Add PowerLevelSelector.tsx.

It's extracting the current behavior of the privileged users and muted of `RolesRoomSettingsTab.tsx` into a dedicated component.
It's also adding a new apply button.

res/css/_components.pcss

@@ -323,6 +323,7 @@
 @import "./views/rooms/wysiwyg_composer/components/_FormattingButtons.pcss";
 @import "./views/rooms/wysiwyg_composer/components/_LinkModal.pcss";
 @import "./views/settings/_AvatarSetting.pcss";
+@import "./views/settings/_PowerLevelSelector.pcss";
 @import "./views/settings/_CrossSigningPanel.pcss";
 @import "./views/settings/_CryptographyPanel.pcss";
 @import "./views/settings/_FontScalingPanel.pcss";

res/css/views/settings/_PowerLevelSelector.pcss

@@ -0,0 +1,21 @@
+/*
+ *
+ * Copyright 2024 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * /
+ */
+
+.mx_PowerLevelSelector_Button {
+    align-self: flex-start;
+}

src/components/views/settings/PowerLevelSelector.tsx

@@ -0,0 +1,140 @@
+/*
+ *
+ * Copyright 2024 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * /
+ */
+
+import React, { useState, JSX, PropsWithChildren } from "react";
+import { Button } from "@vector-im/compound-web";
+import { compare } from "matrix-js-sdk/src/utils";
+
+import { useMatrixClientContext } from "../../../contexts/MatrixClientContext";
+import PowerSelector from "../elements/PowerSelector";
+import { _t } from "../../../languageHandler";
+import SettingsFieldset from "./SettingsFieldset";
+
+/**
+ * Display in a fieldset, the power level of the users and allow to change them.
+ * The apply button is disabled until the power level of an user is changed
+ */
+interface PowerLevelSelectorProps {
+    /**
+     * The power levels of the users
+     * The key is the user id and the value is the power level
+     */
+    userLevels: Record<string, number>;
+    /**
+     * Whether the user can change the power levels of other users
+     */
+    canChangeLevels: boolean;
+    /**
+     * The current user power level
+     */
+    currentUserLevel: number;
+    /**
+     * The callback when the apply button is clicked
+     * @param value - new power level for the user
+     * @param userId - the user id
+     */
+    onClick: (value: number, userId: string) => void;
+    /**
+     * Filter the users to display
+     * @param user
+     */
+    filter: (user: string) => boolean;
+    /**
+     * The title of the fieldset
+     */
+    title: string;
+}
+
+export function PowerLevelSelector({
+    userLevels,
+    canChangeLevels,
+    currentUserLevel,
+    onClick,
+    filter,
+    title,
+    children,
+}: PropsWithChildren<PowerLevelSelectorProps>): JSX.Element | null {
+    const matrixClient = useMatrixClientContext();
+    const [currentPowerLevel, setCurrentPowerLevel] = useState<{ value: number; userId: string } | null>(null);
+
+    // If the power level has changed, we need to enable the apply button
+    const powerLevelChanged = Boolean(
+        currentPowerLevel && currentPowerLevel.value !== userLevels[currentPowerLevel?.userId],
+    );
+
+    // We sort the users by power level, then we filter them
+    const users = Object.keys(userLevels)
+        .sort((userA, userB) => sortUser(userA, userB, userLevels))
+        .filter(filter);
+
+    // No user to display, we return the children into fragment to convert it to JSX.Element type
+    if (!users.length) return <>{children}</>;
+
+    return (
+        <SettingsFieldset legend={title}>
+            {users.map((userId) => {
+                // We only want to display users with a valid power level aka an integer
+                if (!Number.isInteger(userLevels[userId])) return;
+
+                const isMe = userId === matrixClient.getUserId();
+                // If I can change levels, I can change the level of anyone with a lower level than mine
+                const canChange = canChangeLevels && (userLevels[userId] < currentUserLevel || isMe);
+
+                // When the new power level is selected, the fields are rerendered and we need to keep the current value
+                const userLevel = currentPowerLevel?.userId === userId ? currentPowerLevel?.value : userLevels[userId];
+
+                return (
+                    <PowerSelector
+                        value={userLevel}
+                        disabled={!canChange}
+                        label={userId}
+                        key={userId}
+                        onChange={(value) => setCurrentPowerLevel({ value, userId })}
+                    />
+                );
+            })}
+
+            <Button
+                size="sm"
+                kind="primary"
+                // mx_Dialog_nonDialogButton is necessary to avoid the Dialog CSS to override the button style
+                className="mx_Dialog_nonDialogButton mx_PowerLevelSelector_Button"
+                onClick={() => {
+                    if (currentPowerLevel !== null) {
+                        onClick(currentPowerLevel.value, currentPowerLevel.userId);
+                        setCurrentPowerLevel(null);
+                    }
+                }}
+                disabled={!powerLevelChanged}
+            >
+                {_t("action|apply")}
+            </Button>
+        </SettingsFieldset>
+    );
+}
+
+/**
+ * Sort the users by power level, then by name
+ * @param userA
+ * @param userB
+ * @param userLevels
+ */
+function sortUser(userA: string, userB: string, userLevels: PowerLevelSelectorProps["userLevels"]): number {
+    const powerLevelDiff = userLevels[userA] - userLevels[userB];
+    return powerLevelDiff !== 0 ? powerLevelDiff : compare(userA.toLocaleLowerCase(), userB.toLocaleLowerCase());
+}

