feat(frontend): 投稿ウインドウにMFM要素を追加するボタンの追加 (#12788)

* functionPicker の追加

* Update CHANGELOG.md

* fix lint errors

* Add addMfmFunction

* add enableQuickAddMfmFunction setting

* Update CHANGELOG.md

issue 番号を追加

* Update index.d.ts

* change 'functionPicker' to 'mfmFunctionPicker'

* Change indent from 4 space to 1 tab

---------

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/frontend/src/scripts/mfm-function-picker.ts

@@ -0,0 +1,61 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and other misskey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Ref, nextTick } from 'vue';
+import * as os from '@/os.js';
+import { i18n } from '@/i18n.js';
+import { MFM_TAGS } from '@/const.js';
+
+/**
+ * MFMの装飾のリストを表示する
+ */
+export function mfmFunctionPicker(src: any, textArea: HTMLInputElement | HTMLTextAreaElement, textRef: Ref<string>) {
+	return new Promise((res, rej) => {
+		os.popupMenu([{
+			text: i18n.ts.addMfmFunction,
+			type: 'label',
+		}, ...getFunctionList(textArea, textRef)], src);
+	});
+}
+
+function getFunctionList(textArea: HTMLInputElement | HTMLTextAreaElement, textRef: Ref<string>) : object[] {
+	const ret: object[] = [];
+	MFM_TAGS.forEach(tag => {
+		ret.push({
+			text: tag,
+			icon: 'ti ti-icons',
+			action: () => add(textArea, textRef, tag),
+		});
+	});
+	return ret;
+}
+
+function add(textArea: HTMLInputElement | HTMLTextAreaElement, textRef: Ref<string>, type: string) {
+	const caretStart: number = textArea.selectionStart as number;
+	const caretEnd: number = textArea.selectionEnd as number;
+
+	MFM_TAGS.forEach(tag => {
+		if (type === tag) {
+			if (caretStart === caretEnd) {
+				// 単純にFunctionを追加
+				const trimmedText = `${textRef.value.substring(0, caretStart)}$[${type} ]${textRef.value.substring(caretEnd)}`;
+				textRef.value = trimmedText;
+			} else {
+				// 選択範囲を囲むようにFunctionを追加
+				const trimmedText = `${textRef.value.substring(0, caretStart)}$[${type} ${textRef.value.substring(caretStart, caretEnd)}]${textRef.value.substring(caretEnd)}`;
+				textRef.value = trimmedText;
+			}
+		}
+	});
+
+	const nextCaretStart: number = caretStart + 3 + type.length;
+	const nextCaretEnd: number = caretEnd + 3 + type.length;
+
+	// キャレットを戻す
+	nextTick(() => {
+		textArea.focus();
+		textArea.setSelectionRange(nextCaretStart, nextCaretEnd);
+	});
+}