FileSystemUtils.java

package org.commcare.android.resource.installers;

import org.javarosa.core.reference.InvalidReferenceException;
import org.javarosa.core.reference.ReferenceManager;

import java.io.File;

public class FileSystemUtils {

    //Hate this
    private static final String validExtChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

    public static String extension(String input) {
        int invalid = -1;
        //we wanna go from the last "." to the next non-alphanumeric character.
        for (int i = 1; i < input.length(); ++i) {
            if (validExtChars.indexOf(input.charAt(i)) == -1) {
                invalid = i;
                break;
            }
        }
        if (invalid == -1) {
            return input;
        }
        return input.substring(0, invalid);
    }

    protected static boolean moveFrom(String oldLocation, String newLocation, boolean force) throws InvalidReferenceException {
        File newFile = new File(ReferenceManager.instance().DeriveReference(newLocation).getLocalURI());
        File oldFile = new File(ReferenceManager.instance().DeriveReference(oldLocation).getLocalURI());

        if (!oldFile.exists()) {
            //Nothing should be allowed to exist in the new location except for the incoming file
            //due to the staging rules. If there's a file there, it's this one.
            return newFile.exists();
        }

        if (oldFile.exists() && newFile.exists()) {
            //There's a destination file where this file is
            //trying to move to. Something might have failed to unstage
            if (force) {
                //If we're recovering or something, wipe out the destination.
                //we've gotta recover!
                if (!newFile.delete()) {
                    return false;
                } else {
                    //new file is gone. Let's get ours in there!
                }
            } else {
                //can't copy over an existing file. An unstage might have failed.
                return false;
            }
        }

        return oldFile.renameTo(newFile);
    }
}