element-call/src/reactions/useReactionsSender.tsx

/*
Copyright 2024 Milton Moura <miltonmoura@gmail.com>

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

import { EventType, RelationType } from "matrix-js-sdk";
import {
  createContext,
  use,
  type ReactNode,
  useCallback,
  useMemo,
  type JSX,
} from "react";
import { type MatrixRTCSession } from "matrix-js-sdk/lib/matrixrtc";
import { logger } from "matrix-js-sdk/lib/logger";
import { useObservableEagerState } from "observable-hooks";

import { useMatrixRTCSessionMemberships } from "../useMatrixRTCSessionMemberships";
import { useClientState } from "../ClientContext";
import { ElementCallReactionEventType, type ReactionOption } from ".";
import { type CallViewModel } from "../state/CallViewModel";

interface ReactionsSenderContextType {
  supportsReactions: boolean;
  toggleRaisedHand: () => Promise<void>;
  sendReaction: (reaction: ReactionOption) => Promise<void>;
}

const ReactionsSenderContext = createContext<
  ReactionsSenderContextType | undefined
>(undefined);

export const useReactionsSender = (): ReactionsSenderContextType => {
  const context = use(ReactionsSenderContext);
  if (!context) {
    throw new Error("useReactions must be used within a ReactionsProvider");
  }
  return context;
};

/**
 * Provider that handles sending a reaction or hand raised event to a call.
 */
export const ReactionsSenderProvider = ({
  children,
  rtcSession,
  vm,
}: {
  children: ReactNode;
  rtcSession: MatrixRTCSession;
  vm: CallViewModel;
}): JSX.Element => {
  const memberships = useMatrixRTCSessionMemberships(rtcSession);
  const clientState = useClientState();
  const supportsReactions =
    clientState?.state === "valid" && clientState.supportedFeatures.reactions;
  const room = rtcSession.room;
  const myUserId = room.client.getUserId();
  const myDeviceId = room.client.getDeviceId();
  const myMembershipIdentifier = `${myUserId}:${myDeviceId}`;

  const myMembershipEvent = useMemo(
    () =>
      memberships.find(
        (m) => m.sender === myUserId && m.deviceId === myDeviceId,
      )?.eventId,
    [memberships, myUserId, myDeviceId],
  );

  const reactions = useObservableEagerState(vm.reactions$);
  const myReaction = useMemo(
    () =>
      myMembershipIdentifier !== undefined
        ? reactions[myMembershipIdentifier]
        : undefined,
    [myMembershipIdentifier, reactions],
  );

  const handsRaised = useObservableEagerState(vm.handsRaised$);
  const myRaisedHand = useMemo(
    () =>
      myMembershipIdentifier !== undefined
        ? handsRaised[myMembershipIdentifier]
        : undefined,
    [myMembershipIdentifier, handsRaised],
  );

  const toggleRaisedHand = useCallback(async () => {
    if (!myMembershipIdentifier) {
      return;
    }
    const myReactionId = myRaisedHand?.reactionEventId;

    if (!myReactionId) {
      try {
        if (!myMembershipEvent) {
          throw new Error("Cannot find own membership event");
        }
        const reaction = await room.client.sendEvent(
          rtcSession.room.roomId,
          EventType.Reaction,
          {
            "m.relates_to": {
              rel_type: RelationType.Annotation,
              event_id: myMembershipEvent,
              key: "🖐️",
            },
          },
        );
        logger.debug("Sent raise hand event", reaction.event_id);
      } catch (ex) {
        logger.error("Failed to send raised hand", ex);
      }
    } else {
      try {
        await room.client.redactEvent(rtcSession.room.roomId, myReactionId);
        logger.debug("Redacted raise hand event");
      } catch (ex) {
        logger.error("Failed to redact reaction event", myReactionId, ex);
        throw ex;
      }
    }
  }, [
    myMembershipEvent,
    myMembershipIdentifier,
    myRaisedHand,
    rtcSession,
    room,
  ]);

  const sendReaction = useCallback(
    async (reaction: ReactionOption) => {
      if (!myMembershipIdentifier || myReaction) {
        // We're still reacting
        return;
      }
      if (!myMembershipEvent) {
        throw new Error("Cannot find own membership event");
      }
      await room.client.sendEvent(
        rtcSession.room.roomId,
        ElementCallReactionEventType,
        {
          "m.relates_to": {
            rel_type: RelationType.Reference,
            event_id: myMembershipEvent,
          },
          emoji: reaction.emoji,
          name: reaction.name,
        },
      );
    },
    [myMembershipEvent, myReaction, room, myMembershipIdentifier, rtcSession],
  );

  return (
    <ReactionsSenderContext
      value={{
        supportsReactions,
        toggleRaisedHand,
        sendReaction,
      }}
    >
      {children}
    </ReactionsSenderContext>
  );
};