import { useCallback, useEffect, useRef } from 'react';
import { CallMembership } from 'matrix-js-sdk/lib/matrixrtc/CallMembership';
import { useSetAtom } from 'jotai';
import { CallEmbed, useCallControlState } from '../plugins/call';
import { useSetting } from '../state/hooks/settings';
import { settingsAtom } from '../state/settings';
import { useMatrixClient } from './useMatrixClient';
import { useCallMembersChange, useCallSession } from './useCall';
import { useCallJoined } from './useCallEmbed';
import { playCallJoinSound, playCallLeaveSound } from '../utils/callSounds';
import { createCallSoundDebouncer } from '../utils/callSoundDebounce';
import { toastQueueAtom } from '../state/toast';
import { DEAFEN_CATCHUP_MIN_MS, deafenCatchUpText } from '../utils/deafenCatchUp';
import { getMemberName } from '../utils/room';

const membershipKey = (m: CallMembership): string => `${m.sender}|${m.deviceId}`;
const userOfKey = (key: string): string => key.slice(0, key.indexOf('|'));

/**
 * Plays a local sound effect when another participant joins or leaves
 * the call you are in. Style (or off) is configured in Settings → Calls.
 *
 * [Gitea #145] Cues go through `createCallSoundDebouncer` so a participant
 * whose connection flaps (leave + rejoin within seconds) is not announced
 * twice; membership UI is unaffected.
 */
export function useCallJoinLeaveSounds(embed: CallEmbed): void {
  const mx = useMatrixClient();
  const [style] = useSetting(settingsAtom, 'callJoinLeaveSound');
  const joined = useCallJoined(embed);
  const session = useCallSession(embed.room);

  const prevKeysRef = useRef<Set<string> | null>(null);
  const styleRef = useRef(style);
  styleRef.current = style;

  // [Gitea #128] Undeafen catch-up: snapshot who is here when you deafen, diff
  // when you undeafen, one toast if it changed and you were deafened ≥ 10 s.
  // Rides the same membership stream as the sounds — no new subscriptions.
  const { sound } = useCallControlState(embed.control);
  const setToast = useSetAtom(toastQueueAtom);
  const usersNow = useRef<Set<string>>(new Set());
  const deafenedAt = useRef<{ at: number; users: Set<string> } | null>(null);
  useEffect(() => {
    if (!joined) {
      deafenedAt.current = null;
      return;
    }
    if (!sound) {
      if (!deafenedAt.current)
        deafenedAt.current = { at: Date.now(), users: new Set(usersNow.current) };
      return;
    }
    const snap = deafenedAt.current;
    deafenedAt.current = null;
    if (!snap || Date.now() - snap.at < DEAFEN_CATCHUP_MIN_MS) return;
    const text = deafenCatchUpText(snap.users, usersNow.current, (u) =>
      getMemberName(embed.room, u),
    );
    if (text) {
      setToast({
        id: `deafen-catchup-${Date.now()}`,
        displayName: 'Lotus Chat',
        body: text,
        roomName: embed.room.name ?? 'Voice call',
        roomId: embed.roomId,
      });
    }
  }, [sound, joined, embed, setToast]);

  // One debouncer per joined call, so pending leave cues die with the call.
  const debouncerRef = useRef<ReturnType<typeof createCallSoundDebouncer> | null>(null);
  useEffect(() => {
    if (!joined) return undefined;
    const debouncer = createCallSoundDebouncer({
      play: (kind) => {
        const current = styleRef.current;
        if (current === 'off') return;
        if (kind === 'join') playCallJoinSound(current);
        else playCallLeaveSound(current);
      },
    });
    debouncerRef.current = debouncer;
    return () => {
      debouncer.dispose();
      if (debouncerRef.current === debouncer) debouncerRef.current = null;
    };
  }, [joined]);

  // Snapshot current members when the session (re)starts so we never play
  // sounds for participants who were already present.
  useEffect(() => {
    prevKeysRef.current = new Set(session.memberships.map(membershipKey));
  }, [session]);

  useCallMembersChange(
    session,
    useCallback(
      (members: CallMembership[]) => {
        const next = new Set(members.map(membershipKey));
        const prev = prevKeysRef.current ?? next;
        prevKeysRef.current = next;
        usersNow.current = new Set(
          Array.from(next, userOfKey).filter((u) => u !== mx.getSafeUserId()),
        );

        const debouncer = debouncerRef.current;
        if (!joined || style === 'off' || !debouncer) return;

        const myPrefix = `${mx.getSafeUserId()}|`;
        // Per USER: a device switch (leave on A, join on B) is a flap too.
        const joinedUsers = new Set<string>();
        const leftUsers = new Set<string>();
        next.forEach((key) => {
          if (!prev.has(key) && !key.startsWith(myPrefix)) joinedUsers.add(userOfKey(key));
        });
        prev.forEach((key) => {
          if (!next.has(key) && !key.startsWith(myPrefix)) leftUsers.add(userOfKey(key));
        });
        // A user still present on another device neither joined nor left, and
        // a second device of someone already here is not a new arrival.
        const stillPresent = new Set(Array.from(next, userOfKey));
        const wasPresent = new Set(Array.from(prev, userOfKey));
        leftUsers.forEach((u) => {
          if (!stillPresent.has(u)) debouncer.left(u);
        });
        joinedUsers.forEach((u) => {
          if (!wasPresent.has(u)) debouncer.joined(u);
        });
      },
      [joined, style, mx],
    ),
  );
}