import { useMemo, useState } from 'react'
import { Bell, Layers, Folder, Eye, Pencil, Check, X, Loader2 } from 'lucide-react'
import { cn } from '@/lib/utils'
import { Button } from '@/components/ui/button'
import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover'
import {
  usePendingSharesQuery,
  useAcceptShareMutation,
  useDeclineShareMutation,
} from '../../hooks/useSharingQueries'
import { toast } from '../ToastContainer'
import type { PendingShare } from '../../services/api'
import { Avatar } from './Avatar'

/** Share invite notification bell. Sits in the LeftSidebar user
 *  section — polls /sharing/pending every 60s and shows a red-orange
 *  count badge when there are pending invites. Click opens a popover
 *  listing each invite with Accept / Decline inline. */
export function NotificationBell() {
  const [open, setOpen] = useState(false)
  const { data } = usePendingSharesQuery()
  const acceptMutation = useAcceptShareMutation()
  const declineMutation = useDeclineShareMutation()

  const invites = useMemo(() => {
    if (!data) return [] as Array<PendingShare & { kind: 'heap' | 'folder' }>
    return [
      ...data.heaps.map((h) => ({ ...h, kind: 'heap' as const })),
      ...data.folders.map((f) => ({ ...f, kind: 'folder' as const })),
    ]
  }, [data])

  const count = invites.length
  const isMutating = acceptMutation.isPending || declineMutation.isPending

  const handleAccept = (invite: PendingShare & { kind: 'heap' | 'folder' }) => {
    acceptMutation.mutate(
      { kind: invite.kind, targetId: invite.target_id },
      {
        onSuccess: () => {
          toast.success(`Joined ${invite.target_name}`)
        },
      },
    )
  }
  const handleDecline = (invite: PendingShare & { kind: 'heap' | 'folder' }) => {
    declineMutation.mutate({ kind: invite.kind, targetId: invite.target_id })
  }

  return (
    <Popover open={open} onOpenChange={setOpen}>
      <PopoverTrigger asChild>
        <button
          type="button"
          className={cn(
            'relative inline-flex h-7 w-7 items-center justify-center rounded-md text-text-muted transition-colors',
            'hover:bg-surface-2 hover:text-text',
            count > 0 && 'text-text',
          )}
          aria-label={count > 0 ? `${count} pending invite${count === 1 ? '' : 's'}` : 'Notifications'}
          title={count > 0 ? `${count} pending invite${count === 1 ? '' : 's'}` : 'No pending invites'}
        >
          <Bell className="h-4 w-4" />
          {count > 0 && (
            <span className="absolute -right-0.5 -top-0.5 inline-flex min-w-[14px] items-center justify-center rounded-full bg-primary px-1 text-[9px] font-semibold leading-[14px] tabular-nums text-black shadow-[0_0_0_1.5px_var(--bg,theme(colors.bg))]">
              {count}
            </span>
          )}
        </button>
      </PopoverTrigger>
      <PopoverContent align="start" sideOffset={6} className="w-80 p-0">
        <div className="flex items-center justify-between border-b border-border px-3 py-2">
          <div className="text-sm font-semibold text-text">Pending invites</div>
          {count > 0 && (
            <span className="text-[11px] tabular-nums text-text-faint">{count}</span>
          )}
        </div>

        {count === 0 ? (
          <div className="px-3 py-4 text-xs text-text-muted">
            No pending invites.
          </div>
        ) : (
          <ul className="max-h-80 divide-y divide-border overflow-y-auto">
            {invites.map((invite) => {
              const TypeIcon = invite.kind === 'heap' ? Layers : Folder
              return (
                <li
                  key={`${invite.kind}:${invite.share_id}`}
                  className="flex flex-col gap-2 px-3 py-2.5"
                >
                  <div className="flex items-start gap-2.5">
                    <Avatar
                      name={invite.owner_username}
                      imageUrl={invite.owner_avatar_url}
                      size="sm"
                    />
                    <div className="min-w-0 flex-1">
                      <div className="text-sm leading-tight text-text">
                        <span className="font-medium">
                          {invite.owner_display_name || invite.owner_username}
                        </span>
                        <span className="text-text-muted"> shared </span>
                        <span className="inline-flex items-center gap-1 align-baseline">
                          <TypeIcon className="inline h-3 w-3 text-text-muted" />
                          <span className="font-medium">{invite.target_name}</span>
                        </span>
                      </div>
                      <div className="mt-0.5 flex items-center gap-1 text-[11px] text-text-muted">
                        {invite.permission === 'write' ? (
                          <>
                            <Pencil className="h-2.5 w-2.5" />
                            Can edit
                          </>
                        ) : (
                          <>
                            <Eye className="h-2.5 w-2.5" />
                            Can view
                          </>
                        )}
                      </div>
                    </div>
                  </div>
                  <div className="flex items-center justify-end gap-2">
                    <Button
                      variant="ghost"
                      size="sm"
                      disabled={isMutating}
                      onClick={() => handleDecline(invite)}
                      className="h-7 text-text-muted hover:bg-reject/10 hover:text-reject"
                    >
                      <X className="mr-1 h-3.5 w-3.5" />
                      Decline
                    </Button>
                    <Button
                      size="sm"
                      disabled={isMutating}
                      onClick={() => handleAccept(invite)}
                      className="h-7"
                    >
                      {acceptMutation.isPending ? (
                        <Loader2 className="mr-1 h-3.5 w-3.5 animate-spin" />
                      ) : (
                        <Check className="mr-1 h-3.5 w-3.5" />
                      )}
                      Accept
                    </Button>
                  </div>
                </li>
              )
            })}
          </ul>
        )}
      </PopoverContent>
    </Popover>
  )
}