/*
 * Copyright (C) 2018 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.tools.analytics

import com.android.utils.ILogger
import com.google.common.base.Charsets
import com.google.common.hash.Hashing
import java.io.IOException
import java.nio.charset.Charset

/**
 * Anonymizes strings for analytics reporting. Each string is sha256 encoded with a salt that is
 * unique per user and rotated every 28 days with a predictable time window.
 */
object Anonymizer {
  /** Anonymizes a utf8 string. Logs any issues reading the salt for anonymizing.  */
  @Throws(IOException::class)
  @JvmStatic
  fun anonymizeUtf8(logger: ILogger, data: String?): String {
    return anonymize(logger, data, Charsets.UTF_8)
  }

  /**
   * Anonymizes a string based on provided charset. Logs any issues reading the salt for
   * anonymizing.
   */
  @Throws(IOException::class)
  @JvmStatic
  fun anonymize(
    logger: ILogger, data: String?, charset: Charset): String {
    if (data == null || data == "") {
      return ""
    }
    val hasher = Hashing.sha256().newHasher()
    hasher.putBytes(AnalyticsSettings.salt)
    hasher.putString(data, charset)
    return hasher.hash().toString()
  }
}