// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.chrome.browser.identity;

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;

import org.chromium.base.VisibleForTesting;

import java.util.UUID;

import javax.annotation.Nullable;

/**
 * Generates unique IDs that are {@link UUID} strings.
 */
public class UuidBasedUniqueIdentificationGenerator implements UniqueIdentificationGenerator {
    public static final String GENERATOR_ID = "UUID";
    private final Context mContext;
    private final String mPreferenceKey;

    public UuidBasedUniqueIdentificationGenerator(Context context, String preferenceKey) {
        mContext = context;
        mPreferenceKey = preferenceKey;
    }

    @Override
    public String getUniqueId(@Nullable String salt) {
        SharedPreferences preferences = PreferenceManager
                .getDefaultSharedPreferences(mContext);
        String storedUniqueId = preferences.getString(mPreferenceKey, null);
        if (storedUniqueId != null) {
            return storedUniqueId;
        }

        // Generate a new unique ID.
        String uniqueId = getUUID();

        // Store the field so we ensure we always return the same unique ID.
        SharedPreferences.Editor editor = preferences.edit();
        editor.putString(mPreferenceKey, uniqueId);
        editor.apply();
        return uniqueId;

    }

    @VisibleForTesting
    String getUUID() {
        return UUID.randomUUID().toString();
    }
}