"use client"

import * as React from "react"
import FullCalendar from "@fullcalendar/react"
import dayGridPlugin from "@fullcalendar/daygrid"
import timeGridPlugin from "@fullcalendar/timegrid"
import interactionPlugin from "@fullcalendar/interaction"
import type { DateSelectArg, DatesSetArg, EventClickArg, EventInput } from "@fullcalendar/core"

import { getBookings } from "@/lib/api/bookings"
import { getFacilitySessions } from "@/lib/api/facilities"
import { ApiError } from "@/lib/api/core-http"
import type { Booking, BookingStatus } from "@/lib/models/booking"
import type { FacilitySession } from "@/lib/models/facility"
import { formatCurrency } from "@/lib/format"
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
} from "@/components/ui/dialog"
import { StatusBadge } from "@/components/hexa/status-badge"

const STATUS_COLORS: Record<BookingStatus, string> = {
  Confirmed: "#2563eb",
  CheckedIn: "#16a34a",
  Completed: "#6b7280",
  NoShow: "#dc2626",
  Cancelled: "#dc2626",
}

const SESSION_COLOR = "#7c3aed"
const NOT_HELD_COLOR = "#9ca3af"

function bookingToEvent(booking: Booking): EventInput {
  const color = STATUS_COLORS[booking.status] ?? "#2563eb"
  return {
    id: `booking-${booking.bookingId}`,
    title: `${booking.facilityName ?? "Facility"} — ${booking.isGuest ? booking.guestName ?? "Guest" : "Member"}`,
    start: booking.startTime,
    end: booking.endTime,
    backgroundColor: color,
    borderColor: color,
    extendedProps: { kind: "booking", booking },
  }
}

function sessionToEvent(session: FacilitySession): EventInput {
  const notHeld = session.isCancelled
  const label = session.facilityClassName ?? session.facilityName ?? "Session"
  const capacityLabel = session.isUnlimitedCapacity ? `${session.bookedCount} booked` : `${session.bookedCount}/${session.capacity} booked`

  return {
    id: `session-${session.facilitySessionId}`,
    title: notHeld ? `${label} — Not held` : `${label} — ${capacityLabel}`,
    start: session.startTime,
    end: session.endTime,
    backgroundColor: notHeld ? "transparent" : SESSION_COLOR,
    borderColor: notHeld ? NOT_HELD_COLOR : SESSION_COLOR,
    textColor: notHeld ? NOT_HELD_COLOR : undefined,
    classNames: notHeld ? ["opacity-70", "border-dashed"] : [],
    extendedProps: { kind: "session", session },
  }
}

type SelectedEvent = { kind: "booking"; booking: Booking } | { kind: "session"; session: FacilitySession } | null

function EventDetailDialog({ event, onOpenChange }: { event: SelectedEvent; onOpenChange: (open: boolean) => void }) {
  return (
    <Dialog open={!!event} onOpenChange={onOpenChange}>
      <DialogContent className="sm:max-w-sm">
        <DialogHeader>
          <DialogTitle>{event?.kind === "booking" ? "Booking Details" : "Class Occurrence"}</DialogTitle>
        </DialogHeader>

        {event?.kind === "booking" && (
          <div className="grid grid-cols-2 gap-3 rounded-lg border p-3 text-sm">
            <div>
              <p className="text-muted-foreground">Facility</p>
              <p className="font-medium">{event.booking.facilityName ?? "—"}</p>
            </div>
            <div>
              <p className="text-muted-foreground">Status</p>
              <StatusBadge status={event.booking.status === "Cancelled" || event.booking.status === "NoShow" ? "danger" : "success"}>
                {event.booking.status}
              </StatusBadge>
            </div>
            <div>
              <p className="text-muted-foreground">Who</p>
              <p className="font-medium">{event.booking.isGuest ? event.booking.guestName ?? "Guest" : "Member"}</p>
            </div>
            <div>
              <p className="text-muted-foreground">Payment</p>
              <p className="font-medium">
                {event.booking.paymentStatus}
                {event.booking.amountCharged > 0 && ` · ${formatCurrency(event.booking.amountCharged)}`}
              </p>
            </div>
          </div>
        )}

