Refactor key import flow and implement support for replacing

app/src/main/java/app/passwordstore/ui/pgp/PGPKeyImportActivity.kt

@@ -13,7 +13,10 @@ import app.passwordstore.R
 import app.passwordstore.crypto.KeyUtils.tryGetId
 import app.passwordstore.crypto.PGPKey
 import app.passwordstore.crypto.PGPKeyManager
-import com.github.michaelbull.result.mapBoth
+import app.passwordstore.crypto.errors.KeyAlreadyExistsException
+import com.github.michaelbull.result.Err
+import com.github.michaelbull.result.Ok
+import com.github.michaelbull.result.Result
 import com.github.michaelbull.result.runCatching
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import dagger.hilt.android.AndroidEntryPoint
@@ -23,6 +26,11 @@ import kotlinx.coroutines.runBlocking
 @AndroidEntryPoint
 class PGPKeyImportActivity : AppCompatActivity() {
 
+  /**
+   * A [ByteArray] containing the contents of the previously selected file. This is necessary for
+   * the replacement case where we do not want users to have to pick the file again.
+   */
+  private var lastBytes: ByteArray? = null
   @Inject lateinit var keyManager: PGPKeyManager
 
   private val pgpKeyImportAction =
@@ -35,36 +43,68 @@ class PGPKeyImportActivity : AppCompatActivity() {
             contentResolver.openInputStream(uri)
               ?: throw IllegalStateException("Failed to open selected file")
           val bytes = keyInputStream.use { `is` -> `is`.readBytes() }
-          val (key, error) = runBlocking { keyManager.addKey(PGPKey(bytes)) }
+          importKey(bytes, false)
-          if (error != null) throw error
-          key
         }
-        .mapBoth(
+        .run(::handleImportResult)
-          { key ->
-            if (key != null) {
-              MaterialAlertDialogBuilder(this)
-                .setTitle(getString(R.string.pgp_key_import_succeeded))
-                .setMessage(getString(R.string.pgp_key_import_succeeded_message, tryGetId(key)))
-                .setPositiveButton(android.R.string.ok) { _, _ -> finish() }
-                .setOnCancelListener { finish() }
-                .show()
-            } else {
-              finish()
-            }
-          },
-          { throwable ->
-            MaterialAlertDialogBuilder(this)
-              .setTitle(getString(R.string.pgp_key_import_failed))
-              .setMessage(throwable.message)
-              .setPositiveButton(android.R.string.ok) { _, _ -> finish() }
-              .setOnCancelListener { finish() }
-              .show()
-          }
-        )
     }
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     pgpKeyImportAction.launch(arrayOf("*/*"))
   }
+
+  override fun onDestroy() {
+    lastBytes = null
+    super.onDestroy()
+  }
+
+  private fun importKey(bytes: ByteArray, replace: Boolean): PGPKey? {
+    lastBytes = bytes
+    val (key, error) = runBlocking { keyManager.addKey(PGPKey(bytes), replace = replace) }
+    if (replace) {
+      lastBytes = null
+    }
+    if (error != null) throw error
+    return key
+  }
+
+  private fun handleImportResult(result: Result<PGPKey?, Throwable>) {
+    when (result) {
+      is Ok<PGPKey?> -> {
+        val key = result.value
+        if (key == null) {
+          finish()
+          // This return convinces Kotlin that the control flow for `key == null` definitely
+          // terminates here and allows for a smart cast below.
+          return
+        }
+        MaterialAlertDialogBuilder(this)
+          .setTitle(getString(R.string.pgp_key_import_succeeded))
+          .setMessage(getString(R.string.pgp_key_import_succeeded_message, tryGetId(key)))
+          .setPositiveButton(android.R.string.ok) { _, _ -> finish() }
+          .setOnCancelListener { finish() }
+          .show()
+      }
+      is Err<Throwable> -> {
+        if (result.error is KeyAlreadyExistsException && lastBytes != null) {
+          MaterialAlertDialogBuilder(this)
+            .setTitle(getString(R.string.pgp_key_import_failed))
+            .setMessage(getString(R.string.pgp_key_import_failed_replace_message))
+            .setPositiveButton(R.string.dialog_yes) { _, _ ->
+              handleImportResult(runCatching { importKey(lastBytes!!, replace = true) })
+            }
+            .setNegativeButton(R.string.dialog_no) { _, _ -> finish() }
+            .setOnCancelListener { finish() }
+            .show()
+        } else {
+          MaterialAlertDialogBuilder(this)
+            .setTitle(getString(R.string.pgp_key_import_failed))
+            .setMessage(result.error.message)
+            .setPositiveButton(android.R.string.ok) { _, _ -> finish() }
+            .setOnCancelListener { finish() }
+            .show()
+        }
+      }
+    }
+  }
 }

app/src/main/res/values/strings.xml

@@ -372,6 +372,7 @@
   <string name="place_shortcut_on_home_screen">Place shortcut on home screen</string>
   <string name="password_list_fab_content_description">Create new password or folder</string>
   <string name="pgp_key_import_failed">Failed to import PGP key</string>
+  <string name="pgp_key_import_failed_replace_message">An existing key with this ID was found, do you want to replace it?</string>
   <string name="pgp_key_import_succeeded">Successfully imported PGP key</string>
   <string name="pgp_key_import_succeeded_message">The key ID of the imported key is given below, please review it for correctness:\n%1$s</string>
   <string name="pref_category_pgp_title">PGP settings</string>