[HOLD for payment 2023-12-12] [$500] mWeb/Safari- Chat - Focus is in the start of the message when opening a report with a draft message

[izarutskaya]

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Issue found when executing PR: #31295

Version Number: 1.4.2-0
Reproducible in staging?: Y
Reproducible in production?: Y
If this was caught during regression testing, add the test name, ID and link from TestRail:
Email or phone of affected tester (no customers):
Logs: https://stackoverflow.com/c/expensify/questions/4856
Expensify/Expensify Issue URL:
Issue reported by: Applause-Internal Team
Slack conversation: @

Action Performed:

1. Open any chat and enter a message without sending it
2. Go back to LHN and open the same chat

Expected Result:

The focus is on the end of the message so user can continue typing

Actual Result:

The focus is on the start of the message. User needs to manually move the cursor to the end to continue

Workaround:

Unknown

Platforms:

Which of our officially supported platforms is this issue occurring on?

• Android: Native
• Android: mWeb Chrome
• iOS: Native
• iOS: mWeb Safari
• MacOS: Chrome / Safari
• MacOS: Desktop

Screenshots/Videos

Bug6287152_1700658449599.RPReplay_Final1700650930.mp4

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• bernhardoj | Contributor | 27867013

[melvin-bot]

Triggered auto assignment to @conorpendergrast (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[melvin-bot]

Job added to Upwork: https://www.upwork.com/jobs/~01fc3a996f2399bc80

[melvin-bot]

Bug0 Triage Checklist (Main S/O)

• This "bug" occurs on a supported platform (ensure Platforms in OP are ✅)
• This bug is not a duplicate report (check E/App issues and #expensify-bugs)
  • If it is, comment with a link to the original report, close the issue and add any novel details to the original issue instead
• This bug is reproducible using the reproduction steps in the OP. S/O
  • If the reproduction steps are clear and you're unable to reproduce the bug, check with the reporter and QA first, then close the issue.
  • If the reproduction steps aren't clear and you determine the correct steps, please update the OP.
• This issue is filled out as thoroughly and clearly as possible
  • Pay special attention to the title, results, platforms where the bug occurs, and if the bug happens on staging/production.
• I have reviewed and subscribed to the linked Slack conversation to ensure Slack/Github stay in sync

[melvin-bot]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @burczu (External)

[PiyushChandra17]

@izarutskaya Not reproducible on latest main

[erquhart]

Proposal

Please re-state the problem that we are trying to solve in this issue.

For mobile Safari, when a draft message is opened, the cursor is at the beginning of the message instead of the end.

What is the root cause of that problem?

The only time we don't set the initial selection is for mobile Safari if shouldAutoFocus is truthy, otherwise we always set the initial selction.

App/src/pages/home/report/ReportActionCompose/ComposerWithSuggestions/ComposerWithSuggestions.js

Lines 130 to 138 in f1e085b

	const shouldAutoFocus = !modal.isVisible && (shouldFocusInputOnScreenFocus || (isEmptyChat && !ReportActionsUtils.isTransactionThread(parentAction))) && shouldShowComposeInput;
	const valueRef = useRef(value);
	valueRef.current = value;
	const [selection, setSelection] = useState(() => ({
	start: isMobileSafari && !shouldAutoFocus ? 0 : value.length,
	end: isMobileSafari && !shouldAutoFocus ? 0 : value.length,
	}));

But we're not using shouldAutoFocus to set focus, we're intentionally setting it to false for mobile:

App/src/pages/home/report/ReportActionCompose/ComposerWithSuggestions/ComposerWithSuggestions.js

Lines 58 to 60 in f1e085b

	// We want consistent auto focus behavior on input between native and mWeb so we have some auto focus management code that will
	// prevent auto focus on existing chat for mobile device
	const shouldFocusInputOnScreenFocus = canFocusInputOnScreenFocus();

What changes do you think we should make in order to solve the problem?

