element-call/src/grid/SpotlightPortraitLayout.tsx

/*
Copyright 2024 New Vector Ltd.

SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE in the repository root for full details.
*/

import { type ReactNode, type CSSProperties } from "react";
import { useObservableEagerState } from "observable-hooks";
import classNames from "classnames";

import { type CallLayout, arrangeTiles } from "./CallLayout";
import { type SpotlightPortraitLayout as SpotlightPortraitLayoutModel } from "../state/layout-types.ts";
import styles from "./SpotlightPortraitLayout.module.css";
import { useUpdateLayout, useVisibleTiles } from "./Grid";
import { useBehavior } from "../useBehavior";

interface GridCSSProperties extends CSSProperties {
  "--grid-gap": string;
  "--grid-tile-width": string;
  "--grid-tile-height": string;
}

/**
 * An implementation of the "spotlight portrait" layout, in which the spotlight
 * tile is shown across the top of the screen, and the grid of participants
 * scrolls behind it.
 */
export const makeSpotlightPortraitLayout: CallLayout<
  SpotlightPortraitLayoutModel
> = ({ minBounds$ }) => ({
  scrollingOnTop: false,

  fixed: function SpotlightPortraitLayoutFixed({
    ref,
    model,
    Slot,
  }): ReactNode {
    useUpdateLayout();

    return (
      <div ref={ref} className={styles.layer}>
        <div className={styles.spotlight}>
          <Slot
            className={styles.slot}
            id="spotlight"
            model={model.spotlight}
          />
        </div>
      </div>
    );
  },

  scrolling: function SpotlightPortraitLayoutScrolling({
    ref,
    model,
    Slot,
  }): ReactNode {
    useUpdateLayout();
    useVisibleTiles(model.setVisibleTiles);
    const { width } = useObservableEagerState(minBounds$);
    const { gap, tileWidth, tileHeight } = arrangeTiles(
      width,
      // TODO: We pretend that the minimum height is the width, because the
      // actual minimum height is difficult to calculate
      width,
      model.grid.length,
    );
    const withIndicators = useBehavior(model.spotlight.media$).length > 1;

    return (
      <div
        ref={ref}
        className={styles.layer}
        style={
          {
            "--grid-gap": `${gap}px`,
            "--grid-tile-width": `${Math.floor(tileWidth)}px`,
            "--grid-tile-height": `${Math.floor(tileHeight)}px`,
          } as GridCSSProperties
        }
      >
        <div
          className={classNames(styles.spotlight, {
            [styles.withIndicators]: withIndicators,
          })}
        />
        <div className={styles.grid}>
          {model.grid.map((m) => (
            <Slot key={m.id} className={styles.slot} id={m.id} model={m} />
          ))}
        </div>
      </div>
    );
  },
});