"use client";

import { useCallback, useRef, useState } from "react";
import { useRouter } from "next/navigation";
import { AnimatePresence, motion } from "framer-motion";
import { Bell, X } from "lucide-react";
import { useTicketEvents } from "@/lib/events/use-ticket-events";
import { isTicketVisibleTo } from "@/lib/tickets/visibility";

interface Toast {
  id: string;
  title: string;
  body: string;
  href: string;
}

// A single, reused AudioContext. Two separate browser behaviors fight it:
// (1) autoplay policy — a context created/resumed outside a real user
// gesture starts "suspended" and stays silent; (2) power-saving
// auto-suspend — Chrome can suspend an already-unlocked context again
// after a stretch of no audio activity, independent of (1). Neither fails
// loudly: start()/stop() never throw, the chime just doesn't sound.
// Fix: keep the unlock listeners attached for the whole session (not just
// the first click) so any later click also re-resumes a context the
// browser suspended for power-saving, and actually await resume() before
// scheduling a chime instead of assuming it completes synchronously.
let sharedAudioContext: AudioContext | null = null;

function getAudioContext(): AudioContext | null {
  if (typeof window === "undefined") return null;
  const AudioCtor = window.AudioContext ?? (window as unknown as { webkitAudioContext?: typeof AudioContext }).webkitAudioContext;
  if (!AudioCtor) return null;
  if (!sharedAudioContext) sharedAudioContext = new AudioCtor();
  return sharedAudioContext;
}

if (typeof window !== "undefined") {
  const unlockAudio = () => {
    const ctx = getAudioContext();
    if (ctx?.state === "suspended") ctx.resume();
  };
  window.addEventListener("pointerdown", unlockAudio);
  window.addEventListener("keydown", unlockAudio);
}

/** A short two-tone chime via the Web Audio API — no audio asset needed. */
async function playChime() {
  const ctx = getAudioContext();
  if (!ctx) return;
  try {
    if (ctx.state === "suspended") await ctx.resume();
    if (ctx.state !== "running") return; // still not unlocked by a user gesture yet — nothing to do

    const now = ctx.currentTime;
    for (const [freq, start] of [[880, 0], [1175, 0.12]] as const) {
      const osc = ctx.createOscillator();
      const gain = ctx.createGain();
      osc.type = "sine";
      osc.frequency.value = freq;
      gain.gain.setValueAtTime(0.0001, now + start);
      gain.gain.exponentialRampToValueAtTime(0.25, now + start + 0.01);
      gain.gain.exponentialRampToValueAtTime(0.0001, now + start + 0.25);
      osc.connect(gain);
      gain.connect(ctx.destination);
      osc.start(now + start);
      osc.stop(now + start + 0.25);
    }
  } catch {
    // audio isn't critical to the notification — a silent toast still works
  }
}

/**
 * In-page toast + sound for new tickets and customer messages, shown
 * regardless of tab focus. Complements DesktopNotifications, which only
 * fires the native OS notification while the tab is in the background —
 * this is the "still on the page" case.
 */
export function TicketToasts({ currentUser }: { currentUser: { id: string; role: "admin" | "agent" } }) {
  const router = useRouter();
  const [toasts, setToasts] = useState<Toast[]>([]);
  const idCounter = useRef(0);

  const pushToast = useCallback((title: string, body: string, href: string) => {
    const id = `${Date.now()}-${idCounter.current++}`;
    setToasts((prev) => [...prev, { id, title, body, href }]);
    void playChime();
    setTimeout(() => setToasts((prev) => prev.filter((t) => t.id !== id)), 6_000);
  }, []);

  useTicketEvents("/api/events", (event) => {
    if (event.type === "ticket.created") {
      if (!isTicketVisibleTo(event.ticket, currentUser)) return;
      pushToast("Новая заявка", event.ticket.subject, `/tickets/${event.ticket.id}`);
    } else if (event.type === "message.created" && event.message.authorType === "customer" && !event.ticketIsNew) {
      if (!isTicketVisibleTo({ assigneeId: event.assigneeId }, currentUser)) return;
      pushToast(`Сообщение от ${event.message.authorName}`, event.message.body.slice(0, 120), `/tickets/${event.ticketId}`);
    }
  });

  function dismiss(id: string) {
    setToasts((prev) => prev.filter((t) => t.id !== id));
  }

  return (
    <div className="pointer-events-none fixed bottom-4 right-4 z-50 flex w-full max-w-sm flex-col gap-2">
      <AnimatePresence initial={false}>
        {toasts.map((toast) => (
          <motion.div
            key={toast.id}
            initial={{ opacity: 0, y: 12, scale: 0.96 }}
            animate={{ opacity: 1, y: 0, scale: 1 }}
            exit={{ opacity: 0, scale: 0.96 }}
            transition={{ duration: 0.15 }}
            className="card pointer-events-auto flex items-start gap-2 p-3 shadow-md"
          >
            <span className="mt-0.5 flex h-6 w-6 shrink-0 items-center justify-center rounded-full bg-accent-soft text-accent-soft-text">
              <Bell size={13} />
            </span>
            <button
              onClick={() => {
                dismiss(toast.id);
                router.push(toast.href);
              }}
              className="min-w-0 flex-1 text-left"
            >
              <p className="truncate text-sm font-medium">{toast.title}</p>
              <p className="line-clamp-2 text-xs text-text-muted">{toast.body}</p>
            </button>
            <button onClick={() => dismiss(toast.id)} className="text-text-faint hover:text-text" aria-label="Закрыть">
              <X size={13} />
            </button>
          </motion.div>
        ))}
      </AnimatePresence>
    </div>
  );
}