package com.sensitiveinfo.internal.storage

import android.content.Context
import android.content.SharedPreferences

/**
 * Tracks the active master-key version for each service.
 *
 * Version numbers start at `INITIAL_VERSION` for services that have never been rotated and are
 * bumped monotonically by [bump]. The registry is backed by a dedicated, non-secret
 * [SharedPreferences] file so rotation state survives process restarts without touching the
 * Keystore.
 */
internal class KeyVersionRegistry(context: Context) {
  private val preferences: SharedPreferences = context.applicationContext
    .getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)

  /** Returns the active version for [service], or [INITIAL_VERSION] if no rotation has occurred. */
  fun get(service: String): Int = preferences.getInt(service, INITIAL_VERSION)

  /** Increments and persists the version for [service], returning the new value. */
  fun bump(service: String): Int {
    val next = get(service) + 1
    preferences.edit().putInt(service, next).apply()
    return next
  }

  companion object {
    const val INITIAL_VERSION: Int = 1
    private const val PREFS_NAME = "rnsi.key_versions"
  }
}