Improve user operations

Resolve #2197
Resolve #3367

src/server/api/endpoints/admin/show-user.ts

@@ -0,0 +1,40 @@
+import $ from 'cafy';
+import ID, { transform } from '../../../../misc/cafy-id';
+import define from '../../define';
+import User from '../../../../models/user';
+
+export const meta = {
+	desc: {
+		'ja-JP': '指定したユーザーの情報を取得します。',
+	},
+
+	requireCredential: true,
+	requireModerator: true,
+
+	params: {
+		userId: {
+			validator: $.type(ID),
+			transform: transform,
+			desc: {
+				'ja-JP': '対象のユーザーID',
+				'en-US': 'The user ID which you want to suspend'
+			}
+		},
+	}
+};
+
+export default define(meta, (ps, me) => new Promise(async (res, rej) => {
+	const user = await User.findOne({
+		_id: ps.userId
+	});
+
+	if (user == null) {
+		return rej('user not found');
+	}
+
+	if (me.isModerator && user.isAdmin) {
+		return rej('cannot show info of admin');
+	}
+
+	res(user);
+}));