From 88cab67320067d373e6923fb9bd7be8a689445c0 Mon Sep 17 00:00:00 2001
From: Andrew Courtice <andrewcourtice@users.noreply.github.com>
Date: Wed, 8 Sep 2021 15:31:05 +1000
Subject: [PATCH] feat(transaction): added transaction triggers and mutator
 helpers

---
 extensions/transaction/package.json     |  6 +--
 extensions/transaction/src/constants.ts |  1 +
 extensions/transaction/src/index.ts     | 69 ++++++++++++++++++-------
 extensions/transaction/src/types.ts     | 15 ++++--
 4 files changed, 63 insertions(+), 28 deletions(-)

diff --git a/extensions/transaction/package.json b/extensions/transaction/package.json
index b4a0d942..733ad606 100644
--- a/extensions/transaction/package.json
+++ b/extensions/transaction/package.json
@@ -38,12 +38,12 @@
         "build": "tsup",
         "prepublish": "yarn build"
     },
+    "dependencies": {
+        "@harlem/extension-snapshot": "^2.0.0-beta.9"
+    },
     "peerDependencies": {
         "@harlem/core": "^2.0.0-alpha.0"
     },
-    "dependencies": {
-        "@harlem/utilities": "^2.0.0-beta.9"
-    },
     "devDependencies": {
         "@harlem/core": "^2.0.0-beta.9"
     }
diff --git a/extensions/transaction/src/constants.ts b/extensions/transaction/src/constants.ts
index c065c047..1cdf8cc3 100644
--- a/extensions/transaction/src/constants.ts
+++ b/extensions/transaction/src/constants.ts
@@ -4,6 +4,7 @@ export const EVENTS = {
     transaction: {
         before: 'transaction:before',
         after: 'transaction:after',
+        success: 'transaction:success',
         error: 'transaction:error',
     },
 };
\ No newline at end of file
diff --git a/extensions/transaction/src/index.ts b/extensions/transaction/src/index.ts
index 7bcfbc3a..3ef4b138 100644
--- a/extensions/transaction/src/index.ts
+++ b/extensions/transaction/src/index.ts
@@ -1,59 +1,88 @@
+import snapshotExtension from '@harlem/extension-snapshot';
+
 import {
     SENDER,
     EVENTS,
 } from './constants';
 
-import {
-    clone,
-    overwrite,
-} from '@harlem/utilities';
-
 import {
     BaseState,
+    EventPayload,
     InternalStore,
-    ReadState,
+    Mutator,
 } from '@harlem/core';
 
 import type {
     Transactor,
     Transaction,
     TransactionEventData,
+    TransactionHookHandler,
 } from './types';
 
 export * from './types';
 
 export default function transactionExtension<TState extends BaseState>() {
     return (store: InternalStore<TState>) => {
-        function rollback(snapshot: ReadState<TState>) {
-            store.write('$transaction-rollback', SENDER, state => overwrite(state, snapshot));
-        }
+        const {
+            snapshot,
+        } = snapshotExtension({
+            mutationName: '$transaction-rollback',
+        })(store);
+
 
-        function transaction<TPayload>(name: string, transactor: Transactor<TPayload>): Transaction<TPayload> {
-            return payload => {
-                const snapshot = clone(store.state) as ReadState<TState>;
+        function transaction<TPayload>(name: string, transactor: Transactor<TState, TPayload>): Transaction<TPayload> {
+            const mutate = (mutator: Mutator<TState, undefined, void>) => store.write(name, SENDER, mutator);
 
-                const eventData = {
-                    payload,
+            return ((payload: TPayload) => {
+                const snap = snapshot();
+                const providedPayload = store.providers.payload(payload) ?? payload;
+
+                const emit = (event: string) => store.emit(event, SENDER, {
                     transaction: name,
-                } as TransactionEventData;
+                    payload: providedPayload,
+                } as TransactionEventData);
 
-                store.emit(EVENTS.transaction.before, SENDER, eventData);
+                emit(EVENTS.transaction.before);
 
                 try {
-                    transactor(payload!);
+                    const providedPayload = store.providers.payload(payload) ?? payload;
+
+                    transactor(providedPayload, mutate);
+                    emit(EVENTS.transaction.success);
                 } catch (error) {
-                    rollback(snapshot);
-                    store.emit(EVENTS.transaction.error, SENDER, eventData);
+                    snap.apply();
+                    emit(EVENTS.transaction.error);
 
                     throw error;
+                } finally {
+                    emit(EVENTS.transaction.after);
                 }
+            }) as Transaction<TPayload>;
+        }
 
-                store.emit(EVENTS.transaction.after, SENDER, eventData);
+        function getTransactionTrigger(eventName: string) {
+            return <TPayload = any>(actionName: string | string[], handler: TransactionHookHandler<TPayload>) => {
+                const transactions = ([] as string[]).concat(actionName);
+
+                return store.on(eventName, (event?: EventPayload<TransactionEventData>) => {
+                    if (event && transactions.includes(event.data.transaction)) {
+                        handler(event.data);
+                    }
+                });
             };
         }
 
+        const onBeforeTransaction = getTransactionTrigger(EVENTS.transaction.before);
+        const onAfterTransaction = getTransactionTrigger(EVENTS.transaction.after);
+        const onTransactionSuccess = getTransactionTrigger(EVENTS.transaction.success);
+        const onTransactionError = getTransactionTrigger(EVENTS.transaction.error);
+
         return {
             transaction,
+            onBeforeTransaction,
+            onAfterTransaction,
+            onTransactionSuccess,
+            onTransactionError,
         };
     };
 }
\ No newline at end of file
diff --git a/extensions/transaction/src/types.ts b/extensions/transaction/src/types.ts
index dbd58349..e2101436 100644
--- a/extensions/transaction/src/types.ts
+++ b/extensions/transaction/src/types.ts
@@ -1,8 +1,13 @@
-export type Transactor<TPayload> = undefined extends TPayload ? (payload?: TPayload) => void : (payload: TPayload) => void;
-export type Transaction<TPayload> = (payload?: TPayload) => void;
-export type TransactionRollback = () => void;
+import type {
+    BaseState,
+    Mutator,
+} from '@harlem/core';
 
-export interface TransactionEventData {
+export type Transactor<TState extends BaseState, TPayload = undefined> = (payload: TPayload, mutator: (mutate: Mutator<TState, undefined, void>) => void) => void;
+export type Transaction<TPayload> = undefined extends TPayload ? (payload?: TPayload) => void : (payload: TPayload) => void;
+export type TransactionHookHandler<TPayload> = (data: TransactionEventData<TPayload>) => void;
+
+export interface TransactionEventData<TPayload = any> {
     transaction: string;
-    payload: any;
+    payload: TPayload;
 }
\ No newline at end of file