test/components/views/settings/PowerLevelSelector-test.tsx

@@ -0,0 +1,112 @@
+/*
+ *
+ * Copyright 2024 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * /
+ */
+
+import { render, screen } from "@testing-library/react";
+import React, { ComponentProps } from "react";
+import userEvent from "@testing-library/user-event";
+
+import { PowerLevelSelector } from "../../../../src/components/views/settings/PowerLevelSelector";
+import { stubClient } from "../../../test-utils";
+import MatrixClientContext from "../../../../src/contexts/MatrixClientContext";
+
+describe("PowerLevelSelector", () => {
+    const matrixClient = stubClient();
+
+    const currentUser = matrixClient.getUserId()!;
+    const userLevels = {
+        [currentUser]: 100,
+        "@alice:server.org": 50,
+        "@bob:server.org": 0,
+    };
+
+    const renderPLS = (props: Partial<ComponentProps<typeof PowerLevelSelector>>) =>
+        render(
+            <MatrixClientContext.Provider value={matrixClient}>
+                <PowerLevelSelector
+                    userLevels={userLevels}
+                    canChangeLevels={true}
+                    currentUserLevel={userLevels[currentUser]}
+                    title="title"
+                    // filter nothing by default
+                    filter={() => true}
+                    onClick={jest.fn()}
+                    {...props}
+                >
+                    empty label
+                </PowerLevelSelector>
+            </MatrixClientContext.Provider>,
+        );
+
+    it("should render", () => {
+        renderPLS({});
+        expect(screen.getByRole("group")).toMatchSnapshot();
+    });
+
+    it("should display only the current user", async () => {
+        // Display only the current user
+        renderPLS({ filter: (user) => user === currentUser });
+
+        // Only alice should be displayed
+        const userSelects = screen.getAllByRole("combobox");
+        expect(userSelects).toHaveLength(1);
+        expect(userSelects[0]).toHaveAccessibleName(currentUser);
+
+        expect(screen.getByRole("group")).toMatchSnapshot();
+    });
+
+    it("should be able to change the power level of the current user", async () => {
+        const onClick = jest.fn();
+        renderPLS({ onClick });
+
+        // Until the power level is changed, the apply button should be disabled
+        // compound button is using aria-disabled instead of the disabled attribute, we can't toBeDisabled on it
+        expect(screen.getByRole("button", { name: "Apply" })).toHaveAttribute("aria-disabled", "true");
+
+        // Change current user power level to 50
+        const select = screen.getByRole("combobox", { name: currentUser });
+        expect(select).toHaveValue("100");
+
+        // After the user level changes, the apply button should be enabled
+        await userEvent.selectOptions(select, "50");
+        expect(select).toHaveValue("50");
+        expect(screen.getByRole("button", { name: "Apply" })).toHaveAttribute("aria-disabled", "false");
+
+        // Click on Apply should call onClick with the new power level
+        await userEvent.click(screen.getByRole("button", { name: "Apply" }));
+        expect(onClick).toHaveBeenCalledWith(50, currentUser);
+    });
+
+    it("should not be able to change the power level if `canChangeLevels` is false", async () => {
+        renderPLS({ canChangeLevels: false });
+
+        // The selects should be disabled
+        const userSelects = screen.getAllByRole("combobox");
+        userSelects.forEach((select) => expect(select).toBeDisabled());
+    });
+
+    it("should be able to change only the level of someone with a lower level", async () => {
+        const userLevels = {
+            [currentUser]: 50,
+            "@alice:server.org": 100,
+        };
+        renderPLS({ userLevels });
+
+        expect(screen.getByRole("combobox", { name: currentUser })).toBeEnabled();
+        expect(screen.getByRole("combobox", { name: "@alice:server.org" })).toBeDisabled();
+    });
+});