| 1 | import { useEffect, useLayoutEffect, useRef, type RefObject } from "react"; |
| 2 | |
| 3 | // Plain-textarea IME guard (#8593/#8409). While a composition is active the |
| 4 | // composer textarea renders uncontrolled (value={undefined}), so no unrelated |
| 5 | // re-render (autosize, selection tracking, run-strip ticker) can write |
| 6 | // node.value and cancel the in-flight composition — React 19's updateTextarea |
| 7 | // compares the controlled value against the live DOM value on every commit, |
| 8 | // which is what swallowed the first CJK keystroke. onChange still flows into |
| 9 | // state; compositionend (or a non-composing commit input) ends the freeze and |
| 10 | // the next render resyncs against the live DOM value without clobbering it. |
| 11 | |
| 12 | export interface ComposerImeGuardOptions { |
| 13 | taRef: RefObject<HTMLTextAreaElement | null>; |
| 14 | text: string; |
| 15 | // Drives listener (re)attachment: the plain textarea unmounts while an |
| 16 | // invocation token mounts the rich input. |
| 17 | invocationCount: number; |
| 18 | textRef: RefObject<string>; |
| 19 | lastSelectionRef: RefObject<{ start: number; end: number }>; |
| 20 | setText: (next: string) => void; |
| 21 | setPlainSelection: (selection: { start: number; end: number }) => void; |
| 22 | } |
| 23 | |
| 24 | export interface ComposerImeGuard { |
| 25 | composingRef: RefObject<boolean>; |
| 26 | lastCompositionEndAt: RefObject<number>; |
| 27 | // Feeds the textarea's onChange into the freeze bookkeeping. |
| 28 | trackImeInputChange: (nativeEvent: InputEvent, inputType: string | undefined, value: string) => void; |
| 29 | } |
| 30 | |
| 31 | export function useComposerImeGuard(options: ComposerImeGuardOptions): ComposerImeGuard { |
| 32 | const { taRef, text, invocationCount, textRef, lastSelectionRef, setText, setPlainSelection } = options; |
| 33 | const composingRef = useRef(false); |
| 34 | const lastCompositionEndAt = useRef(0); |
| 35 | const setTextRef = useRef(setText); |
| 36 | const setPlainSelectionRef = useRef(setPlainSelection); |
| 37 | setTextRef.current = setText; |
| 38 | setPlainSelectionRef.current = setPlainSelection; |
| 39 | // Latest text the IME path itself produced, so a programmatic setText |
| 40 | // landing mid-composition can be told apart from IME input and force a |
| 41 | // resync. |
| 42 | const imeStateTextRef = useRef<string | null>(null); |
| 43 | |
| 44 | // Native composition listeners, the same mechanism the rich input uses: |
| 45 | // React's synthetic composition events fall back to keyCode-229 inference |
| 46 | // wherever CompositionEvent is missing, and the freeze bookkeeping must run |
| 47 | // synchronously with the browser's composition lifecycle. |
| 48 | useEffect(() => { |
| 49 | const node = taRef.current; |
| 50 | if (!node) return; |
| 51 | const onStart = () => { |
| 52 | composingRef.current = true; |
| 53 | imeStateTextRef.current = textRef.current; |
| 54 | }; |
| 55 | const onEnd = () => { |
| 56 | composingRef.current = false; |
| 57 | lastCompositionEndAt.current = Date.now(); |
| 58 | imeStateTextRef.current = null; |
| 59 | // compositionend's DOM value is authoritative: an IME cancel restores |
| 60 | // the pre-composition text while state may still hold the provisional |
| 61 | // text. |
| 62 | if (node.value !== textRef.current) { |
| 63 | const nextSelection = { |
| 64 | start: node.selectionStart ?? node.value.length, |
| 65 | end: node.selectionEnd ?? node.value.length, |
| 66 | }; |
| 67 | textRef.current = node.value; |
| 68 | setTextRef.current(node.value); |
| 69 | lastSelectionRef.current = nextSelection; |
| 70 | setPlainSelectionRef.current(nextSelection); |
| 71 | } |
| 72 | }; |
| 73 | node.addEventListener("compositionstart", onStart); |
| 74 | node.addEventListener("compositionend", onEnd); |
| 75 | return () => { |
| 76 | node.removeEventListener("compositionstart", onStart); |
| 77 | node.removeEventListener("compositionend", onEnd); |
| 78 | // Unmounting the textarea mid-composition (e.g. an invocation token |
| 79 | // swaps in the rich input) may never deliver compositionend; leaving |
| 80 | // composingRef stuck would suppress Enter-to-send forever. |
| 81 | if (composingRef.current) { |
| 82 | composingRef.current = false; |
| 83 | lastCompositionEndAt.current = Date.now(); |
| 84 | imeStateTextRef.current = null; |
| 85 | } |
| 86 | }; |
| 87 | }, [invocationCount, taRef, textRef, lastSelectionRef]); |
| 88 | |
| 89 | // Programmatic setText (history recall, menu inserts, draft switches) |
| 90 | // bypasses the textarea's onChange, so while the IME freeze renders the |
| 91 | // textarea uncontrolled those writes would never reach the DOM. A text |
| 92 | // change the IME path did not produce forces an authoritative resync and |
| 93 | // ends the frozen composition: programmatic content wins. |
| 94 | useLayoutEffect(() => { |
| 95 | if (!composingRef.current) return; |
| 96 | if (imeStateTextRef.current === text) return; |
| 97 | composingRef.current = false; |
| 98 | imeStateTextRef.current = null; |
| 99 | const node = taRef.current; |
| 100 | if (!node) return; |
| 101 | node.value = text; |
| 102 | const caret = Math.min(lastSelectionRef.current.start, text.length); |
| 103 | try { |
| 104 | node.setSelectionRange(caret, caret); |
| 105 | } catch { |
| 106 | // Detached/jsdom node: caret restore is best-effort. |
| 107 | } |
| 108 | }, [text, taRef, lastSelectionRef]); |
| 109 | |
| 110 | const trackImeInputChange = (nativeEvent: InputEvent, inputType: string | undefined, value: string) => { |
| 111 | if (!composingRef.current) return; |
| 112 | if (nativeEvent.isComposing || inputType === "insertCompositionText") { |
| 113 | // Mid-composition edits still reach state so app logic (menus, |
| 114 | // counters, drafts) sees the live text; the uncontrolled render keeps |
| 115 | // the provisional text out of React's DOM sync. |
| 116 | imeStateTextRef.current = value; |
| 117 | return; |
| 118 | } |
| 119 | // A non-composition input while frozen is the commit (Chromium can fire |
| 120 | // it before compositionend; WebView2 can deliver the committed text in a |
| 121 | // following non-composing input): end the freeze so this render resyncs |
| 122 | // normally. |
| 123 | composingRef.current = false; |
| 124 | imeStateTextRef.current = null; |
| 125 | }; |
| 126 | |
| 127 | return { composingRef, lastCompositionEndAt, trackImeInputChange }; |
| 128 | } |
| 129 |