Remove the conditionals from the initial selection state - we should always set it. It won't have impact if the the composer isn't focused, so any dependency between autofocus logic and initial selection state is just added complexity.

const [selection, setSelection] = useState({ start: value.length, end: value.length })

[bernhardoj]

Proposal

Please re-state the problem that we are trying to solve in this issue.

If we have a composer draft in a chat with existing messages and reopen that chat, the composer will auto-focus and put the cursor at the front of the input text.

What is the root cause of that problem?

When we open a chat with existing messages on a mobile screen, the autofocus shouldn't work (it fails on isEmptyChat).

App/src/pages/home/report/ReportActionCompose/ComposerWithSuggestions/ComposerWithSuggestions.js

Line 130 in 704f3f7

const shouldAutoFocus = !modal.isVisible && (shouldFocusInputOnScreenFocus || (isEmptyChat && !ReportActionsUtils.isTransactionThread(parentAction))) && shouldShowComposeInput;

And if autofocus is false, we will set the input selection to 0, only on Safari.

App/src/pages/home/report/ReportActionCompose/ComposerWithSuggestions/ComposerWithSuggestions.js

Lines 135 to 138 in 704f3f7

	const [selection, setSelection] = useState(() => ({
	start: isMobileSafari && !shouldAutoFocus ? 0 : value.length,
	end: isMobileSafari && !shouldAutoFocus ? 0 : value.length,
	}));

It is added in this PR #19293 to fix #15105.

The reason we want to set it to 0 if autofocus is false is because if we set it to > 0, the input will be autofocused regardless of the autofocus attribute and we want to avoid that.

The selection here is 0 and we pass it to Composer, but somehow the composer is still autofocused and it is because, in the Composer component, we have a selection state that has an initial value of the draft length.

App/src/components/Composer/index.js

Lines 176 to 179 in 704f3f7

	const [selection, setSelection] = useState({
	start: initialValue.length,
	end: initialValue.length,
	});

Thus, the composer is autofocused. Then, we have a useEffect that will update the selection state if selection prop is changed.

App/src/components/Composer/index.js

Lines 193 to 200 in 704f3f7

	useEffect(() => {
	setSelection((prevSelection) => {
	if (!!prevSelection && selectionProp.start === prevSelection.start && selectionProp.end === prevSelection.end) {
	return;
	}
	return selectionProp;
	});
	}, [selectionProp]);

In our case, the selection props is 0.

There is also another code that caused the unwanted autofocus.

App/src/pages/home/report/ReportActionCompose/ComposerWithSuggestions/ComposerWithSuggestions.js

Lines 511 to 513 in 704f3f7

	useEffect(() => {
	// Scrolls the composer to the bottom and sets the selection to the end, so that longer drafts are easier to edit
	updateMultilineInputRange(textInputRef.current, shouldAutoFocus);

The code above will (run on mount) set the selection to the end of the composer and scroll the composer to the bottom. This means we have 2 selection logic, 1 with the fix of #15105 (with a state), and 1 without the fix (with a native method).

That's why the composer is always autofocused and the selection is at the start of the text.

What changes do you think we should make in order to solve the problem?

First, we should move the mWeb Safari fix to updateMultilineInputRange. In updateMultilineInputRange, we already pass shouldAutoFocus, so we can use the same logic as in ComposerWithSuggestion, that is don't set the selection if it's an mWeb Safari and the autofocus is false.

const shouldSetSelection = !(Browser.isMobileSafari() && !shouldAutoFocus);
if (shouldSetSelection) {
    input.setSelectionRange(length, length);
}

Now, update the selection initial value in ComposerWithSuggestion to 0.

const [selection, setSelection] = useState(() => ({start: 0, end: 0}));

Next, initialize the selection state in Composer based on the selection prop.

const [selection, setSelection] = useState({
    start: selectionProp.start,
    end: selectionProp.end,
});

This will make sure the input won't be autofocused when it shouldn't (the real issue) on mWeb Safari but the input is still scrolled to the bottom.

[conorpendergrast]

I have reproduced on iOS, in Safari 👍