"use client";

import { useEffect, useState } from "react";
import { MonthCalendar, type CalendarMarker } from "./MonthCalendar";
import { ResendVerificationButton } from "@/components/auth/ResendVerificationButton";
import { TextAreaField, FormError } from "@/components/FormField";
import { track } from "@/lib/analytics/client";
import { berlinDateKey, formatBerlinDate, formatBerlinTime } from "@/lib/calendar/timezone";

type SlotsResponse = { durationMinutes: number; slots: Record<string, { start: string; end: string }[]> };

function dateKey(d: Date) {
  return berlinDateKey(d);
}

const fmtTime = (iso: string) => formatBerlinTime(new Date(iso), { hour: "2-digit", minute: "2-digit" });
const fmtDate = (iso: string) => formatBerlinDate(new Date(iso), { weekday: "long", day: "2-digit", month: "long" });

export function BookingWidget({
  offerSlug,
  isLoggedIn,
  isVerified,
}: {
  offerSlug: string;
  isLoggedIn: boolean;
  isVerified: boolean;
}) {
  const [slotsByDay, setSlotsByDay] = useState<SlotsResponse["slots"]>({});
  const [loading, setLoading] = useState(true);
  const [loadError, setLoadError] = useState(false);
  const [selectedDay, setSelectedDay] = useState<Date | null>(null);
  const [selectedSlot, setSelectedSlot] = useState<string | null>(null);
  const [appointmentType, setAppointmentType] = useState<"onsite" | "online">("onsite");
  const [message, setMessage] = useState("");
  const [submitting, setSubmitting] = useState(false);
  const [result, setResult] = useState<{ ok: boolean; error?: string } | null>(null);

  useEffect(() => {
    const controller = new AbortController();
    const from = new Date();
    const to = new Date(from.getTime() + 28 * 24 * 60 * 60 * 1000);
    fetch(`/api/booking/slots?offer=${encodeURIComponent(offerSlug)}&from=${dateKey(from)}&to=${dateKey(to)}`, { signal: controller.signal })
      .then((res) => { if (!res.ok) throw new Error("Slots unavailable"); return res.json(); })
      .then((data: SlotsResponse) => setSlotsByDay(data.slots ?? {}))
      .catch(() => { if (!controller.signal.aborted) setLoadError(true); })
      .finally(() => { if (!controller.signal.aborted) setLoading(false); });
    return () => controller.abort();
  }, [offerSlug]);

  if (result?.ok) {
    return (
      <div className="rounded-3xl bg-anouma-cream-light p-8">
        <p className="text-xs font-medium uppercase tracking-wide text-anouma-dustyrose">Deine Anfrage</p>
        {selectedSlot && (
          <p className="mt-2 font-serif text-2xl font-medium text-anouma-plum">
            {fmtDate(selectedSlot)}, {fmtTime(selectedSlot)} Uhr
          </p>
        )}
        <p className="mt-4 text-sm font-medium text-anouma-plum">Status: Termin vorgeschlagen</p>
        <p className="mt-3 text-sm leading-relaxed text-anouma-plum">
          Der Termin ist noch nicht verbindlich. Du erhältst eine E-Mail, sobald Anna den Termin bestätigt.
        </p>
      </div>
    );
  }

  if (!isLoggedIn) {
    return (
      <div className="rounded-3xl bg-anouma-cream-light p-8 text-center">
        <p className="text-base text-anouma-plum">
          Melde dich an oder erstelle ein Konto, um einen Termin anzufragen.
        </p>
        <div className="mt-5 flex flex-wrap justify-center gap-3">
          <a
            href={`/login?next=/angebote/${offerSlug}`}
            className="rounded-full bg-anouma-mauve-dark px-6 py-2.5 text-sm font-medium text-white hover:bg-anouma-plum"
          >
            Anmelden
          </a>
          <a
            href="/registrieren"
            className="rounded-full border border-anouma-mauve-dark/40 px-6 py-2.5 text-sm font-medium text-anouma-plum hover:bg-white"
          >
            Konto erstellen
          </a>
        </div>
      </div>
    );
  }

  if (!isVerified) {
    return (
      <div className="rounded-3xl bg-anouma-cream-light p-8 text-center">
        <p className="text-base text-anouma-plum">Bitte bestätige zuerst deine E-Mail-Adresse.</p>
        <p className="mt-2 text-sm text-anouma-plum/70">Erst danach kannst du einen Termin anfragen.</p>
        <ResendVerificationButton variant="session" className="mt-5 flex justify-center" />
      </div>
    );
  }

