"use client";

import { useState, useTransition } from "react";
import { Button } from "@/components/ui/button";
import {
  disconnectCalendarAction,
  listAvailableCalendarsAction,
  selectCalendarAction,
  syncNowAction,
} from "../actions/calendar";
import type { RemoteCalendarInfo } from "@/services/calendar/types";

export interface ConnectionState {
  connected: boolean;
  accountEmail?: string;
  selectedCalendarName?: string;
  lastSyncAt?: string;
  lastSyncError?: string | null;
}

export function CalendarConnectionPanel({ initial, configured }: { initial: ConnectionState; configured: boolean }) {
  const [state, setState] = useState(initial);
  const [isPending, startTransition] = useTransition();
  const [message, setMessage] = useState<string | null>(null);
  const [calendars, setCalendars] = useState<RemoteCalendarInfo[] | null>(null);

  const sync = () => {
    setMessage(null);
    startTransition(async () => {
      const result = await syncNowAction();
      setMessage(result.success ? "Sync complete." : (result.error ?? "Sync failed."));
    });
  };

  const disconnect = () => {
    setMessage(null);
    startTransition(async () => {
      await disconnectCalendarAction();
      setState({ connected: false });
      setMessage("Disconnected. Existing calendar events were left as they are.");
    });
  };

  const loadCalendars = () => {
    setMessage(null);
    startTransition(async () => {
      const result = await listAvailableCalendarsAction();
      if (!result.success) {
        setMessage(result.error ?? "Couldn't load calendars.");
        return;
      }
      setCalendars(result.calendars ?? []);
    });
  };

  const chooseCalendar = (calendar: RemoteCalendarInfo) => {
    startTransition(async () => {
      const result = await selectCalendarAction(calendar.id, calendar.name);
      if (result.success) {
        setState((prev) => ({ ...prev, selectedCalendarName: calendar.name }));
        setCalendars(null);
        setMessage(`Now syncing to "${calendar.name}".`);
      }
    });
  };

  if (!state.connected) {
    return (
      <div className="border-line rounded-jumbo border bg-white p-5">
        <p className="mb-1 text-sm font-bold">Google Calendar</p>
        <p className="text-muted mb-4 text-xs">
          Sync your confirmed appointments to your own Google Calendar. This connects a Google account separately
          from sign-in — you can use a different one if you like.
        </p>
        {message && <p className="text-danger mb-3 text-xs font-medium">{message}</p>}
        {configured ? (
          <Button asChild size="sm">
            <a href="/api/staff/calendar/google/authorize">Connect Google Calendar</a>
          </Button>
        ) : (
          <p className="text-muted text-xs">Google Calendar sync is not configured on this deployment yet.</p>
        )}
      </div>
    );
  }

  return (
    <div className="border-line rounded-jumbo border bg-white p-5">
      <p className="mb-1 text-sm font-bold">Google Calendar</p>
      <div className="text-muted mb-4 space-y-1 text-xs">
        <p>Connected as {state.accountEmail}</p>
        <p>Syncing to &ldquo;{state.selectedCalendarName}&rdquo;</p>
        {state.lastSyncAt && <p>Last synced {new Date(state.lastSyncAt).toLocaleString()}</p>}
        {state.lastSyncError && <p className="text-danger">Last sync error: {state.lastSyncError}</p>}
      </div>

      {message && <p className="text-muted mb-3 text-xs font-medium">{message}</p>}

      {calendars ? (
        <ul className="mb-4 space-y-2">
          {calendars.map((calendar) => (
            <li key={calendar.id}>
              <button
                type="button"
                onClick={() => chooseCalendar(calendar)}
                className="border-line w-full rounded-lg border px-3 py-2 text-left text-xs font-bold hover:bg-stone"
              >
                {calendar.name} {calendar.primary && "(primary)"}
              </button>
            </li>
          ))}
        </ul>
      ) : null}

      <div className="flex flex-wrap gap-2">
        <Button size="sm" isLoading={isPending} onClick={sync}>
          Sync Now
        </Button>
        <Button size="sm" variant="secondary" isLoading={isPending} onClick={loadCalendars}>
          Change Calendar
        </Button>
        <Button size="sm" variant="destructive" isLoading={isPending} onClick={disconnect}>
          Disconnect
        </Button>
      </div>
    </div>
  );
}