Undo puts account back where it was

NovaCrypto · Feb 12, 2018 · 6415aeb · 6415aeb
1 parent 409ce82
commit 6415aeb
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Showing 4 changed files with 53 additions and 20 deletions.
diff --git a/account/src/main/java/io/github/novacrypto/account/AccountModelIntents.kt b/account/src/main/java/io/github/novacrypto/account/AccountModelIntents.kt
@@ -28,6 +28,9 @@ sealed class AccountModelIntent {
 fun AccountModel.toAddIntent() =
         UserModelIntent.AddAccountIntent(this).forward()
 
+fun AccountModel.toInsertIntent(index: Int) =
+        UserModelIntent.AddAccountIntent(this, index).forward()
+
 fun AccountModel.toRemoveIntent() =
         UserModelIntent.RemoveAccountIntent(this.id).forward()
 

diff --git a/account/src/main/java/io/github/novacrypto/account/UserModel.kt b/account/src/main/java/io/github/novacrypto/account/UserModel.kt
@@ -26,7 +26,7 @@ data class UserModel(
 )
 
 sealed class UserModelIntent {
-    class AddAccountIntent(val account: AccountModel) : UserModelIntent()
+    class AddAccountIntent(val account: AccountModel, val index: Int? = null) : UserModelIntent()
     class RemoveAccountIntent(val accountId: AccountId) : UserModelIntent()
     class ForwardAccountModelIntent(
             val accountId: AccountId,

diff --git a/account/src/main/java/io/github/novacrypto/account/UserModelViewState.kt b/account/src/main/java/io/github/novacrypto/account/UserModelViewState.kt
@@ -61,35 +61,50 @@ private fun UserModelViewState.transformWithIntent(intent: UserModelViewStateInt
 
 private fun UserModel.transformWithIntent(intent: UserModelIntent) =
         when (intent) {
-            is UserModelIntent.AddAccountIntent -> Pair(copy(accounts = accounts + intent.account), null)
+            is UserModelIntent.AddAccountIntent -> {
+                copy(accounts = if (intent.index != null) {
+                    accounts.insert(intent.account, intent.index)
+                } else {
+                    accounts + intent.account
+                }).withNoUndo()
+            }
             is UserModelIntent.RemoveAccountIntent -> {
-                val existingAccount = findAccount(intent.accountId)
-                        ?: throw cannotFind(intent.accountId)
-                Pair(copy(accounts = accounts - existingAccount),
-                        UserModelViewStateUndoModel("Removed account '${existingAccount.name}'",
-                                existingAccount.toAddIntent()))
+                withAccountAndIndexForId(intent.accountId) { account, index ->
+                    Pair(copy(accounts = accounts - account),
+                            UserModelViewStateUndoModel("Removed account '${account.name}'",
+                                    account.toInsertIntent(index)))
+                }
             }
             is UserModelIntent.ForwardAccountModelIntent -> {
-                val accountIdx = findAccountIndex(intent.accountId)
-                if (accountIdx != -1) {
-                    val newAccounts = accounts.replace(accountIdx, accountModelReducer(intent.intent, accounts[accountIdx]))
-                    Pair(copy(accounts = newAccounts), null)
-                } else {
-                    throw cannotFind(intent.accountId)
+                withAccountAndIndexForId(intent.accountId) { account, index ->
+                    val newAccounts = accounts.replace(index, accountModelReducer(intent.intent, account))
+                    copy(accounts = newAccounts).withNoUndo()
                 }
             }
         }
 
+private fun <T> UserModel.withAccountAndIndexForId(accountId: AccountId, transform: (account: AccountModel, index: Int) -> T): T {
+    val accountIdx = accounts.indexOfFirst { it.id == accountId }.also {
+        if (it == -1) throw cannotFind(accountId)
+    }
+    val existingAccount = accounts[accountIdx]
+    return transform(existingAccount, accountIdx)
+}
+
+private fun UserModel.withNoUndo() = Pair(this, null)
+
+private inline fun <E> List<E>.copyAndModify(modify: MutableList<E>.() -> Unit): List<E> =
+        toMutableList().apply(modify)
+
+private fun <E> List<E>.insert(newItem: E, index: Int) =
+        copyAndModify {
+            this.add(index, newItem)
+        }
+
 private fun <E> List<E>.replace(index: Int, replacement: E) =
-        toMutableList().apply {
+        copyAndModify {
             this[index] = replacement
         }
 
-private fun UserModel.findAccountIndex(accountId: AccountId) =
-        accounts.indexOfFirst { it.id == accountId }
-
 private fun cannotFind(accountId: AccountId) =
         UserReportableException("Cannot find account $accountId")
-
-private fun UserModel.findAccount(accountId: AccountId) =
-        accounts.getOrNull(findAccountIndex(accountId))
diff --git a/account/src/test/java/io/github/novacrypto/UserModelIntentTests.kt b/account/src/test/java/io/github/novacrypto/UserModelIntentTests.kt
@@ -301,6 +301,21 @@ class UserModelUndo {
                 }
     }
 
+    @Test
+    fun `an undone remove is in the same position it was before`() {
+        val account1 = AccountModel()
+        val account2 = AccountModel()
+        Observable.just(
+                account1.toAddIntent(),
+                account2.toAddIntent(),
+                account1.toRemoveIntent(),
+                undo()
+        ).toUserModelStream()
+                .assertWithLastAndThirdToLastElements { lastMinusTwo, last ->
+                    lastMinusTwo.userModel.accounts `should equal` last.userModel.accounts
+                }
+    }
+
     @Test
     fun `if there is nothing to undo, undo does nothing`() {
         val account = AccountModel()