        {event?.kind === "session" && (
          <div className="grid grid-cols-2 gap-3 rounded-lg border p-3 text-sm">
            <div>
              <p className="text-muted-foreground">Class</p>
              <p className="font-medium">{event.session.facilityClassName ?? event.session.facilityName ?? "—"}</p>
            </div>
            <div>
              <p className="text-muted-foreground">Status</p>
              <StatusBadge status={event.session.isCancelled ? "neutral" : "success"}>
                {event.session.isCancelled ? "Not held" : "Scheduled"}
              </StatusBadge>
            </div>
            <div>
              <p className="text-muted-foreground">Booked</p>
              <p className="font-medium">
                {event.session.bookedCount}
                {!event.session.isUnlimitedCapacity && ` / ${event.session.capacity}`}
              </p>
            </div>
            {event.session.isCancelled && event.session.notHeldReason && (
              <div className="col-span-2">
                <p className="text-muted-foreground">Reason</p>
                <p className="font-medium">{event.session.notHeldReason}</p>
              </div>
            )}
          </div>
        )}
      </DialogContent>
    </Dialog>
  )
}

interface BookingCalendarProps {
  /** Fired when the user drags a time range in day/week view -- the parent switches to Book Now
   * and pre-fills the dragged time. */
  onQuickBook?: (draft: { startTime: string; endTime: string }) => void
}

/** Calendar view of bookings and class occurrences -- one merged view, no per-facility split;
 * the facility is still chosen in Book Now, same as today. Refetches both for whatever range
 * FullCalendar currently has visible. */
function BookingCalendar({ onQuickBook }: BookingCalendarProps) {
  const [events, setEvents] = React.useState<EventInput[]>([])
  const [loading, setLoading] = React.useState(false)
  const [error, setError] = React.useState<string | null>(null)
  const [viewType, setViewType] = React.useState("dayGridMonth")
  const [selectedEvent, setSelectedEvent] = React.useState<SelectedEvent>(null)

  async function handleDatesSet(arg: DatesSetArg) {
    setViewType(arg.view.type)
    setLoading(true)
    setError(null)
    try {
      const [bookings, sessions] = await Promise.all([
        getBookings({
          fromDate: arg.start.toISOString(),
          toDate: arg.end.toISOString(),
        }),
        getFacilitySessions({
          fromDate: arg.start.toISOString(),
          toDate: arg.end.toISOString(),
          includeCancelled: true,
        }),
      ])
      setEvents([...bookings.map(bookingToEvent), ...sessions.map(sessionToEvent)])
    } catch (err) {
      setError(err instanceof ApiError ? err.message : "Couldn't load the calendar for this range.")
    } finally {
      setLoading(false)
    }
  }

  function handleEventClick(arg: EventClickArg) {
    const props = arg.event.extendedProps as { kind: "booking"; booking: Booking } | { kind: "session"; session: FacilitySession }
    setSelectedEvent(props)
  }

  function handleSelect(arg: DateSelectArg) {
    onQuickBook?.({ startTime: arg.start.toISOString(), endTime: arg.end.toISOString() })
  }

  return (
    <div className="rounded-lg border p-3">
      <div className="mb-3 flex flex-wrap items-center gap-3 text-xs text-muted-foreground">
        {loading && <span>Loading…</span>}
        {error && <span className="text-destructive">{error}</span>}
        {(Object.keys(STATUS_COLORS) as BookingStatus[]).map((status) => (
          <span key={status} className="flex items-center gap-1.5">
            <span className="inline-block size-2.5 rounded-full" style={{ backgroundColor: STATUS_COLORS[status] }} />
            {status}
          </span>
        ))}
        <span className="flex items-center gap-1.5">
          <span className="inline-block size-2.5 rounded-full" style={{ backgroundColor: SESSION_COLOR }} />
          Class
        </span>
        <span className="flex items-center gap-1.5">
          <span className="inline-block size-2.5 rounded-full border border-dashed" style={{ borderColor: NOT_HELD_COLOR }} />
          Not held — open
        </span>
        <span className="ml-auto">Drag a time range in Day/Week view to start a booking.</span>
      </div>
      <FullCalendar
        plugins={[dayGridPlugin, timeGridPlugin, interactionPlugin]}
        initialView="dayGridMonth"
        headerToolbar={{ left: "prev,next today", center: "title", right: "timeGridDay,timeGridWeek,dayGridMonth" }}
        height="auto"
        nowIndicator
        events={events}
        datesSet={handleDatesSet}
        eventDisplay="block"
        eventClick={handleEventClick}
        selectable={viewType !== "dayGridMonth"}
        selectMirror
        snapDuration="00:15:00"
        select={handleSelect}
      />
      <EventDetailDialog event={selectedEvent} onOpenChange={(open) => !open && setSelectedEvent(null)} />
    </div>
  )
}

export { BookingCalendar }