserId = isDigit ? lastFolder : "";
                }

                if (TextUtils.isEmpty(rawUserId)) {
                    storageDirectories.add(rawEmulatedStorageTarget + File.separator + context.getPackageName());
                } else {
                    storageDirectories.add(rawEmulatedStorageTarget + File.separator + rawUserId + File.separator + context.getPackageName());
                }
            }

            if (!TextUtils.isEmpty(rawSecondaryStoragesStr)) {
                String[] rawSecondaryStorages = rawSecondaryStoragesStr.split(File.pathSeparator);
                for (int index  = 0; index < rawSecondaryStorages.length; index++) {
                    storageDirectories.add(rawSecondaryStorages[index] + File.separator + context.getPackageName());
                }
            }
        }

        return storageDirectories.toArray(new String[storageDirectories.size()]);
    }

    public static String hashKeyForDisk(String key) {
        String cacheKey;
        try {
            final MessageDigest mDigest = MessageDigest.getInstance("MD5");
            mDigest.update(key.getBytes());
            cacheKey = bytesToHexString(mDigest.digest());
        } catch (NoSuchAlgorithmException e) {
            cacheKey = String.valueOf(key.hashCode());
        }
        return cacheKey;
    }

    private static String bytesToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(0xFF & bytes[i]);
            if (hex.length() == 1) {
                sb.append('0');
            }
            sb.append(hex);
        }
        return sb.toString();
    }

    public static File saveBufferedSourceToDirectory(BufferedSource bufferedSource, File directory, String name) throws IOException {
        if (!directory.exists()) {
            if (!directory.mkdirs()) {
                throw new IOException("Failed Creating  Directory");
            }
        }

        File writeFile = new File(directory, name);
        if (writeFile.exists()) {
            if (writeFile.delete()) {
                writeFile = new File(directory, name);
            } else {
                throw new IOException("Failed Deleting Existing File for Overwrite");
            }
        }

        BufferedSink bufferedSink = null;
        try {
            bufferedSink = Okio.buffer(Okio.sink(writeFile));
            bufferedSink.writeAll(bufferedSource);
        } finally {
            if (bufferedSource != null) {
                bufferedSource.close();
            }
            if (bufferedSink != null) {
                bufferedSink.close();
            }
        }

        return writeFile;
    }

    public static void deleteFiles(File inputFile) {
        if (inputFile.isDirectory()) {
            for (File childFile : inputFile.listFiles()) {
                deleteFiles(childFile);
            }
        }

        inputFile.delete();
    }
}