  const markers: CalendarMarker[] = Object.keys(slotsByDay).map((key) => ({ date: new Date(key), status: "public" }));
  const daySlots = selectedDay ? (slotsByDay[dateKey(selectedDay)] ?? []) : [];

  async function submit() {
    if (!selectedSlot) return;
    setSubmitting(true);
    setResult(null);
    try {
      const res = await fetch("/api/booking/request", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        credentials: "include",
        body: JSON.stringify({ offerSlug, start: selectedSlot, appointmentType, message }),
      });
      const data = await res.json().catch(() => ({}));
      if (!res.ok) {
        setResult({ ok: false, error: data.error || "Anfrage fehlgeschlagen." });
        setSubmitting(false);
        return;
      }
      setResult({ ok: true });
      // Event only — never the offer/date/message content.
      track("booking_started");
    } catch {
      setResult({ ok: false, error: "Verbindung fehlgeschlagen." });
      setSubmitting(false);
    }
  }

  if (loading) {
    return <p className="text-sm text-anouma-plum/70">Verfügbare Termine werden geladen …</p>;
  }
  if (loadError) return <FormError>Verfügbare Termine konnten nicht geladen werden. Bitte lade die Seite erneut.</FormError>;

  return (
    <div className="space-y-6">
      <div className="grid gap-6 lg:grid-cols-[minmax(0,340px)_1fr]">
        <MonthCalendar markers={markers} onSelectDay={(day) => { setSelectedDay(day); setSelectedSlot(null); }} selectedDay={selectedDay} />
        <div>
          {!selectedDay && <p className="text-sm text-anouma-plum/70">Wähle einen markierten Tag, um freie Zeiten zu sehen.</p>}
          {selectedDay && daySlots.length === 0 && (
            <p className="text-sm text-anouma-plum/70">An diesem Tag ist leider kein Termin frei.</p>
          )}
          {selectedDay && daySlots.length > 0 && (
            <div>
              <p className="text-sm font-medium text-anouma-plum">{fmtDate(daySlots[0].start)}</p>
              <div className="mt-3 flex flex-wrap gap-2">
                {daySlots.map((slot) => (
                  <button
                    key={slot.start}
                    type="button"
                    onClick={() => setSelectedSlot(slot.start)}
                    className={`inline-flex min-h-11 items-center justify-center rounded-full border px-4 text-sm font-medium transition-colors ${
                      selectedSlot === slot.start
                        ? "border-anouma-mauve-dark bg-anouma-mauve-dark text-white"
                        : "border-anouma-taupe/40 text-anouma-plum hover:border-anouma-mauve-dark"
                    }`}
                  >
                    {fmtTime(slot.start)}
                  </button>
                ))}
              </div>
            </div>
          )}
        </div>
      </div>

      {selectedSlot && (
        <div className="rounded-3xl bg-anouma-cream-light p-6">
          <p className="text-sm font-medium text-anouma-plum">
            Ausgewählt: {fmtDate(selectedSlot)}, {fmtTime(selectedSlot)} Uhr
          </p>

          <fieldset className="mt-4">
            <legend className="text-sm font-medium text-anouma-plum">Terminart</legend>
            <div className="mt-2 flex gap-4">
              <label className="flex items-center gap-2 text-sm text-anouma-plum">
                <input
                  type="radio"
                  name="appointmentType"
                  checked={appointmentType === "onsite"}
                  onChange={() => setAppointmentType("onsite")}
                />
                Vor Ort
              </label>
              <label className="flex items-center gap-2 text-sm text-anouma-plum">
                <input
                  type="radio"
                  name="appointmentType"
                  checked={appointmentType === "online"}
                  onChange={() => setAppointmentType("online")}
                />
                Online
              </label>
            </div>
          </fieldset>

          <TextAreaField
            label="Nachricht (optional)"
            id="booking-message"
            value={message}
            onChange={(e) => setMessage(e.target.value)}
            rows={3}
            wrapperClassName="mt-4"
          />

          {result?.error && <FormError className="mt-3">{result.error}</FormError>}

          <button
            type="button"
            onClick={submit}
            disabled={submitting}
            className="mt-5 rounded-full bg-anouma-mauve-dark px-7 py-3 text-sm font-medium text-white hover:bg-anouma-plum disabled:opacity-60"
          >
            {submitting ? "Wird gesendet …" : "Terminanfrage senden"}
          </button>
        </div>
      )}
    </div>
  );
}