import React, { useCallback, useEffect, useState } from 'react';
import FocusTrap from 'focus-trap-react';
import {
  Dialog,
  Overlay,
  OverlayCenter,
  OverlayBackdrop,
  Header,
  config,
  Box,
  Text,
  IconButton,
  Icon,
  Icons,
  color,
  Button,
  Spinner,
} from 'folds';
import { MatrixError, Room } from 'matrix-js-sdk';
import { useAtomValue } from 'jotai';
import { useMatrixClient } from '../../hooks/useMatrixClient';
import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
import { stopPropagation } from '../../utils/keyboard';
import { getSpaceChildren, isSpace } from '../../utils/room';
import { mDirectAtom } from '../../state/mDirectList';
import { Membership } from '../../../types/matrix/room';

const LEAVE_DELAY_MS = 300;

/**
 * Delays execution for a specified time
 */
function delay(ms: number): Promise<void> {
  return new Promise<void>((resolve) => {
    setTimeout(resolve, ms);
  });
}

/**
 * Leaves multiple rooms sequentially with rate limiting
 */
async function leaveRoomsSequentially(
  mx: ReturnType<typeof useMatrixClient>,
  roomIds: string[],
  onProgress?: (current: number, total: number) => void
): Promise<void> {
  const total = roomIds.length;

  for (let i = 0; i < roomIds.length; i++) {
    const roomId = roomIds[i];
    onProgress?.(i, total);

    try {
      await mx.leave(roomId);
      await delay(LEAVE_DELAY_MS);
    } catch {
      // Continue leaving other rooms even if one fails
    }
  }

  onProgress?.(total, total);
}

/**
 * Gets direct child room IDs from a space that can be left (excluding DMs and subspaces)
 */
function getDirectChildRoomsToLeave(
  mx: ReturnType<typeof useMatrixClient>,
  spaceRoom: Room,
  mDirects: Set<string>
): string[] {
  const childIds = getSpaceChildren(spaceRoom);

  return childIds.filter((childId) => {
    // Skip DMs
    if (mDirects.has(childId)) {
      return false;
    }

    const childRoom = mx.getRoom(childId);
    if (!childRoom) {
      return false;
    }

    // Skip subspaces (only leave rooms, not nested spaces)
    if (isSpace(childRoom)) {
      return false;
    }

    // Only include rooms we're actually joined to
    if (childRoom.getMyMembership() !== Membership.Join) {
      return false;
    }

    return true;
  });
}

type LeaveSpacePromptProps = {
  roomId: string;
  onDone: () => void;
  onCancel: () => void;
};
export function LeaveSpacePrompt({ roomId, onDone, onCancel }: LeaveSpacePromptProps) {
  const mx = useMatrixClient();
  const mDirects = useAtomValue(mDirectAtom);
  const [progress, setProgress] = useState<{ current: number; total: number } | null>(null);

  const [leaveState, leaveRoom] = useAsyncCallback<undefined, MatrixError, []>(
    useCallback(async () => {
      const spaceRoom = mx.getRoom(roomId);

      if (spaceRoom) {
        // Get direct child rooms to leave (excluding DMs and subspaces)
        const childRoomsToLeave = getDirectChildRoomsToLeave(mx, spaceRoom, mDirects);

        if (childRoomsToLeave.length > 0) {
          // Leave child rooms first
          await leaveRoomsSequentially(mx, childRoomsToLeave, (current, total) => {
            setProgress({ current, total });
          });
        }
      }

      // Clear progress and leave the space itself
      setProgress(null);
      await mx.leave(roomId);
    }, [mx, roomId, mDirects])
  );

  const handleLeave = () => {
    leaveRoom();
  };

  useEffect(() => {
    if (leaveState.status === AsyncStatus.Success) {
      onDone();
    }
  }, [leaveState, onDone]);

  const isLoading = leaveState.status === AsyncStatus.Loading;
  const getButtonText = () => {
    if (!isLoading) return 'Leave';
    if (progress) return `Leaving Rooms: ${progress.current}/${progress.total}`;
    return 'Leaving Space...';
  };

  return (
    <Overlay open backdrop={<OverlayBackdrop />}>
      <OverlayCenter>
        <FocusTrap
          focusTrapOptions={{
            initialFocus: false,
            onDeactivate: onCancel,
            clickOutsideDeactivates: true,
            escapeDeactivates: stopPropagation,
          }}
        >
          <Dialog variant="Surface">
            <Header
              style={{
                padding: `0 ${config.space.S200} 0 ${config.space.S400}`,
                borderBottomWidth: config.borderWidth.B300,
              }}
              variant="Surface"
              size="500"
            >
              <Box grow="Yes">
                <Text size="H4">Leave Space</Text>
              </Box>
              <IconButton size="300" onClick={onCancel} radii="300">
                <Icon src={Icons.Cross} />
              </IconButton>
            </Header>
            <Box style={{ padding: config.space.S400 }} direction="Column" gap="400">
              <Box direction="Column" gap="200">
                <Text priority="400">
                  Are you sure you want to leave this space? You will also leave all rooms directly
                  in this space (except DMs).
                </Text>
                {leaveState.status === AsyncStatus.Error && (
                  <Text style={{ color: color.Critical.Main }} size="T300">
                    Failed to leave space! {leaveState.error.message}
                  </Text>
                )}
              </Box>
              <Button
                type="submit"
                variant="Critical"
                onClick={handleLeave}
                before={
                  isLoading ? <Spinner fill="Solid" variant="Critical" size="200" /> : undefined
                }
                aria-disabled={isLoading || leaveState.status === AsyncStatus.Success}
              >
                <Text size="B400">{getButtonText()}</Text>
              </Button>
            </Box>
          </Dialog>
        </FocusTrap>
      </OverlayCenter>
    </Overlay>
  );
}