package com.peachpasswords.vault

import android.content.Context
import androidx.security.crypto.EncryptedSharedPreferences
import androidx.security.crypto.MasterKey
import dagger.hilt.android.qualifiers.ApplicationContext
import javax.inject.Inject
import javax.inject.Singleton

/**
 * Remembers the id of the entry the user last opened so a fresh unlock can land
 * straight back on it (matching the extension, which opens the last entry rather
 * than the list). Stored in EncryptedSharedPreferences — an entry id is a weak
 * pointer, but it should not be trivially readable at rest, and it sits in the
 * same encrypted-prefs family as the duress/license stores.
 *
 * The id is only a hint: the post-unlock resolver re-validates it against the
 * live vault, so a stale id (entry since deleted) silently falls back to the
 * first entry.
 */
@Singleton
class LastViewedEntryStore @Inject constructor(
    @ApplicationContext context: Context,
) {
    private val masterKey = MasterKey.Builder(context)
        .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
        .build()

    private val prefs = EncryptedSharedPreferences.create(
        context,
        PREFS_FILE,
        masterKey,
        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM,
    )

    fun get(): String? = prefs.getString(KEY_LAST_VIEWED, null)

    fun set(id: String) { prefs.edit().putString(KEY_LAST_VIEWED, id).apply() }

    fun clear() { prefs.edit().remove(KEY_LAST_VIEWED).apply() }

    companion object {
        private const val PREFS_FILE = "peach_nav_prefs"
        private const val KEY_LAST_VIEWED = "last_viewed_entry_id"
    }
}