From 08fd17481f2778038bdac88dd7d566816f752b7e Mon Sep 17 00:00:00 2001
From: Jorge Manrubia <jorge@37signals.com>
Date: Mon, 28 Oct 2024 12:16:17 +0100
Subject: [PATCH] Fix: duplicated newlines when using dictation on iOS 18+.
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This fixes a bug that started to happen with iOS 18, where you would get duplicated newlines
after completing the dictation.

The bug happens because, upon dictation completion, iOS sends the sequence of `beforeinput` events
very quickly. With the `insertParagraph` ones, it can happen that the internal document range fails
to update, resulting in duplicated newlines and missed content.

This workaround is necessary due to the inability to distinguish text entered in dictation mode, as
iOS WebKit doesn’t trigger composition events during dictation (https://bugs.webkit.org/show_bug.cgi?id=261764).
---
 src/test/system/level_2_input_test.js            | 13 ++++++++++---
 src/test/test_helpers/input_helpers.js           |  3 +--
 src/trix/controllers/level_2_input_controller.js | 16 ++++++++++------
 src/trix/core/helpers/events.js                  | 13 +++++++++++++
 4 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/test/system/level_2_input_test.js b/src/test/system/level_2_input_test.js
index 150419b74..a430beca2 100644
--- a/src/test/system/level_2_input_test.js
+++ b/src/test/system/level_2_input_test.js
@@ -52,11 +52,18 @@ const performInputTypeUsingExecCommand = async (command, { inputType, data }) =>
 
   await nextFrame()
 
+  const isInsertParagraph = inputType === "insertParagraph"
+
   triggerInputEvent(document.activeElement, "beforeinput", { inputType, data })
-  document.execCommand(command, false, data)
-  assert.equal(inputEvents.length, 2)
+
+  // See `shouldRenderInmmediatelyToDealWithiOSDictation` to deal with iOS 18+ dictation bug.
+  if (!isInsertParagraph) {
+    document.execCommand(command, false, data)
+    assert.equal(inputEvents[1].type, "input")
+  }
+
+  assert.equal(inputEvents.length, isInsertParagraph ? 1 : 2)
   assert.equal(inputEvents[0].type, "beforeinput")
-  assert.equal(inputEvents[1].type, "input")
   assert.equal(inputEvents[0].inputType, inputType)
   assert.equal(inputEvents[0].data, data)
 
diff --git a/src/test/test_helpers/input_helpers.js b/src/test/test_helpers/input_helpers.js
index 8990adeaf..35c782bfb 100644
--- a/src/test/test_helpers/input_helpers.js
+++ b/src/test/test_helpers/input_helpers.js
@@ -276,9 +276,8 @@ const simulateKeypress = async (keyName) => {
       await deleteInDirection("right")
       break
     case "return":
-      await nextFrame()
       triggerInputEvent(document.activeElement, "beforeinput", { inputType: "insertParagraph" })
-      await insertNode(document.createElement("br"))
+      break
   }
 }
 
diff --git a/src/trix/controllers/level_2_input_controller.js b/src/trix/controllers/level_2_input_controller.js
index 65b302157..e2b73490b 100644
--- a/src/trix/controllers/level_2_input_controller.js
+++ b/src/trix/controllers/level_2_input_controller.js
@@ -1,4 +1,4 @@
-import { getAllAttributeNames, squishBreakableWhitespace } from "trix/core/helpers"
+import { getAllAttributeNames, shouldRenderInmmediatelyToDealWithiOSDictation, squishBreakableWhitespace } from "trix/core/helpers"
 import InputController from "trix/controllers/input_controller"
 import * as config from "trix/config"
 
@@ -73,14 +73,18 @@ export default class Level2InputController extends InputController {
     beforeinput(event) {
       const handler = this.constructor.inputTypes[event.inputType]
 
-      // Handles bug with Siri dictation on iOS 18+.
-      if (!event.inputType) {
-        this.render()
-      }
+      const inmmediateRender = shouldRenderInmmediatelyToDealWithiOSDictation(event)
 
       if (handler) {
         this.withEvent(event, handler)
-        this.scheduleRender()
+
+        if (!inmmediateRender) {
+          this.scheduleRender()
+        }
+      }
+
+      if (inmmediateRender) {
+        this.render()
       }
     },
 
diff --git a/src/trix/core/helpers/events.js b/src/trix/core/helpers/events.js
index 4248830d3..0e5f18811 100644
--- a/src/trix/core/helpers/events.js
+++ b/src/trix/core/helpers/events.js
@@ -43,3 +43,16 @@ export const keyEventIsKeyboardCommand = (function() {
     return (event) => event.ctrlKey
   }
 })()
+
+export function shouldRenderInmmediatelyToDealWithiOSDictation(inputEvent) {
+  if (/iPhone|iPad/.test(navigator.userAgent)) {
+    // Handle duplicated newlines when using dictation on iOS 18+. Upon dictation completion, iOS sends
+    // the list of insertText / insertParagraph events in a quick sequence. For newlines, if we don't render
+    // the editor synchronously, the internal range fails to update and results in duplicated newlines.
+    // This workaround is necessary because iOS doesn't send composing events as expected while dictating:
+    // https://bugs.webkit.org/show_bug.cgi?id=261764
+    return !inputEvent.inputType || inputEvent.inputType === "insertParagraph"
+  } else {
+    return false
+  }
+}